Windward Bio Group based in Switzerland

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This Amendment No. 3 to the draft registration statement has not been filed publicly with the U.S. Securities and

Exchange Commission and all information contained herein remains confidential.

As confidentially submitted to filed with the U.S. Securities and Exchange Commission on October 13, 23, 2026.

Registration Statement No. 333-

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Presentation of financial information 2 changes

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We have made rounding adjustments to some of the figures included in this prospectus.

We have made rounding adjustments to some of the figures included in this prospectus. Accordingly, numerical figures shown as totals in some tables may not be an arithmetic aggregation of the figures that preceded them.

Prospectus summary 18 changes

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WIN027 is an ultra-long-acting bispecific antibody that simultaneously targets TSLP and interleukin-13, or IL-13, two clinically validated drivers of inflammatory disease. We believe that dual inhibition of these pathways has the potential to deliver deeper and more durable disease control than targeting either pathway alone. WIN027 is currently in a Phase 1 healthy volunteer study with investigational new drug applications, or INDs, open in the United States, Australia and the People's Republic of China, or the PRC, assessing safety and pharmacokinetics. In an interim analysis of the Phase 1 study, we observed a 62-day half-life, low immunogenicity and low rate of injection site reactions, with full pharmacokinetic and immunogenicity data expected in the first half of 2027. We initiated study start-up activities in September 2026 in a global Phase 2b study in COPD fully powered on the registrational endpoint of exacerbation rate ratio and a second global Phase 2 study in atopic dermatitis, which are planned to begin patient recruitment in the first half of 2027. Our partner Qyuns Therapeutics Co., Ltd., or Qyuns, initiated their Phase 2 studies in atopic dermatitis and chronic rhinosinusitis with nasal polyps, or CRSwNP, in September 2026 in the PRC and plans to begin a Phase 2 study in asthma by the end of the year. Topline results from these studies are expected over the course of 2027 and 2028.

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WIN378 is currently being evaluated

Windward Bio holds global rights to WIN378 excluding Greater China and certain Asian markets ** Exclusivity based on pending applications and anticipated patent extensions *** Asthma and CRSwNP Phase 2 These studies are planned in the PRC only, conducted and funded by Qyuns Therapeutics; see "—WIN027" on page 5 for more information **** Lead optimization stage with potential in respiratory and dermatology; see "—Additional bispecific programs" on page 5 for more information IP=intellectual property, mAb=monoclonal antibody WIN378 is an ultra-long-acting and potentially novel fully human monoclonal antibody that is designed to inhibit the TSLP ligand. WIN378 has been engineered to achieve half-life extension and silenced effector function. In nonclinical studies, WIN378 has been observed to have greater potency than the currently approved anti-TSLP treatment, has two binding sites to TSLP and fully overlaps the same binding site as Tezspire , tezepelumab. WIN378 has been studied in a Phase 1 trial, which evaluated an extended half-life that we believe may support twice-yearly dosing, demonstrated a low rate of antidrug antibodies, and was well tolerated up to the highest dose tested.

WIN378 is currently being evaluated in POLARIS-1, a Phase 2/3 study in severe, uncontrolled asthma. A pre-planned interim analysis from the Phase 2 portion of the study was completed in the second half of 2026. Following dose selection based on the interim analysis, we initiated the Phase 3 portion of POLARIS-1 in September 2026, with topline results expected in the second first half of 2028. 2029. Study start-up activities were initiated in September 2026 for a second Phase 3 study (POLARIS-2), which is planned to begin patient recruitment in the first half of 2027 with topline results expected in the second first half of 2029. Separately, a Phase 2 study of WIN378 in COPD, SIRIUS, was initiated in June 2026 and we expect topline results in the second half of 2027. We have observed the following results in the Phase 1 clinical trial for WIN378: an extended half-life supporting twice-yearly subcutaneous dosing, a low rate of antidrug antibodies, and no treatment-related serious adverse events were observed. The pre-planned interim analysis of the Phase 2 portion of POLARIS-1 demonstrated the following results:

Separately, a Phase 2 study of WIN378 in COPD, SIRIUS, was initiated in June 2026 and we expect topline results in the second half of 2027. We have observed the following results in the Phase 1 clinical trial for WIN378: an extended half-life supporting twice-yearly subcutaneous dosing, a low rate of antidrug antibodies, and no treatment-related serious adverse events were observed. The pre-planned interim analysis of the Phase 2 portion of POLARIS-1 demonstrated the following results:

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Significant and sustained effects on FEV1 (up to 174 mL mean increase, placebo-adjusted mean increases up to 256 267 mL, p=0.033), FeNO and blood eosinophils, key biomarkers that correlate with asthma exacerbations. These effects were rapid and sustained through Week 24 after a single dose of WIN378.

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WIN027 is currently in a Phase 1 healthy volunteer study with INDs open in the United States, Australia and the PRC assessing safety and pharmacokinetics. Based on blinded interim data as of June 2026, we have observed a 62-day half-life, low immunogenicity and low rate of injection site reactions, with full pharmacokinetic and immunogenicity data expected in the first half of 2027. We initiated study start-up activities in September 2026 for a global Phase 2b study in COPD, fully powered on the registrational endpoint of exacerbation rate ratio, as well as a global Phase 2 study in atopic dermatitis, which are planned to begin patient recruitment in the first half of 2027.

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AD=atopic dermatitis, COPD=chronic obstructive pulmonary disease, HV=healthy volunteer, TLR=topline results, W=week; remaining studies, not funded by the expected IPO proceeds, are already funded Additional bispecific programs are in the lead optimization phase. The current program is a next-generation bispecific targeting T2 and non-T2 pathways, with two complementary cytokines. Work to date has included the evaluation of various formats, production at small scale, and the evaluation of productivity, purity and light chain mispairing. Further work has characterized the blocking of both cytokines and a HELA cell-based potency assay has been developed and used to compare the bispecifics' potencies to monospecific benchmarks. Of the three formats evaluated, a lead nonclinical target format has been identified and selected, with potential across skin and respiratory indications, including atopic dermatitis, asthma, COPD and other inflammatory and fibrotic skin and lung diseases. We expect to initiate Phase 1 clinical development for these potential skin and respiratory indications in the next 18 months, subject to standard regulatory requirements. The lead format demonstrating benchmark-comparable affinity, cellular potency and manufacturability is currently being engineered for half-life extension prior to characterization in nonhuman primate studies.

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We have taken advantage of certain reduced reporting

We have taken advantage of certain reduced reporting requirements in this prospectus. Accordingly, the information contained herein may be different than the information you receive from other public companies in which you hold equity securities registered under the Exchange Act. As an emerging growth company we can also delay adopting new or revised financial accounting standards until such time as those standards apply to private companies. We may take advantage of this extended transition period under the JOBS Act for adopting new or revised financial accounting standards.

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Accordingly, there may be less publicly available information concerning our company than there is for U.S. public companies.

In addition, foreign private issuers

Our status as a foreign private issuer also exempts us from compliance with certain laws and regulations of the SEC and certain regulations of the Nasdaq Global Market, or Nasdaq. Consequently, we are not subject to all of the disclosure requirements applicable to U.S. public companies. For example, we are exempt from certain rules under the Exchange Act that regulate disclosure obligations and procedural requirements related to the solicitation of proxies, consents or authorizations applicable to a security registered under the Exchange Act. Our executive officers, directors and principal shareholders are also exempt from the "short-swing" profit recovery provisions of Section 16(b) of the Exchange Act. Moreover, we are not required to file periodic reports and financial statements with the SEC as frequently or as promptly as U.S. public companies. Accordingly, there may be less publicly available information concerning our company than there is for U.S. public companies.

In addition, foreign private issuers are not required to file their annual report on Form 20-F until four months after the end of each fiscal year, while U.S. domestic issuers that are accelerated filers are required to file their annual report on Form 10-K within 75 days after the end of each fiscal year. Foreign private issuers are also exempt from the Regulation Fair Disclosure, aimed at preventing issuers from making selective disclosures of material information. Additionally, Nasdaq rules allow foreign private issuers to follow home country practices in lieu of certain of Nasdaq corporate governance rules. As a result, our shareholders may not have the same protections afforded to shareholders of companies that are subject to all Nasdaq corporate governance requirements.

Foreign private issuers are also exempt from the Regulation Fair Disclosure, aimed at preventing issuers from making selective disclosures of material information. Additionally, Nasdaq rules allow foreign private issuers to follow home country practices in lieu of certain of Nasdaq corporate governance rules. As a result, our shareholders may not have the same protections afforded to shareholders of companies that are subject to all Nasdaq corporate governance requirements.

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Approximately $ million to fund the advancement of our bispecific programs through the completion of IND-enabling studies; and ∎ The remainder for working capital and general corporate purposes, including personnel costs, facilities, and other operational expenses.

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no issuance or exercise of outstanding options or settlement of outstanding restricted share units after June 30, the settlement conversion of all of our 397,495 53,429,037 outstanding Series B Warrants for preferred shares into the same number of common shares at the same nominal value immediately prior to the completion of this offering, (based on a cashless exercise), or the Series B Warrant Settlement; Preferred Share Conversion;

the settlement of all of our 397,495 outstanding Series B Warrants for common shares immediately prior to the completion of this offering (based on a cashless exercise), or the Series B Warrant Settlement;

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Risk factors 89 changes

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Risks Related to Our Limited Operating History, Financial

History, Financial Condition and Need for Additional Capital

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We are a clinical-stage biopharmaceutical company with

We are a clinical-stage biopharmaceutical company with a limited operating history. We were formed in July 2024 and began operations in January 2025 and our operations to date have been limited to pre-commercial activities. We have not yet demonstrated an ability to generate revenues, obtain regulatory approvals, manufacture any product on a commercial scale or arrange for a third party to do so on our behalf or conduct sales and marketing activities necessary for successful product commercialization. Our limited operating history as a company makes any assessment of our future success and viability subject to significant uncertainty. We will encounter risks and difficulties frequently experienced by early-stage biopharmaceutical companies in rapidly evolving fields, and we have not yet demonstrated an ability to successfully overcome such risks and difficulties. If we do not address these risks and difficulties successfully, our business will suffer.

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We anticipate that our expenses will increase

increase substantially if, and as, we:

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marketable securities in the amount of $207.3 million. Based upon our current operating plan, we believe that the net proceeds from this offering together with our existing cash, cash equivalents and marketable securities will enable us to fund the completion of our ongoing POLARIS-1, our ongoing Phase 2/3 trial and our confirmatory POLARIS-2 Phase 3 trial of WIN378 in asthma, fund the completion of our planned global Phase 2b trial of WIN027 in COPD, planned global Phase 2 trial of WIN027 in atopic dermatitis, the advancement of our bispecific programs through the completion of IND-enabling studies, and our operating expenses and capital expenditure requirements through . We have based this estimate on assumptions that may prove to be wrong, and we could expend our available capital resources sooner than we expect. We may also raise additional financing on an opportunistic basis in the future. For example, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans.

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addition, our assumptions about the development potential of WIN378 are substantially based on the data generated from nonclinical and clinical studies, including the Phase 1 clinical data, conducted by Kelun and HBM pursuant to the Kelun-HBM Agreement. In contrast, our assumptions about the development potential of WIN027 are based more substantially on nonclinical and early clinical data generated by Qyuns prior to the Qyuns Agreement, as our own clinical development program for WIN027 remains at an earlier stage. We are dependent on Kelun and Qyuns having conducted their research and development in accordance with the applicable protocols, informed consent, legal and regulatory requirements, and scientific standards; having accurately reported the results of all nonclinical and clinical studies conducted with respect to WIN378 and WIN027 and having correctly collected the data and regulatory materials from these studies.

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If we are unable to advance WIN378 and/or

and/or WIN027 in clinical development for one or more of the indications that we are pursuing, or to obtain regulatory approval and ultimately commercialize WIN378 and/or WIN027, or experience significant delays in doing so, our business will be materially harmed.

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Kelun-HBM Agreement and the Qyuns Agreement, we are obligated to make significant payments to our licensors across the full development and commercialization lifecycle of WIN378 and WIN027. Under the Kelun-HBM Agreement, we may be required to pay Kelun and HBM aggregate development milestone payments of up to $320.0 million (excluding the $10.0 million milestone payments already paid in 2025 and July 2026 in total) for WIN378, aggregate sales milestone payments of up to $600 million per product upon achievement of specified annual net sales thresholds, and low single-digit to low double-digits tiered royalties (a spread of not more than 5 percentage points) on net sales of WIN378 in our licensed worldwide territory (excluding Greater China and several Southeast and West Asian countries). In addition, under the Kelun-HBM Agreement, following the completion of this offering, we may elect, subject to certain conditions, to satisfy up to 50% of the remaining of each of our first seven development milestone payments, which is up to $73.75 million, payable under the Kelun-HBM Agreement by issuing our common shares, rather than in cash; provided that each of Kelun and HBM may not hold, in the aggregate, 20% or more of our outstanding share capital on a fully diluted basis as a result of such equity issuance. Any such issuance of common shares in satisfaction of milestone payments would dilute the ownership interests of our existing shareholders. Under the Qyuns Agreement, we may be required to pay Qyuns aggregate development milestone payments of up to $100 million for WIN027, aggregate sales milestone payments of up to $570 million upon achievement of specified annual net sales thresholds, and mid-single digit to high-single digit tiered royalties on net sales of WIN027 in our licensed worldwide territory (excluding Greater China).

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In addition, we may be unable

Outside the United States, an increasing number of

of laws, regulations, and industry standards govern privacy, data security, and the transfer of personal data between jurisdictions. For example, the European Union's General Data Protection Regulation, or EU GDPR, the United Kingdom's General Data Protection Regulation, or UK GDPR (together with the EU GDPR, the GDPR), and the Swiss Federal Act on Data Protection impose strict requirements for collecting and processing personal data including relating to collecting and processing of sensitive data (referred to as special category data under GDPR), such as health data, ensuring there is a legal basis or condition to justify the processing of personal data, where required, requirements relating to obtaining consent of individuals, disclosures about how personal data is to be used, limitations on retention of information, limitations on the cross- border cross-border disclosure of personal data, implementing safeguards to protect the security and confidentiality of personal data, where required providing notification of data breaches, maintaining records of processing activities and documenting data protection impact assessments where there is high risk processing and taking certain measures when engaging third-party processors. Under GDPR, companies may face temporary or definitive bans on data processing and other corrective activities, fines of up to € 20 million under the EU GDPR (and 17.5 million under the UK GDPR) or 4% of annual global turnover, whichever is greater, and private litigation related to processing of personal data brought by classes of data subjects or consumer protection organizations authorized at law to represent their interests. Additionally, in the European Union, the Network and Information Security Directive, or NIS2, regulates resilience and incident response capabilities of entities operating in a number of sectors, including the health sector. Non-compliance with NIS2 may, similar to non-compliance with other privacy or security laws, lead to adverse consequences, including a material adverse effect on our business, financial position and results of operations.

Additionally, we may receive personal data collected and processed by our business partners in the PRC. The PRC enacted the Personal Information Protection Law, or the PIPL, in 2021. The PIPL establishes a comprehensive data privacy and protection framework that applies to the processing of personal information both within the PRC and outside of the PRC where such processing is conducted for the purpose of providing products or services to, or analyzing or evaluating the behavior of, individuals in the PRC. The PIPL imposes significant fines for serious violations of up to RMB 50 million or 5% of annual revenue from the prior year. Certain industry-specific Chinese laws and regulations also impose requirements for processing of certain specific types of data. The PRC's Regulations on the Administration of Human Genetic Resources, or the HGR Regulation, prohibit foreign organizations, individuals, and entities established or actually controlled by them from collecting, preserving, or exporting the PRC's human genetic resources. Foreign parties may access or use the PRC's human genetic resources upon satisfying applicable regulatory requirements, including through approved international collaboration with qualified Chinese institutions and completing required governmental approval, filing, and information backup procedures. In addition, provision of human genetic resources information to foreign entities requires filing with the PRC's National Health Commission and submission of information backup, and transfers that may affect public health, national security or social public interest must pass a security review. We may need to provide necessary assistance for our Chinese business partners to comply with their obligations under Chinese privacy and data security laws and regulations, and our data processing activities may be subject to obligations applicable to the recipient of personal data collected or generated in the PRC.

Foreign parties may access or use the PRC's human genetic resources upon satisfying applicable regulatory requirements, including through approved international collaboration with qualified Chinese institutions and completing required governmental approval, filing, and information backup procedures. In addition, provision of human genetic resources information to foreign entities requires filing with the PRC's National Health Commission and submission of information backup, and transfers that may affect public health, national security or social public interest must pass a security review. We may need to provide necessary assistance for our Chinese business partners to comply with their obligations under Chinese privacy and data security laws and regulations, and our data processing activities may be subject to obligations applicable to the recipient of personal data collected or generated in the PRC.

In addition, we may be unable to transfer personal data from the PRC, the European Union / European Economic Area (EU 27 Member States, Norway, Iceland and Liechtenstein), or EEA, the United Kingdom, or UK, and other jurisdictions to the United States or other countries due to data localization requirements or restrictions on cross-border data flows. In particular, the European Union, the United Kingdom and Switzerland have significantly restricted the transfer of personal data to the United States and other countries whose privacy laws the European Commission, UK Secretary of State or Swiss Federal Council (as applicable) generally regard as inadequate. There are also restrictions on personal data exports from the PRC—under the PIPL, entities exporting personal data are required to meet certain conditions, including, to the extent applicable, satisfaction of the security assessments conducted by competent government authorities, signing and filing of standard contracts or obtaining certifications from qualified institutions (unless an exemption applies), and fulfillment of notice and consent requirements. Data qualifying as "important data" must also be localized in the PRC unless a security assessment is passed. Other jurisdictions may equally adopt or have already adopted similarly stringent data localization and cross-border data transfer laws. Although there are currently various mechanisms that may be used to transfer personal data from the EU/EEA, the United Kingdom and Switzerland to the United States in compliance with law, such as the EU standard contractual clauses, which are also recognized by Switzerland, the United Kingdom's International Data Transfer Agreement / Addendum, the EU-U.S. Data Privacy Framework, the UK extension thereto (which allows for transfers to relevant U.S.-based organizations who self-certify compliance and participate in the EU-U.S. Data Privacy Framework) and the Swiss-U.S. Data Privacy Framework, or Framework, these mechanisms are subject to legal challenges, and there is no assurance that we can satisfy or rely on these measures to lawfully transfer personal data to the United States. If there is no lawful manner for us to transfer personal data from the PRC, the EU/EEA, the United Kingdom, Switzerland, or other jurisdictions to the United States (or other countries), or if the requirements for a legally-compliant transfer are too onerous, we could face significant adverse consequences, including the interruption or degradation of our operations, the need to relocate part of or all of our business or data processing activities to other jurisdictions at significant expense, increased exposure to regulatory actions, substantial fines and penalties, the inability to transfer data and work with collaborators, vendors and other third parties, and injunctions against our processing or transferring of personal data necessary to operate our business. Additionally, companies that transfer personal data across national borders are subject to increased scrutiny from regulators, individual litigants, and activist groups. For example, some European regulators have ordered certain companies to suspend or permanently cease certain transfers of personal data out of the EU for allegedly violating the GDPR's cross-border data transfer limitations.

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There can be no assurance that any of our clinical trials will ultimately be successful or support further clinical development of WIN378, WIN027, or any other potential future product candidates. There is a high failure rate for drugs proceeding through clinical trials. Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in early-stage development, and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, adverse safety or efficacy observations made in clinical trials. For example, we expect to report initial readouts from our POLARIS-1 Phase 3 study evaluating WIN378 in patients with asthma in the second first half of 2028. 2029. These readouts may not be positive, may not meet the trial's pre-specified endpoints, or may not support the continuation of WIN378's development in asthma or other indications, any of which would have a material adverse effect on our business.

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Our failure to successfully initiate and

In addition, clinical investigators may serve as scientific advisors or consultants to us from time to time and may receive cash compensation in connection with such services. If these relationships and any related compensation result in perceived or actual conflicts of interest or the FDA concludes that the financial relationship may have affected the interpretation of the nonclinical study or clinical trial, the integrity of the data generated at the applicable nonclinical study or clinical trial site may be questioned and the utility of the nonclinical study or clinical trial itself may be jeopardized, which could result in the delay or rejection by the FDA. Any such delay or rejection could prevent us from commercializing our product candidates, if approved.

Our failure to successfully initiate and complete clinical trials and to demonstrate the efficacy and safety necessary to obtain regulatory approval to market WIN378, WIN027 or any other potential future product candidates would also significantly harm our business. Our development costs will also increase if we experience delays in testing or regulatory approvals and we may be required to obtain additional funds to complete clinical trials. We cannot assure you that our clinical trials will begin as planned or be completed on schedule, if at all, or that we will not need to restructure or otherwise modify our trials after they have begun. Significant clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize WIN378, WIN027 or any other potential future product candidates or allow our competitors to bring products to market before we do and impair our ability to successfully commercialize WIN378, WIN027 or any other potential future product candidates, which may harm our business, financial condition, results of operations and growth prospects. In addition, many of the factors that cause, or lead to, delays of clinical trials may ultimately lead to the denial of regulatory approval of WIN378, WIN027 or any other potential future product candidates.

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If unacceptable side effects

effects arise in the development of WIN378, WIN027 or any other potential future product candidates, we, the FDA, competent authorities of individual EU Member States, or other comparable foreign regulatory authorities, the IRBs, or independent ethics committees at the institutions in which our trials are conducted, could suspend, limit or terminate our clinical trials, or the independent safety monitoring committee could recommend that we suspend, limit or terminate our trials, or the FDA, competent authorities of individual EU Member States or other comparable foreign regulatory authorities could order us to cease clinical trials, or the FDA, the European Commission, or other comparable foreign regulatory authorities could deny approval of WIN378, WIN027 or any other potential future product candidates for any or all targeted indications. Treatment-emergent side effects that are deemed to be drug-related could delay recruitment of clinical trial subjects or may cause subjects that enroll in our clinical trials to discontinue participation in our clinical trials. In addition, these side effects may not be appropriately recognized or managed by the treating medical staff. We may need to train medical personnel using WIN378, WIN027 or any other potential future product candidates to understand the side effect profiles for our clinical trials and upon any commercialization of WIN378, WIN027 or any other potential future product candidates. Inadequate training in recognizing or managing the potential side effects of WIN378, WIN027 or any other potential future product candidates could result in harm to patients that are administered WIN378, WIN027 or any other potential future product candidates. Any of these occurrences may adversely affect our business, financial condition, results of operations and growth prospects significantly.

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Our potential competitors include large pharmaceutical and

and biotechnology companies, specialty pharmaceutical and generic drug companies, academic institutions, government agencies and research institutions. See the section titled "Business—Competition" included elsewhere in this prospectus for examples of the competition that WIN378 or WIN027 faces.

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we obtain approval for WIN378, WIN027 or any other potential future product candidates, we may face competition based on many different factors, including the efficacy, safety and tolerability of our products, the ease with which our products can be administered, the timing and scope of regulatory approvals for these products, the availability and cost of manufacturing, marketing and sales capabilities, price, reimbursement coverage and patent position. Existing and future competing products could present superior treatment alternatives, including being more effective, safer, less expensive or marketed and sold more effectively than any products we may develop. Competitive products may make any products we develop obsolete or noncompetitive before we recover the expense of developing and commercializing WIN378, WIN027 or any other potential future product candidates. Such competitors could also recruit our employees, which could negatively impact our level of expertise and our ability to execute our business plan.

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The Biologics Price Competition and Innovation Act of 2009, or the

The Biologics Price Competition and Innovation Act of 2009, or the BPCIA, created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor's own nonclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of its product.

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In addition to the risk associated with biosimilars

biosimilars of our product candidates, the launch of biosimilars to products that compete with our product candidates may intensify competition in the therapeutic areas we target by lowering the overall price point and expanding access to alternative treatments. As these lower-cost biosimilars gain market share, payors may preferentially encourage their use or impose access restrictions that make it more difficult for our product candidates to obtain favorable coverage, reimbursement or formulary placement. These dynamics could materially limit our market opportunity and adversely affect our commercial prospects.

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arise regarding intellectual property subject to a licensing agreement, including:

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Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action.

On September 16, 2011, the Leahy-Smith America Invents Act, or the Leahy-Smith Act, was signed into law and included several significant changes to U.S. patent law that impacted how patent rights could be prosecuted, enforced and defended. In particular, the Leahy-Smith Act also included provisions that switched the United States from a "first-to-invent" system to a "first-to-file" system, allowed third-party submission of prior art to the USPTO during patent prosecution and set forth additional procedures to attack the validity of a patent by the USPTO are administered post grant proceedings. Under a first-to-file system, assuming the other requirements for patentability are met, the first inventor to file a patent application generally will be entitled to the patent on an invention regardless of whether another inventor had made the invention earlier. The USPTO developed regulations and procedures governing the administration of the Leahy-Smith Act, and many of the substantive changes to patent law associated with the Leahy-Smith Act, and in particular, the first-to-file provisions, became effective on March 16, 2013. administered post grant proceedings. Under a first-to-file system, assuming the other requirements for patentability The Leahy-Smith Act also introduced new procedures providing opportunities for third parties to challenge any issued patent in the USPTO. Included in these new procedures is a process known as Inter Partes Review, or IPR, which has been generally used by many third parties since the enactment of the Leahy-Smith Act to invalidate patents. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action.

The Leahy-Smith Act also introduced new procedures providing opportunities for third parties to challenge any issued patent in the USPTO. Included in these new procedures is a process known as Inter Partes Review, or IPR, which has been generally used by many third parties since the enactment of the Leahy-Smith Act to invalidate patents. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action.

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Geopolitical actions in the United States and in foreign

Geopolitical actions in the United States and in foreign countries could increase the uncertainties and costs surrounding the prosecution or maintenance of patent applications and the maintenance, enforcement or defense of issued patents. For example, the United States and foreign government actions related to Russia's invasion of Ukraine may limit or prevent filing, prosecution and maintenance of patent applications in Russia. Government actions may also prevent maintenance of issued patents in Russia. These actions could result in abandonment or lapse of patents or patent applications, resulting in partial or complete loss of patent rights in Russia. If such an event were to occur, it could have a material adverse effect on our business. In addition, a decree was adopted by the Russian government in March 2022, allowing Russian companies and individuals to exploit inventions owned by patentees that have citizenship or nationality in, are registered in, or have predominately primary place of business or profit-making activities in the United States and other countries that Russia has deemed unfriendly without consent or compensation. Consequently, we would not be able to prevent third parties from practicing its inventions in Russia or from selling or importing products made using its inventions in and into Russia. Accordingly, our competitive position may be impaired, and our business, financial condition, results of operations and growth prospects may be adversely affected.

Accordingly, our competitive position may be impaired, and our business, financial condition, results of operations and growth prospects may be adversely affected.

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While it is our policy to

it is our policy to require our employees and contractors who may be involved in the development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who in fact develops intellectual property that we regard as our own or such assignments may not be self-executing or may be breached. Our licensors may face similar obstacles. We could be subject to ownership disputes arising, for example, from conflicting obligations of employees, consultants or others who are involved in developing our products or product candidates. Litigation may be necessary to defend against any claims challenging inventorship or ownership. If we or our licensors fail in defending any such claims, we may have to pay monetary damages and may lose valuable intellectual property rights, such as exclusive ownership of, or the right to use or enforce, intellectual property, which could adversely impact our business, financial condition and results of operations. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees.

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We are a Swiss corporation. Our corporate affairs are governed by our articles of association and by the laws governing companies incorporated in Switzerland. The rights of our shareholders and the responsibilities of our directors are in many ways different from the rights and obligations of shareholders and directors of companies governed by the laws of U.S. jurisdictions. For example, in the performance of its duties, our board of directors is required by Swiss law to consider our interests, and may also have regard to the interest of our shareholders, our employees and other stakeholders, in all cases with due observation of the principles of due care and loyalty. It is possible that some of these parties will have interests that are different from, or in addition to, your interests as a shareholder. See the sections of this prospectus titled "Comparison of Shareholder Rights under Swiss and Delaware Corporate Law," "Management—Corporate Governance Practices" and "Description of Share Capital and Articles of Association."

For example, in the performance of its duties, our board of directors is required by Swiss law to consider our interests, and may also have regard to the interest of our shareholders, our employees and other stakeholders, in all cases with due observation of the principles of due care and loyalty. It is possible that some of these parties will have interests that are different from, or in addition to, your interests as a shareholder. See the sections of this prospectus titled "Comparison of Shareholder Rights under Swiss and Delaware Corporate Law," "Management—Corporate Governance Practices" and "Description of Share Capital and Articles of Association."

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liabilities against us, our directors and senior management.

These restrictions are more stringent than those

These restrictions are more stringent than those applicable to many of our competitors organized in the United States or other jurisdictions, and may adversely affect our ability to attract, retain and incentivize qualified directors and executive officers, particularly in competition with companies not subject to comparable restrictions. Non- compliance with these requirements may also expose our directors and executive officers to criminal sanctions under Swiss law.

U.S. investors may have difficulty enforcing civil liabilities against us, our directors and senior management.

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These provisions may limit a

These provisions may limit a shareholder's ability to bring a claim in a judicial forum of its choosing for disputes with us or any of our directors, shareholders, officers, or others, or may increase the cost of doing so, both of which may discourage lawsuits with respect to such claims. In the event a court finds the forum selection provisions contained in our amended and restated articles of association to be unenforceable or inapplicable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could harm our results of operations.

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The Swiss rules that require investors to disclose their interest in a company if they reach, exceed or fall below certain ownership thresholds only applies to issuers that have a listing for their equity securities in Switzerland. Since our common shares are listed exclusively on Nasdaq, a U.S. market, the disclosure obligations regarding major shareholdings according to art. 120 of the Swiss Financial Markets Infrastructure Act and its implementing provisions do not apply to us. Likewise, the Swiss takeover regime does not apply to us.

Furthermore, since Swiss law restricts

The Swiss rules that require investors to disclose their interest in a company if they reach, exceed or fall below certain ownership thresholds only applies to issuers that have a listing for their equity securities in Switzerland. Since our common shares are listed exclusively on Nasdaq, a U.S. market, the disclosure obligations regarding major shareholdings according to art. 120 of the Swiss Financial Markets Infrastructure Act and its implementing provisions do not apply to us. Likewise, the Swiss takeover regime does not apply to us. In particular, the duty to make a mandatory bid offer for all outstanding listed equity securities of a company by any person or group of persons that acquires more than one third of a company's voting rights does not apply to us. In addition, the Swiss takeover regime imposes certain restrictions and obligations on bidders in a voluntary public takeover offer that are designed to protect shareholders. However, these protections are applicable only to issuers that list their equity securities in Switzerland and, because our common shares will be listed exclusively on Nasdaq, will not be applicable to us.

Furthermore, since Swiss law restricts our ability to implement rights plans or U.S.-style "poison pills," our ability to resist an unsolicited takeover attempt or to protect minority shareholders in the event of a change of control transaction may be limited. Therefore, our shareholders may not be protected in the same degree in a public takeover offer or a change-of-control transaction as are shareholders in a Swiss company listed in Switzerland.

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Upon the completion of this

this offering, the holders of approximately common shares, or % of our outstanding common shares following this offering, will have rights, subject to some conditions, to require us to file registration statements covering the sale of their shares or to include their shares in registration statements that we may file for ourselves or our other shareholders. We also intend to register the offer and sale of all common shares that we may issue under our equity incentive plans. Once we register the offer and sale of shares for the holders of registration rights and shares that may be issued under our equity incentive plans, these shares will be able to be sold in the public market upon issuance, subject to the lock-up agreements described in the section titled "Underwriting" included elsewhere in this prospectus.

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We do not currently intend to pay dividends and,

Our amended and restated articles of association provide for conditional share capital for financing, acquisitions and other purposes in an amount equal to approximately % of our outstanding share capital. Common shares may be issued out of this conditional capital through the exercise or mandatory exercise of conversion, exchange, option, subscription or other rights to acquire shares or through obligations to acquire common shares, which are granted to or imposed on shareholders or third parties alone or in connection with bonds, notes, options, warrants or other financial instruments issued by us or any of our group companies. Our amended and restated articles of association provide for an exclusion of the advance subscription rights of our shareholders in connection with the issuance of any such financial instruments and the exclusion of the pre-emptive subscription rights of our shareholders in connection with the issuance of common shares upon exercise of any such financial instruments. See "Description of Share Capital and Articles of Association—Certain Important Provisions of our Articles of Association, Organizational Regulations and Swiss Law—Our Conditional Share Capital" included elsewhere in this prospectus. Such shares may be issued at a price below the respective stock exchange price, and such financial instruments may be issued below their intrinsic value. As a result, our existing shareholders may experience significant dilution of their ownership interests if and when such financial instruments are issued and subsequently converted into or exercised for our common shares. This may adversely affect the per share value of our common shares.

We do not currently intend to pay dividends and, consequently, our shareholders' ability to achieve a return on their investment will depend on appreciation of the value of our common shares.

We have never declared or paid dividends, whether in cash, in kind or otherwise, since our incorporation.

have never declared or paid dividends, whether in cash, in kind or otherwise, since our incorporation. Even if future operations lead to significant levels of distributable profits, we currently intend to retain all available funds and any future earnings to support operations and to finance the growth and development of our business. We do not intend to declare or pay any dividends in the foreseeable future, and we may never be able to do so. Any proposal of our board of directors to the general meeting of shareholders to pay future dividends will be at the discretion of our board of directors after taking into account various factors, including our business prospects, cash requirements, financial performance and new product development, and subject to approval by the general meeting of shareholders. In addition, payment of future dividends is subject to certain limitations pursuant to Swiss law. See "Description of Share Capital and Articles of Association—Dividends and Other Distributions" included elsewhere in this prospectus. Also, we are a holding company with no material direct operations. As a result, we would be largely dependent on dividends or other distributions from our subsidiaries in order to pay a dividend. Our subsidiaries are subject to legal requirements of their respective jurisdictions of incorporation that may restrict their paying dividends or making other distributions to us. As a result, investors cannot rely on dividend income from our common shares and any investment return on our common shares will depend upon increases in the value for our common shares, which is not certain.

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Swiss law reserves for approval by

Swiss law reserves for approval by shareholders certain corporate actions over which a board of directors would have authority in some other jurisdictions. For example, the payment of dividends and the cancellation of treasury shares must be approved by shareholders (other than a cancellation of treasury shares within a capital range). Swiss law also requires that our shareholders themselves resolve to, or authorize our board of directors to, increase our share capital or cancel treasury shares. While our shareholders may resolve to create a capital range and thereby authorize our board of directors to issue new shares or cancel treasury shares without additional shareholder approval, Swiss law limits this authorization to 50% of the share capital registered in the commercial register of the Canton of Basel-Stadt, Switzerland, at the time of the authorization. The authorization, furthermore, has a limited duration of up to five years and must be renewed by the shareholders from time to time thereafter (or in the event of an earlier lapse of the capital range in accordance with Swiss law) in order to be available for raising capital. Additionally, subject to specified exceptions, including exceptions explicitly described in our articles of association, Swiss law grants subscription rights to existing shareholders to subscribe for new issuances of shares, which may be limited or withdrawn under certain conditions. Swiss law also does not provide as much flexibility in the various rights and regulations that can attach to different classes of shares as do the laws of some other jurisdictions. These Swiss law requirements relating to our capital management may limit our flexibility, and situations may arise where greater flexibility would have provided benefits to our shareholders. See "Description of Share Capital and Articles of Association" included elsewhere in this prospectus.

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There can be no assurance that we will take any action to register or otherwise qualify an offering of subscription rights or shares under the laws of any jurisdiction other than the United States where the offering of such rights is restricted. If shareholders in such jurisdictions were unable to exercise their subscription rights, their ownership interest in us will be diluted.

We may not be able to

We must meet certain financial and liquidity

Under Swiss corporate law, shareholders may receive

Under Swiss corporate law, shareholders may receive certain subscription rights to subscribe on a pro-rata basis for issuances of equity securities or other securities that are convertible into equity securities. Due to the laws and regulations in certain jurisdictions, however, shareholders who are not residents of the United States may not be able to exercise such rights unless we take action to register or otherwise qualify the rights offering, including, for example, by complying with prospectus requirements under the laws of that jurisdiction. There can be no assurance that we will take any action to register or otherwise qualify an offering of subscription rights or shares under the laws of any jurisdiction other than the United States where the offering of such rights is restricted. If shareholders in such jurisdictions were unable to exercise their subscription rights, their ownership interest in us will be diluted.

We may not be able to satisfy listing requirements of Nasdaq or obtain or maintain a listing of our common shares on Nasdaq.

We must meet certain financial and liquidity criteria in order to list our common shares on Nasdaq. If we violate Nasdaq's listing requirements, our common shares may be delisted. If we fail to meet any of Nasdaq's listing standards, our common shares may be delisted. In addition, our board of directors may determine that the cost of maintaining our listing on a national securities exchange outweighs the benefits of such listing and may therefore propose to the general meeting of shareholders to approve a delisting of our common shares. A delisting of our common shares from Nasdaq may materially impair our shareholders' ability to buy and sell our common shares and could have an adverse effect on the market price of, and the efficiency of the trading market for, our common shares. The delisting of our common shares could significantly impair our ability to raise capital and the value of your investment.

Other General Risks and Our Status as a Swiss Company with Foreign Private Issuer Status Unfavorable global economic and geopolitical conditions could adversely affect our business, financial condition, results of operations and share price.

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It is possible that some of our contractual counterparties, including Kelun and Qyuns, could be impacted by such future legislation or government policies. If any of the other third parties that we engage to supply any materials or manufacture products for our nonclinical studies and clinical trials should cease to continue to do so, or if we are prevented or restricted from using their services for any reason, we could experience delays in advancing these studies and trials while we identify and qualify replacement suppliers.

We are currently in the process of transferring the manufacturing of WIN378 clinical trial material from Kelun's facilities in the PRC to contract manufacturing organizations in the United States. Qyuns continues to manufacture WIN027 clinical trial material at its facilities in the PRC. We plan to transfer the manufacturing of WIN027 clinical trial material to contract manufacturing organizations outside of the PRC. To the extent WIN378 and/or WIN027 clinical trial material continues to be manufactured in the PRC pending such a transfer, and if Kelun or Qyuns were to be designated as a "biotechnology company of concern," our ability to access federal funding in connection with that manufacturing relationship could be adversely affected. Any additional executive action, legislative action or potential sanctions with the PRC could materially impact our current manufacturing collaborators, Kelun and Qyuns, and our agreement with them. We continue to assess the legislation as it develops to determine the effect, if any, on our contractual relationships. Furthermore, any disruptions to our supply chain as a result of unfavorable global economic conditions, including due to geopolitical conflicts or public health crises, could negatively impact the timely execution of our ongoing and future clinical trials.

Any additional executive action, legislative action or potential sanctions with the PRC could materially impact our current manufacturing collaborators, Kelun and Qyuns, and our agreement with them. We continue to assess the legislation as it develops to determine the effect, if any, on our contractual relationships. Furthermore, any disruptions to our supply chain as a result of unfavorable global economic conditions, including due to geopolitical conflicts or public health crises, could negatively impact the timely execution of our ongoing and future clinical trials.

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Natural disasters, pandemics, epidemics or public health crises could severely disrupt our operations, and have a material adverse impact on our business, financial condition, results of operations and growth prospects. If natural disasters, pandemics, epidemics, power outages, public health crises or other events occurred that affected our supply chains or prevented us from conducting our clinical trials, releasing clinical trial results or delaying our ability to obtain regulatory approval for our product candidates, it may be difficult or, in certain cases, impossible for us to continue our business for a substantial period of time.

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The complexity of announced or future tariffs may also increase the risk that we or our customers or suppliers may be subject to civil or criminal enforcement actions in the United States or foreign jurisdictions related to compliance with trade regulations. Foreign governments may also adopt non-tariff measures, such as procurement preferences or informal disincentives to engage with, purchase from or invest in U.S. entities, which may limit our ability to compete internationally and attract non-U.S. investment, employees, customers and suppliers. Foreign governments may also take other retaliatory actions against U.S. entities, such as decreased intellectual property protection, increased enforcement actions, or delays in regulatory approvals, which may result in heightened international legal and operational risks. In addition, the United States and other governments have imposed and may continue to impose additional sanctions, such as trade restrictions or trade barriers, which could restrict us from doing business directly or indirectly in or with certain countries or parties and may impose additional costs and complexity to our business.

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As a public company, we will incur significant

We expect the rules and regulations applicable

As a public company, we will incur significant legal, accounting and other expenses that we did not incur as a private company. In connection with this offering, we will become subject to the reporting requirements of the Exchange Act, which require, among other things, that we file with the Securities and Exchange Commission, or SEC, annual and current reports with respect to our business and financial condition. In addition, the Sarbanes-Oxley Act of 2002, as amended, or the Sarbanes-Oxley Act, as well as rules subsequently adopted by the SEC and Nasdaq to implement provisions of the Sarbanes-Oxley Act, impose significant requirements on public companies, including requiring establishment and maintenance of effective disclosure and financial reporting controls and changes in corporate governance practices. Further, in July 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act, or the Dodd-Frank Act was enacted. Recent legislation permits emerging growth companies to implement many of these requirements over a longer period and up to five years from the pricing of this offering. Shareholder activism, the current political environment and the current high level of government intervention and regulatory reform may lead to substantial new regulations and disclosure obligations, which may lead to additional compliance costs and impact the manner in which we operate our business in ways we cannot currently anticipate. In addition, in Switzerland, certain legislation affecting public companies will impose additional disclosure and compliance requirements on us, including in respect of executive compensation.

We expect the rules and regulations applicable to public companies to substantially increase our legal and financial compliance costs and to make some activities more time-consuming and costly. If these requirements divert the attention of our management and personnel from other business concerns, they could have an adverse effect on our business. The increased costs will decrease our net income or increase our net loss, and may require us to reduce costs in other areas of our business or increase the prices of our products or services. For example, we expect these rules and regulations to make it more difficult and more expensive for us to obtain director and officer liability insurance and we may be required to incur substantial costs to maintain the same or similar coverage. We cannot predict or estimate the amount or timing of additional costs we may incur to respond to these requirements. The impact of these requirements could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors, our board committees or on our executive committee. In addition, these rules and regulations are often subject to varying interpretations, in many cases due to their lack of specificity and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices.

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becoming a publicly traded company, we will be required, pursuant to Section 404 of the Sarbanes-Oxley Act, to furnish a report by management on, among other things, the effectiveness of our internal control over financial reporting as of the end of the fiscal year that coincides with the filing of our second annual report on Form 20-F.

Upon becoming a publicly traded company, we will be required, pursuant to Section 404 of the Sarbanes-Oxley Act, to furnish a report by management on, among other things, the effectiveness of our internal control over financial reporting as of the end of the fiscal year that coincides with the filing of our second annual report on Form 20-F. However, for as long as we are an emerging growth company or a non-accelerated filer, our independent registered public accounting firm will not be required to attest to the effectiveness of our internal controls over financial reporting pursuant to Section 404(b) of the Sarbanes-Oxley Act. We could be an emerging growth company for up to five years following completion of this initial public offering. An independent assessment of the effectiveness of our internal controls over financial reporting could detect problems that our management's assessment might not. Undetected material weaknesses in our internal controls over financial reporting could lead to restatements of our financial statements and require us to incur the expense of remediation.

Our disclosure controls and procedures

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and 9 more changes in the filing

Use of proceeds 3 changes

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Approximately $ million to fund the advancement of our bispecific programs through the completion of IND-enabling studies; and ∎ The remainder for working capital and general corporate purposes, including personnel costs, facilities, and other operational expenses.

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Based on our current plans and business conditions,

conditions, we believe our existing cash, cash equivalents and marketable securities, together with the net proceeds from this offering, will be sufficient to enable us to fund our operating expenses and capital expenditure requirements through . This determination is based on certain assumptions that may prove incorrect and we may use our available capital resources sooner than expected. We do not have any committed external sources of funds as of the date of this prospectus. In the future, we may meet any future cash needs through the sale of additional equity securities, raising debt financing, obtaining working capital lines of credit, interest income earned on our interest-bearing cash deposits, or a combination of these sources.

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Dividend policy 1 change

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Dividends are usually due and payable after the resolution has been passed by the general meeting of shareholders or at a later date as determined by the shareholders' resolution. Under Swiss law, the statute of limitations with respect to dividend payments is five years. Dividends not collected within five years of their due date accrue to the Company and will be allocated to our statutory retained earnings.

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Capitalization 2 changes

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The following table should be read together with

with "Management's Discussion and Analysis of Financial Condition and Results of Operations," "Use of Proceeds" and the unaudited condensed consolidated interim financial statements and related notes included elsewhere in this prospectus.

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Dilution 2 changes

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Our pro forma net tangible book value as

value as of June 30, 2026 was $ million or $ per share. Pro forma net tangible book value per share represents the amount of our total tangible assets (net of deferred offering costs of $ million) less our total liabilities and divided by the number of our common shares outstanding as of June 30, 2026, after giving effect to the Preferred Share Conversion and the Series B Warrant Settlement. Pro forma net tangible book value per share represents our pro forma net tangible book value divided by the total number of common shares outstanding as of June 30, 2026, after giving effect to the pro forma adjustments described above.

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MD&A 55 changes

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WIN378 is currently being

being evaluated in POLARIS-1, a Phase 2/3 study in severe uncontrolled asthma. Study start-up activities were initiated in September 2026 for a second Phase 3 study (POLARIS-2), which is planned to begin patient recruitment in the first half of 2027. A Phase 2 study of WIN378 in COPD, SIRIUS, was initiated in June 2026. We expect that the next data readout for WIN378 will be A preplanned analysis of the Phase 2 interim analysis portion of POLARIS-1 was completed in the second half of 2026.

WIN027 is currently in a Phase 1 healthy volunteer study with INDs open in the United States, Australia and the PRC, assessing safety and pharmacokinetics. We initiated study start-up activities in September 2026 for our two global Phase 2 studies—a global Phase 2 study in COPD fully powered on the registrational endpoint of exacerbation rate ratio and a second global Phase 2 study in atopic dermatitis, which are planned to begin patient recruitment in the first half of 2027. We expect that the next data readout for WIN027 will be the full Phase 1 results in the first half of 2027.

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Series A and Series B

On January 10, 2025, we

January 10, 2025, we launched a $200.0 million Series A financing round, which was paid in two tranches. On January 23, 2025, we completed the first tranche for $75.0 million. In connection with the closing of the first tranche, we issued 11,961,724 Series A preferred shares and 1,212,120 common shares at a price of $6.27 and $0.01 per share, respectively. On July 11, 2025, we completed the second tranche for $125.0 million. In connection with the closing of the second tranche, we issued 19,936,203 Series A Preferred Shares at a price of $6.27 per share.

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We may be required to make additional payments to Kelun and HBM based on the occurrence or non-occurrence of future events, including development milestones of up to $320.0 million for WIN378 (excluding the total $10.0 million milestone payments as described below), as well as sales-related milestones of up to $600.0 million. Additionally, we may be required to pay tiered royalties through six tiers, ranging from low single digits to low double-digits (a spread of not more than 5 percentage points) on net sales of WIN378 products, to Kelun and HBM.

On September 25, 2025, we achieved the first

On September 25, 2025, we achieved the first development milestone associated with the WIN378 License, which required us to make a payment to Kelun and HBM, in total, of $5.0 million, during the year ended December 31, 2025.

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On December 19, 2025, we entered into a

We may be required to

On December 19, 2025, we entered into a License and Collaboration Agreement with Qyuns, which became effective on the same day. Under this agreement, we received a license, or our WIN027 License, for a clinical-stage, long-acting anti-TSLPxIL-13 bispecific antibody developed by Qyuns, or WIN027, with broad therapeutic application across immunological diseases. The WIN027 License allows us to research, manufacture, develop and commercialize products globally, except for Greater China.

As consideration for the WIN027 License, we made

As consideration for the WIN027 License, we made payments of cash and equity interests to Qyuns and its affiliates, totaling $30.0 million. In the first quarter of 2026, $15.0 million was paid in cash, and the remaining was paid in our equity interest valued at $15.0 million.

We may be required to make additional payments to Qyuns based on the occurrence or non-occurrence of future events, including development milestones of up to $100.0 million, as well as sales-related milestones of up to $570.0 million. Additionally, we may be required to pay mid-single digit to high-single digit tiered royalties to Qyuns.

Factors Affecting the Comparability of Results of Operations

Factors Affecting the Comparability of Results of Operations Our business was incorporated on July 5, 2024 and as such, financial conditions and results of operation for the period from July 5, 2024 to December 31, 2024, or the 2024 period, does not represent an entire twelve-month fiscal year. As such, the year ended December 31, 2025 and the 2024 period are not directly comparable. At the time of our inception, we were in the early stages of organizational activity and the nature of our expenses incurred differed from the expenses incurred more recently in the normal course of our business.

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To date, we have not generated any revenue from product

To date, we have not generated any revenue from product sales or services, and we do not expect to generate any revenue from the sale of products in the near future, if ever. If our development efforts for WIN378 or other product candidates are successful and result in regulatory approval, we may generate revenues in the future from product sales, payments from existing or potential future collaboration or license agreements with third parties, or any combination thereof.

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general and administrative expenses are primarily related to operating expenses such as insurance costs, travel expenses and facility expenses not otherwise included in research and development expenses, as well as expenses of external advisors, including professional fees for legal, accounting, audit, and tax services. These expenses also include salaries and benefits for our general and administrative personnel, including share-based compensation for the personnel in our executive, finance, accounting, legal, human resources, business development, information technology and other administrative areas. Depreciation expense is recognized on our assets used in supporting our general and administrative functions.

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Depreciation expense increased by

increased by $0.1 million in the year ended December 31, 2025, compared to the period from July 5, 2024 to December 31, 2024. This increase was primarily driven by the acquisition of additional assets required to carry out our research and development activities, including equipment used in clinical trials.

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Depreciation increased by $0.1 million in the year ended December 31, 2025, compared to the 2024 period.

Depreciation increased by $0.1 million in the year ended December 31, 2025, compared to the 2024 period. This increase was primarily driven by the acquisition of assets to build out our administrative functions. We did not have any such assets in the 2024 period.

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Depreciation increased by $0.2 million in the six months ended June

June 30, 2026 compared to the six months ended June 30, 2025. The increase was primarily driven by the acquisition of additional assets required to carry out our research and development activities, including equipment used in clinical trials.

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Financial income, financial expense and foreign exchange differences, net Our financial income was $2.2 million during the six months ended June 30, 2026, compared to $0.7 million during the six months ended June 30, 2025. This increase was driven by fair value gains on financial assets measured at fair value through profit or loss and interest income earned on cash equivalents and marketable securities driven by the investment of the proceeds from the first tranche of our Series B financing round.

This increase was driven by fair value gains on financial assets measured at fair value through profit or loss and interest income earned on cash equivalents and marketable securities driven by the investment of the proceeds from the first tranche of our Series B financing round.

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Our income taxes were insignificant during

during the six months ended June 30, 2026 and 2025.

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During the year ended December 31, 2025, net cash

cash used in operating activities was $33.3 million, resulting primarily from the net loss incurred during the year ended December 31, 2025. The net loss in this period was driven by the increases in expense associated with research and development activities, including additional service and materials expenses driven by the initiation of our POLARIS-1 Phase 2/3 asthma study for WIN378. These outflows were partially offset by interest received of $1.8 million.

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Investing Activities

During the year ended December 31, 2025, net

During the six months ended June 30, 2025, operating activities used

operating activities used $9.7 million of cash, resulting primarily from our net loss incurred during our operations in the six months ended June 30, 2025. Net cash from changes in operating assets and liabilities was primarily driven by timing of our payment of trade payables and recognition of accrued expenses primarily related to our CRO and CDMO relations.

Net cash used in operating activities for the six months ended June

six months ended June 30, 2026 increased by $16.2 million compared to net cash used in operating activities for the six months ended June 30, 2025. This increase was driven by an increase in net loss recognized of $19.9 million. These cash outflows were partially offset by an increase in interest received of $1.7 million in the six months ended June 30, 2026 compared to the six months ended June 30, 2025.

During the year ended December 31, 2025, net cash used in investing activities was $144.2 million, resulting primarily from outflows for the purchase of financial assets of $194.2 million and $25.0 million of cash payments to Kelun and HBM for our WIN378 License, which includes an upfront payment of $20.0 million to Kelun and HBM and the payment of our first development-related milestone of $5.0 million. These outflows were partially offset by cash inflows from proceeds received from our financial assets.

During the 2024 period, cash flows provided by investing activities were not significant as our operations began in January 2025.

During the six months ended June

During the six months ended June 30, 2026, investing activities used $83.3 million of cash, driven primarily by outflows from the purchase of additional financial assets and the payment of cash to Qyuns for our WIN027 License. These outflows were partially offset by cash inflows from proceeds received from our financial assets.

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Net cash used in investing activities for the six months ended June 30, 2026 increased by $32.0 million compared to net cash used in investing activities for the six months ended June 30, 2025. This increase was driven by an increase in our purchases of financial assets of $56.5 million, partially offset by greater proceeds received from financial assets of $19.2 million in the six months ended June 30, 2026 compared to June 30, 2025 and lower payments related to our license-related intangible assets in the period ending June 30, 2026 compared to the same period in 2025.

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During the year ended December 31, 2025,

During the year ended December 31, 2025, financing activities provided $197.0 million of cash inflows. The cash inflows primarily related to the proceeds received from closing both the first and second tranche of our Series A financing round for a total inflow of $200.0 million, partially offset by the payment of $2.2 million of transaction costs and payments on lease obligations of $0.8 million.

During the 2024 period, no cash was provided by or used in financing activities as our operations began in January 2025.

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Estimates and Significant Judgements

Critical Accounting Policies, Estimates

and Significant Judgments

Our management's discussion and analysis of our financial condition and results of operations is based on our audited consolidated financial statements, which we have prepared in accordance with International Financial Reporting Standards, or IFRS. The preparation of our consolidated financial statements requires us to make estimates, assumptions and judgments that may affect the reported amounts of assets, liabilities, and expenses. We base our estimates and assumptions on our historical expenses and other factors that we believe to be reasonable under the circumstances, the results of which form the basis for making judgements judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We continue to evaluate our estimates and assumptions on an ongoing basis. Actual results may differ from our estimates under different assumptions or conditions.

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We have a limited operating history

operating history and have experienced net losses and have used significant cash in our operating activities since our inception. We expect to continue to incur net losses and have significant cash outflows for the foreseeable future. As of June 30, 2026, we held cash, cash equivalents and marketable securities of $207.3 million.

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Process Research and Development (IPR&D)

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The determination of the recoverable value of our

recoverable value of our IPR&D intangible asset includes key estimates that are highly sensitive to, and dependent upon key assumptions, including anticipated market share and pricing, expected patent life and market exclusivity periods, estimated research and development costs, the probability of success of the product candidate and the discount rate used to discount future cashflows. While we have not recognized any impairment on these assets as of June 30, 2026, it is possible that changes to these key assumptions could result in impairments in future periods.

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Business 121 changes

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volume in one second, a key measure of lung function) of up to 174 mL (placebo-adjusted mean increase up to 256 267 mL, p=0.033).

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Pharmacokinetic-pharmacodynamic modeling demonstrated the enhanced potency of WIN378, which achieved an EC 50 of 0.63 mg/ml ug/ml for FeNO reduction, a marker of airway inflammation.

The primary study results at week 24 are expected in the first half of 2027. The final study results at week 48 are expected to be available in the second half of 2027. Two twice-yearly dose levels were selected for the Phase 3 portion of POLARIS-1, which was initiated in September 2026 with topline results at week 48 expected in the second half of 2028. In September 2026, we also initiated study start-up activities for a second Phase 3 study (POLARIS-2), which is planned to begin patient recruitment in the first half of 2027, with topline results expected in the second half of 2029.

In September 2026, we also initiated study start-up activities for a second Phase 3 study (POLARIS-2), which is planned to begin patient recruitment in the first half of 2027, with topline results expected in the first half of 2029.

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We initiated study start-up activities in September 2026 for our two global Phase 2b studies, which are planned to begin patient recruitment in the first half of 2027, including a globally conducted, dose-ranging study in COPD fully powered on the registrational endpoint of exacerbation rate ratio. Our Phase 2b trial is designed with registrational-quality features, including treatment period, exacerbations as primary endpoint, appropriate key secondary endpoints including lung function, hierarchical type 1 error control, independent data and safety monitoring, and a population aligned with the intended indication. We also plan to initiate a global atopic dermatitis study in the first half of 2027 with topline results expected in the second half of 2028. Qyuns initiated their Phase 2 studies in atopic dermatitis and CRSwNP in September 2026 in the PRC and plans to begin a Phase 2 study in asthma by the end of 2026. Topline results from these studies are expected over the course of 2027 and 2028.

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We were founded in 2024 and launched in January

AD=atopic dermatitis, COPD=chronic obstructive pulmonary disease, HV=healthy volunteer, TLR=topline results, W=week; remaining studies, not funded by the expected IPO proceeds, are already funded Additional bispecific programs are in the lead optimization phase. The current program is a next-generation bispecific targeting T2 and non-T2 pathways, with two complementary cytokines. Work to date has included the evaluation of various formats, production at small scale, and the evaluation of productivity, purity and light chain mispairing. Further work has characterized the blocking of both cytokines and a HELA cell-based potency assay has been developed and used to compare the bispecifics' potencies to monospecific benchmarks. Of the three formats evaluated, a lead nonclinical target format has been identified and selected, with potential across skin and respiratory indications, including atopic dermatitis, asthma, COPD and other inflammatory and fibrotic skin and lung diseases. We expect to initiate Phase 1 clinical development for these potential skin and respiratory indications in the next 18 months, subject to standard regulatory requirements. The lead format demonstrating benchmark-comparable affinity, cellular potency and manufacturability is currently being engineered for half-life extension prior to characterization in nonhuman primate studies.

We were founded in 2024 and launched in January 2025. Our management team has significant experience spanning drug discovery and development, global commercialization, finance, business development, and corporate strategy. We have collectively been responsible for the discovery, development, or commercialization of over 20 medicines. Our management team has worked together previously, including at VectivBio and Therachon, where we built each biotechnology company from inception through public offerings and eventually strategic acquisitions, consistently meeting or exceeding corporate objectives. Our executive leadership is described under " Our team " below.

We have not generated any product

generated any product revenue to date and have funded our operations principally through private placements of equity. As of June 30, 2026, we had cash, cash equivalents and marketable securities of $207.3 million.

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Advance WIN378, our lead ultra-long-acting anti-TSLP monoclonal antibody, through clinical development for the treatment of asthma, a severe disease with low adherence to short-acting biologics. We believe WIN378 has the potential to be a differentiated anti-TSLP therapy based on its potent inhibition of a clinically validated target, twice-yearly dosing profile, low immunogenicity and unique dual-site binding to the TSLP ligand. Through our ongoing Phase 2/3 POLARIS-1 asthma study, we aim to establish WIN378 as a differentiated treatment option for patients with severe asthma, including those with low eosinophil counts who remain underserved by current biologic therapies. In the pre-planned interim analysis of the Phase 2 portion of POLARIS-1, significant improvements in lung function and airway inflammation were observed with twice-yearly dosing of WIN378. Near maximal effects were seen as early as week 2 and sustained through week 24. WIN378 was well tolerated with no treatment-related serious adverse events, withdrawals or discontinuations; adverse events were balanced between active arms and placebo, with low rates of injection site reactions and antidrug antibodies. The pharmacology analysis demonstrated a half-life of up to 75 days, with clinical effects consistent with twice-yearly dosing. The next data readout is the primary analysis at week 24 in the first half of 2027. The final study results at week 48 will be available in the second half of 2027. The Phase 3 portion of the study was initiated in September 2026, evaluating two twice-yearly dose levels of WIN378, with topline results at week 48 expected in the second first half of 2028. 2029. In September 2026, study start-up activities were initiated for a second Phase 3 study in asthma (POLARIS-2), which is planned to begin patient recruitment in the first half of 2027, with topline results expected in the second first half of 2029.

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Advance WIN027, our long-acting anti-TSLP anti-IL-13 bispecific antibody, through clinical development for the treatment of COPD and atopic dermatitis, diseases in which there is the potential for significant improvement over currently approved biologics . We believe dual blockade of TSLP and IL-13 may provide deeper and more durable disease control than inhibition of either pathway alone. We are advancing WIN027 through an ongoing Phase 1 trial in healthy volunteers. Based on blinded interim data as of June 2026, we have observed a 62-day half-life, low immunogenicity and low rate of injection site reactions, with full pharmacokinetic and immunogenicity data expected in the first half of 2027. We plan to initiate a global Phase 2b in COPD, fully powered on the registrational endpoint of exacerbation rate ratio, in the first half of 2027. Topline results are expected in the first half of 2029. We also plan to initiate a global Phase 2 study in atopic dermatitis in the first half of 2027 with topline results expected in the second half of 2028. Qyuns initiated their Phase 2 studies in atopic dermatitis and CRSwNP in September 2026 in the PRC and plans to begin a Phase 2 study in asthma by the end of 2026. Topline results from these studies are expected over the course of 2027 and 2028.

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Windward Bio holds global rights to WIN378 excluding Greater China and certain Asian markets ** Exclusivity based on pending applications and anticipated patent extensions *** Asthma and CRSwNP Phase 2 These studies are planned in the PRC only, conducted and funded by Qyuns Therapeutics; see "—WIN027" on page 119 for more information **** Lead optimization stage with potential in respiratory and dermatology; see "—Additional bispecific programs" on page 119 for more information IP=intellectual property, mAb=monoclonal antibody WIN378 is an ultra-long-acting and potentially novel fully human monoclonal antibody that is designed to inhibit the TSLP ligand. This clinically validated target plays a key role in the development and progression of a wide array of immunological diseases, including asthma and COPD. WIN378 has been engineered to achieve half-life extension and silenced effector function. In nonclinical studies, WIN378 has been observed to have greater potency than the currently approved anti-TSLP treatment, has two binding sites to TSLP and fully overlaps the same binding site as Tezspire , tezepelumab.

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WIN378 is currently being evaluated in POLARIS-1, a Phase 2/3 study in severe uncontrolled asthma. A pre-planned interim analysis from the Phase 2 dose-finding portion of the study was completed in the second half of 2026, and the primary study results at week 24 are expected in the first half of 2027. The final study results at week 48 will be available in the second half of 2027. Following dose selection based on the interim analysis, we initiated the Phase 3 portion of POLARIS-1 in September 2026 with topline results expected in the second first half of 2028. 2029. We have also initiated study start-up activities for a second Phase 3 study (POLARIS-2) which is planned to begin patient recruitment in the first half of 2027 with topline results expected in the second first half of 2029. Separately, a Phase 2 study of WIN378 in COPD, SIRIUS, was initiated in June 2026 with topline results expected in the second half of 2027. We have observed the following results in the Phase 1 clinical trial for WIN378: an extended half-life supporting twice-yearly subcutaneous dosing, a low rate of antidrug antibodies, and no treatment-related serious adverse events were observed. In the interim analysis of the Phase 2 portion of POLARIS-1, significant improvements in lung function and airway inflammation were observed with twice-yearly dosing of WIN378. Near maximal effects were seen as early as Week 2 and sustained through Week 24. While these results may not translate to similar safety or efficacy results in the ongoing Phase 3 portions of our POLARIS studies in patients with asthma or our SIRIUS Phase 2 study in patients with COPD, we believe WIN378 is differentiated from currently approved treatments primarily through its potential for twice-yearly subcutaneous dosing.

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licensed global rights (excluding Greater China) for WIN027 from Qyuns (also known as QX027N) and retain all decision-making rights in our territory. Although we do not conduct or fund, and have no direct economic rights with respect to, Qyuns-sponsored programs in the PRC, the data generated from these clinical trials directly informs the design and conduct of our WIN027 clinical development programs and potential regulatory filings outside Greater China, and more importantly, the potential value of WIN027 outside of Greater China. Results from a trial of WIN027 anywhere in the world will impact and be relevant to the value and potential of WIN027 on a global basis. Under our license and collaboration agreement with Qyuns, Qyuns is required to provide us with copies of and access to data, results and supporting documentation generated from its development activities. We have the right to use and reference such information in connection with our development of WIN027 and our pursuit and maintenance of regulatory approvals outside Greater China, where we hold exclusive development and commercialization rights. Furthermore, pursuant to our license and collaboration agreement with Qyuns, we and Qyuns have established a joint steering committee that oversees and coordinates the development, manufacture and commercialization of compounds and product candidates, including cross-territory clinical trials.

WIN027 is currently in a Phase 1 HV study with INDs open in the United States, Australia and the PRC assessing safety and pharmacokinetics. We expect that the next data readout for WIN027 will be the full Phase 1 results in the first half of 2027. Based on blinded interim data as of June 2026, we have observed a 62-day half-life, low immunogenicity, a low rate of injection site reactions, and have not observed any treatment-related serious adverse events, with full pharmacokinetic and immunogenicity data expected in the first half of 2027. We plan to initiate multiple Phase 2 studies. We initiated study start-up activities in September 2026 for a global, dose-ranging finding Phase 2 study in COPD, fully powered on the registrational endpoint of exacerbation rate ratio, which is planned to begin patient recruitment in the first half of 2027. Topline results are expected in the first half of 2029. Our Phase 2b trial is designed with registrational-quality features, including treatment period, exacerbations as primary endpoint, appropriate key secondary endpoints including lung function, hierarchical type 1 error control, independent data and safety monitoring, and a population aligned with the intended indication. We also initiated study start-up activities in September 2026 for an additional Phase 2 study in atopic dermatitis which is planned to begin patient recruitment in the first half of 2027 with initial data topline results expected in the first second half of 2028. . Qyuns initiated their Phase 2 studies in atopic dermatitis and CRSwNP in September 2026 in the PRC and plans to begin a Phase 2 study in asthma by the end of the year. Topline results from these studies are expected over the course of 2027 and 2028.

Additional bispecific programs are in the lead

in the lead optimization phase. The current program is a next-generation bispecific targeting T2 and non-T2 pathways, with two complementary cytokines. Work to date has included the evaluation of various formats, production at small scale, and the evaluation of productivity, purity and light chain mispairing. Further work has characterized the blocking of both cytokines and a HELA cell-based potency assay has been developed and used to compare the bispecifics' potencies to monospecific benchmarks. Of the three formats evaluated, a lead nonclinical target format has been identified and selected, with potential across skin and respiratory indications, including atopic dermatitis, asthma, COPD and other inflammatory and fibrotic skin and lung diseases. We expect to initiate Phase 1 clinical development for these potential skin and respiratory indications in the next 18 months, subject to standard regulatory requirements. The lead format demonstrating benchmark-comparable affinity, cellular potency and manufacturability is currently being engineered for half-life extension prior to characterization in nonhuman primate studies.

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Note: Third-party data do not reflect head-to-head comparisons

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J et al. N Engl J Med 2017; Menzies-Gow A et al. N Engl J Med 2021; Bleecker ER et al. Lancet 2016; FitzGerald JM et al. Lancet 2016; Pavord ID et al. Lancet 2012; Ortega HG et al. N Engl J Med 2014; Busse W et al. J Allergy Clin Immunol 2001;

1 Castro M et al. N Engl J Med 2018; Corren J et al. N Engl J Med 2017;

Menzies-Gow A et al. N Engl J Med 2021; Bleecker ER et al. Lancet 2016; FitzGerald JM et al. Lancet 2016; Pavord ID et al. Lancet 2012; Ortega HG et al. N Engl J Med 2014; Busse W et al. J Allergy Clin Immunol 2001; Sol r M et al. Eur Respir J 2001; 2 Bhatt SP et al. N Engl J Med 2023; Bhatt SP et al. N Engl J Med 2024; Singh D et al. Lancet Respir Med 2025; Pavord ID et al. N Engl J Med 2017; Sciurba FC et al. N Engl J Med 2025; Criner GJ et al. N Engl J Med 2019; Sciurba et al. N Engl J Med 2026; 3 Silverberg JI et al. N Engl J Med 2023; Blauvelt A et al. Br J Dermatol 2023; Simpson EL et al. N Engl J Med 2016; Silverberg JI et al. Lancet 2024 aste=astegolimab, benra=benralizumab, dupi=dupilumab, EOS=baseline eosinophil count (cells/ L), itep=itepekimab, mepo=mepolizumab, MOA=mechanism of action, nemo=nemolizumabo, teze=tezepelumab, tozo=tozorakimab Severe Asthma Disease Overview Asthma is a common, chronic and heterogeneous respiratory disease characterized by inflammation of the airways and respiratory symptoms that vary over time and in intensity. It can result in significant morbidity and mortality if not adequately controlled. The World Health Organization estimated that asthma impacted over 360 million people worldwide. Mortality is substantial and, importantly, largely preventable: approximately 440,000 people worldwide died from asthma in 2023, more than 1,000 deaths every day. The prevalence of asthma in the United States is approximately 28 million.

approximately 440,000 people worldwide died from asthma in 2023, more than 1,000 deaths every day. The prevalence of asthma in the United States is approximately 28 million.

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The most important biological distinction is between type-2 and non-type-2 asthma, which is defined by the kind of inflammation present in the airways. Type-2 asthma is driven by the activation of a type-2 immune response and its signature cytokines, principally IL-4, IL-5, and IL-13. These cytokines increase production of immunoglobulin E, or IgE, the antibody central to allergic reactions; recruit and activate eosinophils, a type of white blood cell that drives airway inflammation;

These cytokines increase production of immunoglobulin E, or IgE, the antibody central to allergic reactions; recruit and activate eosinophils, a type of white blood cell that drives airway inflammation; and raise the level of nitric oxide in exhaled breath. Type-2 disease itself takes more than one form. It includes allergic asthma, which is typically allergen-driven and often begins in childhood, and later-onset eosinophilic asthma, which can arise in adulthood without a clear allergic trigger. A number of biologics target this subgroup including the anti-IL-5 class (Nucala , mepolizumab; Fasenra , benralizumab; and Exdensur , depemokimab-ulaa), the anti-IL-4/IL-13 class (Dupixent , dupilumab), the anti-IgE class (Xolair , omalizumab) as well as anti-TSLP (Tezspire , tezepelumab).

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Clinical Development of

of WIN378 in Asthma and COPD

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demonstrated that WIN378 was generally well tolerated, as all treatment-emergent adverse events were Grade 2 or lower, showed no trend of increasing frequency with dose, and were reported at a comparable overall rate in the WIN378 and placebo groups, and showed no trend of increasing frequency with dose. The pharmacokinetics, or PK, was linear, and exposures increased in an approximately dose-proportional manner. The observed serum half-life was up to at least 65 days and population-pharmacokinetic modeling supports dosing as infrequently as twice a year. The antidrug-antibody incidence was also observed to be low (4%), and only 2 of 40 WIN378-treated participants, one of which was a transient response, were observed to have antidrug antibodies. There were no associated safety signals reported and no observed effect on pharmacokinetics.

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The Phase 2 portion of the study

The Phase 2 portion of the study is designed for efficient use of patients to generate information to select doses to be used in the pivotal program. It is a randomized, double-blind, placebo-controlled dose-ranging study, randomized in an overall 3:1:1:3 ratio to receive doses of WIN378, or placebo, administered as two subcutaneous doses 24 weeks apart over a 48-week period. The randomization ratio is based on our application of the MCP-Mod (Multiple Comparison Procedure – Modeling) methodology. MCP-Mod is a statistical approach for the design and analysis of dose-finding studies that combine multiple comparison procedures with dose-response modeling. MCP-Mod makes more efficient use of dose-ranging data and supports more robust dose selection than conventional pairwise comparisons. The methodology has been formally qualified by the European Medicines Agency and is recognized by the U.S. Food and Drug Administration as a fit-for-purpose approach to dose finding.

The Phase 2 is designed to characterize the pharmacokinetics, safety, immunogenicity, and pharmacodynamic activity of WIN378, including its effects on biomarkers of airway inflammation, such as FeNO and EOS, and on lung function as measured by FEV1. Data from Phase 2 was used to inform selection of the dose levels to be carried into the Phase 3 portion of POLARIS-1 and into the subsequent second Phase 3 (POLARIS-2). The first POLARIS-1 Phase 2 participant was randomized in July 2025, and a total of 147 participants were randomized by May 2026, exceeding the initial enrollment target of 120 patients. A pre-planned interim analysis was completed in the second half of 2026 after the first 98 patients had reached at least week 12. The primary study results at week 24 are expected in the first half of 2027. The final study results at week 48 will be available in the second half of 2027.

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At the time of the interim analysis, 57 participants were randomized to placebo and 17, 17, and 56 participants randomized to WIN378 150 mg, 300 mg, and 600 mg, respectively. Baseline demographics and disease characteristics were consistent with an uncontrolled, moderate-to-severe asthma population with persistent airway obstruction despite stable treatment with medium- to high-dose inhaled corticosteroids and at least one additional asthma controller medication. Baseline characteristics were observed to be generally well-balanced across study arms.

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Ly N, et al. J Clin Pharmacol 2021;61(7):901–912. Tezepelumab PK/PD modelling to guide Phase 3 dose selection.

WIN378 was well tolerated, with no treatment-related serious adverse events, withdrawals or discontinuations observed as of the cut-off date. Adverse events were balanced between active arms and placebo. There were no treatment-related serious adverse events, or SAEs. There were four SAEs unrelated to treatment; these were all Grade 3 with two in active dose arms and two in placebo. Less than 1% of participants experienced injection site reactions and 2.2% developed antidrug antibodies (ADAs), a measure of immunogenicity. ADAs had no impact on the pharmacology of WIN378 . There were four withdrawals from the study unrelated to treatment and no discontinuations related to treatment.

The observed half-life of WIN378 in the Phase 2 population was up to 75 days . The pharmacokinetics of WIN378 were linear and demonstrated an extended half-life in an adult asthma population suitable for twice-yearly dosing. Concentrations that predict clinically meaningful reductions in asthma exacerbations were achieved with single doses of WIN378 given with subcutaneous administration every 6 months.

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Pre-bronchodilator FEV1 improved from baseline to Week 24 by up to 174 mL compared with a decline of 93 mL for placebo (placebo-adjusted differences of 256 267 mL; p<0.05). Increases in FEV 1 occurred as early as Week 2 and were sustained through week 24.

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The observed pharmacokinetics and pharmacodynamics support

The pharmacodynamic effects observed in the interim analysis were consistent with the improved potency of WIN378 predicted by nonclinical assays. Based on the observed a PopPK/PD model that relates concentrations of drug to reductions in FeNO response, in patients with uncontrolled asthma despite medium or high-dose ICS treatment, we determined that the half-maximal effective concentration, or EC50, of WIN378 was 0.63 g/mL. An independent publication based on the published tezepelumab Phase 2b PATHWAY study, using the same model, estimated the EC50 for tezepelumab is FeNO at 2.5 g/mL and for AAER at 1.7 ug/mL. In addition, 100% of patients taking the 300mg and 600mg dose of WIN378 had a 90% FeNO response would be predicted to be above the EC90, the concentration at Cavg.ss after which 90% of the first dose over 24 weeks. maximum FeNO-lowering effect is achieved.

pharmacokinetics and pharmacodynamics support twice-yearly dosing. Two twice-yearly dose levels were selected for Phase 3.

Reductions in FeNO and increases in FEV1 at Week 24 were seen across all dose levels of WIN378. At Week 24, WIN378 produced dose-related reductions in FeNO (absolute and placebo-adjusted differences at 150 mg, 300 mg, and 600 mg, respectively) and increases in FEV1 (absolute and placebo-adjusted differences across all three dose levels). The 600 mg dose showed the greatest placebo-adjusted improvement in both FeNO reduction and FEV1 increase among the doses tested.

The operationally seamless design of POLARIS-1 allowed for immediate initiation of the Phase 3 portion of the study which occurred in September 2026. Topline results of the Phase 3 are expected in the second first half of 2028. 2029. The trial is designed to enroll approximately 450 600 additional participants (with 150 200 patients/arm) with severe, uncontrolled asthma, randomized 1:1:1, to evaluate the effect of WIN378 on the annualized asthma exacerbation rate (AAER), the endpoint that regulatory authorities regard as the principal measure of efficacy for biologic therapies in asthma.

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advance WIN378 into POLARIS-2, our second pivotal Phase 3 trial in severe uncontrolled asthma. POLARIS-2 is designed as a multicenter, multinational, double-blind, randomized, placebo-controlled trial enrolling approximately 800 600 adult and adolescent participants (ages 12 to 75). Participants will have maintained on background medium or high-dose inhaled corticosteroid therapy plus at least one additional controller medication and are expected to be randomized 1:1:1 to one of two dose levels of subcutaneous WIN378 or placebo. Study start-up activities have begun, and the study is planned to begin enrolling patients in the first half of 2027 using the same two dose levels being evaluated in the Phase 3 portion of POLARIS-1 with topline results expected in the second first half of 2029.

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WIN027 is accumulating human safety

WIN027 is accumulating human safety and PK data. A first-in-human Phase 1 trial, QX027N-101 (Qyuns-sponsored, People's Republic of China, or the PRC), is ongoing: a randomized, double-blind, placebo-controlled single- and multiple-ascending-dose study in healthy adults and in patients with moderate-to-severe atopic dermatitis. As of the most recent blinded interim data lock (June 2026), five single-ascending-dose cohorts (150 mg, 450 mg, 900 mg, 1200 mg and 1800 mg, administered subcutaneously) and one multiple-dose cohort were clinically complete, with a safety analysis population of 75 participants and a pharmacokinetic, or PK, analysis population of 55 participants. Our interim results demonstrated that WIN027 was generally well tolerated, there were no serious adverse events, deaths, discontinuations or withdrawals and all treatment-emergent adverse events were Grade 2 or lower. Immunogenicity was low, with antidrug antibodies observed in approximately 3% of participants. Injection site reactions, all Grade 1, were observed in less than 5% of participants. PK was linear and approximately dose-proportional across the single-ascending-dose cohorts, and non-compartmental analysis of the interim data determined a half-life of 62 days, supporting dosing every three months or less frequently. Full PK and immunogenicity data from the ongoing multiple-ascending-dose cohorts will be available in the first half of 2027.

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Qyuns initiated its Phase 2 program including studies in atopic dermatitis and CRSwNP in September 2026 in the PRC and plans to begin a Phase 2 study in asthma by the end of the year. Topline results from these studies are expected over the course of 2027 and 2028.

Subject to the results of these initial dose-finding and proof-of-concept studies we will initiate Phase 3 studies in the indications with the highest probability of significantly shifting the treatment paradigm beyond currently existing single-pathway-targeting biologics.

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Consistent with our capital-efficient operating

Drug substance is currently produced at 200L scale using a modern, high-yielding antibody manufacturing process. The very efficient manufacturing process is employed to generate the bispecific antibody from two separately produced parent antibodies.

The drug product is a high concentration, preservative-free liquid filled into single-use glass vials, for which stability data support storage at standard refrigerated temperatures for extended time periods.

We are a clinical-stage biopharmaceutical company and

Consistent with our capital-efficient operating model, we do not own or operate and currently have no plans to establish any manufacturing facilities. All our drug development, manufacturing, storage, distribution and testing are outsourced to third-party manufacturers and facilities. Our manufacturing strategy enables us to more efficiently direct financial resources to the research, development, and commercialization of programs rather than diverting resources to internally develop and maintain manufacturing facilities. In parallel with the clinical development program, we are executing an integrated chemistry, manufacturing and controls, or CMC, strategy intended to provide robust and uninterrupted cGMP compliant supply of drug substance and drug product to support further global development of WIN378 and, if approved, commercial supply. Historical and current clinical trial material has been sourced from our partner, Kelun Biotech. We expect to complete the transfer of our drug substance and drug product manufacturing for WIN378 to U.S.-based contract manufacturers to support Phase 3 and commercial supply by the end of 2026. Drug substance is produced by our CDMO in the United States using an industry-standard monoclonal antibody manufacturing process that has been scaled to 2,000-liter single-use bioreactors, which can support anticipated clinical and launch volumes. The drug product is a high concentration, preservative-free liquid filled into single-use 2 mL glass vials, for which stability data support storage at standard refrigerated temperatures for extended time periods. A pre-filled syringe (PFS) presentation and an autoinjector are under development for later clinical and commercial use. Consistent with other biologics programs, we plan to complete process performance qualification for both drug substance and drug product, along with validation of analytical methods, in advance of any BLA submission in United States or any marketing application elsewhere.

Drug substance is produced by our CDMO in the United States using an industry-standard monoclonal antibody manufacturing process that has been scaled to 2,000-liter single-use bioreactors, which can support anticipated clinical and launch volumes. The drug product is a high concentration, preservative-free liquid filled into single-use 2 mL glass vials, for which stability data support storage at standard refrigerated temperatures for extended time periods. A pre-filled syringe (PFS) presentation and an autoinjector will be developed are under development for later clinical and commercial use. Consistent with other biologics programs, we plan to complete process performance qualification for both drug substance and drug product, along with validation of analytical methods, in advance of any BLA submission in the United States or any marketing application elsewhere.

Our commercial presentation strategy

Our commercial presentation strategy for WIN378 in severe asthma focuses on subcutaneous self- or clinician-administered formats. Our clinical trials are conducted using a vial & syringe presentation, and we plan to conduct, in parallel to Phase 3 studies, a bridging trial in healthy volunteers to demonstrate comparability between the vial and syringe presentation and a pre-filled syringe as well as an autoinjector. This bridging study is subject to completion of the necessary stability, human factors and device-related regulatory work for the PFS, and additional human factors studies and device performance testing for the autoinjector. From a regulatory perspective, we currently expect both the prefilled syringe and autoinjector presentations of WIN378 to be regulated as biologic–device combination products, with the biologic constituent part providing the primary mode of action. We anticipate pursuing approval under the BLA pathway, with device-related requirements addressed as part of the FDA's combination product review.

In parallel with the clinical development program, we are executing an integrated CMC strategy intended to provide robust and uninterrupted cGMP compliant supply of drug substance and drug product to support further global development of WIN027 and, if approved, commercial supply. Consistent with our capital-efficient operating model, we do not own or operate and currently have no plans to establish any manufacturing facilities. All our drug development, manufacturing, storage, distribution and testing are outsourced to third-party manufacturers and facilities. Currently, CellularForce (a Qyuns subsidiary) in Taizhou, China is producing Drug Substance, or DS, and Drug Product, or DP, for the initial clinical trials. Prior to pivotal trials, we expect to complete our DS and DP manufacturing transfer to reputable U.S.-based contract manufacturers to support Phase 3 and commercial supply. Drug substance is currently produced at 200L scale using a modern, high-yielding antibody manufacturing process. The very efficient manufacturing process is employed to generate the bispecific antibody from two separately produced parent antibodies. The drug product is a high concentration, preservative-free liquid filled into single-use glass vials, for which stability data support storage at standard refrigerated temperatures for extended time periods. A pre-filled syringe (PFS) presentation and an autoinjector will be developed for later clinical and commercial use. Consistent with other biologics programs, we plan to complete process performance qualification for both drug substance and drug product, along with validation of analytical methods, in advance of any BLA submission in the United States or any marketing application elsewhere.

Our commercial presentation strategy for

Our commercial presentation strategy for WIN027 focuses on subcutaneous self- or clinician-administered formats. Our initial clinical trials are conducted using a vial and syringe presentation, and we plan to introduce a pre-filled syringe as well as an autoinjector at a later stage, subject to completion of the necessary stability, human factors and device-related regulatory work for the PFS and the autoinjector. From a regulatory perspective, we currently expect both the prefilled syringe and autoinjector presentations of WIN027 to be regulated as biologic–device combination products, with the biologic constituent part providing the primary mode of action. We anticipate pursuing approval under the BLA pathway, with device-related requirements addressed as part of the FDA's combination product review.

We are a clinical-stage biopharmaceutical company and do not have any products approved for sale. We have not established a sales, marketing, or product-distribution organization and do not currently have commercial capabilities.

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Research and development is central to our

The biotechnology and biopharmaceutical industries are

Research and development is central to our business and is focused on advancing our pipeline of long-acting antibody product candidates, as described above under "Our pipeline" and the related program descriptions. Information regarding our research and development expenses is set forth in the section of this prospectus titled "Management's Discussion and Analysis of Financial Condition and Results of Operations."

biotechnology and biopharmaceutical industries are characterized by continuing technological advancement and significant competition. While we believe that our programs, technology, development experience and scientific knowledge provide us with competitive advantages, we face competition from major pharmaceutical and biotechnology companies, academic institutions, governmental agencies and public and private research institutions, among others. Any product candidates that we successfully develop and commercialize will compete with existing therapies and new therapies that may become available in the future. Many of the companies with which we are currently competing or will compete against in the future have significantly greater financial resources and expertise in research and development, manufacturing, nonclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industry may result in even more resources being concentrated among a smaller number of our competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites, patient enrollment for clinical trials as well as in acquiring technologies complementary to, or necessary for, our programs.

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WIN378 would compete with the approved products in asthma and COPD including short-acting anti-TSLP therapy. WIN378 may also compete with other ultra-long-acting anti-TSLP candidates in development. We believe WIN378 has a differentiated combination of attributes that other ultra-long-acting TSLPs do not have including: well-characterized pharmacology that supports twice-yearly dosing, a silenced effector function that minimizes potential inflammatory and autoimmune effects, better potency relative to the currently approved anti-TSLP treatment, differentiated binding properties whereby WIN378 binds to two different sites on the ligand of TSLP, and a low rate of injection site reactions.

We are aware of two ultra-long-acting products in

We are aware of two ultra-long-acting products in mid-to-late-stage development that have the potential to be dosed twice yearly: GB-0895 from Generate Biomedicines and GSK5784283 from GSK.

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WIN027 would compete with other bispecific candidates

WIN027 would compete with other bispecific candidates targeting TSLP and IL-13 (or related combinations). There are a number of bispecific antibodies that target both TSLP and IL-13 and at least one known long-acting bispecific that is in Phase 2, CM512/BEL512 from Keymed and Belenos Bio, who share rights to the program.

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We strive to protect and enhance the proprietary

We strive to protect and enhance the proprietary technology, inventions and improvements that are commercially important to the development of our business, including seeking, maintaining and defending patent rights, whether developed internally or licensed from third parties. We may also rely on trademarks, copyrights and trade secrets relating to our proprietary technology platform and on know-how, continuing technological innovation and in-licensing opportunities to develop, strengthen and maintain our proprietary and intellectual property position. We additionally may rely on regulatory and other protections afforded through data exclusivity, market exclusivity and patent term extensions, where available.

Our commercial success depends in part upon our ability to obtain and maintain patent and other proprietary protection for commercially important technologies, inventions and trade secrets related to our business, defend and enforce our intellectual property rights, particularly our patent rights, preserve the confidentiality of our trade secrets and operate without infringing valid and enforceable intellectual property rights of others.

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As of August 26, 2026, our owned and

As of August 26, 2026, our owned and licensed patent estate contains seven patent families, and includes one issued U.S. patent, two issued patents in Japan, thirty-one granted patents in Europe, one issued patent in Russia, as well as two pending U.S non-provisional patent applications, two pending U.S. provisional patent applications, two PCT applications, and twenty-one pending patent applications in various jurisdictions outside of the U.S. With respect to WIN378, we license one pending U.S. non-provisional patent application, two issued foreign patents (Japan and Russia) as well as eight foreign patent applications, which are pending in Australia, Europe, Japan, New Zealand, Canada, South Korea, Mexico, each of which is directed to anti-TSLP antibodies and compositions containing them. Unless extended, patents issuing in this family are expected to expire in 2040. We also license one pending patent application in the United States and ten foreign patent applications, which are pending in Australia, Brazil, Canada, Europe, Israel, India, Japan, South Korea, New Zealand, and Russia, each of which is directed to formulations containing an anti-TSLP antibody. Unless extended, any patents issuing in this family are expected to expire in 2044. We own one U.S. provisional patent application directed to methods of treatment, including treatment of COPD, and one U.S. patent provisional application directed to methods of treating asthma. Unless extended, any patents issuing in this family are expected to expire in 2047.

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In the United States, the term of a

In the United States, the term of a patent covering an FDA-approved drug may be eligible for a patent term extension under the Hatch-Waxman Act as compensation for the loss of patent term during the FDA regulatory review process. The period of extension may be up to five years beyond the expiration of the patent, but cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval. Only one patent among those eligible for an extension may be extended, and a given patent may only be extended once. Similar provisions are available in Europe and in certain other jurisdictions to extend the term of a patent that covers an approved drug. If our product candidates receive FDA approval, we intend to apply for patent term extensions, if available, to extend the term of patents that cover the approved product candidates. We also intend to seek patent term extensions in any jurisdictions where they are available, however, there is no guarantee that the applicable authorities, including the FDA, will agree with our assessment of whether such extensions should be granted, and even if granted, the length of such extensions.

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For additional information regarding intellectual property risks, see Part I, Item 1A, "Risk Factors—Risks Related to Our Intellectual Property."

In addition, we plan to rely on regulatory protection based on orphan drug exclusivities, data exclusivities, and market exclusivities. See the section titled "—Government Regulation" below for additional information.

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License and Collaboration

Agreement with Sichuan Kelun-Biotech and Harbour Biomed

License and Collaboration Agreement with Sichuan Kelun-Biotech and Harbour Biomed On December 31, 2024, we entered into a license and collaboration agreement with Sichuan Kelun-Biotech BioPharmaceutical Co., Ltd., or Kelun, and Harbour BioMed (Shanghai) Co., Ltd., or HBM, and such agreement, the Kelun-HBM Agreement. Under the Kelun-HBM Agreement, Kelun and HBM granted us an exclusive, worldwide, excluding certain Asian countries and territories, such excluded countries including Greater China, which are reserved to Kelun and HBM (collectively, the Retained Territory), sublicensable license under Kelun and HBM's interest in certain patents, know-how and inventions to manufacture, develop, use, promote, sell, offer for sale, import and otherwise commercialize WIN378 (also known as HBM9378/SKB378), an ultra-long-acting monoclonal antibody targeting thymic stromal lymphopoietin, developed by Kelun and HBM, or WIN378, and pharmaceutical products containing WIN378 as an active ingredient, WIN378 Products, in all fields of use. Kelun and HBM also granted us a non-exclusive, sublicensable license under such patents and know-how to manufacture and have manufactured WIN378 Products anywhere in the world, including the Retained Territory, solely for the purpose of exploiting WIN378 Products outside the Retained Territory. Under the Kelun-HBM Agreement, Kelun and HBM retain the right to develop and commercialize WIN378 Products in the Retained Territory. Without our mutual agreement, Kelun and HBM may not undertake certain development activities in the Retained Territory that could jeopardize patient safety or impact the commercial success of WIN378 in our Territory.

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On December 19, 2025, we entered into a license and collaboration agreement with Qyuns Therapeutics Co., Ltd., or Qyuns, and such agreement, the Qyuns Agreement.

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and 41 more changes in the filing

Management 27 changes

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The following table sets forth the name

name and position of each of our executive officers and directors, as well as their respective ages as of October 9, 2026.

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Omar Khwaja, M.D., Ph.D. Dr. Khwaja has served as our Chief Medical Officer since January 2025.

Omar Khwaja, M.D., Ph.D. Dr. Khwaja has served as our Chief Medical Officer since January 2025. Previously, Dr. Khwaja served as Chief Medical Officer at VectivBio Holding AG from May 2021 to June 2023, where he oversaw drug development and medicine, and Chief Medical Officer and Head of Research & Development at Voyager Therapeutics (Nasdaq: VYGR) from April 2019 to May 2021. Previously, from January 2013 to April 2019, he served as Global Head of Rare Diseases and Neuroscience Translational Medicine at F. Hoffmann-La Roche AG (OTC: RHHBY). Preceding Dr. Khwaja's industry experience in drug development, he practiced medicine and taught in academia for over a decade, including as Director of the Clinical Neurogenetics program at Boston Children's Hospital and as a member of faculty at Harvard Medical School. He is a fellow of the Royal College of Physicians, serves as a chair or member of a number of industry and foundation scientific or clinical advisory boards, and is also part of the advisory board for Pureos Bioventures. Dr. Khwaja received his M.D. and Ph.D. in Human Molecular Genetics from the University of Cambridge.

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Following the completion of the offering, our compensation

Our compensation committee will review and propose

propose to our board of directors our compensation principles as well as the compensation for the members of the board of directors, the Chief Executive Officer and other members of the executive committee. Pursuant to our articles of association, our compensation committee consists of no less than three members of our board of directors.

Following the completion of the offering, our compensation committee will consist of , and . will serve as chair of the compensation committee. Under Swiss law, the members of our compensation committee must be elected by our general meeting of shareholders and the aggregate amount of compensation of our board of directors and of our executive committee must be approved by our general meeting of shareholders, in each case commencing with our first annual general meeting of shareholders as a public company to be held in 2027. Our board of directors appoints the chair of the compensation committee and in case of any vacancies may appoint substitute members from among the members of the board of directors, in each case until completion of the next annual general meeting of shareholders.

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We will also reimburse our directors for their reasonable out-of-pocket expenses in connection with attending board and committee meetings.

reasonable out-of-pocket expenses in connection with attending board and committee meetings.

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Shares subject to share awards granted under our 2026 Plan

Shares subject to share awards granted under our 2026 Plan that expire or terminate without being exercised in full or that are paid out in cash rather than in shares will not reduce the number of shares available for issuance under our 2026 Plan. Shares withheld under an award to satisfy the exercise, strike or purchase price of a share award or to satisfy a tax withholding obligation will not reduce the number of shares available for issuance under our 2026 Plan. If any of our common shares issued pursuant to a share award are forfeited back to or repurchased or reacquired by us (i) because of a failure to meet a contingency or condition required for the vesting of such shares; (ii) to satisfy the exercise, strike or purchase price of a share award; or (iii) to satisfy a tax withholding obligation in connection with a share award, the shares that are forfeited or repurchased or reacquired will revert to and again become available for issuance under our 2026 Plan.

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Restricted Share Unit Awards . Restricted share unit awards are granted under restricted share unit award agreements adopted by the administrator. Restricted share unit awards may be granted in consideration for any form of legal consideration that may be acceptable to our board of directors and permissible under applicable law. A restricted share unit award may be settled by cash, delivery of shares, a combination of cash and shares as deemed appropriate by the administrator, or in any other form of consideration set forth in the restricted share unit award agreement. Additionally, dividend equivalents may be credited in respect of shares covered by a restricted share unit award. Except as otherwise provided in the applicable award agreement, or other written agreement between us and the recipient, restricted share unit awards that have not vested will be forfeited once the participant's continuous service ends for any reason.

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Changes to Capital Structure . In the event there is a

is a specified type of change in our capital structure, such as a share split, reverse share split, or recapitalization, appropriate adjustments will be made to (i) the class and maximum number of shares reserved for issuance under our 2026 Plan, (ii) the class and maximum number of shares by which the share reserve may increase automatically each year, (iii) the class and maximum number of shares that may be issued on the exercise of ISOs, and (iv) the class and number of shares and exercise price, strike price, or purchase price, if applicable, of all outstanding share awards.

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Corporate Transactions . Our ESPP provides that in

in the event of a corporate transaction (as defined in the ESPP), any then-outstanding rights to purchase our common shares under our ESPP may be assumed, continued, or substituted for by any surviving or acquiring entity (or its parent company). If the surviving or acquiring entity (or its parent company) elects not to assume, continue, or substitute for such purchase rights, then the participants' accumulated payroll contributions will be used to purchase our common shares within 10 business days, or such other period specified by our board of directors, before such corporate transaction, and such purchase rights will terminate immediately after such purchase.

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2025, 2026, options to purchase 127,400 2,109,516 of our common shares and 930,800 restricted shares were outstanding under our 2025 Plan, no 769,616 restricted share units were granted in under our 2025 plan, and 1,539,604 1,860,609 of our common shares remained available for future awards under our 2025 Plan.

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Acceptable consideration for the purchase of common shares issued upon the exercise of an option includes (i) payment of the exercise price in cash; (ii) in the sole discretion of our board of directors or the duly authorized committee of our board of directors, a cash settlement or net settlement of the option (the latter only following this offering); or (iii) in the sole discretion of our board of directors or the duly authorized committee of our board of directors, a cashless exercise (including a same day sale or sale-to-cover).

(ii) in the sole discretion of our board of directors or the duly authorized committee of our board of directors, a cash settlement or net settlement of the option (the latter only following this offering); or (iii) in the sole discretion of our board of directors or the duly authorized committee of our board of directors, a cashless exercise (including a same day sale or sale-to-cover).

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Upon a Change of Control, subject to the Shareholders'

Shareholders' Agreement (as defined in the 2025 Plan), participants have the right (and, if demanded by our board of directors, the obligation) to: (i) exercise all vested options (including those vesting solely due to the Change of Control) immediately prior to the effective date and sell the resulting shares to the acquiror at the change of control price of our common shares; (ii) sell all vested options directly to the acquiror at the change of control price of our common shares, which, in the case of an option, is equal to the applicable per-share transaction price less the exercise price of the option; and/or (iii) sell shares resulting from the vesting of vested restricted share units to the acquiror at the change of control price of our common shares.

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As noted above, no further awards will be granted under our 2025 Plan on or after the effectiveness of our 2026 Plan.

Plan Amendment or Termination . Our board of directors has the authority to amend, suspend, or discontinue our 2025 Plan at any time, provided that such action does not alter or impair the existing rights of any participant without such participant's consent unless required by mandatory law or such participant is fairly compensated by other grants or cash payments. Our board of directors may cancel outstanding awards and replace them with new awards based on the fair market value on the new grant date, provided the terms of a re-grant are not more favorable to the participants than the cancelled awards. As noted above, no further awards will be granted under our 2025 Plan on or after the effectiveness of our 2026 Plan.

2025 Restricted Share Purchase Agreements

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In March 2026, the Company

Company acquired all shares in Windward Bio 27 AG (formerly LE2025 Therapeutics AG) from its founding shareholders (all of whom are executive officers of the Company), to whom the Company, in consideration therefor, issued, in the aggregate, 3,399,466 common shares with a nominal value of CHF 0.01 each (the 2026 founder shares) by way of an ordinary share capital increase, which were fully paid up by way of contribution in kind ( Sacheinlage ) of all shares in Windward Bio 27 AG in the Company.

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Related party transactions 5 changes

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Prior to or in connection with this

this offering, we have entered, or intend to enter, as the case may be, into indemnification agreements with each of our directors and executive officers.

Furthermore, our articles of association contain provisions governing the indemnification of the members of our board of directors and of our executive committee to the extent not included in insurance coverage or paid by third parties and to the extent permitted by Swiss law. In addition, under general principles of Swiss employment law, an employer may be required to indemnify an employee against losses and expenses incurred by such employee in the proper execution of his or her duties under the employment agreement with the employer (see the sections of this prospectus titled "Management—Insurance and Indemnification" and "Comparison of Shareholder Rights under Swiss and Delaware Corporate Law—Indemnification of Directors and Executive Committee and Limitation of Liability").

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Prior to the completion of this offering,

completion of this offering, we expect to adopt a related party transaction policy. Our related party transaction policy will set forth our procedures for the identification, review, consideration and approval or ratification of related person transactions. The policy will become effective immediately upon the execution of the underwriting agreement for this offering. For purposes of our policy only, a related person transaction is a transaction, arrangement or relationship, or any series of similar transactions, arrangements or relationships, in which we or any of our subsidiaries and any related person are, were or will be participants in which the amount involved exceeds $120,000 or which is unusual in its nature or conditions. Transactions involving compensation for services provided to us as an employee or director are not covered by this policy. A related person is any executive officer, director or beneficial owner of more than 5% of any class of our voting securities, including any of their immediate family members and any entity owned or controlled by such persons.

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Principal stockholders 11 changes

The following table sets forth information with respect to the beneficial ownership of our common shares as of June September 30, 2026, and following the completion of the offering for:

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is determined in accordance with the rules of the SEC. These rules generally attribute beneficial ownership of securities to persons who possess sole or shared voting power or investment power with respect to those securities and include common shares issuable upon the exercise of options or settlement of restricted share units that are immediately exercisable within 60 days of June September 30, 2026. Percentage ownership calculations are based on 15,491,686 common shares, 31,897,927 Series A preferred shares, 5,582,139 Series A junior preferred shares, 15,948,971 Series B preferred shares, each outstanding as of June September 30, 2026 and rights to purchase or exercise additional convertible securities within 60 days of June September 30, 2026.

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Except as otherwise indicated in

As of June September 30, 2026, to our knowledge, common shares, representing % of our issued and outstanding shares, were held by U.S. shareholders of record, before giving effect to the re-designation of all of our issued and outstanding Series A Preferred shares, Series A junior preferred shares Share Conversion and the Series B preferred shares, into common shares on a 1 to 1 basis Warrant Settlement in connection with this offering.

Except as otherwise indicated in the table below, addresses of the directors, executive officers and named beneficial owners are in care of Windward Bio Group AG, Aeschenplatz 6, 4052 Basel, Switzerland.

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Bonita, a member of Advisors, is a member of the Company's board of directors. The address for the OPI IX entities is c/o OrbiMed Advisors LLC, 601 Lexington Avenue, 54 th Floor, New York, NY (3) Dr. Santarelli has a total of 7,112,939 common shares (including common shares issuable upon conversion of equity awards), consisting of (i) 6,867,158 common shares and (ii) options to purchase up to 245,781 common shares, of which 27,317 47,798 common shares are exercisable within 60 days of June September 30, 2026.

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Dr. D'Augusta has a total of 1,441,444 common shares (including common shares issuable upon conversion of equity awards), consisting of (i) 1,391,636 common shares and (ii) options to purchase up to 49,808 common shares, of which 5,552 9,701 common shares are exercisable within 60 days of June September 30, 2026.

Dr. Khwaja has a total of 1,441,444 common shares (including common shares issuable upon conversion of equity awards), consisting of (i) 963,200 common shares and (ii) options to purchase up to 478,244 common shares, of which 53,156 93,008 common shares are exercisable within 60 days of June September 30, 2026.

Mr. Harris has a total of 1,441,444 common shares (including common shares issuable upon conversion of equity awards), consisting of (i) 1,391,636 common shares and (ii) 49,808 restricted share units, of which 8,308 12,458 restricted share units are time vested and subject to liquidity event within 60 days of June September 30, 2026 and remain subject to a liquidity event.

Mr. Applebaum has a total of 1,441,444 common shares (including common shares issuable upon conversion of equity awards), consisting of (i) 1,391,636 common shares and (ii) 49,808 restricted share units, of which 8,308 12,458 restricted share units are time vested and subject to liquidity event within 60 days of June September 30, 2026 and remain subject to a liquidity event.

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Mr. Kapadia has a total of 150,000 restricted share units, of which 18,750 28,125 restricted share units are time vested and subject to liquidity event within 60 days of June September 30, 2026 and remain subject to a liquidity event.

Description of the securities 5 changes

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As of June 30, 2026, our share capital as registered in the

As of September 30, 2026, our share capital as registered in the commercial register of the Canton of Basel-Stadt, Switzerland, or the Commercial Register, amounts to CHF 689,714.23 and is divided into 68,971,423 registered shares ( Namenaktien ) with a nominal value of CHF 0.01 each, consisting of 15,542,386 common shares ( Stammaktien ), 31,897,927 Series A preferred shares ( Vorzugsaktien A ), 5,582,139 Series A junior preferred shares ( Vorzugsaktien A Junior ) and 15,948,971 Series B preferred shares ( Vorzugsaktien B ). The preferred shares provide for preferential rights with respect to dividend distributions and/or liquidation proceeds for the Series A preferred shares, the Series A junior preferred shares and the Series B preferred shares, as described in our articles of association. Each issued share is fully paid.

Immediately prior to the completion of

completion of this offering, (i) the then outstanding 31,897,927 Series A preferred shares, 5,582,139 Series A junior preferred shares and 15,948,971 Series B preferred shares will be converted on a 1:1 basis into common shares and (ii) common shares will be issued upon cashless exercise of the Series B Warrants. All shares will rank pari passu with each other and no preferred shares will be outstanding.

Upon the closing of this offering, based on the number of registered shares outstanding as of June September 30, 2026, the changes to our share capital occurring prior to the completion of this offering and described in the preceding paragraphs, based on an assumed initial public offering price of $ per share, which is the midpoint of the price range set forth on the cover page of this prospectus, our outstanding fully paid-in share capital will consist of common shares (or common shares if the underwriters exercise their option to purchase additional common shares in the offering in full), with a nominal value of CHF 0.01 each.

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Shares eligible for future sale 3 changes

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Based on the number of common shares outstanding as of June September 30, 2026, and assuming (1) no exercise of the underwriters' option to purchase additional common shares and (2) no exercise of any of our other outstanding options, we will have outstanding an aggregate of common shares following this offering. All of the common shares to be sold in the U.S. offering, and any common shares sold upon exercise of the underwriters' option to purchase additional common shares sold in the offering, will be freely tradable in the U.S. public market without restriction or further registration under the Securities Act, unless the common shares are held by any of our "affiliates" as such term is defined in Rule 144 of the Securities Act (subject, in each case, to the terms of the lock-up agreements referred to below, as applicable). The number of common shares available for sale immediately after this offering will be the number sold in the offering less any common shares held by our directors, officers and certain shareholders that are subject to lock-up agreements through 180 days after the date of this prospectus. The common shares held by existing shareholders are "restricted securities," as that term is defined in Rule 144 under of the Securities Act. Restricted securities may be sold in the United States on the Nasdaq Global Market only if registered or if their resale qualifies for exemption from registration described below under Rule 144 or Rule 701 promulgated under the Securities Act.

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1% of the number of common shares then outstanding, which will equal approximately common shares immediately after the consummation of the offering based on the number of common shares outstanding as of June September 30, 2026; or the average weekly trading volume of our common shares on the Nasdaq Global Market during the four calendar weeks preceding the filing of a notice on Form 144 with respect to the sale.

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Securities Act, as in effect on the date of this prospectus, permits resales of shares in reliance upon Rule 144 but without compliance with certain restrictions of Rule 144, including the holding period requirement. Most of our employees, executive officers or directors who purchased shares under a written compensatory plan or contract may be entitled to rely on the resale provisions of Rule 701, but all holders of Rule 701 shares are required to wait until 90 days after the date of this prospectus before selling their shares. However, substantially all Rule 701 shares are subject to lock-up agreements as described below above and in the section of this prospectus titled "Underwriting" and will become eligible for sale upon the expiration of the restrictions set forth in those agreements.

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Swiss tax implications for our holders 2 changes

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Facilitation of the Implementation of the U.S. Foreign Account Tax Compliance Act, or FATCA Switzerland has concluded an intergovernmental agreement with the United States to facilitate the implementation of FATCA. The agreement ensures that the accounts held by U.S. persons with Swiss financial institutions are disclosed to the U.S. tax authorities either with the consent of the account holder or by means of group requests within the scope of administrative assistance. Information will not be transferred automatically in the absence of consent, and instead will be exchanged only within the scope of administrative assistance on the basis of the double taxation agreement between the United States and Switzerland. In this regard, on July 17, 2019, the U.S. Senate approved the 2009 protocol, or the Protocol, amending the double taxation agreement regarding income tax between Switzerland and the United States, or the amended DTA. The Protocol had been approved by the Swiss Federal Assembly on June 18, 2010. On September 20, 2019, Switzerland and the United States exchanged the instruments of ratification of the Protocol.

of the Implementation of the U.S. Foreign Account Tax Compliance Act, or FATCA Switzerland has concluded an intergovernmental agreement with the United States to facilitate the implementation of FATCA. The agreement ensures that the accounts held by U.S. persons with Swiss financial institutions are disclosed to the U.S. tax authorities either with the consent of the account holder or by means of group requests within the scope of administrative assistance. Information will not be transferred automatically in the absence of consent, and instead will be exchanged only within the scope of administrative assistance on the basis of the double taxation agreement between the United States and Switzerland. In this regard, on July 17, 2019, the U.S. Senate approved the 2009 protocol, or the Protocol, amending the double taxation agreement regarding income tax between Switzerland and the United States, or the amended DTA. The Protocol had been approved by the Swiss Federal Assembly on June 18, 2010. On September 20, 2019, Switzerland and the United States exchanged the instruments of ratification of the Protocol. With the exchange of the ratification instruments, the amended DTA formally entered into force. The Protocol introduces a mechanism for the exchange of information upon request in tax matters between Switzerland and the United States, which is in line with international standards, and allows the United States to make group requests under FATCA concerning non-consenting U.S. accounts and non-consenting non-participating foreign financial institutions. On June 27, 2024, Switzerland and the United States signed a new intergovernmental agreement to facilitate the implementation of FATCA that will change the current direct-notification-based regime to a regime where the relevant information is sent to the Swiss Federal Tax Administration, which in turn provides the information to the U.S. tax authorities. In Switzerland, the implementation of the new intergovernmental agreement requires an amendment to national law, which will be decided by the Swiss Federal Assembly. According to communication from the State Secretariat for International Finance, such amendment is currently expected to enter into force in Switzerland on January 1, 2029, at the earliest.

Plan of distribution 11 changes

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In addition, the foregoing restrictions shall not apply to the establishment or amendment of a written trading plan meeting the requirements of Rule 10b5-1 under the Exchange Act relating to the transfer, sale or other disposition of common shares or related securities, provided that no transfers, sales or other dispositions of common shares or related securities occur during the Lock-up Period and any public disclosure, announcement or filing under the Exchange Act made by us or any person regarding the establishment or amendment of such plan during the Lock-up Period shall include a statement that the securityholder is not permitted to transfer, sell or otherwise dispose of securities under such plan during the Lock-up Period in contravention of the lock-up agreement, and any no public announcement shall be voluntarily made regarding the establishment or amendment of such plan during the Lock-up Period.

Jefferies LLC, TD Securities (USA) LLC and Piper Sandler

Sandler & Co. may, in their sole discretion and at any time or from time to time before the termination of the 180-day period release all or any portion of the securities subject to lock-up agreements. There are no existing agreements between the underwriters and any of our shareholders who will execute a lock-up agreement, providing consent to the sale of common shares prior to the expiration of the Lock-up Period.

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The above selling restriction is in addition to any other

any other selling restrictions set out below.

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No common shares have been offered or sold, and no common shares may be offered or sold, in Hong Kong, by means of any document, other than to persons whose ordinary business is to buy or sell shares or debentures, whether as principal or agent; or to "professional investors" as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong (the SFO), and any rules made under that Ordinance; or in other circumstances which do not result in the document being a "prospectus" as defined in the Companies Ordinance (Cap. 32) of Hong Kong (the CO), or which do not constitute an offer or invitation to the public for the purpose of the CO or the SFO. No document, invitation or advertisement relating to the common shares has been issued or may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted under the securities laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" as defined in the SFO and any rules made under that Ordinance.

or in other circumstances which do not result in the document being a "prospectus" as defined in the Companies Ordinance (Cap. 32) of Hong Kong (the CO), or which do not constitute an offer or invitation to the public for the purpose of the CO or the SFO. No document, invitation or advertisement relating to the common shares has been issued or may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted under the securities laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" as defined in the SFO and any rules made under that Ordinance.

This prospectus has not

prospectus has not been registered with the Registrar of Companies in Hong Kong. Accordingly, this prospectus may not be issued, circulated or distributed in Hong Kong, and the common shares may not be offered for subscription to members of the public in Hong Kong. Each person acquiring the common shares will be required, and is deemed by the acquisition of the common shares, to confirm that he is aware of the restriction on offers of the common shares described in this prospectus and the relevant offering documents and that he is not acquiring, and has not been offered any common shares in circumstances that contravene any such restrictions.

Each person acquiring the common shares will be required,

and is deemed by the acquisition of the common shares, to confirm that he is aware of the restriction on offers of the common shares described in this prospectus and the relevant offering documents and that he is not acquiring, and has not been offered any common shares in circumstances that contravene any such restrictions.

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Index to condensed consolidated interim financial statements 8 changes

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As permitted by Regulation S-K, Item 601(b)(10)(iv) of the Securities Exchange Act of 1934, as amended, certain confidential portions of this exhibit have been redacted from the publicly filed document. The Registrant agrees to furnish a supplemental copy of any omitted schedule or similar attachment to the Securities and Exchange Commission upon its request.

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Previously submitted.

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Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form F-1 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in , Basel, Switzerland on this 23rd day of October, 2026.

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/s/ Claudia D'Augusta

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/s/ Timothy Anderson

/s/ Naveed I. Siddiqi

/s/ Otello Stampacchia

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Pursuant to the requirements of the Securities Act of 1933, the undersigned, the duly authorized representative in the United States of the registrant has signed this registration statement, on , October 23, 2026.

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