GSK to acquire RAPT Therapeutics in strategic push into long-acting food allergy biologics

GSK plc has signed a definitive agreement to acquire RAPT Therapeutics Inc., a clinical-stage biotechnology company focused on inflammatory and immunologic diseases, for approximately $2.2 billion in equity value. The deal brings GSK full global rights, excluding Greater China, to ozureprubart, a long-acting anti-IgE monoclonal antibody currently in Phase 2b development for food allergy prevention. The acquisition builds on GSK’s immunology strategy by adding a differentiated pipeline candidate with extended dosing potential and high relevance in a large unmet market.

Ozureprubart is being studied for its ability to prevent food-allergic reactions with a quarterly injection schedule. Current standard-of-care anti-IgE therapies typically require administration every two to four weeks. GSK’s management highlighted that the acquisition aligns with the company’s commitment to de-risked pipeline additions focused on validated mechanisms of action and commercially meaningful differentiation. The transaction is expected to close in the first quarter of 2026.

Why GSK is betting on quarterly anti-IgE dosing to reshape food allergy care

GSK’s pursuit of ozureprubart represents a calculated move to address a well-validated but still underserved therapeutic space. Immunoglobulin E, or IgE, plays a central role in triggering severe allergic reactions, including life-threatening anaphylaxis. Existing anti-IgE therapies such as omalizumab have shown efficacy in allergic asthma and food allergy, but their frequent dosing schedules pose significant compliance challenges, particularly in pediatric populations.

Ozureprubart is designed to bind and neutralize IgE with a half-life that supports dosing intervals of up to twelve weeks. In a therapeutic area where 94 percent of severe reactions are IgE mediated and where real-world persistence rates are poor due to injection burden, this profile could significantly expand both adherence and eligibility. GSK has estimated that as many as 25 percent of patients with food allergies are currently ineligible for existing anti-IgE therapies.

The company plans to position ozureprubart as a prophylactic treatment for both adult and pediatric populations. The ongoing prestIgE Phase 2b trial is evaluating the drug as monotherapy. Topline data from this study is expected in 2027. If successful, the asset could proceed to pivotal trials targeting both high-risk populations and segments currently underserved by biologics.

How the RAPT Therapeutics acquisition fits into GSK’s capital allocation priorities

The acquisition of RAPT Therapeutics follows a disciplined pattern seen across GSK’s recent M&A activities. Rather than making large, platform-centric buys, the company has increasingly favored bolt-on deals focused on single assets or targeted franchises. These transactions have typically involved pipeline programs with either late-stage potential or strong mechanistic validation.

The $2.2 billion valuation for RAPT Therapeutics includes a per-share cash payment of $58. After accounting for cash on RAPT’s balance sheet, GSK’s estimated net outlay is $1.9 billion. This marks a substantial but measured investment for a company with ongoing balance sheet flexibility following its Haleon consumer health spinout. GSK has stated that it will account for the transaction as a business combination, and the deal structure includes a standard tender offer followed by a second-step merger under Delaware law.

From a pipeline perspective, ozureprubart adds to GSK’s respiratory, inflammation and immunology franchise, which has been under active buildout. Other recent acquisitions, including Bellus Health and Aiolos Bio, have similarly aimed at extending GSK’s competitive presence in immune-mediated diseases where durable response and patient quality of life are critical endpoints.

Understanding the competitive landscape for anti-IgE therapies and where ozureprubart fits

The anti-IgE treatment space has long been dominated by omalizumab, marketed by Genentech as Xolair. Although Xolair is approved for allergic asthma and chronic idiopathic urticaria, its use in food allergies is currently off-label. GSK appears to be positioning ozureprubart for label-seeking indications with clearer FDA-approved pathways, which could include both food and environmental allergies.

The company’s core differentiation claim centers on extended dosing. If ozureprubart can deliver similar or superior protection against anaphylaxis with four injections per year, it could become a preferred option among caregivers, patients and health systems. Compliance challenges in pediatric allergy are well documented, and quarterly dosing could increase treatment uptake significantly.

However, ozureprubart will face competition not only from omalizumab biosimilars but also from new modalities in development. These include oral immunotherapy approaches, sublingual tablets, microbiome modulation, and T-cell targeted agents. Each comes with tradeoffs in terms of risk profile, dosing complexity, and immune tolerance durability.

GSK’s commercial advantage lies in its global allergy infrastructure. The company already maintains strong primary care and specialty networks for respiratory conditions. Leveraging these for ozureprubart could accelerate physician adoption, particularly in Europe and North America, where food allergy prevalence is rising.

What makes ozureprubart a strategic asset with beyond-food-allergy potential

While the current acquisition centers on food allergy, ozureprubart’s mechanism opens the door to broader application. IgE is a relevant target in other allergic and inflammatory diseases, including chronic rhinosinusitis with nasal polyps, atopic dermatitis, and allergic bronchopulmonary aspergillosis. These conditions often require long-term management and have significant quality-of-life burdens.

By investing in a long-acting anti-IgE platform, GSK may be creating optionality for label expansions or new indications that could further de-risk the asset’s commercial potential. The transaction also includes continued development obligations and royalty payments to Shanghai Jeyou Pharmaceutical Co. Ltd, which retains rights to ozureprubart in mainland China, Macau, Taiwan, and Hong Kong.

These regional carve-outs suggest that GSK sees a strategic opportunity to concentrate on high-income allergy markets, where biologics uptake is stronger and reimbursement frameworks for chronic immunologic treatments are well established.

What risks could delay or diminish the value of this acquisition for GSK

Despite its scientific promise, ozureprubart remains a pre-pivotal asset. The Phase 2b prestIgE study will not read out until 2027, leaving a multi-year clinical and regulatory path before any potential commercial launch. There is no guarantee that quarterly dosing will yield equal or superior efficacy to current anti-IgE therapies, and trial designs will need to be sensitive to cross-allergen protection, pediatric tolerability, and real-world effectiveness.

Moreover, as biologic competition intensifies, payer scrutiny on price and differentiation will increase. GSK will need to demonstrate not only non-inferiority but compelling value in terms of fewer emergency visits, reduced caregiver burden, and improved adherence metrics.

Integration is another area of potential execution risk. RAPT Therapeutics is a clinical-stage company with focused operations. GSK must ensure continuity of scientific and operational leadership to avoid disruptions in trial progress. The value of the acquisition depends heavily on seamless progression through late-stage development and early commercial buildout.

Lastly, market perception around the transaction may be shaped by broader sentiment on GSK’s R&D productivity. Institutional investors have responded cautiously but favorably to the company’s more focused capital strategy. Still, the ozureprubart bet will be judged by outcomes and long-term impact on growth, not just headline price.

How this move may influence broader sector behavior in allergy and inflammation

GSK’s acquisition of RAPT Therapeutics may also set off ripple effects across the biopharmaceutical sector. As large pharmaceutical companies seek to deepen their pipelines in immune-related diseases, validated targets like IgE offer a compelling middle ground between novelty and risk mitigation. Rivals such as Sanofi, Bristol Myers Squibb, and AstraZeneca may now accelerate their own search for mid-stage immunology assets with platform or indication expansion potential.

The food allergy space, once neglected due to complex immunopathology and trial design challenges, is now emerging as a focal point of biopharma investment. Regulatory openness to surrogate endpoints and preventive trials, combined with payer willingness to reimburse biologics that reduce emergency care use, has improved the economics of development.

If ozureprubart succeeds, it could become the first biologic specifically approved for food allergy prevention with a quarterly dosing schedule. That would not only be a milestone for GSK but also a validation of long-acting immunomodulation as a commercially viable path in allergic diseases.

What comes next for GSK and ozureprubart after deal closure

Pending regulatory approvals and satisfaction of customary closing conditions, GSK expects to complete the acquisition in the first quarter of 2026. A tender offer for all outstanding RAPT Therapeutics shares will be followed by a second-step merger under Delaware law.

Once the transaction closes, GSK will assume full development and commercialization responsibility for ozureprubart outside of China and related territories. The prestIgE Phase 2b trial is already underway, with the next key milestone being its 2027 data readout.

In parallel, GSK is likely to initiate planning for pivotal Phase 3 trials in both adult and pediatric populations. Manufacturing scale-up, regulatory engagement, and health economics modeling will be essential in the coming two years to prepare for potential launch.

For investors and competitors, the next signal to watch will be whether GSK initiates expanded indication studies or begins to integrate ozureprubart into its broader immunology launch strategy. Either path would confirm the asset’s centrality to GSK’s next-generation inflammation portfolio.

Key takeaways on GSK’s $2.2 billion acquisition of RAPT Therapeutics and ozureprubart

• GSK is acquiring RAPT Therapeutics for $2.2 billion to gain global rights to ozureprubart, a Phase 2b anti-IgE antibody for food allergy.

• Ozureprubart offers the potential for 12-week dosing, addressing compliance and eligibility gaps in existing IgE therapies.

• The deal strengthens GSK’s respiratory and immunology pipeline with a validated mechanism and late-stage asset.

• Approximately 94 percent of severe food allergies are IgE-mediated, making ozureprubart a clinically targeted play.

• Data from the ongoing prestIgE Phase 2b study is expected in 2027, aligning with GSK’s medium-term pipeline strategy.

• GSK’s capital allocation strategy continues to favor de-risked innovation with clear unmet need and path to commercialization.

• Execution risk remains tied to regulatory trial design, pediatric safety profiles, and real-world performance benchmarks.

• The acquisition excludes Greater China, where RAPT’s partner Shanghai Jeyou Pharmaceutical retains regional rights.

• Competitors in allergy biologics may face pressure to innovate on dosing schedules or expand eligible patient populations.

• Investors will view the deal as a medium-horizon catalyst with sentiment linked to 2027 readout and long-term immunology leadership.