GSK to Acquire RAPT Therapeutics in $2.2 Billion Deal for Promising Food Allergy Drug

GSK strikes $2.2 billion deal for RAPT Therapeutics and a long-acting food allergy antibody

GSK has signed a definitive agreement to acquire RAPT Therapeutics for $58.00 per share, valuing the equity at an estimated $2.2 billion. Net of cash acquired, the upfront investment is $1.9 billion. Closing is targeted for the first quarter of 2026, via a tender offer followed by a second-step merger.

The prize here is ozureprubart, a long-acting anti-IgE monoclonal antibody being developed to prevent food allergy reactions before they happen. It sits squarely in GSK’s Respiratory, Immunology & Inflammation pipeline and plays to the company’s established allergy prescriber base.

Ozureprubart: a long-acting anti-IgE with 12-week dosing potential

IgE (immunoglobulin E) is a clinically validated target for allergic disease and is currently the only approved systemic route shown to protect patients from harmful allergic and inflammatory responses. The RNS notes that around 94% of severe food allergies are IgE-mediated.

Today’s anti-IgE options for food allergy typically require injections every 2 to 4 weeks. Ozureprubart aims to stretch that to every 12 weeks. That matters for two reasons: it could improve adherence and outcomes, and it may open the door to approximately 25% of patients who are currently ineligible for existing therapy.

“Prophylactic” simply means preventative. If ozureprubart’s profile holds up, it could provide sustained protection against food allergens with far fewer injections, which is especially relevant given most patients are children.

Why less frequent dosing is a big deal

Fewer injections means less burden on families and clinics, fewer missed doses, and potentially better real-world outcomes. GSK’s Chief Scientific Officer, Tony Wood, pitches ozureprubart as a “potential best-in-class” option aligned with GSK’s strategy to acquire assets addressing validated targets with clear unmet need.

RAPT’s CEO, Brian Wong, highlights the benefit of GSK’s global development and commercial infrastructure – exactly what you want behind a large, long-acting antibody in a high-need category.

The food allergy burden is large and growing

The RNS underscores the scale of unmet need in the US alone:

Diagnosed with food allergies (US)	Over 17 million people
People with severe reactions (US)	More than 1.3 million
Annual hospital and emergency visits	More than 3 million
Severe patients who are children/adolescents	65%
Share of severe food allergies that are IgE-mediated	Around 94%
Estimated family cost in 2024 (US)	$33 billion

That combination of scale, severity and cost creates a clear commercial rationale for a durable, preventative therapy with a convenient dosing schedule.

Clinical status and next milestones for ozureprubart

Ozureprubart is in phase IIb (the prestIgE study) as monotherapy, with data expected in 2027. Phase III trials are planned to target at-risk adult and paediatric populations. In short: a meaningful clinical catalyst in 2027, followed by pivotal studies aimed at the groups who need protection most.

As ever, clinical development is where the value will be earned or lost. The RNS does not disclose efficacy or safety data at this stage. Investors should recognise the timing – there is a multi-year runway to pivotal data and any regulatory filings thereafter.

Deal structure, rights and closing conditions

• Consideration: $58.00 per share, estimated equity value of $2.2 billion; $1.9 billion upfront net of cash acquired.
• Rights: Global rights to the ozureprubart programme, excluding mainland China, Macau, Taiwan and Hong Kong.
• Partner economics: GSK will be responsible for success-based milestone and royalty payments owed to Shanghai Jeyou Pharmaceutical Co., Ltd.
• Process: A tender offer will start within 10 business days of signing, followed by a second-step merger under Delaware law at the same price for any untendered shares.
• Regulatory: The deal requires expiration or termination of the Hart-Scott-Rodino waiting period in the US.
• Accounting: GSK will account for the transaction as a business combination.
• Expected close: First quarter of 2026.

Quick glossary: A “tender offer” is when a buyer offers to purchase shares directly from shareholders, typically at a premium. The “Hart-Scott-Rodino Act” requires US antitrust clearance before closing. A “business combination” is standard accounting for an acquisition.

Key deal numbers at a glance

Per-share price	$58.00
Estimated equity value	$2.2 billion
Upfront net of cash acquired	$1.9 billion
Tender offer launch window	Within 10 business days of signing
Expected closing	Q1 2026
Lead asset	Ozureprubart (anti-IgE mAb), phase IIb
Phase IIb readout timing	2027 (prestIgE study)
Geographic rights carve-out	Mainland China, Macau, Taiwan, Hong Kong

Why this matters for GSK shareholders

On the positive side, this is a clear, strategic bet on a validated biology with a meaningful twist – 12-week dosing and potential access for patients currently shut out of existing options. It fits GSK’s commercial footprint in allergy and enhances its Respiratory, Immunology & Inflammation pipeline with a large addressable need.

The flip side is timing and execution risk. Clinical proof is still in front of us, with phase IIb data not due until 2027 and pivotal trials thereafter. The deal also carries standard closing conditions and responsibilities for milestones and royalties to a partner. The RNS does not disclose expected financial impact on earnings or any revenue projections.

What to watch next

• Launch of the tender offer and filing of the Schedule TO, followed by RAPT’s Schedule 14D-9.
• HSR antitrust review in the US and other customary closing conditions.
• Transaction closing in Q1 2026.
• Clinical updates on ozureprubart, including the prestIgE phase IIb readout expected in 2027 and the design of planned phase III trials in at-risk adult and paediatric populations.

Bottom line

GSK is buying a potentially best-in-class anti-IgE antibody with a standout dosing profile in a disease area crying out for durable, preventative options. If ozureprubart delivers on its 12-week promise, it could reshape how high-risk patients manage food allergies – and GSK has the infrastructure to take it global.

The opportunity is big, the timeline is measured, and the usual clinical and regulatory hurdles apply. For now, this looks like a disciplined pipeline build against a validated target with clear unmet need, with 2027 shaping up as the first major data waypoint.