The star of the acquisition, anti-IgE antibody ozureprubart, is being tested as a prophylactic treatment for food allergies, potentially setting up a competition for GSK with Roche’s Xolair.
The first major business play of new GSK CEO Luke Miels’s tenure is the $2.2 billion acquisition of RAPT Therapeutics, a deal centered on an investigational antibody that could position the company as a new player in the food allergy arena.
Under the terms of the agreement, GSK is scooping up all outstanding shares of RAPT for $58 apiece in cash, according to the pharma’s announcement early Tuesday morning. Taking into account cash it will get as part of the buyout, GSK’s upfront net investment will amount to $1.9 billion.
At $57.50, RAPT is up 63.8% in pre-market trading Tuesday from its previous closing price of $35.10.
The star of the takeover is ozureprubart, an investigational long-acting anti-IgE monoclonal antibody being proposed as a prophylactic treatment for food allergies. Around 94% of severe food allergies are linked to IgE reactions, GSK said in its news release on Tuesday, adding that IgE is a validated target shown to elicit protection against allergic and inflammatory responses.
Compared with other anti-IgE agents, which need to be injected every two to four weeks, ozureprubart is designed for dosing once every 12 weeks, a profile the pharma said supports “improved compliance and patient outcomes.”
In October last year, RAPT launched the Phase IIb prestIgE study to test ozureprubart in patients with food allergies. Data from this study is expected in 2027, according to Tuesday’s release.
Aside from food allergies, RAPT is also testing ozureprubart for chronic spontaneous urticaria. Topline data presented in October 2025 showed that a dose every 12 weeks significantly reduced urticaria activity at weeks 8 through 16.
With ozureprubart, GSK will be primed to challenge Roche and its IgE blocker Xolair, which in February 2024 became the first FDA-approved therapy to reduce allergic reactions, including anaphylaxis, caused by food. A month later, Roche released data from the Phase III OUtMATCH trial, which compared Xolair against oral immunotherapy and found that it elicited significantly better tolerance to peanuts and two other food allergens.
Xolair brought in almost 2.23 billion Swiss francs—or around $2.82 billion—in the first nine months of 2025. This revenue figure also takes into account the drug’s other indications, including allergic asthma, chronic hives and chronic rhinosinusitis with nasal polyps.
The deal comes just three weeks into Miels’ tenure atop GSK. He was appointed CEO in September last year and officially took the reins on Jan. 1. He succeeds Emma Walmsley, who became pharma’s first woman CEO in 2017 and who led the pharma for nine years.
