Shares in RAPT Therapeutics Inc (NASDAQ:RAPT) soared 63.6% on Tuesday after pharmaceutical major GSK plc (LSE:GSK) said it plans to acquire the company in an all-cash deal priced at $58 per share, valuing RAPT at approximately $2.2 billion.
The proposed acquisition would give GSK control of RAPT’s food allergy pipeline, led by ozureprubart, an anti-IgE monoclonal antibody currently in Phase IIb development for the prevention of reactions to multiple food allergens, including peanut, milk, egg, cashew and walnut.
GSK pointed to several potential advantages of ozureprubart versus existing therapies such as Xolair, notably a longer dosing interval of every 8–12 weeks compared with Xolair’s 2–4 week schedule. The company also said the drug could be suitable for patients with higher IgE levels or greater body weight who are not eligible for Xolair. In addition, GSK noted that ozureprubart has four times higher binding affinity than Xolair and is capable of removing bound IgE.
Food allergies represent a sizeable commercial opportunity, with more than 17 million diagnosed patients in the United States, including around 6 million children. Roughly 40% of sufferers are allergic to more than one food, and about half have experienced severe allergic reactions.
Top-line results from ozureprubart’s Phase IIb prestIgE trial are expected in 2027. The asset has also delivered encouraging Phase II data in China for Chronic Spontaneous Urticaria, where it showed numerically stronger responses than Xolair following a single dose.
The transaction excludes rights in mainland China, Macau, Taiwan and Hong Kong. After adjusting for RAPT’s existing cash, the net value of the deal is estimated at around $1.9 billion.
Separately, GSK announced that Shionogi & Co will purchase Pfizer’s 11.7% stake in ViiV Healthcare for $2.125 billion. The transaction will lift Shionogi’s holding to 21.7%, while GSK retains its majority stake of 78.3%.