A&O Shearman advises GSK on USD2.2 billion acquisition of RAPT Therapeutics

The acquisition includes ozureprubart, a potentially best-in-class, long-acting anti-IgE monoclonal antibody, currently in phase IIb clinical development for prophylactic protection against food allergens. 

Current anti-IgE treatment for food allergies involves injections every 2 to 4 weeks, which can be a significant burden, particularly since most patients are children. Ozureprubart’s clinical profile offers the potential for less frequent dosing every 12 weeks, supporting improved compliance and patient outcomes; as well as providing a new option to approximately 25% of patients currently ineligible for existing therapy. Ozureprubart complements GSK’s extensive commercial footprint and prescriber base in allergy. 

Under the terms of the agreement, GSK will commence a tender offer to acquire all outstanding shares of RAPT common stock for USD58 per share in cash, representing an estimated upfront investment (net of cash acquired) by GSK of USD1.9bn. Closing is expected in Q1 2026, subject to customary closing conditions. 

The A&O Shearman team advising GSK is led by M&A partners George Karafotias (New York) and Matthew Appleton (London), with New York M&A partner Beth Troy and associates Andrew Calamari, Lucy Chen, and Roy Ji.  

Employment and benefits advice is provided by partner Brian Jebb and associates Gina Marini and Alexandra Kasper. Intellectual property advice is provided by partners Nigel Parker, Alex Touma and Jill Ge, and senior associate Megan McMellon. Antitrust advice is provided by partner Jessica Delbaum, counsel Jessica Bowring, and associate Regina Loureiro. Tax advice is provided by partner Larry Crouch, and associate Brandon Fawbush.