British pharmaceutical giant GSK has entered an agreement to acquire US-based clinical-stage biopharmaceutical company RAPT Therapeutics for around USD2.2 billion. A&O Shearman, Cooley and Lang Yue Law Firm provided legal support.
A key asset in the acquisition is ozureprubart, a long-acting anti-IgE monoclonal antibody initially developed by Chinese company Jeyou Pharmaceutical. The drug, currently in phase IIb clinical development, is designed to prevent allergic reactions to food.
In December 2024, RAPT struck an agreement with Jeyou Pharmaceutical to obtain global development and commercialisation rights to the antibody JYB1904 (ozureprubart) outside the Chinese mainland, Hong Kong, Macau and Taiwan. RAPT agreed to pay an upfront fee of USD35 million, with potential milestone payments and future sales-based royalties totalling up to USD673 million.
Under the terms of the latest agreement, GSK will acquire all outstanding RAPT common shares for USD58 apiece in cash, representing a premium of around 65% above the company’s share price prior to the acquisition. On completion, GSK will obtain full development and commercialisation rights to ozureprubart outside the Chinese mainland, Hong Kong, Macau and Taiwan, and will assume the associated payment obligations to Jeyou Pharmaceutical.
A&O Shearman acted as GSK’s legal counsel, with M&A partners George Karafotias and Matthew Appleton leading the team, and support from M&A partner Beth Troy. Partner Brian Jebb advised on employment and compensation matters. Partners Nigel Parker, Alex Touma and Jill Ge supported intellectual property matters. Partner Jessica Delbaum and counsel Jessica Bowring advised on antitrust matters, while partner Larry Crouch counselled on tax matters.
Lang Yue Law Firm, A&O Shearman’s joint operation partner in China, advised GSK on PRC data compliance and corporate matters, and assisted with cross-border implementation. The team included senior counsel Jane Jiang and counsel Paul Jing.
Cooley acted as RAPT’s legal counsel, led by partners Jamie Leigh, Bill Roegge, Lindsey O’Crump and Courtney Tygesson.
The acquisition will be executed through a tender offer followed by a merger and is expected to be completed in the first quarter of 2026.
Jeyou Pharmaceutical, founded in Shanghai, recently closed a series A financing round, raising close to RMB2 billion (USD288 million).
