GSK grows in immunology, acquires Rapt Therapeutics, food allergy drugs in $2.2B deal
GlaxoSmithKline's business in immunology and inflammation is primarily focused on respiratory drugs, but the company has been expanding its reach through commercial deals. The pharmaceutical giant is now increasing the risk of food allergies with its $2.2 billion acquisition of Rapt Therapeutics. Rapt Therapeutics is a biotech company whose lead program offers potential dosing and efficacy advantages over blockbuster products marketed by two of GSK's Big Pharma peers.
GlaxoSmithKline will pay $58 per share in cash for Rapt shares, a 65.2% premium to the stock's closing price on Friday, according to financial terms announced on Tuesday. When South San Francisco-based Rapt went public in 2019, its shares were priced at $12 per share.
Rapt drug ozureprubart is a monoclonal antibody designed to inhibit immunoglobulin E (IgE), a type of antibody produced in large amounts by the body in response to allergens. One anti-IgE antibody drug is already available for food allergy patients, omalizumab, which is injected every two to four weeks. The drug was first approved in 2003 to treat moderate to severe asthma. The FDA approved the antibody in 2024 to treat food allergy, the latest in a series of immunological indications for the blockbuster product, marketed under the Xolair brand name by Roche subsidiary Genentech and partners at Novartis. Roche, which records sales of the drug in the United States, reported revenue of 2.4 billion Swiss francs ($3.1 billion) for Xolair across all its approved indications.
Rapt's ozureprubart (formerly RPT904) was developed by making targeted changes to the omalizumab sequence to extend its half-life and improve its drug-like properties. This long-acting antibody can be administered every 12 weeks to protect against food allergens. Phase 2b testing of ozureprubart as monotherapy is underway, targeting 100 participants aged 12 to 55 years with established food allergies. Placebo-controlled studies test doses every 8 or 12 weeks; data are expected next year.
Leerink Partners analyst Thomas Smith wrote in a note to investors that the drug Rapt shows best-in-class potential in treating IgE-mediated diseases. Among them, he said, is food allergy, a huge business opportunity for the approximately 17 million diagnosed patients in the United States, providing ample room for new options with better efficacy and less frequent medication. Smith added that the drug Rapt may be able to treat patients with elevated baseline IgE levels who are not candidates for Xolair. Leerink believes there is no overlap in specific indications with GSK's immunology pipeline, reducing the regulatory risk of completing the acquisition.
“Overall, we believe the acquisition of RAPT is a strong strategic fit for GlaxoSmithKline, which can leverage its respiratory, immunology and inflammation (RI&I) expertise, combined with its broad commercial infrastructure, to unlock potentially multiple blockbuster opportunities for ozureprubart in food allergy and other IgE-mediated indications,” Smith wrote. “We believe the transaction is likely to be a competitive process involving multiple bidders, but the possibility of future competitive bidding cannot be ruled out.”
GlaxoSmithKline said the Rapt drug builds on its experience and expertise in inflammation and immunology, and also fits in with the company's existing relationships with allergists who prescribe respiratory medications. GlaxoSmithKline's immunology product pipeline has been growing. Last year, GSK spent $1.2 billion to acquire Boston Pharmaceuticals' efimosfermin, a drug in development to treat inflammation and fibrosis caused by fatty liver disease (MASH). The 2025 commercial deal also brings GSK's COPD drug candidates from startups Empirico and Hengrui Pharmaceuticals. Tony Wood, GSK's chief scientific officer, said in a prepared statement that ozureprubart has best-in-class potential for treating food allergies.
“Food allergies can have serious health consequences for patients on existing treatments, which require injections every two weeks,” he said. “Ozureprubart offers the opportunity to provide continued protection to patients when administered every 12 weeks and is consistent with our approach to acquiring assets that address proven targets and clear unmet medical needs.”
Rapt licensed ozureprubart from a Chinese biotech company now known as Shanghai Jieyou Pharmaceutical Co., Ltd. The 2024 deal gives Rapt a new lead program after the company discontinued zelnecirnon, an experimental treatment for asthma and atopic dermatitis. In early 2024, the FDA paused clinical testing of the oral small molecule drug following reports of liver failure.
The ozureprubart deal gives Rapt global rights to the drug, excluding mainland China, Hong Kong, Macau and Taiwan, where Jeyou retains rights. Rapt paid $35 million upfront and may make an additional $672.5 million in milestone payments, according to the company's regulatory filing. If ozureprubart enters the market, Jeyou will also receive royalties on net sales. Under the acquisition agreement, GlaxoSmithKline assumes responsibility for these payments. Rapt's pipeline also includes cancer drug tivumecirnon, an oral, small-molecule CCR4 antagonist designed to block the migration of immunosuppressive regulatory T cells into tumors. Rapt said in regulatory filings that it has been seeking partners to develop the drug.
While the Rapt acquisition values the biotech company at about $2.2 billion, GlaxoSmithKline (GSK) estimates its payment, after deducting cash in Rapt's account, will be about $1.9 billion. The acquisition agreement requires a majority of Rapt shareholders to tender their shares. GlaxoSmithKline expects to close the deal this quarter.
Photo by GlaxoSmithKline
