GSK Makes Major Move in Liver Disease Market with $2B Efimosfermin Deal

GSK has significantly bolstered its position in the competitive liver disease market by acquiring rights to efimosfermin alfa, a promising phase III-ready drug candidate, from Boston Pharmaceuticals. The deal, potentially worth up to $2 billion, marks a substantial investment in the treatment of steatotic liver diseases, particularly metabolic dysfunction-associated steatohepatitis (MASH) and alcohol-related liver disease (ALD).

Deal Structure and Financial Details

GSK will pay $1.2 billion upfront to Boston Pharmaceuticals, with an additional $800 million tied to success-based milestones. The British pharmaceutical giant will also assume responsibility for certain milestone payments and royalties owed to Novartis, the original owner of efimosfermin alfa.

This acquisition represents the largest MASH-related deal in nearly a decade, according to Leerink Partners analyst Thomas Smith. The substantial investment underscores the growing importance of the liver disease market, which has gained momentum following Madrigal Pharmaceuticals' recent FDA approval for Rezdiffra, the first drug specifically approved for MASH.

Efimosfermin's Potential and Mechanism of Action

Efimosfermin alfa is a long-acting analog of the FGF21 hormone, designed to be administered via subcutaneous injection once per month. The drug regulates metabolic processes in the liver, reducing fat levels, inflammation, and fibrosis in patients with MASH.

Phase II studies have shown promising results, with GSK touting efimosfermin alfa's "best-in-class" potential. The company highlighted data suggesting potentially greater fibrosis improvement compared to other therapeutic approaches, with benefits expected independent of background GLP-1 therapy.

Tony Wood, GSK's Chief Scientific Officer, emphasized the drug's potential, stating, "The FGF21 class has shown some of the most exciting data in MASH including first-in-disease evidence of cirrhosis reversal, and efimosfermin has the potential to define a new standard-of-care with its monthly dosing and tolerability profile."

GSK's Strategic Positioning in Liver Disease

The acquisition of efimosfermin alfa complements GSK's existing liver disease pipeline, which includes GSK'990, an investigational siRNA therapy currently in Phase II development for MASH and ALD. The company has expressed plans to explore potential combination therapies using both assets.

This deal extends GSK's recent streak of liver disease-focused acquisitions and partnerships, including agreements with Wave Life Sciences and Arrowhead Pharmaceuticals, as well as the purchase of Elsie Biotechnologies for its nucleic acid technology.

GSK aims to launch efimosfermin by 2029, positioning itself as a major player in the rapidly evolving liver disease treatment landscape. The company's commitment to this therapeutic area is evident in its willingness to make significant investments despite recent setbacks in other areas, such as the discontinuation of its TIGIT antibody program with iTeos Therapeutics.