GSK Secures Late-Stage Liver Disease Drug with $1.2B Upfront Payment to Boston Pharmaceuticals

In a significant move that underscores the growing importance of liver disease treatments in the pharmaceutical industry, GlaxoSmithKline (GSK) has announced a major deal with Boston Pharmaceuticals. The British pharmaceutical giant will pay $1.2 billion upfront to acquire efimosfermin, a promising late-stage liver disease candidate, with potential additional payments of up to $800 million based on milestone achievements.

Efimosfermin: A Potential Game-Changer in Liver Disease Treatment

Efimosfermin, Boston Pharmaceuticals' lead asset, is a once-monthly fibroblast growth factor 21 (FGF21) analog therapeutic. The drug has successfully completed mid-stage tests and is now phase 3-ready. It targets steatotic liver disease (SLD), a condition characterized by fat accumulation in the liver that can lead to progressive damage, including scarring and cirrhosis.

The therapy has shown promising results in treating metabolic dysfunction-associated steatohepatitis (MASH), including cirrhosis. GSK also plans to explore its potential in alcohol-related liver disease (ALD), another form of SLD. According to GSK's data, ALD affects approximately 26 million patients globally, and together with MASH, is the leading cause of liver transplants in the United States.

Clinical Efficacy and Market Potential

In November 2024, Boston Pharmaceuticals released phase 2 data for efimosfermin, demonstrating significant improvements in liver fibrosis. After 24 weeks of treatment, 45.2% of patients receiving 300 mg of efimosfermin showed a one stage or greater improvement in fibrosis without worsening of MASH, compared to 20.6% in the placebo group.

Tony Wood, Ph.D., Chief Scientific Officer at GSK, highlighted 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."

Efimosfermin's monthly dosing regimen sets it apart from similar drugs in development, such as Akero Therapeutics' efruxifermin and 89bio's pegozafermin, which require weekly administration. This could provide a significant advantage in patient compliance and quality of life.

Strategic Implications for GSK

This acquisition significantly expands GSK's hepatology pipeline, positioning the company as a major player in the rapidly growing liver disease market. The deal comes just a day after GSK discontinued work on its TIGIT antibody belrestotug due to poor trial data, demonstrating the company's agility in portfolio management.

GSK already has an earlier-stage liver disease asset, GSK'990, a siRNA therapeutic being evaluated for subsets of patients with SLD. The company has indicated potential plans to explore combination therapies with efimosfermin and GSK'990 in future studies.

With the first launch of efimosfermin expected in 2029, GSK is positioning itself to capitalize on a market that could be worth tens of billions of dollars. The recent approval of Madrigal's Rezdiffra for MASH has reinvigorated interest in liver disease treatments, following years of setbacks in the field.