Resmetirom

GSK is putting a further $800 million on the table for efimosfermin, Boston Pharmaceuticals’ lead asset, should it hit certain milestones. \n GSK has already moved on from its decision to drop a cancer asset on Tuesday by snagging a late-stage liver disease candidate for a hefty $1.2 billion upfront.That drug in question is efimosfermin, Boston Pharmaceuticals’ lead asset. The asset has already passed midstage tests and is now a phase 3-ready therapy to help stop the progression of steatotic liver disease (SLD), a condition where fat builds up in the liver. If left untreated, this can lead to increasing levels of liver damage through scarring and cirrhosis.GSK will pay $1.2 billion upfront for the drug while also putting a further $800 million on the table should efimosfermin hit certain milestones.The therapy, which was once owned by Novartis, works as a once-monthly fibroblast growth factor 21 (FGF21) analog therapeutic and is being assessed in metabolic dysfunction-associated steatohepatitis (MASH), including cirrhosis, with GSK eyeing future work in alcohol-related liver disease (ALD), both of which are forms of SLD. The British Big Pharma already has an earlier-stage liver disease asset in GSK’990, a siRNA therapeutic being evaluated for subsets of patients with SLD. GSK said in its Wednesday morning release that there is potential to combine efimosfermin with GSK’990 in future studies.In November 2024, Boston posted phase 2 data that showed that after 24 weeks, 14 of the 31 patients who received 300 mg of efimosfermin had a one-stage or greater improvement in fibrosis without worsening of MASH, compared to seven of the 34 people on placebo. The difference between the proportion of people who met the criteria, 45.2% and 20.6%, was statistically significant.The drug is similar to Akero Therapeutics’ efruxifermin and 89bio’s pegozafermin, both of which work as FGF21 analogues. While efruxifermin and pegozafermin are given weekly, Boston has modified efimosfermin\'s fusion protein to extend its half-life so the therapy can be administered monthly.Liver disease is becoming a major area of research. After years of weak data and safety issues across multiple pharma studies, last year’s approval of Madrigal Pharmaceuticals\' Rezdiffra in MASH marked a new hope for a market potentially worth tens of billions of dollars.GSK’s figures show that ALD affects around 26 million patients globally, and, together with MASH, typically caused by longstanding obesity, is the leading reason for liver transplant in the U.S.“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,” Tony Wood, Ph.D., chief scientific officer at GSK, said in the release. “Efimosfermin will significantly expand our hepatology pipeline and provide us the opportunity to develop a new potential best-in-class medicine with first launch expected in 2029.”This morning\'s asset deal comes a day after GSK dropped work on its iTeos Therapeutics-partnered TIGIT antibody belrestotug amid poor trial data.

GSK’s new asset efimosfermin has already performed well in a Phase II trial, with the drugmaker saying it is now ‘Phase III ready’. Image credit: Getty/JUSTIN TALLIS. Just a day after dropping a $625m cancer asset, GSK has inked a deal worth a potential $2bn to acquire Boston Pharmaceuticals’ efimosfermin, a drug ready to hit Phase III trials for the treatment of liver disease. The UK big pharma company will pay $1.2bn upfront for Boston’s subsidiary BP Asset IX, which will give the company access to efimosfermin. GSK has also agreed to pay additional milestone payments totalling $800m, along with tiered royalties to Novartis, which originally owned the therapy. Shares in London-listed GSK opened relatively unchanged following the news, though climbed into the mid-morning to a share price high of £1,382.00 (correct at 11am GMT+1). The company has a market cap of £56.98bn. Efimosfermin is being developed to treat and prevent the progression of steatotic liver disease (SLD), a build-up of fat in liver cells. SLD is a broad disease term used to encompass various causes of fat accumulation in the liver. If untreated, fat build-up in cells can progress to more severe stages that include fibrosis and cirrhosis. GSK’s new asset is taken once monthly via a subcutaneous injection. Efimosfermin is a long-acting variant of fibroblast growth factor 21 (FGF21) that is designed to regulate key metabolic pathways to decrease both liver fat and inflammation, and reverse liver fibrosis. The therapy has already performed well in a Phase II trial (NCT06920043) in patients with moderate-to-advanced (F2 or F3) metabolic dysfunction-associated steatohepatitis (MASH), a form of SLD. Data, posted by Boston in November 2024, demonstrated that efimosfermin has ‘significant therapeutic potential’ in liver disease. Of the 31 patients receiving the injection, 14 had a one-stage or greater improvement in fibrosis without MASH progression, compared to just seven out of 34 in the placebo group. GlobalData Strategic Intelligence US Tariffs are shifting - will you react or anticipate? Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis. By GlobalData Learn more about Strategic Intelligence Whilst there are other FGF21 drugs in development – such as Akero Therapeutics efruxifermin and 89bio’s pegozafermin – Boston designed efimosfermin with an extended half-life to allow monthly dosing while Akero and 89bio’s assets require weekly dosing, GSK’s drug could be set for an early market advantage. GSK has also earmarked efimosfermin’s potential to combine with its in-house siRNA therapeutic GSK’990 to address more advanced stages of SLD. According to GlobalData estimates, the MASH market is anticipated to reach sales of $25.7bn in 2032 across the seven major markets (7MM: US, France, Germany, Italy, Spain, the UK, and Japan). The market was revived in March 2024 when Madrigal Pharmaceuticals’ Rezdiffra (resmetirom) won the first US Food and Drug Administration (FDA) approval for a MASH treatment. GlobalData noted an increase in drug partnership deal values in the MASH arena in 2024. Eli Lilly continued this trend into this year when it agreed to pay $630m for a Phase I RNA-based candidate from South Korea-based biotech OliX Pharmaceuticals in February 2025. GSK said the purchase of Boston’s drug aligns with its R&D focus on “science related to the immune system”. The deal agreement comes just a day after the drugmaker dropped an anti-TIGIT antibody it previously attained the rights for in a $625m upfront deal. GSK’s chief scientific officer Tony Wood said: “Efimosfermin will significantly expand our hepatology pipeline and provide us the opportunity to develop a new potential best-in-class medicine with its first launch expected in 2029. It complements GSK‘990, also in development for alcohol-related liver disease and MASH, offering GSK options to develop both monotherapy and potential combinations to improve patient outcomes.”