The phase 2 study was a 24-week, randomized, double-blind, placebo-controlled study with 84 participants aged 18-75 years, BMI at least 27 kg/m², with biopsy-confirmed MASH and F2 or F3 fibrosis.[1][2][3] Participants were randomized 1:1 to subcutaneous injection of efimosfermin alfa (BOS-580) 300 mg once every 4 weeks or placebo.[1][2][3] Efimosfermin significantly improved fibrosis: 45.2% of those treated achieved at least a 1-grade improvement in fibrosis without MASH deterioration versus 20.6% in the placebo group (p=0.038).[1] Resolution of MASH without worsening of fibrosis was achieved by 67.7% of those treated versus 29.4% in the placebo group (p=0.002).[1] Treatment with once-monthly efimosfermin was generally well tolerated.[2][5] The most common adverse events were mild to moderate gastrointestinal events such as nausea, diarrhea, and vomiting, with a low rate of discontinuation.[3][5] The results support the further development of efimosfermin for the treatment of MASH-related fibrosis.[2]