GSK plc secures U.S. Food and Drug Administration Breakthrough and European Medicines Agency PRIME designations for efimosfermin in MASH, supported by phase II fibrosis and disease resolution data.
Written By: Mahathi Palivela, PharmD
Reviewed By: Pharmacally Editorial Team
GSK plc has received regulatory designations in the United States and Europe for efimosfermin, an investigational therapy for metabolic dysfunction‑associated steatohepatitis (MASH).
The U.S. Food and Drug Administration granted Breakthrough Therapy Designation, while the European Medicines Agency awarded Priority Medicines (PRIME) status; both are intended to accelerate the development and review of treatments for serious conditions with unmet medical need.
The designations are supported by phase II data in patients with moderate to advanced fibrosis (F2/F3) and cirrhosis (F4). At 48 weeks, efimosfermin showed improvements in liver fibrosis and resolution of MASH compared with placebo. The therapy demonstrated a generally favorable safety profile, with mild and transient adverse events including nausea, vomiting, and diarrhoea.
Efimosfermin is currently being evaluated in phase III trials, including ZENITH‑1 and ZENITH‑2, in patients with F2/F3 fibrosis. Additional phase III studies in patients with cirrhosis (F4) are expected to begin later this year as development progresses into late‑stage clinical evaluation.
MASH is a chronic and progressive liver disease affecting up to 5% of the global population and is a leading cause of liver transplantation in the United States and Europe.
Fibrosis is a key driver of disease progression and is associated with increased risks of cirrhosis, liver failure, and liver cancer. Treatment options remain limited, particularly for advanced disease, and there are currently no approved therapies for cirrhotic MASH.
Efimosfermin is a long‑acting analogue of fibroblast growth factor 21 (FGF21), administered as a once‑monthly subcutaneous injection, designed to reduce liver fat, decrease inflammation, and reverse fibrosis through metabolic regulation.
Kaivan Khavandi, SVP, R&D Head Respiratory, Immunology & Inflammation (RI&I), and Head of Translational & Development Sciences, GSK, stated that the designations highlight the therapy’s potential to address a significant unmet need and improve standards of care by directly targeting liver fibrosis. The therapy remains investigational and is not approved for use in any market.
Reference
GSK’s Investigational Liver Therapy, Efimosfermin Receives US FDA Breakthrough Therapy and EMA Priority Medicines (PRIME) Designations For MASH, 27 April 2026https://www.gsk.com/en-gb/media/press-releases/gsk-s-investigational-liver-therapy-efimosfermin-receives-us-fda-breakthrough-therapy/
About the Writer
Mahathi Palivela is pursuing PharmD and has a strong interest in Clinical Pharmacy and Patient safety. She is passionate about handling and analyzing patient data, and translating clinical insights into clear, meaningful summaries. She aims to apply this interest in Medical Writing and Pharmacovigilance, focusing on improving patient outcomes through careful data interpretation and communication.