Biopharmaceutical company GSK plc (LON:GSK) (NYSE:GSK) announced on Wednesday that it has agreed to acquire BP Asset IX Inc, a subsidiary of US-based Boston Pharmaceuticals, to gain full rights to efimosfermin alfa, a phase III-ready investigational therapy for steatotic liver disease (SLD).

The transaction includes a USD1.2bn upfront payment plus up to USD800m in success-based milestone payments.

Efimosfermin is a once-monthly fibroblast growth factor 21 analog being developed to treat metabolic dysfunction-associated steatohepatitis and alcohol-related liver disease, both subsets of SLD. Phase II data demonstrated rapid and significant reversal of liver fibrosis and halted disease progression, positioning it as a potential new standard-of-care.

This acquisition aligns with GSK's strategic focus on immunology and fibrotic diseases and significantly strengthens its pipeline targeting liver conditions. Efimosfermin may complement GSK'990, a siRNA therapeutic, offering potential for combination treatment approaches.

SLD, affecting up to 5% of the global population, presents a substantial unmet need with limited treatment options and a high economic burden. The USA alone could see USD40-100bn in savings over 20 years through effective fibrosis interventions.

Efimosfermin's clinical profile includes low immunogenicity, extended half-life, and benefits in triglyceride reduction and glycaemic control, offering both efficacy and convenience in a monthly dosing regimen.

As part of the agreenent GSK will also assume tiered royalty obligations to Swiss pharmaceutical company Novartis Pharma AG (SIX:NOVN) (NYSE:NVS). The transaction will be accounted for as a business combination and is subject to regulatory approval.