PIPELINE

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• Efimosfermin alfa (formerly BOS-580) is a long-acting, once-monthly FGF21 analogue under development for the treatment of metabolic dysfunction-associated steatohepatitis (MASH), previously known as non-alcoholic steatohepatitis (NASH).

• Efimosfermin is currently being studied in Phase 2 clinical trials in participants at risk for or with biopsy-confirmed MASH

Efimosfermin is an investigational fusion protein based on human IgG and FGF21, modified to provide an extended systemic half-life. Efimosfermin is produced in mammalian cells, which is known to improve the quality of glycosylation. The molecule has demonstrated specificity for three FGF21 receptors in non-clinical studies which suggests efimosfermin may allow for a balanced pharmacological effect.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a highly prevalent, silent disease. MASLD is also closely associated with metabolic co-morbidities such as diabetes mellitus 2 (T2D) and hypertension. Metabolic dysfunction-associated steatohepatitis (MASH) is a severe form of MASLD.

MASH is a growing global epidemic fueled by increasing levels of obesity and metabolic disease. It is estimated that 3 to 5% of the global population is affected by MASH, though the disease is underdiagnosed. Prevalence of MASH will increase by 15-56% depending on region by 2030. The potential ability of FGF21-based MASH therapies to treat patients with T2D could be particularly important given the prevalence of T2D in MASH patients and the role of FGF21 in improving glycemic control. If MASH is left untreated and progresses to advanced fibrosis (cirrhosis), which can lead to liver failure, liver cancer or death.

In a Phase 2a trial, reductions in markers of liver injury and fibrosis in phenotypic MASH patients and improvements in markers of metabolic health were observed with once-monthly dosing of efimosfermin. To date, efimosfermin has demonstrated low discontinuation rates in clinical trials. The most commonly observed adverse events have been of GI in nature.