Boston Pharma’s once-monthly injection efimosfermin alfa offers a convenient dosing option for MASH patients while also achieving promising rates of fibrosis and MASH improvement, according to a Phase II readout.
Boston Pharmaceuticals on Friday unveiled Phase II data for its investigational therapy efimosfermin alfa, touting significant fibrosis improvements in patients with metabolic dysfunction–associated steatohepatitis.
Efimosfermin alfa is an investigational and long-acting analog of the fibroblast growth factor 21 (FGF21) protein, which helps regulate metabolic processes to reduce liver fat and prevent liver inflammation and damage. This mechanism of action allows efimosfermin alfa to decrease liver damage and potentially reverse fibrosis, while also improving metabolic health.
Unlike other FGF21 analogs for metabolic dysfunction-associated steatohepatitis (MASH)—such as Akero’s efruxifermin and 89bio’s pegozafermin, both of which are in Phase III development and are dosed weekly—Boston Pharma’s efimosfermin alfa is administered once-monthly. This more convenient schedule could give efimosfermin alfa an edge in the MASH market, according to Mazen Noureddin, lead investigator of the study and director of the Houston Research Institute.
“For patients with MASH, maintaining their treatment regimen is essential for the overall effective management of this debilitating disease,” Noureddin added.
Boston Pharma’s readout on Friday, presented at the American Association for the Study of Liver Diseases’ The Liver Meeting, showed that 45.2% of patients treated with efimosfermin alfa saw at least a one-stage improvement in fibrosis without worsening of MASH. In comparison, 20.6% of placebo comparators hit this endpoint, resulting in a statistically significant treatment difference, with a p-value of 0.038.
Efimosfermin alfa also resulted in MASH resolution without fibrosis worsening in 67.7% of treated patients, versus 29.4% in the placebo group. This was also a statistically significant effect. In addition, a greater percentage of patients treated with the FGF21 analog achieved MASH resolution with at least a one-stage improvement in fibrosis.
In terms of safety, efimosfermin alfa showed a good tolerability profile over 24 weeks of treatment, with an overall low incidence of injection-site reactions and gastrointestinal toxicities. Dropouts due to side effects were also uncommon.
In an investor note, Jefferies analyst Michael Yee said that Boston Pharma’s readout on Friday “looks encouraging” and serves to further validate targeting the FGF21 pathway for MASH. Still, Yee pointed out that efimosfermin alfa is still in mid-stage development. Akero, one of its chief FGF21 competitors, is “years ahead with three Phase III studies ongoing,” with a regulatory milestone coming as soon as 2026 or 2027.
Boston Pharma will continue the Phase II development of efimosfermin alfa through 24 additional weeks in its open-label extension phase in patients with F2 and F3 fibrosis. CEO Sophie Kornowski in a statement said that results from this extension phase, alongside data from the biotech’s advanced fibrosis study, “will enable us to build a comprehensive package for discussions with regulatory authorities ahead of our entry into pivotal studies.”
Elsewhere in the MASH space, Inventiva is also set to present Phase II data at The Liver Meeting for its oral small molecule MASH drug lanifibranor, which it is trialing in combination with empagliflozin in type 2 diabetics. The study hit its primary endpoint, with 50% of patients achieving HbA1c levels lower than 6.5% at 24 weeks, versus 0% in placebo counterparts.
