Boston Pharmaceuticals Present Positive Data for New NASH Treatment

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BOS-580 is an investigational, proprietary, long-acting fibroblast growth factor 21 analog as a monthly and bi-weekly treatment for patients with NASH.

New preliminary results show BOS-580 is showing promise treating patients with non-alcoholic steatohepatitis (NASH).1

Boston Pharmaceuticals announced the promising results from the phase 2a trial evaluating the investigational, proprietary, long-acting fibroblast growth factor 21 (FGF21) analog as a monthly and bi-weekly treatment for patients with NASH.


The treatment is a genetically engineered variant of FGF21 with an extended half-life that allows for the potential of monthly dosing.

“The need for safe and effective treatment options for NASH continues to be acute and may be heightened as its prevalence is expected to increase by 63% in the United States alone by 2030,” said Rohit Loomba, MD, MHSc, chief of the Division of Gastroenterology and Hepatology at University of California San Diego School of Medicine, in a statement. “There is a growing body of evidence demonstrating that FGF21 analogs can potentially increase NASH resolution and improve fibrosis.”

The Trial

In the study, patients treated with BOS-580 achieved a statistically significant reduction in liver fat content, an exploratory endpoint of the trial. There was also statistically significant reductions in other exploratory endpoints, including biomarkers of liver injury and fibrosis.

There were 102 patients with phenotypic NASH included in the study. Each participant was randomized to receive bi-weekly subcutaneous doses of placebo or BOS-580 at 75mg, 150mg, or 300mg over 12 weeks.

The results show more than 70% of patients in the BOS-580 150mg group had a reduction in liver fat by at least 50%. Compared to 3% of the placebo group.

In the 300mg group, the investigators found patients treated with BOS-580 had at least 45% reduction in alanine transaminase from baseline with similar reductions in aspartate aminotransferase found.

The soluble marker of fibrosis PRO-C3 was decreased by approximately 30% for the 300mg group, compared to 5% of the placebo group.

Safety and Tolerability

The trial also featured a low discontinuation rate because of treatment-emergent adverse events (4.6% in treated patients vs. 5.4% in the placebo group).

The most common adverse events in the study drug group were gastrointestinal, mild to moderate, and transient, including nausea, vomiting, and diarrhea.

The data was presented during the European Association for the Study of the Liver (EASL 2023) International Liver Congress in Vienna, Austria as a late-breaking poster.

“Today’s findings strengthen our belief that BOS-580 has the potential to play an important role as a once monthly treatment available to physicians who treat patients suffering from NASH,” Sophie Kornowski, PharmD, CEO of Boston Pharmaceuticals, said in a statement. “We are looking forward to further accelerate the development of our molecule towards pivotal trials and ultimately registration.”


Boston Pharmaceuticals announces Positive phase 2a results from monthly and bi-weekly dosing with investigational bos-580 Nash program at EASL 2023. Business Wire. (2023, June 21).