Merck & Co. has unwrapped a fresh set of clinical data on sotatercept, providing further evidence of the safety and efficacy of the cardiovascular drug candidate ahead of a FDA ruling on whether to approve the jewel of the $11.5 billion Acceleron Pharma buyout.
New Jersey-based Merck laid the groundwork for filings for approval of sotatercept 11 months ago by linking the activin receptor type IIA-Fc fusion protein to improved outcomes in adults with pulmonary arterial hypertension (PAH). Since then, the Big Pharma has dripped out more data while preparing and, in the case of the FDA, filing regulatory submissions.
Merck is using the European Respiratory Society International Congress 2023 to share more results from the pivotal phase 3 trial as well as to publish an interim look at the findings of an open-label extension.
The new phase 3 data come from an exploratory post hoc analysis of the effect of sotatercept on aspects of cardiovascular function. Merck linked the molecule to improvements on measures of hemodynamic status and right-ventricle (RV) function. Compared to placebo, sotatercept appears to improve variables such as mean pulmonary arterial pressure, cardiac efficiency and RV power.
Merck’s new analyses are post hoc and exploratory, preventing firm conclusions from being drawn, but Vallerie McLaughlin, M.D., professor of medicine at the University of Michigan in Ann Arbor, framed the findings as another boost for the prospects of sotatercept.
“This is the first clinical evidence suggesting that sotatercept may positively impact certain measures of right heart function and dimensions. This is encouraging and further supports the primary results from the STELLAR analysis, underscoring the potential of sotatercept to play a critical role in the treatment of PAH,” McLaughlin said in a statement.
Merck also presented early results from the open-label extension it's running to assess the long-term effects of sotatercept. As of April 20, the Big Pharma had enrolled 409 people in the study and tracked them for a median of 462 days, including their exposure to sotatercept in earlier trials.
The safety profile is in line with that seen in earlier studies, with 19.3% of participants suffering serious treatment-emergent adverse events—but only 1.5% dropping out and 1.0% dying as a result—and 22.7% of the subjects having telangiectasia, dilated or broken blood vessels in the skin. On the efficacy front, improvements on the six-minute walk test and a biomarker were “largely maintained.”