Gossamer Bio announced on July 27 that it has regained global development and commercial rights to its pulmonary hypertension candidate seralutinib from Chiesi, following a failed Phase 3 study. The company said it plans to submit an application for U.S. regulatory approval in September, which could lead to a decision by August of next year.
In February, Gossamer’s inhaled tyrosine kinase inhibitor seralutinib did not significantly improve functional performance in a late-stage pulmonary arterial hypertension (PAH) trial called PROSERA. As a result, the company’s stock price dropped sharply. Despite this outcome, Gossamer CEO Faheem Hasnain said during an investor call, “Our conviction in the program has never been stronger.”
According to minutes from a June pre-NDA Type B meeting with the Food and Drug Administration (FDA), Gossamer reported that “the FDA characterized the degree of statistical significance and the magnitude of the treatment effect observed in PROSERA as review issues rather than filing issues.” The planned new drug application will include data from both PROSERA and an earlier Phase 2 study named TORREY. In PROSERA, patients showed a placebo-adjusted improvement of 13.3 meters in a six-minute walk distance test at 24 weeks, with a p-value of 0.0320—missing the prespecified threshold for statistical significance.
Chief Development Officer Caryn Peterson said there was no specific discussion about p-value with regulators before the meeting; however, Chief Financial Officer Bryan Giraudo referenced recent FDA statements suggesting that trials for orphan or rare diseases may be accepted with p-values up to 0.05. Guggenheim analysts wrote that key questions remain regarding whether seralutinib will ultimately receive approval based on current data and how it would fit into existing PAH treatment options if approved.
Chiesi ended its collaboration with Gossamer as part of what CFO Giraudo described as internal reorganization focused on ultrarare diseases at Chiesi. Under their revised agreement, Chiesi paid $5 million to settle obligations but could still collect capped royalties or milestone payments if seralutinib is successful commercially.
Hasnain said that, “our intention is to proceed as an independent company,” noting there are no immediate plans for another partnership. As of June 30, Gossamer reported approximately $57 million in cash and marketable securities; it also announced plans for a reverse stock split aimed at improving its capital structure.
