By Sahil Pandey and Siddhi Mahatole
Feb 23 (Reuters) – Gossamer Bio’s experimental treatment failed to significantly improve exercise capacity in patients with a rare lung condition in a late-stage study, knocking the drug developer’s shares down 80% on Monday.
The inhaled drug, seralutinib, is being developed for pulmonary arterial hypertension — high blood pressure caused by constriction of arteries in the lungs.
At week 24, seralutinib improved six-minute walking distance by 13.3 meters, when adjusted for placebo, falling short of the study’s statistical threshold.
Walking limitations are common in patients with PAH, as reduced blood flow makes even light activity difficult.
CEO Faheem Hasnain said in a conference call with analysts that the late-stage study data, combined with earlier mid‑stage data, form a “compelling package” for the U.S. Food and Drug Administration that the company thinks should be viewed as “clinically meaningful.”
The company said intermediate- and high-risk patients saw a placebo-adjusted improvement of 20 meters in six-minute walking distance.
“We acknowledge seralutinib may have a role in helping patients with more severe PAH and those with underlying connective tissue disorders, but we believe the regulatory pathway to obtain an approval even in those subgroups of patients will be complicated,” Guggenheim analyst Vamil Divan said.
The study enrolled 390 patients on background PAH therapy who received seralutinib or placebo for up to 48 weeks.
The drug’s dry powder formulation allows it to be delivered directly to the lungs, which could limit broader systemic exposure and side effects.
Other approved treatments for PAH include Merck’s Winrevair and Johnson & Johnson’s Tracleer.
The company plans to meet with the FDA.
It will also pause enrollment in a separate late-stage study testing seralutinib for another lung disease while it reviews certain discrepancies in placebo response in the PAH study.
The drug is being developed in partnership with Italy-based Chiesi Group.
(Reporting by Sahil Pandey and Siddhi Mahatole in Bengaluru; Editing by Sahal Muhammed and Devika Syamnath)
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