Gossamer Bio reported that its Phase‑III Prosera study of inhaled tyrosine kinase inhibitor seralutinib in pulmonary arterial hypertension missed the primary endpoint for six‑minute walk distance. The company cited an outsized placebo response; treated patients improved but the placebo‑adjusted gain fell short of the statistical target. Cough and elevated liver enzymes were notable adverse events. The miss sank Gossamer’s stock and leaves the company to pursue additional data analyses and discussions with the FDA on possible next steps.