The 26-week study measured the annualized rate of decline in forced vital capacity, a standard metric tracking the total air volume a patient can exhale after a deep breath. Axatilimab fell short of these targets, prompting the company to halt further investment in the lung disease indication. While the clinical results disappointed investors—driving the stock price down to $14.45 in after-hours trading—the company noted that the drug’s safety and tolerability profile remained consistent with historical data.

Axatilimab maintains its commercial standing elsewhere. The FDA previously approved the drug for patients suffering from chronic graft-versus-host disease who have exhausted two prior lines of therapy. Syndax continues to evaluate the treatment in combination studies for newly diagnosed graft-versus-host cases, shifting its focus away from pulmonary fibrosis entirely.