Syndax Pharmaceuticals stock plunged on Tuesday after the drugmaker reported disappointing trial results for a lung disease treatment, dealing a setback to its efforts to expand the market for one of its approved medicines.

Shares of Syndax fell 17% to $13.80, on pace for their largest percentage decline since May 2025, according to Dow Jones Market Data. The stock is down 34% this year, tracking its worst annual performance since 2024.

Shares of competitors Bristol Myers Squibb and Avalyn Pharma dropped 1.8% and 1.4%, respectively. The Nasdaq Composite declined 0.1%.

Syndax said late Monday a Phase two trial for axatilimab failed to meet its primary goal in patients with idiopathic pulmonary fibrosis, a progressive disease that causes scar tissue to accumulate in the lungs and makes breathing increasingly difficult.

Axatilimab, a treatment already approved by the FDA for a complication of stem-cell transplants, failed to demonstrate a statistically significant benefit in slowing the decline in lung function among patients with IPF, Syndax said.

The trial involved 145 patients and evaluated changes in lung function over 26 weeks. Researchers measured how much air patients could forcefully exhale after taking a deep breath, an indicator of how the disease affects their ability to breathe.

Syndax did not disclose specific results comparing patients who received axatilimab with those given a placebo, though the company said the drug was generally well tolerated and raised no new safety concerns.

Syndax said it would discontinue development of axatilimab for IPF, effectively eliminating an opportunity to expand sales of the treatment.

The treatment, sold under the brand name Niktimvo, accounted for $60.3 million in net revenue through the company's second quarter, during which Syndax said the drug had "substantial commercial opportunity."

Additional trials are under way to expand its use among patients with chronic graft-versus-host disease.