Syndax said its antibody axatilimab failed to slow lung-function decline in a Phase 2 trial and ended development in the disease. The stock fell about 15% after hours, hours after Bristol Myers Squibb reported a Phase 3 win in the same condition.
Idiopathic pulmonary fibrosis produced two very different headlines on Monday. Bristol Myers Squibb's came first, before the open. Syndax Pharmaceuticals' came one minute after the close.
Syndax said the Phase 2 MAXPIRe study, which tested its antibody axatilimab in idiopathic pulmonary fibrosis, a progressive and often fatal scarring of the lungs, "did not meet its primary endpoint of the annualized rate of decline in forced vital capacity," a standard measure of lung function. "Based on the results observed, Syndax does not plan to move forward with further development of axatilimab in IPF," the company said.
Syndax shares closed at $16.55 on Monday, down 2.59%, before the 4:01 p.m. Eastern release. They fell about 15% in after-hours trading, to roughly $14. A close at that level on Tuesday would mark Syndax's steepest one-day decline since May 6, 2025, when the shares lost 22%.
The Trial
MAXPIRe enrolled 145 patients at 62 sites in 14 countries. Patients received axatilimab at 0.3 milligrams per kilogram or a placebo every two weeks, in a two-to-one ratio, for 26 weeks. The annualized rate of decline was estimated from measurements over that period.
The drug was well tolerated, with safety comparable to placebo and no treatment-related deaths in either group. Syndax did not publish the size of the difference between the two groups.
"The MAXPIRe trial did not meet its primary endpoint, and we are disappointed by this outcome given the promising scientific rationale in IPF," said Nick Botwood, head of research and development and chief medical officer.
Where Syndax's Value Sits
Axatilimab is already approved and sold as Niktimvo for chronic graft-versus-host disease, in partnership with Incyte. Niktimvo's net revenue was $60.3 million in the second quarter, according to the company. Syndax said the IPF result does not affect trials in other conditions, and it expects results from studies in newly diagnosed graft-versus-host disease later this year and in early 2028.
"We remain highly focused on further advancing revumenib and axatilimab to frontline in the ongoing clinical trials," Chief Executive Michael Metzger said.
The Contrast With Bristol
Bristol said before Monday's open that its oral drug admilparant met the main goal of its Phase 3 ALOFT-IPF trial, which enrolled about 1,255 patients, at the 60 mg dose. The 120 mg dose slowed lung-function decline but did not reach statistical significance. Bristol shares still closed down 2.6% at $57.58, as analysts questioned the dose pattern.
Contineum Therapeutics, which is developing a drug aimed at the same target as admilparant, fell 36% to about $8.57.
Neither Bristol nor Syndax disclosed effect sizes in its announcement. The two results came from very different trials: a large Phase 3 study of an oral drug against a smaller, shorter Phase 2 study of an antibody that works through a different mechanism.
Market Implications
One reading is that the Syndax result says little about the disease area. Axatilimab targets a different biological pathway, the trial was small, and Bristol's success shows lung-function decline in IPF can be slowed.
A second reading is that IPF remains a difficult field for new drugs. On the same day, one program ended, one Phase 3 drug showed an inconsistent dose response, and a developer sharing Bristol's target lost more than a third of its value.
What To Watch
Detailed MAXPIRe data at a medical meeting, Syndax's graft-versus-host disease readouts and Bristol's full ALOFT-IPF results, including the lung-function difference at each dose, will show how far the two outcomes diverge.