Shares of Syndax Pharmaceuticals have tumbled 17% after a phase 2 flop reported Monday prompted the drugmaker to halt development on its candidate for idiopathic pulmonary fibrosis.
In topline results from the Maxpire phase 2 trial, Syndax’s Niktimvo—a monoclonal antibody also known as axatilimab that blocks the colony-stimulating factor-1 receptor (CSF-1R) protein—did not slow worsening on a measure of lung function in IPF patients compared to placebo, the study's primary endpoint.
The Maxpire trial was Niktimvo’s first test run in IPF. The phase 2 was launched based on lung response data in patients with graft-versus-host disease (GVHD), a condition where Niktimvo is already approved as a third-line therapy.
Syndax did not elaborate on the lung function data behind its decision. But the company did say the drug’s safety profile over the 26-week Maxpire trial was consistent with past studies, with no new safety concerns emerging. The drugmaker emphasized that all other ongoing Niktimvo trials will not be affected by the IPF halt.
While the phase 2 miss is tough to swallow, Jeffries analysts said the IPF indication was always an offshoot from Niktimvo and Syndax’s core strengths. Thus, “our fundamental view on [Syndax] is not meaningfully affected by this,” the analysts wrote in a note to clients this week.
“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 & development and chief medical officer at Syndax, in a statement. He stressed, however, that “there are multiple trials underway in cGVHD where axatilimab has shown remarkable results and we look forward to readouts from these trials later this year and in early 2028.”
Syndax licensed the global rights to Niktimvo in 2016 and then five years later entered into a co-development agreement with Incyte. Per the agreement, the two companies share a 50:50 profit and loss agreement in the U.S. Incyte shares also fell, though only slightly, yesterday.
With the door on IPF now closed, the co-developers will focus on a phase 2 trial set to read out before the year’s end testing Niktimvo in combination Incyte’s Jakafi as a frontline treatment for GVHD. The companies also have a phase 3 trial testing Niktimvo plus steroids as a first-line treatment for GVHD set to read out in early 2028.
“We look forward to working with our partner Incyte as we continue to build Niktimvo into a blockbuster franchise in cGVHD,” said Syndax CEO Michael Metzger in the company's Oct. 12 announcement.
Jeffries analysts also noted that, now that Niktinvo’s focus has narrowed, continued growth of Syndax’s first-in-class acute myeloid leukemia drug, Revuforj, and its advancement up the treatment line, will be critical to the company's success. Syndax currently has two first-line Revuforj phase 3 AML studies in the works. Initial data from those could read out as early as the end of 2027.
While the cancer drug’s sales dipped in the second quarter of 2026, Syndax told Jeffries they now understand the driver of that trend and expect to see a rebound.