Syndax Pharmaceuticals will stop developing axatilimab for idiopathic pulmonary fibrosis after its Phase 2 MAXPIRe trial failed to meet the primary endpoint measuring the annualized rate of decline in forced vital capacity, a measure of lung function.
The company said the findings do not affect ongoing studies of axatilimab in other indications. The antibody is already approved in the United States as Niktimvo for certain patients with chronic graft-versus-host disease.
MAXPIRe enrolled 145 patients across 62 sites in 14 countries. The randomized, double-blind, placebo-controlled study assigned participants in a two-to-one ratio to axatilimab at 0.3 milligrams per kilogram or placebo every two weeks. Randomization accounted for whether patients were receiving background antifibrotic treatment.
The trial ran for 26 weeks. Researchers used lung-function measurements collected during that period and a statistical model to derive an annualized, 52-week rate of decline. Secondary endpoints included time to disease progression, additional lung-function measures and quality of life.
Syndax said axatilimab’s safety and tolerability were comparable to placebo and consistent with previous studies. No new safety signals or treatment-related fatal adverse events occurred. Rates of treatment-emergent adverse events leading to discontinuation were low in both groups.
Nick Botwood, Syndax’s head of research and development and chief medical officer, said the company was disappointed by the result but remained focused on axatilimab studies in chronic graft-versus-host disease, with readouts expected later in 2026 and in early 2028.
Axatilimab blocks the colony stimulating factor-1 receptor. Its FDA approval covers adults and pediatric patients weighing at least 40 kilograms whose chronic graft-versus-host disease has failed at least two previous lines of systemic therapy.
The drug is being evaluated for newly diagnosed chronic graft-versus-host disease in a Phase 2 combination study with ruxolitinib and a Phase 3 combination study with steroids.
Syndax licensed worldwide rights to axatilimab from UCB in 2016 and entered a global co-development and co-commercialization agreement with Incyte in 2021. Chief Executive Michael Metzger said Syndax remains focused on advancing axatilimab and its menin inhibitor revumenib into frontline treatment through ongoing trials. Revumenib is marketed as Revuforj, while axatilimab is marketed as Niktimvo.
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