Karyopharm Therapeutics Inc. (Nasdaq: KPTI) said it plans to submit a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration in August 2026 seeking accelerated approval of selinexor in combination with ruxolitinib for the treatment of myelofibrosis.

The company said it will request Priority Review at the time of submission, which, if granted, would set a Prescription Drug User Fee Act target action date approximately six months after the FDA receives the application.

The planned submission follows FDA engagements in which the agency provided written feedback indicating that spleen volume reduction of 35% or more appears to qualify as a reasonably likely surrogate endpoint to predict overall survival, supporting use of the accelerated approval pathway.

The sNDA will draw on data from the Phase 3 SENTRY trial, a randomized, double-blind study comparing selinexor plus ruxolitinib against placebo plus ruxolitinib in 353 JAK inhibitor-naive myelofibrosis patients. The trial met its co-primary endpoint of spleen volume reduction at week 24. The company said it plans to use long-term overall survival data from the ongoing SENTRY trial to verify clinical benefit, with overall survival serving as a pre-specified secondary endpoint. The trial does not permit patient crossover and remains blinded during follow-up.

SENTRY results were presented at the 2026 American Society of Clinical Oncology Annual Meeting and published in the Journal of Clinical Oncology.

Karyopharm said that if approved, the combination would represent the first approved combination therapy for myelofibrosis patients. Myelofibrosis affects approximately 20,000 patients in the United States, and the only currently approved therapy class is JAK inhibitors, which includes ruxolitinib.