Karyopharm Therapeutics Inc. (NASDAQ:KPTI) shares climbed 10% on Tuesday after the company released mixed results from its Phase 3 SENTRY trial evaluating selinexor in combination with ruxolitinib for patients with frontline myelofibrosis.
The study achieved its first co-primary endpoint, demonstrating a statistically significant improvement in spleen volume reduction. However, the trial did not meet its second co-primary endpoint related to symptom improvement.
The trial enrolled 353 patients who were randomized in a 2:1 ratio to receive either 60 mg of selinexor once weekly alongside ruxolitinib or a placebo plus ruxolitinib. After 24 weeks of treatment, 50% of patients in the combination therapy group achieved at least a 35% reduction in spleen volume (SVR35), compared with 28% of patients receiving ruxolitinib alone.
Both treatment groups experienced symptom improvements from baseline, but the difference between the two arms was not statistically significant. Patients treated with the combination therapy reported an average improvement of 9.89 points in total symptom score, compared with a 10.86-point improvement among those receiving ruxolitinib alone.
The trial also indicated a potentially favorable signal for overall survival. The combination therapy arm showed a hazard ratio of 0.43 compared with ruxolitinib monotherapy. Karyopharm said it will continue monitoring survival outcomes as the data mature.
In exploratory analyses, 32% of patients treated with the combination therapy achieved at least a 20% reduction in variant allele frequency by week 24, compared with 24% in the ruxolitinib-alone group, suggesting possible disease-modifying effects.
The treatment combination showed a manageable safety profile with no new safety concerns identified. The most frequently reported adverse events in the combination group included thrombocytopenia (59%), anemia (57%), and nausea (57%).
Karyopharm said it plans to meet with the U.S. Food and Drug Administration to discuss the results and the possibility of submitting a supplemental new drug application. The company also announced a private placement with RA Capital Management expected to raise approximately $30 million in gross proceeds.