Karyopharm Therapeutics (KPTI) Study result summary

Study design and patient population

• Phase 3 SENTRY trial evaluated selinexor plus ruxolitinib versus ruxolitinib alone or placebo plus ruxolitinib in JAK inhibitor-naïve myelofibrosis patients (N=353), randomized 2:1, with baseline platelet counts >100,000.

• Co-primary endpoints were spleen volume reduction ≥35% (SVR35) and total symptom score (TSS) at week 24.

• Randomization was stratified by risk category, spleen volume, and baseline platelet counts.

• Secondary and exploratory endpoints included overall survival, hemoglobin stabilization, variant allele frequency (VAF) reduction, and bone marrow fibrosis improvement.

• Data cut-off was February 20, 2026.

Efficacy results

• Selinexor plus ruxolitinib achieved a statistically significant SVR35 rate at week 24: 50% vs. 28% for ruxolitinib alone (p<0.0001).

• SVR35 rates were rapid and sustained: 49% vs. 20% at week 12, and 47% vs. 23% at week 36.

• Spleen volume reduction was deeper and more durable with the combination.

• Symptom improvement at week 24 was similar in both arms, with no statistically significant difference (~10-11 point improvement from baseline).

• Greater proportion of patients achieved ≥20% VAF reduction at week 24 with the combination (32% vs. 24%).

Survival and disease modification

• Combination showed a >50% reduction in risk of death vs. ruxolitinib (hazard ratio 0.43, p=0.0222) at median 12-month follow-up.

• Early SVR35 (week 12) correlated with improved overall survival.

• No meaningful difference in progression-free survival, hemoglobin stabilization, or bone marrow fibrosis improvement at data cut-off.

• Confirmed leukemic transformation rate was 1.7% in both arms.