Phase III BOSTON study of Xpovio + Velcade + low-dose dexamethasone meets primary endpoint with a significant increase in progression-free survival in Multiple Myeloma.- Karyopharm

Karyopharm Therapeutics Inc. announced positive top-line results from the randomized Phase III BOSTON study evaluating once-weekly Xpovio (selinexor) in combination with once-weekly Velcade (bortezomib) and low-dose dexamethasone (SVd) compared to standard twice-weekly Velcade plus low-dose dexamethasone (Vd) in patients with multiple myeloma who have received one to three prior lines of therapy. The BOSTON study met its primary endpoint of a statistically significant increase in progression-free survival (PFS). The median PFS in the SVd arm was 13.93 months compared to 9.46 months in the Vd arm, representing a 4.47 month (47%) increase in median PFS (hazard ratio=0.70; p=0.0066). There were no new safety signals on the SVd arm and there was no imbalance in deaths between the two arms in the study. The full top-line data will be submitted for presentation at upcoming medical meetings. About the BOSTON Study : BOSTON is a Phase III randomized, active comparator-controlled, open-label, multicenter study that is designed to compare the efficacy, safety and certain health-related quality of life (HR-QoL) parameters of once-weekly Xpovio (selinexor) in combination with once-weekly Velcade (bortezomib) plus low-dose dexamethasone (SVd) versus twice-weekly Velcade plus low-dose dexamethasone (Vd) in adult patients with relapsed or refractory multiple myeloma who have received one to three prior lines of therapy. The BOSTON study enrolled approximately 402 patients. The primary endpoint of the study is progression-free survival (PFS) and key secondary endpoints include overall response rate (ORR), among others. Additionally, the BOSTON study allows for patients on the Vd control arm to crossover to the SVd arm following objective (quantitative) progression of disease. The BOSTON study is being conducted at over 150 clinical sites internationally. Vd is a standard therapy for previously treated patients with multiple myeloma that is given by injection twice-weekly. Unlike other drugs used to treat multiple myeloma, selinexor is taken orally. Patients randomized to the SVd arm received selinexor (100mg once-weekly), Velcade (1.3 mg/m2 once-weekly given subcutaneously) and dexamethasone (40mg weekly). Patients randomized to the Vd arm received Velcade (twice-weekly) plus low-dose dexamethasone (standard therapy given on the recommended schedule). Sharon Shacham, PhD, MBA, President and Chief Scientific Officer of Karyopharm stated. “In the study, patients on the SVd regimen lived 47% longer without their disease worsening, which we believe represents an important improvement in the treatment of patients with relapsed or refractory multiple myeloma. We plan to submit the full data set for presentations at upcoming medical meetings to share the results with the medical community. We also intend to submit these data as quickly as possible to the FDA as part of a supplemental New Drug Application seeking to expand the approved indication for Xpovio into second line treatment for patients with relapsed or refractory multiple myeloma. If approved, the SVd regimen would be the first and only FDA-approved combination drug regimen that includes once-weekly Velcade therapy for relapsed myeloma.