Approximately 1 in 4 patients with triple-class refractory multiple myeloma had a partial response or better to oral selinexor plus low-dose dexamethasone, according to a recently published study.

The study included 122 patients who had previous exposure to bortezomib, carfilzomib, lenalidomide, pomalidomide, daratumumab and an alkylating agent, and disease refractory to at least 1 proteasome inhibitor, 1 immunomodulatory agent, and daratumumab.

Partial response or better occurred in 26% of patients (95% confidence interval [CI], 19-35] and 2 stringent complete responses occurred; 39% of patients had minimal response or better.

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The researchers wrote that the trial results are notable because the trial allowed patients with reduced renal function, those with thrombocytopenia and neutropenia, heavily pretreated patients, and patients with rapidly progressing disease.

“These characteristics are consistent with the growing population of patients who have exhausted available therapies but still desire to continue therapy,” they wrote.

Patients were treated with oral selinexor 80 mg plus dexamethasone 20 mg twice weekly. The median patient age was 65 years, and patients had a median of 7 prior treatment regimens.

The median duration of response was longer than 4 months. Median progression-free survival was 3.7 months with a median overall survival of 8.6 months.

“The adverse events that were observed in the study were a function of dose, schedule, and baseline clinical characteristics (eg, cytopenias),” the researchers wrote. “Thrombocytopenia, which is due in part to inhibition by selinexor of thrombopoietin signaling in early megakaryopoiesis, was reversible and was managed with dose interruptions and thrombopoietin-receptor agonists.”

Other common side effects included anemia, neutropenia without fever, and hyponatremia.

Disclosure: This study was funded by Karyopharm Therapeutics. For a full list of disclosures, please refer to the original study.

Reference

Chari A, Vogl DT, Gaviatopoulou M, et al. Oral selinexor-dexamethasone for triple class refractory multiple myeloma. N Engl J Med. 2019;381:727-738.