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Karyopharm’s multiple myeloma drug Selinexor succeeds in phase 2b study

PBR Staff Writer Published 01 May 2018

Karyopharm Therapeutics’ selinexor, an oral selective inhibitor of nuclear export (SINE) compound, has succeeded in a phase 2b study by showing a 25.4% overall response rate (ORR) in heavily pretreated patients with refractory multiple myeloma.

The ORR, which was the primary objective of the STORM trial, included two complete responses (CRs) and 29 partial (PRs) or very good partial responses (VGPRs) across patients with penta-refractory myeloma. 

Selinexor also recorded 4.4 months as the median duration of response (DOR), which was defined as a key secondary objective of the STORM trial.

The trial was held in nearly 122 patients with heavily pretreated, penta-refractory myeloma who were administered with 80mg oral selinexor twice a week in combination with 20mg low-dose dexamethasone, also dosed orally twice a week.

Penta-refractory in the phase 2b study has been defined as patients who received at least one alkylating agent, glucocorticoids, two immunomodulatory drugs, two proteasome inhibitors, and Darzalex (daratumumab).

This was for such patients whose condition is refractory to glucocorticoids, at least one PI, at least one IMiD, and Darzalex, and whose disease has advanced after their most recent therapy.

Karyopharm plans to submit its new drug application to the US Food and Drug Administration (FDA) for penta-refractory multiple myeloma during the second half of 2018, followed by a submission to the European Medicines Agency in early 2019.

Earlier this month, selinexor was granted fast track designation from the FDA for the treatment of patients with multiple myeloma who had been subjected to more than three prior lines of therapy.

Karyopharm president and chief scientific officer Sharon Shacham said: “Penta-refractory myeloma is an area of true unmet medical need as these patients have continued to progress despite receiving available therapies. 

“We are fully committed to bringing this new, orally administered potential treatment option to patients who have no other therapy options of proven benefit.”

Selinexor has been designed to bind with and block the nuclear export protein XPO1 (CRM1). This action results to the accumulation of tumor suppressor proteins in the cell nucleus, reinitiating and amplifying their tumor suppressor function.

Image: Selinexor showed a 25.4% ORR in heavily pretreated patients with refractory multiple myeloma in STORM trial. Photo: courtesy of jk1991/