Pharmaceutical company Karyopharm Therapeutics Inc. (Nasdaq:KPTI) revealed on Thursday that the US Food and Drug Administration (FDA) has extended the Prescription Drug User Fee Act (PDUFA) action date for the New Drug Application (NDA) for selinexor for the treatment of relapsed refractory multiple myeloma.

The company stated the previous PDUFA date for for selinexor has been extended by three months from 6 April 2019 to 6 July 2019.

Currently under the US FDA's Priority Review, the NDA is seeking accelerated approval for selinexor in combination with dexamethasone for the treatment of patients with relapsed refractory multiple myeloma who have received at least three prior therapies and whose disease is refractory to at least one proteasome inhibitor (PI), one immunomodulatory agent (IMiD), and one anti-CD38 monoclonal antibody.

Following the US FDA's Oncologic Drugs Advisory Committee (ODAC) meeting to discuss the selinexor NDA ODAC meeting, the company has submitted additional, existing clinical information as an amendment to the NDA, which allowed the US FDA to extend the PDUFA action date by three months.

According to the company, Selinexor is a first-in-class, oral Selective Inhibitor of Nuclear Export (SINE) compound. Selinexor functions by binding with and inhibiting the nuclear export protein XPO1 (also called CRM1), leading to the accumulation of tumour suppressor proteins in the cell nucleus. This reinitiates and amplifies their tumour suppressor function and is believed to lead to the selective induction of apoptosis in cancer cells, while largely sparing normal cells.