Karyopharm presents updated analyses from SIENDO study of selinexor

Karyopharm Therapeutics announced the presentation of updated exploratory subgroup analyses from the SIENDO study in patients with advanced or recurrent TP53 wild-type endometrial cancer at the virtual American Society of Clinical Oncology, or ASCO, Plenary Series. “The primary analysis of the Phase 3 SIENDO study of selinexor maintenance therapy in advanced or recurrent endometrial cancer showed improvements in median progression-free survival – PFS – for the intent-to-treat – ITT – population but were not clinically meaningful. However, an exploratory analysis of a pre-specified subgroup of patients with TP53 wild-type endometrial cancer showed a promising efficacy signal. In the SIENDO study, 263 patients were randomly assigned, with 174 patients allocated to the selinexor arm and 89 patients to the placebo arm. One hundred and thirteen patients with TP53 wild-type endometrial cancer were randomized to receive selinexor vs placebo as maintenance therapy. As of the March 30, 2023 data cut-off date, and a median duration of follow-up of 25.3 months, selinexor-treated patients with TP53 wild-type endometrial cancer had a median PFS of 27.4 months compared to 5.2 months for patients with TP53 wild-type endometrial cancer receiving placebo. Additionally, median PFS was not reached for selinexor-treated TP53 wild-type MSS – pMMR – endometrial cancer patients compared to 4.9 months for TP53 wild-type MSS – pMMR – endometrial cancer patients treated with placebo. No new safety signals were identified as of the last data cut-off date on March 30,” the company stated. “The updated results from SIENDO suggest that selinexor may have the potential to prolong systemic therapy response in patients whose disease is TP53 wild-type. Particularly encouraging are the data observed in the subgroup of patients whose disease are both TP53 wild-type and MSS. We are encouraged by the updated results from this study as it further strengthens the rationale for our ongoing EC-042 Phase 3 study,” said Reshma Rangwala, MD, PhD, Chief Medical Officer of Karyopharm.