Karyopharm's Selinexor Shows Progression-Free Survival of 27.4 Months In Endometrial Cancer With Certain Mutation

Karyopharm Therapeutics Inc KPTI 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 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 was 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. 

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 a placebo. 

No new safety signals were identified as of the last data cut-off date on March 30, 2023. 

The SIENDO exploratory subgroup data provides further rationale for the ongoing pivotal Phase 3 study (XPORT-EC-042) of selinexor as maintenance therapy following systemic therapy in patients with TP53 wild-type advanced or recurrent endometrial cancer.

Karyopharm is currently enrolling patients in the pivotal Phase 3 study of selinexor as a maintenance therapy following systemic therapy in patients with TP53 wild-type advanced or recurrent endometrial cancer.

Price Action: KPTI shares are down 4.09% at $1.53 on the last check Wednesday.