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.