Xpovio Has ‘Potential to Transform’ Treatment of Advanced Endometrial Cancer

Results from the SIENDO trial examining the effects of Xpovio as a frontline maintenance therapy in patients with advanced or recurrent endometrial cancer highlighted a significant survival benefit.

A phase 3 clinical trial measuring the safety and efficacy of using Xpovio (selinexor) as frontline maintenance therapy for patients with advanced or recurrent endometrial cancer showed promising results and met the study’s primary goal.

The SIENDO trial involved 263 patients with stage 4 or recurrent disease who had a partial or complete response after 12 or more weeks of standard taxane-platinum combination chemotherapy. The researchers compared results of Xpovio with a placebo option.

"Women with advanced or recurrent endometrial cancer face a poor prognosis," explains Dr. Vicky Makker, principal investigator and medical oncologist at Memorial Sloan Kettering Cancer Center, in a news release. "Following standard of care, platinum-based chemotherapy, the current paradigm of watchful waiting for recurrence is simply inadequate. Therefore, there is a dire need for new and innovative treatment options for this heterogeneous malignancy that is rising in incidence and disease-related mortality."

Among the patients who received Xpovio (80 mg taken once weekly), there was a median progression-free survival (PFS; time until disease progresses) — which was the primary endpoint of the trial — of 5.7 months, compared with 3.8 months in the placebo group. This was a 50% improvement and a 30% reduction in the risk of disease progression or death.

Additionally, patients who received Xpovio had a longer-term improvement after 12 months, with a 37% increase in the probability that they’d be in remission, compared to patients given placebo.

There were no new safety signals found in the trial, and patients were able to tolerate the treatment — the discontinuation rate due to side effects was 10.5%.

"As an oral, chemotherapy-free treatment, (Xpovio) has the potential to transform the way advanced or recurrent endometrial cancer is treated and I am intrigued to learn more about the patients with the wild-type p53," said Dr. Ignace Vergote, principal investigator and gynecologist oncologist at the European Network for Gynecological Oncological Trail (ENGOT) and the Belgium and Luxembourg Gynecological Oncology Group (BGOG), University of Leuven, Leuven Cancer Institute, Leuven, Belgium. "This study brings us one step closer to offering patients a treatment option that can give them more time with their friends and families."

The SIENDO trial was conducted at multiple sites across the world to focus on treatment with Xpovio, which is a first-in-class oral inhibitor. It works by selectively binding to a protein called XPO1 and is currently approved in the United States in multiple indications including a combination treatment with Velcade (bortezomib) and XVd (dexamethasone) in multiple myeloma, a combination with XVd in heavily pre-treated multiple myeloma as well as for patients with diffuse large B-cell lymphoma.

Karyopharm Therapeutics Inc., a pharmaceutical company partnered with the study, plans to work with the U.S. Food and Drug Administration (FDA) to complete a full analysis of the trial data. It also plans to submit a supplemental New Drug Application (sNDA) to the FDA in early 2022 and share detailed study results at upcoming medical meetings.

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