UPDATED: GSK, with new trial win, looks to expand PD-1 Jemperli in endometrial cancer

As GSK races to match its PD-1 blocking antibody Jemperli to Merck’s superstar Keytruda, new pivotal data could help it expand into a broader endometrial cancer population.

Jemperli, used on top of chemotherapy, helped patients with primary advanced or recurrent endometiral cancer live longer without their disease getting worse compared with chemo alone in a phase 3 trial, GSK said Friday. The drug was shown to help patients across subgroups as well as the overall study population, the company added.

The company plans to make its regulatory submissions for a first-line endometrial cancer indication based on results from the current RUBY trial during the first half of 2023. Full trial results will be published in a medical journal and presented at an upcoming scientific meeting.

Specifically, Jemperli helped patients who are mismatch pair deficient (dMMR) and have high microsatellite instability (MSI-H). It also benefited those who are mismatch repair proficient and microsatellite stable.

Tumors with those genetic characteristics typically respond well to PD-1 inhibitors like Jemperli. The FDA has granted approvals to PD-1 antibodies, including Jemperli, to treat dMMR/MSI-H cancer regardless of their locations.

While it’s too early to collect data on whether Jemperli could extend patients' lives, a “favorable trend” was observed in the overall patient population, GSK said.

“Patients with primary advanced or recurrent endometrial cancer have limited treatment options,” said Hesham Abdullah, Senior Vice President and Global Head of Oncology Development at GSK. “New treatment options are urgently needed to evolve the current standard of care, which is platinum-based chemotherapy.”

Endometrial cancer is the most common gynecologic cancer in the U.S. and the second most common gynecologic cancer globally. Approximately 15-20% of women with the cancer have advanced disease at the time of diagnosis.

Jemperli scored FDA approval last April as a monotherapy in patients with previously treated dMMR endometrial cancer. That go-ahead was based on tumor shrinkage data, and the company is  counting on further data from the original phase 1 GARNET trial to potentially support a conversion of the accelerated approval into a full nod.

The drug aims to live up to Keytruda, a difficult benchmark to reach against Merck’s well-established standard-of-care product. But Jemperli can hold its own, recently shrinking tumors just as well as Keytruda in a phase 2 trial testing Jemperli combined with chemotherapy in patients with newly diagnosed metastatic nonsquamous non-small cell lung cancer.

Editor's Note: A previous version of the story mistakenly referred to the new RUBY trial as the confirmatory trial of Jemperli's accelerated approval in dMMR endometrial cancer. The phase 1 GARNET trial actually serves that purpose in the U.S.