GSK plc announced the US Food and Drug Administration (FDA) has approved Jemperli (dostarlimab-gxly) in combination with carboplatin and paclitaxel (chemotherapy) followed by Jemperli as a single agent for the treatment of adult patients with primary advanced or recurrent endometrial cancer. This approval broadens the previous indication for Jemperli plus chemotherapy to include patients with mismatch repair proficient (MMRp)/microsatellite stable (MSS) tumors who represent 70-75% of patients diagnosed with endometrial cancer and who have limited treatment options. The supplemental Biologics License Application (sBLA) supporting this expanded indication received Priority Review and was approved ahead of the Prescription Drug User Fee Act action date.

Expanded approval is based on results from dual primary endpoints of investigator-assessed progression-free survival (PFS) and overall survival (OS) from Part 1 of the RUBY phase III trial. RUBY Part 1 is the only clinical trial in this setting to show a statistically significant OS benefit in the full population of patients with primary advanced or recurrent endometrial cancer, demonstrating a 31% reduction in risk of death (HR: 0.69; 95% CI: 0.54?0.89) compared to chemotherapy alone. At the 2.5-year landmark, 61% (95% CI: 54-67) of patients in the Jemperli plus chemotherapy group compared to 49% (95% CI: 43-55) in the chemotherapy group were alive.

In addition, a 16.4-month improvement in median OS was observed with Jemperli plus chemotherapy versus chemotherapy alone (44.6 months [95% CI: 32.6?NR] vs. 28.2 months [95% CI: 22.1?35.6], respectively). The median duration of follow-up was more than three years.1 The safety and tolerability analysis from RUBY Part 1 showed a safety profile for Jemperliand carboplatin-paclitaxel that was generally consistent with the known safety profiles of the individual agents.

The most common treatment-emergent adverse events (= 20%) in patients receiving Jemperli plus chemotherapy were nausea, alopecia, fatigue, peripheral neuropathy, anemia, arthralgia, constipation, diarrhea, myalgia, rash, hypomagnesemia, decreased appetite, peripheral sensory neuropathy and vomiting. Endometrial cancer is found in the inner lining of the uterus, known as the endometrium. Endometrial cancer is the most common gynecologic cancer in developed countries,2 with an estimated 1.6 million people living with active disease at any stage and 417,000 new cases reported each year worldwide.3 Incidence rates are expected to rise by approximately 40% between 2020 and 2040.4 Approximately 15-20% of patients with endometrial cancer will be diagnosed with advanced disease at the time of diagnosis.5 Among patients with primary advanced or recurrent endometrial cancer, approximately 70-75% have MMRp/MSS tumors.

RUBY is a two-part global, randomized, double-blind, multi-center phase III trial of patients with primary advanced or recurrent endometrial cancer. Part 1 is evaluating dostarlimab-gxly plus carboplatin-paclitaxel followed by dostarlimab-gxly versus carboplatin-paclitaxel plus placebo followed by placebo. Part 2 is evaluating dostarlimab-gxly plus carboplatin-paclitaxel followed by dostarlimab-gxly plus niraparib versus placebo plus carboplatin-paclitaxel followed by placebo.

In Part 1, the dual-primary endpoints are investigator-assessed PFS based on the Response Evaluation Criteria in Solid Tumors v1.1 and OS. The statistical analysis plan included pre-specified analyses of PFS in the mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) and overall populations and OS in the overall population. Pre-specified exploratory analyses of PFS and OS in the MMRp/MSS population and OS in the dMMR/MSI-H populations were also performed.

RUBY Part 1 included a broad population, including histologies often excluded from clinical trials and had approximately 10% of patients with carcinosarcoma and 20% with serous carcinoma. In Part 2, the primary endpoint is investigator-assessed PFS in the overall population, followed by PFS in the MMRp/MSS population, and OS in the overall population is a key secondary endpoint. Additional secondary endpoints in Part 1 and Part 2 include PFS per blinded independent central review, PFS2, overall response rate, duration of response, disease control rate, patient-reported outcomes, and safety and tolerability.

RUBY is part of an international collaboration between the European Network of Gynaecological Oncological Trial groups (ENGOT), a research network of the European Society of Gynaecological Oncology (ESGO) that consists of 22 trial groups from 31 European countries that perform cooperative clinical trials, and the GOG Foundation, a non-profit organization dedicated to transforming the standard of care in gynecologic oncology.