Dostarlimab/Chemo Earns Expanded Canadian Approval in Primary Advanced, First Recurrent Endometrial Cancer

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Health Canada has expanded the approval of injectable dostarlimab-gxly (Jemperli) plus carboplatin and paclitaxel for the treatment of adult patients with primary advanced or first recurrent endometrial cancer who are eligible to receive systemic therapy, based on findings from part 1 of the phase 3 RUBY trial (NCT03981796).1

The approval follows a previous indication for the PD-1 inhibitor dostarlimab plus carboplatin and paclitaxel, which was granted in November 2023 for patients with mismatch repair–deficient (dMMR)/microsatellite instability–high (MSI-H) tumors. The regulatory decision was also based on an earlier analysis of part 1 of the RUBY study.

“[This] expanded approval of [dostarlimab] for all patients with primary advanced or first recurrent endometrial cancer in Canada is supported by an overall survival benefit across the study population,” said Michelle Horn, country medical director at GSK Canada, in a news release. “This represents a significant milestone and demonstrates [dostarlimab’s] potential to redefine the treatment of cancers with high mortality rates and unmet needs, such as endometrial cancer. [Dostarlimab] remains a backbone of our immuno-oncology program, offering renewed hope to Canadian patients and emphasizing GSK’s dedication, as a research-focused company, to addressing the most common gynecologic cancer in Canada.”

Data from part 1 of the study revealed that both dual primary end points—progression-free survival (PFS) and overall survival (OS)—were met in the overall population of patients with primary advanced or recurrent endometrial cancer (n = 494). Of note, the study is the only trial in this setting to demonstrate a meaningful and statistically significant OS benefit, with a 31% reduction in the risk of death vs chemotherapy alone (HR, 0.69; 95% CI, 0.54-0.89; P = .002).

Patients treated with dostarlimab plus carboplatin/paclitaxel had a median OS of 44.6 months compared with 28.2 months in those treated with carboplatin/paclitaxel alone, which demonstrated a clinically meaningful improvement of 16.4 months.2 In the overall population, the 24-month PFS rate was 36.1% (95% CI, 29.3%-42.9%) in the dostarlimab arm and 18.1% (95% CI, 13.0%-23.9%) in the placebo arm (HR, 0.64; 95% CI, 0.51-0.80; P < .001).3

In the study, patients were randomly assigned to treatment with dostarlimab plus carboplatin/paclitaxel (n = 245) or placebo plus carboplatin/paclitaxel alone (n = 249). Patients received dostarlimab at 500 mg or placebo intravenously plus carboplatin at an area under the curve of 5 mg/mL/min and intravenous paclitaxel at 175 mg/m2 of body surface area every 3 weeks for the first 6 cycles, followed by dostarlimab at 1000 mg or placebo intravenously every 6 weeks for up to 3 years or until disease progression.

“Gynecological oncologists have long awaited an immuno-oncology option to improve survival outcomes for [patients with] endometrial cancer at advanced stages, and newly approved treatments in Canada enhance the cancer care journey by offering more personalized options,” Alon Altman, MD, FRCSC, gynecologic oncologist and professor of obstetrics and gynecology at the University of Manitoba, and chief strategy officer and former president of The Society of Gynecologic Oncology of Canada, said in the news release.1 “Ensuring innovative clinical therapies are publicly available and accessible to all patients in need is also vital as timely treatment is especially crucial for individuals with more advanced endometrial cancer who cannot afford to wait.”

In July 2023, dostarlimab was approved in combination with carboplatin/paclitaxel, followed by single-agent dostarlimab for the treatment of patients with advanced or recurrent endometrial cancer that is dMMR/MSI-H.4 The FDA further expanded the indication of dostarlimab plus carboplatin/paclitaxel in August 2024, for the treatment of patients with primary advanced or recurrent endometrial cancer.5 Both approvals were supported by data from the RUBY study. In January 2025, the European Commission approved frontline dostarlimab plus carboplatin/paclitaxel as treatment for all adult patients with primary advanced or recurrent endometrial cancer who are eligible for systemic therapy.6

“The expanded approval of dostarlimab provides patients with advanced or recurrent endometrial cancer new hope of extending their lives,” said Filomena Servidio-Italiano, president and CEO of the Colorectal Cancer Resource & Action Network, in the news release.1 “The expanded approval of dostarlimab provides patients with advanced or recurrent endometrial cancer new hope of extending their lives. Patients and advocates should be encouraged by this announcement, offering a new treatment option to patients in Canada diagnosed with endometrial cancer. We are optimistic that the Canadian reimbursement and funding systems will support the accessibility of this important therapy for those in need.”

References

1. Health Canada expands Jemperli (dostarlimab for injection) plus chemotherapy approval to all adult patients with primary advanced or first recurrent endometrial cancer, as the first and only immuno-oncology-based treatment to show an overall survival benefit for these patients. News release. GSK. April 17, 2025. Accessed April 18, 2025. https://ca.gsk.com/en-ca/media/press-releases/health-canada-expands-jemperli-dostarlimab-for-injection/
2. Powell MA, Bjørge L, Willmott L, et al. Overall survival in patients with endometrial cancer treated with dostarlimab plus carboplatin-paclitaxel in the randomized ENGOT-EN6/GOG-3031/RUBY trial. Ann Oncol. 2024;35(8):728-738. doi:10.1016/j.annonc.2024.05.546
3. Mirza MR, Chase DM, Slomovitz BM, et al. Dostarlimab for primary advanced or recurrent endometrial cancer. N Engl J Med. 2023;388(23):2145-2158. doi:10.1056/NEJMoa2216334
4. FDA approves dostarlimab-gxly with chemotherapy for endometrial cancer. FDA. July 31, 2023. Accessed April 18, 2025. https://www.fda.gov/drugs/drug-approvals-and-databases/fda-approves-dostarlimab-gxly-chemotherapy-endometrial-cancer
5. FDA expands endometrial cancer indication for dostarlimab-gxly with chemotherapy. FDA. August 1, 2024. Accessed April 18, 2025. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-expands-endometrial-cancer-indication-dostarlimab-gxly-chemotherapy
6. European Commission expands Jemperli (dostarlimab) plus chemotherapy approval to all adult patients with primary advanced or recurrent endometrial cancer. News release. GSK. January 20, 2025. Accessed April 18, 2025. https://www.gsk.com/en-gb/media/press-releases/european-commission-expands-jemperli-dostarlimab-plus-chemotherapy-approval-to-all-adult-patients-with-primary-advanced-or-recurrent-endometrial-cancer/