Key insights
- Merck's Keytruda demonstrated a significant reduction in disease progression or death risk by 43% in a Phase 3 trial for advanced or recurrent endometrial cancer. Patients receiving Keytruda showed substantially longer progression-free survival compared to chemotherapy. While overall survival did not reach statistical significance, favorable trends and a higher objective response rate were observed. Keytruda also exhibited a better safety profile with fewer grade 3 or higher treatment-related adverse events. These results are expected to be presented at an upcoming medical congress and submitted to regulatory authorities.
Merck (MRK) announced results from the Phase 3 KEYNOTE-C93 trial showing that pembrolizumab, sold as Keytruda, as a monotherapy reduced the risk of disease progression or death by 43% compared to platinum doublet chemotherapy in patients with mismatch repair deficient (dMMR) advanced or recurrent endometrial cancer who had not previously received systemic chemotherapy or who experienced recurrence after prior adjuvant therapy.
After a median follow-up of 36.7 months, median progression-free survival (PFS) was 38.2 months for patients receiving Keytruda compared to 8.4 months for those receiving chemotherapy. The 36-month PFS rates were 52.8% and 30.0%, respectively.
A favorable trend in overall survival (OS), a co-primary endpoint, was observed for Keytruda versus chemotherapy (HR=0.77; p=0.1000), though the result did not reach statistical significance. Median OS was not reached in either arm. Follow-up for OS is ongoing.
The confirmed objective response rate was 64.1% for Keytruda versus 62.1% for chemotherapy. Among responders, median duration of response was not reached for Keytruda patients compared to 10.2 months for chemotherapy patients.
Grade 3 or higher treatment-related adverse events occurred in 18.1% of Keytruda-treated patients versus 50.7% of chemotherapy patients. Grade 3 or higher immune-mediated adverse events occurred in 7.4% of Keytruda patients and 3.5% of chemotherapy patients.
The trial enrolled 299 patients who were randomized to receive either Keytruda at 400 mg intravenously every six weeks for up to 18 cycles, or a combination of paclitaxel and carboplatin every three weeks for six cycles.
According to a press release statement from Merck, the results will be presented at the European Society for Medical Oncology Congress 2026 and published simultaneously in The Lancet. Merck said results will be shared with regulatory authorities worldwide. Keytruda currently holds three approved U.S. indications for certain types of endometrial cancer.
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