Merck (MRK) has announced that its flagship cancer drug Keytruda has achieved a landmark result in the treatment of a specific endometrial cancer subtype.
The drug became the first PD-1 inhibitor to demonstrate a statistically significant benefit as a single agent in the front-line treatment of mismatch repair deficient advanced or recurrent endometrial cancer.
Keytruda significantly improved progression-free survival compared to platinum-based chemotherapy in patients who had received no prior systemic chemotherapy or experienced recurrence more than six months after completing adjuvant therapy.
The results come from the Keynote-C93 trial, which also recorded an immature trend toward improvement in overall survival at the interim analysis, with further evaluation of that endpoint planned as the trial continues.
Brian Slomovitz, M.D., from Mount Sinai Medical Center and the study’s principal investigator, said the positive readout positions Keytruda as a new chemo-free option for patients in this first-line setting.
Merck has confirmed it plans to share the trial results with regulatory authorities, raising the prospect of a new approved indication for one of the pharmaceutical industry’s most commercially significant drugs.
Keytruda is described as the first and only PD-1 inhibitor to show a statistically significant and clinically meaningful improvement in progression-free survival as monotherapy compared to platinum doublet chemotherapy in a Phase 3 trial for this patient group.
Its closest rival in the endometrial cancer space is GSK’s Jemperli, which in 2023 became the first PD-1 inhibitor to win FDA approval in the first-line endometrial cancer setting, cleared for use alongside chemotherapy in dMMR tumours.
Both Keytruda and Jemperli were subsequently approved by the FDA in quick succession as combinations with carboplatin and paclitaxel for patients with primary advanced or recurrent endometrial carcinoma approximately two years ago.
Endometrial cancer remains one of the few cancers with increasing mortality rates, making advances in treatment particularly urgent for patients and clinicians alike.
In the United States, approximately 68,270 patients are estimated to be diagnosed with endometrial cancer in 2026, with approximately 14,450 deaths expected from the disease during the same period.
Globally, endometrial cancer is ranked as the sixth most common cancer in women and the 15th most common cancer overall, underscoring the scale of the unmet medical need this new data seeks to address.