The FDA has granted two new endometrial cancer indications to rival immunotherapies: Merck’s Keytruda and AstraZeneca’s Imfinzi.
On Monday, regulators approved Merck’s PD-1 blockbuster Keytruda in combination with chemotherapy, followed by Keytruda as a single agent for adult patients with advanced or recurrent endometrial cancer. It’s Keytruda’s 40th indication, and third in endometrial cancer.
It also makes the drug the first front-line immunotherapy for advanced endometrial cancer patients regardless of mismatch repair status, a biomarker that helps inform treatment decisions. Mismatch repair deficiency, or dMMR, has been associated with having more tumor mutations.
In a Phase 3 trial, dMMR patients who took the Keytruda regimen did not reach a median progression-free survival, compared to patients who took placebo and chemotherapy, who saw a 6.5-month median progression-free survival. In the mismatch repair proficient arm (pMMR), median progression-free survival was 11.1 months for Keytruda patients compared with 8.5 months for those on placebo.
Merck said in February that the Keytruda arm reduced dMMR patients’ risk of disease progression or death by 70% compared with chemotherapy alone.
AstraZeneca also announced an approval on Friday for its PD-L1 Imfinzi to treat advanced or recurrent endometrial cancer in combination with carboplatin and paclitaxel, followed by Imfinzi as a single agent. But that indication is solely for dMMR patients.
The British pharma company said dMMR patients account for 20% to 30% of people with advanced endometrial cancer. While it’s difficult to compare data across separate trials, the Imfinzi regimen reduced dMMR patients’ risk of disease progression or death by 58% compared with chemotherapy alone in a Phase 3 trial, AstraZeneca said.