European Commission Approves Pembrolizumab in MSI-H/dMMR Solid Tumors

Pembrolizumab has been approved by the European Commission in 5 indications of solid tumors that are microsatellite instability–high or deficient mismatch repair.

Pembrolizumab (Keytruda) has been approved by the European Commission for patients with microsatellite instability–high (MSI-H) or mismatch repair deficient (dMMR) tumors, according to a press release from Merck.

The approval is based on results from the phase 2 KEYNOTE-164 trial (NCT02460198)— assessing the monotherapy in patients with previously treated locally advanced unresectable of metastatic colorectal cancer—and the phase 2 KEYNOTE-158 trial (NCT02628067)—examining pembrolizumab in advanced solid tumors.

Patients with colorectal cancer (n = 124) had an objective response rate (ORR) of 34.0% (95% CI, 25.6%-42.9%) with a complete response (CR) rate of 10.0% after a median follow-up of 37.3 months. After a median follow-up of 21.9 years, those with endometrial cancer (n = 83) had an ORR of 51.0% (95% CI, 39.4%-61.8%), a CR rate of 16.0%. Those with gastric cancer (n = 51) had an ORR of 37.0% (95% CI, 24.1%-51.9%), with a CR rate of 14.0% after a median follow-up of 13.9 months. Those with small intestine cancer (n = 27) had an ORR of 56.0% (95% CI, 35.3%-74.5%), with a CR rate of 15.0% and a median follow-up of 29.1 months. Those with biliary cancer (n = 22) had an ORR of 41.0% (95% CI, 20.7%-63.6%), with a CR rate of 14.0%, and a median follow-up of 19.4 months.

“The [European Commission] approval of [pembrolizumab] is an important milestone for patients living with these MSI-H/dMMR cancers who have had few treatment options and face worse outcomes when diagnosed at an advanced stage,” Aurélien Marabelle, MD, PhD, immuno-oncologist at Gustave Roussy Cancer Center and Professor of Clinical Immunology at the University of Paris Saclay, said in the press release.


European Commission approved Merck’s Keytruda (pembrolizumab) for patients with microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) tumors in five different types of cancer. News Release. Merck. April 29, 2022. Accessed May 6, 2022.