Immunotherapy is underutilized in patients with advanced endometrial cancer (EC), even though proven benefits have been observed, according to Bhavana Pothuri, MD, and colleagues, authors of a study on the utilization of immunotherapy among eligible patient with EC.

The checkpoint inhibitor pembrolizumab was FDA-approved for previously treated unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) EC in 2017 and, in combination with lenvatinib, for previously treated recurrent or metastatic microsatellite stable (MSS) EC in 2019. “The use of pembrolizumab in clinical practice after approval has not been extensively studied,” the researchers wrote. “Therefore, we sought to determine the frequency of pembrolizumab use among eligible patients with EC.”

Opportunity Exists to Better Identify Eligible Patients for Treatment

In a retrospective study, the researchers categorized patients undergoing treatment for EC between May 2012 and June 2021. Patients were classified as having received or not received pembrolizumab only if they were eligible after the respective approval dates of pembrolizumab in MSI-H/dMMR tumors or pembrolizumab/lenvatanib in MSS tumors.

Of 1,541 patients screened for EC, 634 had MSS status and 179 had MSI-H/dMMR status. Of the 634 MSS patients screened for EC, 42 met FDA criteria for treatment with pembrolizumab; 61.9% received pembrolizumab and lenvatinib and 38.1% did not.

In patients with MSS EC who did not receive pembrolizumab and lenvatinib, 12 received chemotherapy, three participated in clinical trials, and one was lost to follow-up. Of the 179 MSI-H/dMMR patients screened for EC, 16 met FDA criteria for treatment with pembrolizumab; 81.2% received pembrolizumab and 8.8% did not. Three patients with MSI EC who did not receive pembrolizumab treatment underwent chemotherapy.

This study illustrates that “there is an opportunity to improve the identification of eligible patients and increase the use of checkpoint inhibitors in EC with continued education,” the study authors wrote.