biostudies-literatureBellone SStand Up To CancerNCATS NIH HHSNIH Clinical CenterNCI NIH HHSNational Research Foundation of KoreaFondazione Guido BerlucchiHonorable Tina Brozman FoundationMerckGilead Sciences1206-1218https://www.ebi.ac.uk/biostudies/studies/S-EPMC9465822biostudies-literatureUnknown128(6)<h4>Background</h4>Microsatellite instability-high (MSI-H)/mismatch repair deficiency (dMMR) is a biomarker for responses to immune checkpoint inhibitors (ICIs). Whether mechanisms underlying microsatellite instability alter responses to ICIs is unclear. This article reports data from a prospective phase 2 pilot study of pembrolizumab in patients with recurrent MSI-H endometrial cancer (EC) analyzed by whole exome sequencing (WES) and potential mechanisms of primary/secondary ICI resistance (NCT02899793).<h4>Methods</h4>Patients with measurable MSI-H/dMMR EC confirmed by polymerase chain reaction/immunohistochemistry were evaluated by WES and received 200 mg of pembrolizumab every 3 weeks for ≤2 years. The primary end point was the objective response rate (ORR). Secondary end points includCancerA phase 2 evaluation of pembrolizumab for recurrent Lynch-like versus sporadic endometrial cancers with microsatellite instability.PMC9465822CA‐16359U01 CA176067P30 CA008748CA-16359UL1 TR001863NRF-2019R1A4A102900P30 CA016359U01 CA176067‐01Buza NDong WRoque DMClark MAzodi MGuglielmi ALee JZammataro LSiegel ERSilasi DAElvin JAChoi JHuang GSBonazzoli ESantin ADZeybek BIwasaki AAltwerger GZaidi SRatner EDamast SNagarkatti NBellone SHui PAlexandrov LBMenderes GHarold JASong ETymon-Rosario JRMauricio DSchwartz PEAndikyan VKong YfalseA phase 2 evaluation of pembrolizumab for recurrent Lynch-like versus sporadic endometrial cancers with microsatellite instability.<h4>Background</h4>Microsatellite instability-high (MSI-H)/mismatch repair deficiency (dMMR) is a biomarker for responses to immune checkpoint inhibitors (ICIs). Whether mechanisms underlying microsatellite instability alter responses to ICIs is unclear. This article reports data from a prospective phase 2 pilot study of pembrolizumab in patients with recurrent MSI-H endometrial cancer (EC) analyzed by whole exome sequencing (WES) and potential mechanisms of primary/secondary ICI resistance (NCT02899793).<h4>Methods</h4>Patients with measurable MSI-H/dMMR EC confirmed by polymerase chain reaction/immunohistochemistry were evaluated by WES and received 200 mg of pembrolizumab every 3 weeks for ≤2 years. The primary end point was the objective response rate (ORR). Secondary end points includ2022-01-01T00:00:00Z2022 Mar2026-05-10T06:52:11.991Z2025-02-19T03:26:45.484ZS-EPMC94658223487510710.1002/cncr.34025