Safety, Efficacy, and Biomarker Analyses of Dostarlimab in Patients with Endometrial Cancer: Interim Results of the Phase I GARNET Study

Ana Oaknin, Bhavana Pothuri, Lucy Gilbert, Renaud Sabatier, Jubilee Brown, Sharad Ghamande, Cara Mathews, David M. O’Malley, Rebecca Kristeleit, Valentina Boni, Adriano Gravina, Susana Banerjee, Rowan Miller, Joanna Pikiel, Mansoor R. Mirza, Ninad Dewal, Grace Antony, Yuping Dong, Eleftherios Zografos, Jennifer VenerisAnna V. Tinker

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Purpose: This interim report of the GARNET phase I trial presents efficacy and safety of dostarlimab in patients with advanced or recurrent endometrial cancer (EC), with an analysis of tumor biomarkers as prognostic indicators. Patients and Methods: A total of 153 patients with mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) and 161 patients with mismatch repair proficient (MMRp)/microsatellite stable (MSS) EC were enrolled and dosed. Patients received 500 mg dostarlimab every 3 weeks for four cycles, then 1,000 mg every 6 weeks until progression. Primary endpoints were objective response rate (ORR) and duration of response (DOR). Results: A total of 143 patients with dMMR/MSI-H EC and 156 patients with MMRp/MSS EC were evaluated for efficacy. ORR was 45.5% (n ¼ 65) and 15.4% (n ¼ 24) for dMMR/MSI-H EC and MMRp/MSS EC, respectively. Median DOR for dMMR/MSI-H EC was not met (median follow-up, 27.6 months); median DOR for MMRp/MSS EC was 19.4 months. The ORRs by combined positive score (CPS) ≥1 status were 54.9% and 21.7% for dMMR/MSI-H EC and MMRp/MSS EC, respectively. ORRs by high tumor mutational burden (≥10 mutations/Mb) were 47.8% (43/90) and 45.5% (5/11) for dMMR/MSI-H EC and MMRp/MSS EC, respectively. ORR in TP53mut or POLemut molecular subgroups was 18.1% (17/94) and 40.0% (2/5), respectively. The safety profile of dostarlimab was consistent with previous reports. Conclusions: Dostarlimab demonstrated durable antitumor activity and safety in patients with dMMR/MSI-H EC. Biomarkers associated with EC may identify patients likely to respond to dostarlimab.

Original languageEnglish (US)
Pages (from-to)4564-4574
Number of pages11
JournalClinical Cancer Research
Volume29
Issue number22
DOIs
StatePublished - 2023

ASJC Scopus subject areas

  • General Medicine

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