Assessment of Pembrolizumab Therapy for the Treatment of Microsatellite Instability-High Gastric or Gastroesophageal Junction Cancer among Patients in the KEYNOTE-059, KEYNOTE-061, and KEYNOTE-062 Clinical Trials

Joseph Chao, Charles S. Fuchs, Kohei Shitara, Josep Tabernero, Kei Muro, Eric Van Cutsem, Yung Jue Bang, Ferdinando De Vita, Gregory Landers, Chia Jui Yen, Ian Chau, Anneli Elme, Jeeyun Lee, Mustafa Özgüroǧlu, Daniel Catenacci, Harry H. Yoon, Erluo Chen, David Adelberg, Chie Schin Shih, Sukrut ShahPooja Bhagia, Zev A. Wainberg

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1 Citation (Scopus)

Abstract

Importance: Immunotherapy has been associated with improved outcomes among patients who have received previous treatment for microsatellite instability-high (MSI-H) tumors. Objective: To evaluate the antitumor activity of pembrolizumab therapy vs chemotherapy among patients with MSI-H advanced gastric or gastroesophageal junction (G/GEJ) cancer regardless of the line of therapy in which it was received. Design, Setting, and Participants: This post hoc analysis of the phase 2 KEYNOTE-059 (third-line treatment or higher) single-arm trial and the phase 3 KEYNOTE-061 (second-line treatment) and KEYNOTE-062 (first-line treatment) randomized trials included patients with advanced G/GEJ cancer from 52 sites in 16 countries enrolled in KEYNOTE-059, 148 sites in 30 countries enrolled in KEYNOTE-061, and 200 sites in 29 countries enrolled in KEYNOTE-062. Patients were enrolled from March 2, 2015, to March 26, 2016, in KEYNOTE-059; from June 4, 2015, to July 26, 2016, in KEYNOTE-061; and from September 18, 2015, to May 26, 2017, in KEYNOTE-062, with data cutoff dates of August 8, 2018; October 26, 2017; and March 26, 2019; respectively. Interventions: Pembrolizumab monotherapy in KEYNOTE-059, pembrolizumab monotherapy or chemotherapy (paclitaxel) in KEYNOTE-061, and pembrolizumab monotherapy, pembrolizumab plus chemotherapy (cisplatin and 5-fluorouracil or capecitabine), or chemotherapy alone in KEYNOTE-062. Main Outcomes and Measures: Response was assessed centrally using Response Evaluation Criteria in Solid Tumours (RECIST), version 1.1; MSI-H status was determined centrally by polymerase chain reaction testing. Results: At data cutoff, 7 of 174 patients (4.0%) in KEYNOTE-059, 27 of 514 patients (5.3%) in KEYNOTE-061, and 50 of 682 patients (7.3%) in KEYNOTE-062 had MSI-H tumors. Among those with MSI-H tumors, the median overall survival was not reached (NR) for pembrolizumab in KEYNOTE-059, KEYNOTE-061, and KEYNOTE-062 or for pembrolizumab plus chemotherapy in KEYNOTE-062. The median progression-free survival (PFS) for pembrolizumab was NR (95% CI, 1.1 months to NR) in KEYNOTE-059 and 17.8 months (95% CI, 2.7 months to NR) in KEYNOTE-061 (vs 3.5 months [95% CI, 2.0-9.8 months] for chemotherapy). In KEYNOTE-062, the median PFS was 11.2 months (95% CI, 1.5 months to NR) for pembrolizumab, NR (95% CI, 3.6 months to NR) for pembrolizumab plus chemotherapy, and 6.6 months (95% CI, 4.4-8.3 months) for chemotherapy. The objective response rate (ORR) for pembrolizumab was 57.1% in KEYNOTE-059 and 46.7% (vs 16.7% for chemotherapy) in KEYNOTE-061. In KEYNOTE-062, the ORR was 57.1% for pembrolizumab, 64.7% for pembrolizumab plus chemotherapy, and 36.8% for chemotherapy. Conclusions and Relevance: Findings from this study indicate that MSI-H status may be a biomarker for pembrolizumab therapy among patients with advanced G/GEJ cancer regardless of the line of therapy in which it was received. Trial Registration: ClinicalTrials.gov Identifiers: NCT02335411, NCT02370498, and NCT02494583..

Original languageEnglish
JournalJAMA Oncology
DOIs
Publication statusAccepted/In press - 2021

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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