clinicaltrials.gov Identifier: NCT02335411.

Gastric cancer is the third leading cause of cancer-related deaths worldwide. Over 95% of gastric cancers are adenocarcinomas, which are typically classified based on anatomic location and histologic type. Gastric cancer generally carries a poor prognosis because it is often diagnosed at an advanced stage. Systemic therapy can provide palliation, improved survival, and enhanced quality of life in patients with locally advanced or metastatic disease. The implementation of biomarker testing, especially analysis of HER2 status, microsatellite instability (MSI) status, and the expression of programmed death-ligand 1 (PD-L1), has had a significant impact on clinical practice and patient care. Targeted therapies including trastuzumab, nivolumab, and pembrolizumab have produced encouraging results in clinical trials for the treatment of patients with locally advanced or metastatic disease. Palliative management, which may include systemic therapy, chemoradiation, and/or best supportive care, is recommended for all patients with unresectable or metastatic cancer. Multidisciplinary team management is essential for all patients with localized gastric cancer. This selection from the NCCN Guidelines for Gastric Cancer focuses on the management of unresectable locally advanced, recurrent, or metastatic disease.

Background The multicohort, phase II, nonrandomized KEYNOTE-059 study evaluated pembrolizumab ± chemotherapy in advanced gastric/gastroesophageal junction cancer. Results from cohorts 2 and 3, evaluating first-line therapy, are presented. Methods Patients ≥ 18 years old had previously untreated recurrent or metastatic gastric/gastroesophageal junction adenocarcinoma. Cohort 3 (monotherapy) had programmed death receptor 1 combined positive score ≥ 1. Cohort 2 (combination therapy) received pembrolizumab 200 mg on day 1, cisplatin 80 mg/m 2 on day 1 (up to 6 cycles), and 5-fluorouracil 800 mg/m 2 on days 1–5 of each 3-week cycle (or capecitabine 1000 mg/m 2 twice daily in Japan). Primary end points were safety (combination therapy) and objective response rate per Response Evaluation Criteria in Solid Tumors version 1.1 by central review, and safety (monotherapy). Results In the combination therapy and monotherapy cohorts, 25 and 31 patients were enrolled; median follow-up was 13.8 months (range 1.8–24.1) and 17.5 months (range 1.7–20.7), respectively. In the combination therapy cohort, grade 3/4 treatment-related adverse events occurred in 19 patients (76.0%); none were fatal. In the monotherapy cohort, grade 3–5 treatment-related adverse events occurred in seven patients (22.6%); one death was attributed to a treatment-related adverse event (pneumonitis). The objective response rate was 60.0% [95% confidence interval (CI), 38.7–78.9] (combination therapy) and 25.8% (95% CI 11.9–44.6) (monotherapy). Conclusions Pembrolizumab demonstrated antitumor activity and was well tolerated as monotherapy and in combination with chemotherapy in patients with previously untreated advanced gastric/gastroesophageal junction adenocarcinoma. Clinical Trial ClinicalTrials.gov NCT02335411 Electronic supplementary material The online version of this article (10.1007/s10120-018-00909-5) contains supplementary material, which is available to authorized users.

IMPORTANCEImmunotherapy 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 PARTICIPANTSThis 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.