Fuchs CS, et al. - Researchers aimed to assess the safety and effectiveness of pembrolizumab in a cohort of patients with previously treated gastric or gastroesophageal junction cancer. Findings suggested that a promising activity and manageable safety of pembrolizumab monotherapy was demonstrated in cases having advanced gastric or gastroesophageal junction cancer who received at least 2 lines of treatment previously. In patients with programmed cell death 1 ligand 1 (PD-L1)–positive and PD-L1–negative tumors, durable responses were noted.

Methods

• Authors enrolled 259 patients in 16 countries between March 2, 2015, and May 26, 2016 in the phase 2, global, open-label, single-arm, multicohort KEYNOTE-059 study.
• Patients received a median (range) follow-up of 5.8 (0.5-21.6) months.
• Pembrolizumab, 200 mg was given to the patients intravenously every 3 weeks untill disease progression, investigator or patient decided to withdraw, or the toxic effects became unacceptable.
• Objective response rate and safety were the primary end points.
• They assessed the objective response rate by central radiologic review per Response Evaluation Criteria in Solid Tumors, version 1.1, in all patients and those with programmed cell death 1 ligand 1 (PD-L1)–positive tumors.
• Immunohistochemistry was used to assess the expression of PD-L1.
• Response duration was included in the secondary end points.

Results

• Out of 259 patients enrolled, most of the patients were male (198 [76.4%]) and white (200 [77.2%]); with 62 (24-89) years being the median (range) age.
• Results suggested the objective response rate to be 11.6% (95% CI, 8.0%-16.1%; 30 of 259 patients), with complete response in 2.3% (95% CI, 0.9%-5.0%; 6 of 259 patients).
• As per the findings, median (range) response duration was noted to be 8.4 (1.6+ to 17.3+) months (+ indicates that patients had no progressive disease at their last assessment).
• They noted the objective response rate and median (range) response duration to be 15.5% (95% CI, 10.1%-22.4%; 23 of 148 patients) and 16.3 (1.6+ to 17.3+) months and 6.4% (95% CI, 2.6%-12.8%; 7 of 109 patients) and 6.9 (2.4 to 7.0+) months in patients with PD-L1–positive and PD-L1–negative tumors, respectively.
• One or more grade 3 to 5 treatment-related adverse events were experienced by 46 patients (17.8%).
• Because of treatment-related adverse events, 2 patients (0.8%) discontinued the treatment and 2 deaths were considered to be related to the treatment.