The following article features coverage from the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Pembrolizumab monotherapy showed clinical efficacy in patients with advanced gastric cancer, according to data from KEYNOTE-059 presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois.1

KEYNOTE-059, presented by Charles S. Fuchs, MD, of the Yale Cancer Center in New Haven, Connecticut, is a phase 2 study ( Identifier: NCT02335411) undertaken for patients with advanced gastric cancer.

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Cohort 1, which was the focus of this presentation, evaluated pembrolizumab monotherapy in previously treated patients. Patients in this cohort had measureable recurrent or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma.

Researchers enrolled 259 patients who had progressed on at least 2 prior chemotherapy regimens. Patients received pembrolizumab 200 mg every 3 weeks for up to 2 years or until disease progression. PD-L1 microsatellite instability–high (MSI-H) and genetic profiling were also undertaken.

Median age was 62 years; 51.7% and 48.3% of patients received pembrolizumab as third-line (3L) and fourth or later–line (4L) therapy, respectively; 7.1% of patients had PD-L1-positive tumors.

After a median follow-up of 5.8 months, objective response rate (ORR) was 11.6% (complete response: 2.3%; partial response: 9.3%); 16.2% of patients had stable disease.

ORRs were 16.4% and 6.4% in patients receiving pembrolizumab as 3L and 4L therapy, respectively.

ORR was higher in patients with PD-L1-positive tumors: 15.5% vs 6.4% for patients with PD-L1-negative tumors.

Median duration of response was 8.4 months for all patients, 16.3 months for patients with PD-L1-positive tumors, and 6.9 months for PD-L1-negative tumors.

Overall, median progression-free survival was 2 months and median overall survival was 5.6 months.

In the 7 patients with MSI-H tumors, ORR was 57.1%; in the 167 patients with non-MSI-H tumors, ORR was 9.0%.

Two patients died on treatment, 1 due to acute kidney injury and 1 due to pleural effusion. Two other patients discontinued pembrolizumab due to a treatment-related adverse event.

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“Pembrolizumab represents a potential treatment option for patients with gastric and GEJ cancers who have progressed on 2 or more lines of therapy,” Dr Fuchs concluded.

Read more of Cancer Therapy Advisor‘s coverage of the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting by visiting the conference page.


  1. Fuchs CS, Doi T, Jang RW, et al. KEYNOTE-059 cohort 1: Efficacy and safety of pembrolizumab (pembro) monotherapy in patients with previously treated advanced gastric cancer. J Clin Oncol. 2017;35(suppl; abstr 4003).