SAN FRANCISCO—Pembrolizumab, an anti-PD-1 monoclonal antibody, demonstrated promising antitumor activity and manageable toxicity in patients with advanced gastric cancer, a study (Abstract 3) presented this week at the 2015 Gastrointestinal Cancers Symposium has shown.

The PD-1 pathway is known to help tumors evade surveillance by the immune system, so researchers sought to investigate the safety and efficacy of pembrolizumab in patients with advanced gastric cancer who had distinctive stromal or 1% or more tumor nest cell PD-L1 staining.

For the KEYNOTE-012 study, researchers enrolled 39 patients with PD-L1+ advanced gastric cancer. All patients received pembrolizumab 10 mg/kg intravenously every 2 weeks for up to 2 years or until complete response, disease progression, or unacceptable toxicity.

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Results showed an objective response rate of 22% (95% CI: 10,39) per RECIST v1.1 by independent central review and 33% (95% CI: 19,50) by investigator review. PD-L1 expression level was associated with objective response rate (1-sided P = 0.10).

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In addition, the median duration of response was 24 weeks, the 6-month progression-free survival rate was 24% and the 6-month overall survival rate was 69%. The median follow-up duration was 8.8 months.

In regard to safety, decreased appetite, fatigue, hypoxia, peripheral sensory neuropathy, and pneumonitis were experienced by one patient each. There was also one drug-related death due to hypoxia.


  1. Muro K, Bang Y-J, Shankaran V, et al. Relationship between PD-L1 expression and clinical outcomes in patients (Pts) with advanced gastric cancer treated with the anti-PD-1 monoclonal antibody pembrolizumab (Pembro; MK-3475) in KEYNOTE-012. J Clin Oncol 2015;33:(suppl 3; abstr 3).