What is the role of pembrolizumab in the treatment of colon cancer?

Updated: Apr 15, 2020
  • Author: Tomislav Dragovich, MD, PhD; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Pembrolizumab, which is a monoclonal antibody to programmed cell death–1 protein (PD-1) gained accelerated approval from the FDA in May 2017 for unresectable or metastatic colon cancer that has tested positive for microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR), and has progressed following treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. It is also approved for any solid tumor that has tested positive for MSI-H or dMMR in patients who have had prior treatment and have no satisfactory alternative treatment options. [123]

The approval was based on data from 149 patients with MSI-H or dMMR cancers enrolled across 5 single-arm clinical trials (KEYNOTE). Ninety patients had colorectal cancer (CRC) and the remaining 59 patients had 1 of 14 other tumor types. The objective response rate (ORR) with pembrolizumab was 39.6%, including 11 (7.4%) complete responses (CRs) and 48 (32.2%) partial responses (PRs). Among patients who responded to pembrolizumab, 78% had responses that lasted for at least 6 months.

The accelerated approval for pembrolizumab in this setting is contingent on the results of a confirmatory trial. The approval was preceded by a breakthrough therapy designation the FDA granted to pembrolizumab in November 2015 as a treatment for patients with MSI-H metastatic CRC. [123]

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