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January 2016

PD-L1 Testing in Cancer: Challenges in Companion Diagnostic Development

Author Affiliations
  • 1Princess Margaret Cancer Centre, Drug Development Program Toronto, Ontario, Canada
JAMA Oncol. 2016;2(1):15-16. doi:10.1001/jamaoncol.2015.4685

Advances in the understanding of cancer biology have led to the discovery, development, and validation of biomarkers that provide prognostic, pharmacodynamic, and predictive information. Immune checkpoints maintain self-tolerance and modulate physiologic T-cell responses. Antibody therapies targeting the inhibitory checkpoint PD-1 (programmed cell death protein 1) and PD-L1 (programmed cell death 1 ligand 1) have demonstrated promising activity in several cancers.1 Currently, there is no validated predictive biomarker to select patients likely to respond to anti–PD-1/PD-L1 therapies. However, some PD-L1–positive tumors have demonstrated higher response rates to anti–PD-1/PD-L1 therapies, suggesting that identifying patients with PD-L1 expression may enrich for antitumor responses.1-3

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