To Test for PD-L1 or Not: the Jury's Still Out

Biomarker-directed regimens in cancer not only ensure treatment for the right patient population, it also makes economic sense, especially in today's climate of high-cost specialty medications like the novel immunooncology agents, nivolumab and pembrolizumab—monclonal antibodies developed to inhibit the PD-1 receptor on the surface of T-cells.

However, with the PD-1 and PD-L1 inhibitors, the path to developing a predictive biomarker has been convoluted. Clinical trials in melanoma as well as in lung cancer have yielded mixed results, making it difficult to use protein expression to guide treatment. In addition to between-tumor heterogeneity in protein expression, researchers have known for years about within-tumor heterogeneity, meaning that protein expression may vary even within a single patient's tumor. Add to that the variation in the methods and the antibodies used to detect these proteins, and the complication rises to another level. Although encouraging results were presented at the ongoing meeting of the American Society of Clinical Oncology in Chicago, we need to be cautiously optimistic when using biomarker-guided treatment.

Read more at Reuters: http://reut.rs/1JgYu56