Diagnostic Testing to Identify PD-L1 Inhibitor Response in Lung Cancer

Naiyer A. Rizvi, MD, director of thoracic oncology and immunotherapeutics at Columbia University Medical Center discusses using PD-L1 expression on a tumor and its benefits.

We are pre-identifying patients by PD-L1 expression on the tumor; it’s an immunohistochemical assay and it’s fairly easy to do. High levels of PD-L1 expression do tend to correlate with benefit—it’s not a perfect biomarker; there’s both false positives and negatives. It’s not a binary biomarker, like EGFR mutation testing, but it does provide some guide to who is more likely to benefit.

The approval of pembrolizumab first-line treatment, a single agent in lung cancer was based on KEYNOTE-024 where patients who have more than 50% of PD-L1 expression, which is about a third of non-small cell lung cancer and in those patients, they had a superior response rate, progression-free survival, as well as overall survivor with single-agent pembrolizumab versus chemotherapy.

So, based on that data, and really the standard of care, to test for PD-L1 expression if you’re positive at the 50% threshold and treat with single agent pembrolizumab and not chemotherapy.
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