A better way to assay.

October 30, 2017. You know those black and white lead-in scenes on infomercials where they smash the tomato with a dull knife? If only there were a better way… In non-small cell lung cancer (NSCLC), we now have three effective PD-1/PD-L1 inhibitors, but understanding all the various diagnostic assays and indications can be a headache in practice. Cue full color intro of this useful review article in JCO that walks you through some of the practical aspects (and limitations) of PD-1/PD-L1 assays. To review, pembrolizumab can be used first-line for metastatic NSCLC if >50% of tumor cells express PD-L1, and durvalumab can be used first-line in the consolidative setting of locally-advanced NSCLC regardless of PD-L1 expression. Nivolumab, atezolizumab, and pembro can all be used after first-line chemo when >1% PD-L1 expressed. The efficacies of all these drugs are related to the extent of PD-1/PD-L1 expression, but different assays produce different results...as can the tissue sampled. Cytology specimens and archived samples are probably as good as histology specimens and fresh tissue, but intra- and inter-tumor heterogeneity can impact the extent of PD-L1 expression. If you’re treating NSCLC, it’s probably worth having a better understanding of how your biopsies are processed and interpreted so you can slice and dice PD-1/PD-L1 inhibitors and their indications to perfection.