medwireNews: A comparison of four antibodies for the measurement of programmed cell death ligand 1 (PD-L1) expression in non-small-cell lung cancer (NSCLC) has shown three to be concordant with regard to tumor cell antibody staining and pathologist scoring.
By contrast, the fourth antibody, SP142, was “an outlier,” with significantly lower scores on average for PD-L1 expression in both tumor and immune cells than the other antibodies, the researchers report in JAMA Oncology.
“There appears to be minimal difference between the other 3 assays tested, which could have implications for assay choices in individual pathologists’ laboratories where there is financial pressure to validate only a single PD-L1 assay,” explain David Rimm, from Yale University School of Medicine in New Haven, Connecticut, USA, and co-investigators.
The study included 90 NSCLC specimens assessed by immunohistochemistry using the 22c3, 28-8, E1L3N, and SP142 antibodies on three different assay platforms, all of which are approved by the US Food and Drug Administration for use alongside targeted agents. Thirteen pathologists scored the slides using a unified method.
The 22c3, 28-8, and E1L3N antibodies had high concordance for tumor cell scoring but poorer concordance for immune cells, with a similar pattern for the concordance between pathologists for each of the antibody assays.
“We hope that these observations will lead to future clinical concordance studies in patients treated with [programmed cell death 1] axis therapies,” the team concludes.
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