WCLC 2025 - Posters & ePosters-EP.06.51 Development of Novel IHC Assay for PD-L1 Detection in Non-Small Cell Lung Cancer

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This study presents the development and initial evaluation of a novel immunohistochemistry (IHC) assay, the PD-L1 CAL10 assay, designed to detect PD-L1 expression in non-small cell lung cancer (NSCLC) patients. PD-L1 is a key biomarker used to identify NSCLC patients eligible for targeted immunotherapy. <br /><br />The researchers compared the CAL10 assay to an established comparator assay, PD-L1 SP263. Tissue samples from 136 NSCLC cases were stained and independently scored by two pathologists after separate staining sessions with each antibody, following a washout period. The CAL10 assay slides were processed on the BOND-III platform, while SP263 slides were run on the BenchMark Ultra system.<br /><br />Results demonstrated high agreement between the two assays at clinically relevant tumor proportion score (TPS) cutoffs. At the 50% TPS cutoff, the overall percent agreement (OPA) was 90.4% (95% CI: 86.2-93.4%), with positive percent agreement (PPA) at 95.6% and negative percent agreement (NPA) at 86.4%. At the 1% TPS cutoff, the OPA increased to 96.9% (95% CI: 94.0-98.4%), with PPA of 98.1% and NPA of 91.8%. These data indicate that the PD-L1 CAL10 assay provides comparable staining quality and diagnostic concordance relative to the SP263 assay.<br /><br />While the findings are promising for the CAL10 assay’s potential use in NSCLC PD-L1 testing, further validation studies are necessary to confirm performance and clinical utility. At present, the PD-L1 CAL10 assay remains in the research phase and is not approved for diagnostic use. The study showcases Leica Biosystems’ progress toward expanding PD-L1 testing options in NSCLC, supporting precision immunotherapy patient selection.

Asset Subtitle

Fangru Lian

Meta Tag

Speaker Fangru Lian

Topic Pathology and Biomarkers

Keywords

PD-L1 CAL10 assay

non-small cell lung cancer

NSCLC

immunohistochemistry

IHC assay

PD-L1 expression

tumor proportion score

TPS cutoff

immunotherapy biomarker

Leica Biosystems