A pragmatic workflow for advanced NSCLC diagnosis in routine practice: Integrating histopathology, PD-L1 scoring, and EGFR testing

ABSTRACT Background: Precision treatment of advanced non-small cell lung carcinoma (NSCLC) requires early biomarker availability, yet routine practice is constrained by small biopsies, sequential testing, and limited resources. We assessed whether PD-L1 and EGFR testing were completed from the initial biopsy using a tissue-efficient reflex workflow integrating histologic subtyping, PD-L1 scoring, EGFR analysis, and tumour-infiltrating lymphocyte (TIL) assessment. Methods: In this prospective single-arm feasibility study, 50 stage III or IV NSCLC cases were evaluated. Tumours were subtyped using morphology and minimal immunohistochemistry (TTF-1, Napsin A, p40). PD-L1 immunohistochemistry was performed using a locally validated CAL10-based laboratory-developed test and scored by tumour proportion score (TPS) and combined positive score (CPS). Reflex EGFR testing was attempted in adenocarcinomas with adequate tissue. TILs were graded morphologically. Tissue adequacy and biomarker associations were analysed. Results: Squamous cell carcinoma comprised 56% and adenocarcinoma 44% of cases. Adequate tissue to complete PD-L1 and EGFR testing was available in 59% (13/22) of adenocarcinomas, and was reported within 30 days. EGFR mutations were detected in 31% of tested adenocarcinomas and were associated with TPS <50% and absent TILs. High PD-L1 expression (TPS ≥50%) was observed in 14% of tumours, exclusively in EGFR wild-type cases. TILs were present in 12% of cases and were significantly associated with higher CPS ( P = 0.002), exceeding TPS. Conclusion: A biopsy-level reflex workflow enables feasible, tissue-efficient concurrent molecular and immune profiling in advanced NSCLC. Integration of TPS, CPS, TIL assessment, and EGFR testing within a reflex workflow demonstrates the feasibility of coordinated immuno-molecular profiling from limited biopsy tissue in advanced NSCLC.