Real-world patterns of PD-L1 expression, biomarker testing, and immunotherapy utilization across lung and other solid tumors in an Asian cohort.

Abstract

e23380 Background: Programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) is an established enrichment biomarker guiding immune checkpoint inhibitor (ICI) therapy across multiple solid tumors, as reflected in NCCN and ESMO guidelines. While clinical trials have defined tumor-specific PD-L1 thresholds, limited real-world data are available on PD-L1 expression patterns, concurrent biomarker testing, and alignment with ICI use in Asian oncology practice. We evaluated PD-L1 testing and treatment patterns across lung and other solid tumors in a real-world Asian cohort. Methods: We retrospectively analyzed 339 predominantly Indian solid tumor cases, tested for PD-L1 IHC between 2019 and 2025. Tumor types included lung, gastric, head and neck, liver, breast, and others. PD-L1 expression was assessed using the SP263 assay and categorized by tumor proportion score (TPS) for lung and combined positive score (CPS) for non-lung tumors. Available clinical data included demographics, disease status, histology and subsequent therapy. Patterns of concurrent diagnostic and predictive biomarker testing were also reviewed by tumor type. Our analyses focused on PD-L1 testing patterns by tumor type and intensity, PD-L1 positivity by disease status, and concordance between PD-L1 expression and use of ICIs. Results: Lung cancer accounted for 35% of cases, followed by gastric (12.7%), head and neck (10%), liver (6.8%), breast including TNBC (5.6%), with other cancers comprising less than 5% each. Median age was 60 years. Males comprised 56.6% of the overall cohort and 61.7% of lung cancer cases. PD-L1 positivity (TPS ≥1%) in lung cancer was 52.1%, including 10.1% with TPS ≥50%. PD-L1 positivity across other tumors was highest in head and neck (88.2%), gastric (73.8%), breast (65%), and liver cancers (25%). Treatment data were available for 74 PD-L1–tested NSCLC cases; among PD-L1–positive patients, 20% received PD-1 inhibitor–based therapy, as also one PD-L1 negative case, mostly in combination with chemotherapy. Among other PD-L1–positive tumors, ICI utilization was highest in head and neck (42%), followed by gastric (27%), breast including TNBC (14%) and absent in liver cancers. Conclusions: In this real-world Indian cohort, PD-L1 testing is integrated into multi-biomarker diagnostic pathways across several solid tumors, with substantial variability in expression by tumor type and disease status. Importantly, PD-L1 positivity did not consistently translate into immunotherapy use, underscoring real-world barriers to treatment access and implementation. These findings highlight the clinical relevance of Asian PD-L1 epidemiology and the diagnostic importance of harmonized biomarker testing strategies to optimize patient identification and treatment selection in routine oncology practice.