Objective: Non-small cell lung cancer (NSCLC) is a molecularly heterogeneous disease in which both actionable mutations and PD-L1 expression influence therapeutic decisions. This study aimed to evaluate the molecular profile of NSCLC using next-generation sequencing (NGS) and analyse the association of PD-L1 expression with key genetic alterations.

Material and Methods: A retrospective analysis was conducted on 87 histopathologically confirmed NSCLC cases. Molecular profiling was performed using the Oncomine™ Lung Focus Assay, which targets major actionable mutations. PD-L1 expression was assessed by immunohistochemistry (IHC) using the Tumour Proportion Score (TPS) and categorised as <1% (negative), 1- 49% (weak positive), and ≥50% (strong positive).

Results: A total of 105 molecular alterations were identified across 87 cases, with EGFR being the most frequently mutated gene (36.2%), followed by KRAS (16.2%) and AR amplification (14.3%). Actionable mutations were defined as alterations with approved targeted therapies or clinical trial eligibility were detected in 59.8% of patients, with EGFR exon 19-21 being the most frequent (25.7%), followed by ALK fusions (5.7%), ERBB2 exon 20 (4.8%), KRAS G12C (3.5%), MET exon 14 skipping (2.9%), and BRAF V600E and ROS1 (1.9% each). PD-L1 expression was observed in 45.7% of cases. PD-L1 positivity was lower in EGFR-mutant tumours compared to EGFR wild-type, suggesting reduced immunogenicity in this subgroup. Conversely, KRAS-mutant tumours exhibited higher PD-L1 expression than KRAS wild-type tumours, suggesting a potential predictive role for immunotherapy. ALK-rearranged tumours showed variable but notable PD-L1 expression.

Conclusion: The study underscores the importance of integrating NGS-based molecular testing with PD-L1 evaluation for personalised management of NSCLC. Distinct patterns of PD-L1 expression across molecular subtypes, particularly lower in EGFR-mutated tumours and higher in KRAS-mutated tumours, underscore the need for tailored therapeutic strategies and informed sequencing of targeted therapies and immunotherapies.