Programmed death-ligand 1 expression and use of immune checkpoint inhibitors among patients with advanced non-small-cell lung cancer in a resource-limited country.

Introduction: Immune checkpoint inhibitor (ICI) therapy is an established treatment for advanced non-small-cell lung cancer (NSCLC) and programmed death ligand-1 (PD-L1) expression is a recognized biomarker to determine response to therapy. We retrospectively analyzed NSCLC patients in the Malaysia Lung Cancer Registry (MLCR) and report on the clinical characteristics associated with PD-L1 expression and ICI use in Malaysia, a low- to middle-income country.

Methods: All 901 NSCLC patients in the MLCR who were diagnosed from January 1, 2017 to December 31, 2020 from 14 hospitals across the country were analyzed.

Results: Out of 901 patients, 505 had PDL-1 testing done with complete data available only in 489 patients. The most common histology was adenocarcinoma (84.7%) followed by squamous cell carcinoma (10.2%). The majority (95%) presented with stage 3 or 4. The number and percentage of patients with PDL-1 tumor proportion scores of ≥50%, 1-49%, and <1% were 138 (28.2%), 158 (32.3%), and 193 (39.5%), respectively. In multivariate analysis, the presence of genomic mutation is the only independent characteristic associated with negative PD-L1 expression (crude odds ratio 0.579, 95% confidence interval 0.399-0.840, p = 0.004). Of 292 patients eligible for ICI therapy, only 100 patients (34.2%) received ICIs. Seventy-eight patients received ICI therapy as first-line treatment, 15 patients as second-line treatment, and 7 patients as third-line treatment.

Conclusions: This is the first analysis on PD-L1 expression and ICI use in Malaysia. Despite the proven efficacy of ICI therapy, only 56% of our patients had PD-L1 tests performed and only 34.2% of eligible patients received ICIs.