Association of PD-L1 expression with efficacy of alectinib in advanced NSCLC patients with ALK fusion

Programmed cell death-ligand 1 (PD-L1) expression was found to be a biomarker of inferior efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR-mutated non-small cell lung cancer (NSCLC). However, whether PD-L1 expression could also serve as a similar biomarker in anaplastic lymphoma kinase (ALK)-positive patients, especially for those treated with front-line alectinib, remains unclear. The aim of the study is to investigate the association of PD-L1 expression and efficacy of alectinib in this setting.From January 2018 to March 2020, 225 patients with ALK-rearranged lung cancer were consecutively collected at Shanghai Pulmonary Hospital, Tongji University. Baseline PD-L1 expression was detected using immunohistochemistry (IHC) in 56 patients of advanced ALK-rearranged lung cancer who received front-line alectinib.Among the 56 eligible patients, 30 (53.6%) were PD-L1 expression negative, 19 (33.9%) patients had TPS 1%-49% and 7 (12.5%) had TPS ≥ 50%.We found no statistically significant associations between PD-L1 positivity and objective response rate (ORR, 90.0% vs. 80.8%, p = 0.274) or progression-free survival (PFS, not reached vs. not reached, HR: 0.98, 95 %CI: 0.37-2.61, p = 0.97) in patients treated with alectinib. Meanwhile, patients with PD-L1 high expression (TPS ≥ 50%) had a trend of longer PFS (not reached vs. not reached, p = 0.61).PD-L1 expression might not serve as a predict biomarker for the efficacy of front-line alectinib in ALK-positive NSCLC patients.