Depth of response and treatment outcomes of immune checkpoint inhibitor-based therapy in patients with advanced non-small cell lung cancer and high PD-L1 expression: An exploratory analysis of retrospective multicenter cohort.

The association between depth of response (DpR) and treatment outcomes has been documented across various types of cancer. Immune checkpoint inhibitor (ICI)-based treatment is globally used as first-line treatment for non-small cell lung cancer (NSCLC) with programmed death-ligand 1 (PD-L1) expression ≥ 50%. However, in this population, the significance of DpR is not elucidated. Patients with advanced NSCLC and PD-L1 expression ≥ 50% who received ICI-monotherapy or ICI plus chemotherapy were retrospectively enrolled into this study. Treatment responses were grouped into DpR 'quartiles' by percentage of maximal tumor reduction (Q1 = 1-25%, Q2 = 26-50%, Q3 = 51-75%, and Q4 =  ≥ 76%), and no tumor reduction (NTR). The association between DpR and survival rates were determined using hazard ratios (HR) generated by the Cox proportional hazards model. The Kaplan-Meier method was used to determine survival outcomes. A total of 349 patients were included, of which 214 and 135 patients received pembrolizumab monotherapy and ICI plus chemotherapy, respectively, as first-line treatments. The majority of the patients were male. All DpR quartiles, especially Q4, showed an association with progression-free survival (PFS)/overall survival (OS). In the Q4 cohort, patients who received pembrolizumab had a longer PFS than those who received ICI plus chemotherapy. High DpR was associated with longer PFS and OS, with a more pronounced effect observed with pembrolizumab monotherapy than with ICI plus chemotherapy.