Biomarkers and factors in small cell lung cancer patients treated with immune checkpoint inhibitors: A meta‐analysis

Objective The aim of this meta‐analysis was to summarize the available results of immunotherapy predictors for small cell lung cancer (SCLC) and to provide evidence‐based information for their potential predictive value of efficacy. Methods We searched PubMed, EMBASE, Web of Science, The Cochrane Library, and ClinicalTrials (from January 1, 1975 to November 1, 2021). The hazard ratios (HR) and its 95% confidence intervals (CIs) and tumor response rate of the included studies were extracted. Results Eleven studies were eventually included and the pooled results showed that programmed cell death ligand 1 (PD‐L1) positive: objective response rate (ORR) (relative risk [RR] = 1.39, 95% CI [0.48, 4.03], p = 0.54), with high heterogeneity (p = 0.05, I2 = 56%); disease control rate [DCR] (RR = 1.31, 95% CI [0.04, 38.57], p = 0.88), with high heterogeneity (p = 0.04, I2 = 75%); overall survival (OS) (HR = 0.89, 95% CI [0.74, 1.07], p = 0.22); and progression‐free survival (PFS) (HR = 0.83, 95% CI [0.59, 1.16], p = 0.27), with high heterogeneity (p = 0.005, I2 = 73.1%). TMB‐High (TMB‐H): OS (HR = 0.86, 95% CI [0.74, 1.00], p = 0.05); PFS (HR = 0.71, 95% CI [0.6, 0.85], p upper limit of normal (ULN): OS (HR = 0.95, 95% CI [0.81, 1.11], p = 0.511). Asian patients: OS (HR = 0.87, 95% CI [0.72, 1.04], p = 0.135); White/Non‐Asian patients: OS (HR = 0.83, 95% CI [0.76, 0.90], p