The Predictive Efficacy of Tumor Mutation Burden (TMB) on Nonsmall Cell Lung Cancer Treated by Immune Checkpoint Inhibitors: A Systematic Review and Meta-Analysis

Background Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer, and the majority of NSCLC patients are diagnosed at the advanced stage. Chemotherapy is still the main treatment at present, and the overall prognosis is poor. In recent years, immunotherapy has developed rapidly. Immune checkpoint inhibitors (ICIs) as the representative have been extensively applied for treating various types of cancers. Tumor mutation burden (TMB) as a potential biomarker is used to screen appropriate patients for treatment of ICIs. To verify the predictive efficacy of TMB, a systematic review and meta-analysis were conducted to explore the association between TMB and ICIs.Method PubMed, EMBASE, Cochrane Library, and son on were systematically searched from inception to April 2020. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were estimated.Results A total of 11 studies consisting of 1525 nonsmall cell lung cancer (NSCLC) patients were included. Comparison of high and low TMB: pooled HRs for OS, 0.57 (95% CI 0.32 to 0.99; P = 0.046); PFS, 0.48 (95% CI 0.33 to 0.69; P < 0.001); ORR, 3.15 (95% CI 2.29 to 4.33; P < 0.001). Subgroup analysis values: pooled HRs for OS, 0.75 (95% CI 0.29 to 1.92, P = 0.548) for blood TMB (bTMB), 0.44 (95% CI 0.26 to 0.75, P = 0.003) for tissue TMB (tTMB); for PFS, 0.54 (95% CI 0.29 to 0.98, P = 0.044) and 0.43 (95% CI 0.26 to 0.71, P = 0.001), respectively.Conclusions These findings imply that NSCLC patients with high TMB possess significant clinical benefits from ICIs compared to those with low TMB. As opposed to bTMB, tTMB was thought more appropriate for stratifying NSCLC patients for ICI treatment.