Tumor mutation burden predicts response and survival to immune checkpoint inhibitors: a meta-analysis

Background: Cancer is one of the world's top three causes of death now. Immune checkpoint inhibitors (ICIs) show encouraging ability to treat some malignancies due to its long-term efficacy and low side effects. However, the predictive biomarker of the immunotherapy efficacy has been inconclusive. Thus, exploring new biomarkers is important. Methods: A meta-analysis was conducted to evaluate whether tumor mutation burden (TMB) could be a predictive biomarker of the efficacy of ICIs. Using the PubMed and Cochrane Library databases, we searched for articles about TMB and the prognosis of patients with multiple malignancies conducted from 1984 to May 22, 2020. We identified the relationship between TMB and the clinical efficacy of ICIs by using Stata 12.1 software. Results: Eighteen articles with a total of 4,535 patients were included in this meta-analysis. Results showed that high-TMB patients had better progression-free survival (PFS) than low-TMB patients with cancer treated with ICIs (HR =0.45; 95% CI: 0.36-0.56, P= 0.002). Moreover, high-TMB patients had longer overall survival (OS) than low-TMB patients. However, the heterogeneity was extremely high, so the result regarding OS was meaningless (HR =0.56; 95% CI: 0.44-0.70, P=0.000, I-squares: 72.6%). Conclusions: Our study indicates that high TMB is associated with better PFS. Thus, TMB can be considered as a predictive marker of PFS of patients treated with ICIs in the future.