Interplay between Tumor Mutational Burden and Mutational Profile and its effect on overall survival: A Post Hoc Analysis of Metastatic Patients Treated with Immune Checkpoint Inhibitors

Purpose Solid tumors harboring tumor mutational burden (TMB) ≥ 10 mutations per megabase (mut/Mb) received agnostic approval for pembrolizumab. However, TMB cut-off alone is not a predictor of overall survival (OS). This work aims to analyze the somatic mutational profile’s influence in the outcomes of patients with TMB-high tumors treated with immune checkpoint inhibitors (ICIs). Methods This post-hoc analysis evaluated clinical and molecular features of 1,661 patients with solid tumors treated with ICIs. We performed OS analysis for TMB thresholds of ≥ 10, ≥ 20, and < 10 mut/Mb. For a TMB ≥ 10mut/Mb cutoff, we assessed OS according to mutational profile. For genes exhibiting a correlation with OS (P < 0.05) at the univariate assessment, we conducted a Cox multivariate analysis adjusted by median TMB, sex, age, microsatellite instability (MSI), and histology. Results 1,661 patients were investigated, and 488 harbored a TMB ≥ 10 mut/Mb (29.4%). The median OS was 42 months for TMB ≥ 10 or 20 mut/Mb, and 15 months for TMB < 10 mut/Mb (P < 0.005). In patients harboring TMB ≥ 10mut/Mb, mutations in E2F3 or STK11 were correlated with worse OS, and mutations in NTRK3, PTPRD, RNF43, TENT5C, TET1 or ZFHX3 with better OS. These associations were confirmed by univariate and multivariate analyses (P < 0.05). Melanoma histology and TMB above the median endowed patients with better OS (P < 0.05). MSI status, age, and gender did not have a consistent statistically significant effect on OS Conclusion Combining TMB information and mutation profiles in key cancer genes can be used to better qualify patients for ICI treatment and predict their OS. Key objective Tumor mutational burden (TMB) of ≥ 10 mutations per megabase (mut/Mb) grant agnostic indication of pembrolizumab for advanced solid tumors’ treatment, however a substantial number of patients do not respond to therapy. This work aims to analyze the somatic mutational profile’s influence in the outcomes of patients with TMB ≥ 10mut/Mb tumors treated with ICIs. Knowledge generated Mutation profile can modify survival outcomes to ICIs in patients with TMB ≥ 10 mut/Mb. Mutations in E2F3 or STK11 correlate with worse OS, while mutations in NTRK3, PTPRD, RNF43, TENT5C, TET1 or ZFHX3 correlate with better OS in TMB-high patients receiving ICIs. Relevance We found that the combination of a high TMB and the somatic mutational profile in key cancer genes can be decisive in better qualify patients for ICI treatment. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study used (or will use) ONLY openly available human data that were originally located at https://www.cbioportal.org/study/summary?id=tmb\_mskcc\_2018 I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.