A Systematic Review and Meta‐Analysis of the Impact of Tumour Mutation Burden on Survival Outcomes in Solid Tumours

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Abstract
Background: Tumour mutation burden (TMB) is an emerging pan‐cancer biomarker with predictive value for immune checkpoint inhibitor (ICI) outcomes, yet evidence is inconsistent due to methodological variability and cut‐off thresholds. This systematic review and meta‐analysis evaluated the impact of TMB on overall survival (OS) and progression‐free survival (PFS) across solid tumours in ICI‐treated cohorts and its predictive relevance in non‐ICI‐treated cohorts. Methods: Following PRISMA 2020 guidelines, we searched PubMed, Scopus, ScienceDirect and Cochrane for studies published between 2010 and 2024 reporting hazard ratios (HRs) and 95% confidence intervals (CIs) for OS and PFS in high‐ versus low‐TMB cohorts. High and low TMB were defined by study‐specific cut‐offs, and ultra‐high TMB was defined as the top 20% of cohort‐specific values. Study quality was assessed with the Newcastle‐Ottawa Scale; heterogeneity with I 2 ; publication bias with funnel plots/Egger's test; and robustness by leave‐one‐out analysis. Results: 5278 patients across 28 studies were analysed. High TMB, defined by cohort‐specific cut‐offs, was significantly associated with improved OS and PFS, particularly in non‐small cell lung cancer (OS: HR = 0.56), selected gastrointestinal cancers (OS: HR = 0.36), and advanced/recurrent tumours (OS: HR = 0.52). Benefits were greatest in ICI‐treated patients, especially with combined anti‐PD‐L1/PD‐1 and anti‐CTLA‐4 therapy (OS: HR = 0.47; PFS: HR = 0.50). Chemotherapy‐treated cohorts also showed better outcomes, but less consistently (OS: HR = 0.60; PFS: HR = 0.55). Ultra‐high TMB had better OS than the universal 10 mut/Mb cut‐off (HR = 0.44 vs. 0.58). Non‐beneficial associations were observed in glioma and penile squamous cell carcinoma, highlighting disease‐specific variability. Sequencing platforms and cut‐off definitions remained sources of heterogeneity. Conclusion: TMB demonstrates prognostic relevance and predictive utility in a histology‐ and treatment‐context‐dependent manner, with the most consistent associations in selected ICI‐treated tumours. Associations in non‐ICI‐treated cohorts were weaker and inconsistent, indicating putative predictive value. Standardising TMB assessment and refining relevant thresholds are essential for optimising its role in precision oncology. Trial Registration: PROSPERO Registration Number: CRD42024608809
Funding Information
  • Charlie Teo Foundation (PR11197)

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