Introduction: H3K27M-mutated diffuse midline gliomas (H3-DMGs) are aggressive tumors with a fatal outcome. This study integrating individual patient data (IPD) from published studies aimed to investigate the prognostic impact of different genetic alterations on survival of these patients.Methods: We accessed PubMed and Web of Science to search for relevant articles. Studies were included if they have available data of follow-up and additional molecular investigation of H3-DMGs. For survival

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... ysis, Kaplan-Meier analysis and Cox regression models were utilized, and corresponding hazard ratios (HR) and 95% confidence intervals (CI) were computed to analyze the impact of genetic events on overall survival (OS).Result: We included 30 studies with 669 H3-DMGs. TP53 mutations were the most common second alteration among these neoplasms. In univariate Cox regression model, TP53 mutation was an indicator of shortened survival (HR = 1.446; 95% CI = 1.143-1.829) whereas ACVR1 (HR = 0.712; 95% CI = 0.518-0.976) and FGFR1 mutations (HR = 0.408; 95% CI = 0.208-0.799) conferred prolonged survival. In addition, ATRX loss was also associated with a better OS (HR = 0.620; 95% CI = 0.386-0.996). Adjusted for age, gender, tumor location, and the extent of resection, the presence of TP53 mutations, the absence of ACVR1 or FGFR1 mutations remained significantly poor prognostic factors.Conclusions: We outlined the prognostic importance of additional genetic alterations in H3-DMGs and recommended that these neoplasms should be further molecularly segregated. It could help neuro-oncologists better evaluate the risk stratification of patients and consider pertinent treatments.