Background: Accumulating evidence indicates the essential role of EPHX2 in tumorigenesis. However, to date, no studies have performed a systematic evaluation of EPHX2 gene in human cancers and the predictive role of EPHX2 in cancer immunotherapy response has still not been explored. Methods: In the present study, Oncomine, TIMER2, UALCAN, GEPIA2, PrognoScan, HPA and Kaplan-Meier Plotter database were utilized to comprehensively analyze the expression landscape and prognostic clinical value of

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... HX2 across 33 human cancers. To gain a better understanding of the role of EPHX2 in cancer immunotherapy, the correlations between EPHX2 and tumor immune microenvironment (TME) such as immune cell infiltrations, immune modulators, and the major histocompatibility complex were demonstrated. The underlying EPHX2-associated signaling pathways in cancer were also analysed. Moreover, the correlation between EPHX2 and immunotherapeutic biomarkers such as tumor mutational burden (TMB) and microsatellite instability (MSI) was explored. At last, the potential immune checkpoint blockers (ICB) response was predicted using tumor immune dysfunction and exclusion (TIDE) algorithm. Results: Overall, the mRNA expression of EPHX2 was significantly downregulated in the majority of tumors compared with normal tissues. Despite the significant prognostic value of EPHX2 expression across cancers, EPHX2 played a protective or detrimental role in different kinds of cancers. Generally speaking, immune cell infiltrations, immune modulators and immunotherapeutic biomarkers were all strongly related to the expression of EPHX2. Besides, EPHX2 expression was significantly related to immune-relevant pathways, especially in PAAD, THYM and UVM. Furthermore, our study demonstrated diverse response patterns of ICB in response to EPHX2 expression in different tumor types. Conclusion: Our findings here suggest that EPHX2 could be a prognostic factor in multiple cancers and play an important role in tumor immunity by affecting infiltrating immune cells, TMB and MSI. This study provides further insight into the role of EPHX2 in tumor immunotherapy.