Spotlight on FAM72B: Pan-Cancer Expression Profiles and Its Potential as a Prognostic and Immunotherapeutic Biomarker

<b>Background/Objectives:</b><i>FAM72B</i> (Family with sequence similarity 72 member B) is a gene whose function is not yet fully elucidated and which belongs to the <i>FAM72</i> gene family. Recent studies have indicated that it is involved in the regulation of stem cell proliferation and DNA repair and serves as a valuable prognostic biomarker for a few types of cancer. This study aimed to systematically investigate the expression profile of <i>FAM72B</i> in pan-cancer, its role in the tumor immune microenvironment, and its potential as a prognostic and immunotherapeutic biomarker. <b>Methods:</b> Using bioinformatics tools such as SangerBox3.0, GEPIA2.0, Kaplan-Meier Plotter, and cBioPortal, we systematically analyzed the correlation of <i>FAM72B</i> expression levels with various cancer types, clinical pathological parameters, prognostic value, genetic mutations, genomic heterogeneity, immune checkpoint genes, immune cell infiltration levels, and single-cell-level characteristics. <b>Results:</b><i>FAM72B</i> was found to be overexpressed in most cancers and significantly associated with poor prognosis, although it may exert a protective effect in some cancers like thymoma (THYM). Its expression level was positively correlated with tumor mutation burden (TMB), microsatellite instability (MSI), neoantigen (NEO) levels, and expression of immune checkpoint genes in most cancers, suggesting that patients with high <i>FAM72B</i> expression may respond better to immune checkpoint inhibitors. Moreover, <i>FAM72B</i> expression was significantly correlated with the infiltration levels of various immune cells in the tumor immune microenvironment across pan-cancer. Single-cell sequencing results also demonstrated a significant correlation between <i>FAM72B</i> and the biological functional states of multiple cancers. <b>Conclusions:</b><i>FAM72B</i> holds promise as a potential pan-cancer prognostic biomarker and therapeutic target, providing a novel basis for the development of personalized treatment strategies.