HGH1 (HGH1 cochaperone, also known as FAM203) is a conserved armadillo repeat protein that functions as a molecular cochaperone essential for eukaryotic elongation factor 2 (eEF2) biogenesis. HGH1 recognizes a non-native conformation in eEF2's central domain III and recruits the chaperonin TRiC/CCT complex to facilitate efficient folding of the N-terminal GTPase module 1. The protein also cooperates with Hsp90 to regulate both eEF2 accumulation and posttranslational modification 2, ensuring accurate translation of newly synthesized proteins. In cancer biology, HGH1 has emerged as a significant oncogenic driver. Elevated HGH1 expression is associated with poor prognosis across multiple cancer types and is frequently upregulated in breast cancer tissues 34. HGH1 overexpression promotes cell proliferation through cell cycle regulation and facilitates tumor cell invasion and migration 3. At the molecular level, NSUN2-mediated m5C methylation increases HGH1 mRNA stability, and HGH1 directly interacts with eEF2 to enhance protein synthesis in cancer cells 5. Critically, high HGH1 expression correlates with immune-desert tumor microenvironments characterized by reduced immune infiltration and diminished immunotherapy response 6. Patients with low HGH1 expression show improved survival with immune checkpoint inhibitors, positioning HGH1 as a potential therapeutic target in cancer immunotherapy.