<p>Co-stimulatory molecules are imperative for CD8⁺ T cells to eliminate target cell and maintain sustained cytotoxicity. Despite an advanced understanding of the co-stimulatory molecules deficiency that results in tumor escape, the tumor cell-intrinsic mechanisms that regulate co-stimulatory molecules remain enigmatic, and an in-depth dissection could facilitate the improvement of treatment options. To this end, in this study, we report that the deficiency of the critical costimulatory molecule CD58, mediated by the expression of ATF4 in tumor cells, impairs the formation of immunological synapses (IS) and leads to the deterioration of antitumor immune function of CD8⁺ T cells. Mechanistically, ATF4 transcriptionally upregulated dynamin 1 (DNM1) expression leading to DNM1-dependent endocytosis (DDE)-mediated degradation of CD58. Furthermore, administration of DDE inhibitor prochlorperazine or <i>ATF4</i> knockdown effectively restored CD58 expression, boosting CD8⁺ T cell cytotoxicity and immunotherapy efficiency. Thus, our study reveals that ATF4 in tumor cells weakens CD58 expression to interfere with complete IS formation, and indicates potential approaches to improve the cytolytic function of CD8⁺ T cell in tumor immunotherapy.</p>