IHCH-3185 is an orally active class I HDAC inhibitor (HDAC1 IC50 =102.9 nM) and A2AR antagonist (A2AR Ki =7.6 nM). IHCH-3185 reverses immune gene silencing by inducing histone acetylation and blocks the adenosine signaling pathway to relieve T-cell suppression. IHCH-3185 exhibits antiproliferative activity, induces cell cycle arrest, and significantly improves the tumor microenvironment. IHCH-3185 reduces the proportion of regulatory T cells, increases the CD8+/Treg ratio, and upregulates the expression of key factors such as H2-K1, Cxcl9 and Cxcl10. IHCH-3185 shows significant antitumor potential in CT26 and MC38 mouse tumor models and is suitable for related cancer research.