HPK1-IN-54 (Compound 16) is a potent inhibitor of HPK1 (hematopoietic progenitor kinase 1), enhancing T cell activation and proliferation by blocking HPK1 activity to exert antitumor effects. It has an IC50 of 2.67 nM for HPK1, showing excellent selectivity over the MAP4K family (>100-fold) and other selected kinases (>300-fold). HPK1-IN-54 exhibits moderate in vivo clearance and reasonable oral exposure in both mice and rats. Additionally, in the CT26 mouse colon cancer model, HPK1-IN-54 demonstrates significant antitumor activity and shows a synergistic effect when combined with anti-PD-1 therapy. HPK1-IN-54 holds promise for research in the field of immunology.