Design, synthesis, and biological evaluation of 2,4-diaminopyrimidine derivatives as potent Hematopoietic Progenitor Kinase 1 (HPK1) inhibitors.

HPK1 also referred to as MAP4K1, belongs to the category of mammalian STE20-like protein serine/threonine kinases. Its physiological function involves the down-regulation of T cell signals, and it is regarded as a new immune checkpoint of tumor immunology. In this study, we commenced our investigation with the hit compounds, focusing the efforts on structural optimization and SAR exploration to identify a novel class of 2,4-diaminopyrimidine HPK1 inhibitors.