Design, Synthesis, and biological evaluation of 7H-Pyrrolo[2,3-d]pyrimidines as potent HPK1 kinase inhibitors.

Hematopoietic progenitor kinase 1 (HPK1) has emerged as a promising target for cancer immunotherapy due to its critical role as a negative regulator of T cell receptor (TCR) signaling. Despite this potential, no HPK1 inhibitors have been approved for cancer treatment, underscoring the need for structurally novel inhibitors. Herein, we describe the design, synthesis and biological evaluation of a series of potent HPK1 inhibitors based on our previously identified hit 9. Among them, compound 24 demonstrated strong HPK1 inhibition (IC50 of 10.1 nM) and effectively suppressed phosphorylation of the downstream protein SLP76. Notably, compound 24 exhibited enhanced potency in promoting IL-2 secretion in Jurkat T cells, reduced cellular toxicity, and improved liver microsomal stability compared to hit 9. Overall, this study provides a promising lead compound for further optimization as a candidate for cancer immunotherapy.