ATH-409

ATH-409 is a highly selective, covalent small molecule inhibitor of Interleukin-2-inducible T-cell kinase (ITK). ITK is a member of the TEC family of kinases expressed in T, NK, and mast cells, where it plays a critical role in T-cell receptor (TCR) signaling and T-cell differentiation. By selectively inhibiting ITK while sparing the related kinase RLK, ATH-409 promotes Th1 differentiation and suppresses Th2 cytokine release. It also attenuates T-cell exhaustion and enhances anti-tumor immune responses, particularly when used in combination with immune checkpoint inhibitors such as anti-PD-1 and anti-CTLA-4 antibodies. In preclinical models, ATH-409 has demonstrated the ability to inhibit tumor growth by modulating the immune system rather than through direct cytotoxicity, specifically by increasing the proportion of tumor-infiltrating Th1 cells and alleviating T-cell exhaustion.