Definition

An orally bioavailable inhibitor of the serine/threonine enzyme hematopoietic progenitor kinase 1 (Hpk1; Hpk-1; mitogen-activated protein kinase kinase kinase kinase 1; MAP4K1; MEKKK1), with potential immunostimulating and antineoplastic activities. Upon oral administration, Hpk1 inhibitor BGB-26808 targets, binds to and inhibits the activity of Hpk1. This inhibits Hpk1-mediated signaling pathways and prevents Hpk1-mediated immunosuppression by preventing the inhibition of T-cell receptors (TCR) signaling and effector T cells, disrupting abnormal cytokine expression, and abrogating the immunosuppressive tumor microenvironment (TME). This may activate a cytotoxic T-lymphocyte (CTL)-mediated immune response against tumor cells. Hpk1, expressed in hematopoietic cells, is a negative regulator of TCR signaling and T- and B-cell activation.