PRN694 is an irreversible, highly selective and potent covalent interleukin-2-inducible T-cell kinase ( ITK ) and resting lymphocyte kinase (RLK) dual inhibitor with IC 50 s of 0.3 nM and 1.4 nM, respectively. PRN694 exhibits extended target residence time on ITK and RLK, enabling durable attenuation of effector cells in vitro and in vivo.