Pirtobrutinib (LOXO-305), a highly selective and non-covalent next generation BTK inhibitor, inhibits diverse BTK C481 substitution mutations. Pirtobrutinib causes regression of BTK-dependent lymphoma tumors in mouse xenograft models. Pirtobrutinib is also more than 300-fold selective for BTK versus 370 other kinases tested and shows no significant inhibition of non-kinase off-targets at 1 μM.