BTK inhibitors (BTKi) have become standard of care for treatment of patients with chronic lymphocytic leukemia (CLL). Covalent BTKi (cBTKi) such as ibrutinib, acalabrutinib, and zanubrutinib are effective but alterations in the kinase domain at C481 or BTK gatekeeper residue T474 mutations result in development of resistance. Noncovalent BTK inhibitors (ncBTKi) such as pirtobrutinib are effective in patients with C481x mutations developed through use of cBTKi. However, resistance to ncBTKi can occur owing to second site aberrations in BTK, generating novel mutations such as L528x and T316x. Sometimes, CLL cells with double BTK mutations are also observed. These BTK aberrations underscore a need for new inhibitors that target pan-BTK-mutants. We evaluated the efficacy of a new ncBTKi, docirbrutinib (AS-1763), against 14 BTK mutants, including C481S, T474x, and L528x, as well as gatekeeper and kinase domain double mutants, using biochemical assays, cell-line models, and primary CLL lymphocytes. Docirbrutinib potently inhibited BTK autophosphorylation and mutant BTK–driven cell proliferation, with greater effects than ibrutinib and pirtobrutinib against certain mutants. In treatment-naïve and relapsed/refractory CLL samples, docirbrutinib disrupted B-cell receptor signaling and sensitized cells to apoptosis induced by venetoclax and AZD5991. In a dose-escalation trial (NCT05602363), docirbrutinib decreased CCL3/CCL4 biomarkers and inhibited the B-cell receptor pathway signaling in longitudinal samples from patients with relapsed/refractory CLL. These findings establish docirbrutinib as a pan-mutant ncBTKi with potential to improve outcomes for CLL patients, including those with disease resistant to cBTKi and other ncBTKi.
The alternative text for this image may have been generated using AI.
