Bruton Tyrosine Kinase Degraders: Current Concepts

Bruton tyrosine kinase (BTK) is a key enzyme involved in B-cell development and signaling, making it a crucial target in the treatment of B-cell malignancies, such as chronic lymphocytic leukemia and non-Hodgkin lymphoma. While BTK inhibitors (BTKi), such as ibrutinib, have been effective, resistance-both intrinsic and acquired-poses a significant challenge, often associated with BTK mutations like C481S. To address this, novel BTK degraders have been developed, leveraging proteolysis-targeting chimeras to selectively degrade both wild-type and mutant BTK forms. This approach offers a promising strategy to overcome BTKi resistance. Agents such as NRX-0492, BGB-16673, NX-5948, NX-2127, HZ-Q1060, ABBV-101, and AC676 have shown significant BTK degradation in preclinical and early clinical trials. NRX-0492 demonstrated over 90% BTK degradation with sustained pharmacodynamic effects, whereas BGB-16673 achieved clinical responses in 67% of patients with relapsed/refractory B-cell malignancies. Similarly, NX-5948 and NX-2127 showed potent BTK degradation, with NX-2127, in addition, targeting immunomodulatory proteins, resulting in partial and stable responses in chronic lymphocytic leukemia and non-Hodgkin lymphoma patients. HZ-Q1060, a preclinical candidate, displayed rapid and sustained BTK degradation in vivo. Early-phase trials of ABBV-101 and AC676 are also showing promising results. These BTK degraders have demonstrated favorable safety profiles, with manageable adverse events, and offer a novel therapeutic avenue for patients with BTKi-resistant malignancies. As clinical trials progress, these degraders hold the potential to significantly enhance treatment outcomes, offering a new frontier in personalized cancer therapy.