Bruton tyrosine kinase degradation as a therapeutic strategy for cancer

Area of Science:

• Oncology
• Pharmacology
• Molecular Biology

Background:

• Ibrutinib, a Bruton tyrosine kinase (BTK) inhibitor, is effective for B-cell malignancies but lacks selectivity and faces resistance, notably the C481S-BTK mutation.
• Existing BTK inhibitors primarily function by enzymatic inhibition, which can be circumvented by resistance mechanisms.
• There is a significant unmet need for novel therapeutic strategies to overcome ibrutinib resistance in B-cell lymphomas, particularly mantle cell lymphoma (MCL).

Purpose of the Study:

• To investigate whether small-molecule-induced BTK degradation can overcome limitations associated with traditional BTK enzymatic inhibitors.
• To evaluate the efficacy of BTK degraders against cancer cells, including those with resistance mutations like C481S-BTK.
• To identify and characterize novel compounds capable of inducing targeted protein degradation for potential therapeutic applications in MCL.

Main Methods:

• Assessed the effects of BTK degradation on cancer cell signaling and proliferation.
• Tested the ability of BTK degraders to degrade wild-type and C481S-mutated BTK.
• Discovered and optimized a lead compound (DD-03-171) and evaluated its in vitro antiproliferative effects on MCL cells and in vivo efficacy using patient-derived xenografts.

Main Results:

• BTK degradation effectively suppressed signaling and proliferation in cancer cells.
• BTK degraders demonstrated efficient degradation of both wild-type and C481S-BTK.
• The lead compound DD-03-171 exhibited enhanced antiproliferative activity against MCL cells by inducing the degradation of BTK, IKFZ1, and IKFZ3, and showed efficacy in vivo.

Conclusions:

• Small-molecule-induced BTK degradation is a potent strategy for suppressing cancer cell signaling and proliferation.
• BTK degraders, including the novel compound DD-03-171, can overcome resistance mechanisms like the C481S-BTK mutation.
• "Triple degradation" targeting BTK, IKFZ1, and IKFZ3 represents a promising therapeutic approach for MCL and other B-cell lymphomas, addressing a critical unmet clinical need.