Fig. 2: BTK degradation induced by PROTACs.
a Chemical structures of BTK degraders and their controls. RC-1, RNC-1, and IRC-1 are BTK degraders with reversible covalent, reversible noncovalent, and irreversible covalent warheads, respectively. RC-Ctrl, RNC-Ctrl, and IRC-Ctrl (i.e., ibrutinib) are the corresponding warhead controls for RC-1, RNC-1, and IRC-1, respectively. b MOLM-14 cells were incubated with RC-1, RNC-1, and IRC-1 at different concentrations (0 (blue), 8 (red), 40 (green), and 200 (purple) nM) for 24 h. The BTK levels were quantified by western blotting. Duplicates were performed. c RC-1 dose-dependent BTK degradation in MOLM-14 cells. DC50: compound concentration inducing 50% of protein degradation. Duplicates were performed. d MOLM-14 cells were treated with DMSO (blue), RC-1 (light red), RC-Ctrl (light green), Pomalidomide (purple), RC-Ctrl + Pomalidomide (orange), and RC-1-Me (black) for 24 h. All the compound concentrations are 200 nM. Neither RC-Ctrl, nor pomalidomide, nor a combination of both caused BTK degradation, indicating that the bifunctional PROTAC molecule is essential to facilitate the formation of a ternary complex of {BTK-PROTAC-CRBN} in order to induce BTK degradation. Duplicates were performed. e Linker optimization for reversible covalent BTK degraders. Optimization of the linkers of the RC series of BTK degraders and their corresponding percentage of BTK degradation in MOLM-14 cells (200 nM, 24 h incubation). Note: RC-6 was unstable due to intramolecular cyclization with the Michael acceptor. f Comparison of RC-1 (red circle) and RNC-1 (green square) with other reported BTK degraders. Two previously reported BTK degraders DD-03-171 (blue pyramid) and MT-802 (orange inverted pyramid) were synthesized in house. The cells were treated with compounds for 72 h. Then Alarma blue assays were performed to quantify the cellular viabilities. Data are presented as mean values ± SEM (n = 5 biologically independent samples). Source data are provided as a Source Data file.
