NRX-0492 induces degradation of WT and C481S mutant BTK. Degradation of BTK by NRX-0492 was assessed by Western blot in TMD8 (A) and primary CLL cells (B) and DC₅₀ and DC₉₀ were calculated based on immunoblot quantification. Comparative analysis of BTK degradation in PBMCs from 4 patients exposed to 2nM NRX-0492 for 4 hours using (C) immunoblotting and (D) flow cytometry. NRX-0492 reduced BTK staining intensity in CLL cells but not T cells. (E) Mean fluorescent intensity of anti-BTK AF647 in T cells was used as background control; comparison by paired t test. MFI, mean fluorescent intensity.