Fig. 1.

FcγRIIB is ubiquitously expressed in MCL cells and targeting FcγRIIB by BI-1206 effectively blocks CD20 internalization upon rituximab-based treatment in MCL cells. a, b Flow cytometry analysis was performed to detect FcγRIIB expression on MCL cell lines (a) and primary patient MCL cells (b) including ibrutinib/rituximab-naïve (n = 4), ibrutinib/rituximab-sensitive (n = 13), ibrutinib/rituximab-resistant (n = 5) and CAR T-relapsed (n = 3) MCL samples. c Percentage of rituximab bound CD20 on JeKo-1 cells upon treatment with rituximab (5 μg/ml) with or without BI-1206 (5 μg/ml) for 0, 2 and 5 h. d–f Percentage of rituximab bound CD20 on JeKo-1 cells after 48 h pre-treatment in vitro with increasing concentrations of ibrutinib (d), venetoclax (e) or CHOP (f) followed by treatment with rituximab with or without BI-1206 for 0, 2 and 5 h (Mean ± SD; n = 4). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001