Effect of α-based radioimmunotherapy on survival of athymic mice with Raji xenografts. The mice were intravenously injected with saline, 20, 100, and 250 μg cold rituximab (A); 50, 200, 400, and 1000 kBq/kg 227Th-p-benzyl-DOTA-rituximab (B); 200 and 400 kBq/kg 227Th-p-benzyl-DOTA-trastuzumab (C); or 7.5, 15, and 30 MBq/kg 90Y-ibritumomab-tiuexetan (D). Mice with tumor diameters greater than 20 mm were killed. Median survival times of treated groups were compared with control and cold rituximab (pooled) using the Mantley-Cox log-rank test: P < .001 for 200, 400, and 1000 kBq/kg 227Th-p-benzyl-DOTA-rituximab. The rest of the treatments were not significantly different from the control group (NaCl). The groups receiving 200, 400, and 1000 kBq/kg 227Th-p-benzyl-DOTA-rituximab had also significantly longer survival than the group receiving 20 μg cold rituximab (P < .05, Mantley-Cox log-rank test). The groups receiving 200, 400, and 1000 kBq/kg 227Th-p-benzyl-DOTA-rituximab treatment groups were pooled in panel D, and the pooled group had significantly longer survival than all the 90Y-ibritumomab-tiuexetan treatment groups (P < .01, Mantley-Cox log-rank test). One mouse in the 1000 kBq/kg 227Th-p-benzyl-DOTA-rituximab group died after 42 days. n indicates the number of mice per treatment.
