Activity of rhApo2L/TRAIL and rituximab against disseminated NHL tumor xenografts. BJAB-Luc cells were injected intravenously into CB17 ICR SCID mice. Tumor burden was determined by bioluminescent imaging and shown as the mean relative light units (RLU) for 4 randomized groups (n = 10 mice/group) with equivalent tumor burden at day 13 (A). Mice were treated with vehicle, 60 mg/kg rhApo2L/TRAIL, 4 mg/kg rituximab, or rhApo2L/TRAIL and rituximab. rhApo2L/TRAIL was administered daily for 5 consecutive days followed by a 2-day break and a second round of 5 days of treatment as indicated by the blue bar (panel D). Rituximab was administered once a week for 2 weeks as indicated by the green arrow (panel D). On day 26 (B), the tumor burden for the rituximab group was marginally reduced (P = .062 compared with vehicle, Mann-Whitney test), the tumor burden for the rhApo2L/TRAIL group was significantly lower (P = .009 compared with vehicle), and the tumor burden of the rhApo2L/TRAIL and rituximab group was significantly lower than the vehicle control (P = .004). The tumor burden for the rhApo2L/TRAIL and rituximab group was not significantly lower than the rhApo2L/TRAIL group (P = .275); however, the tumor burden for the rhApo2L/TRAIL and rituximab group was significantly lower than the rituximab group (P = .057). * represents statistical significance of result compared to vehicle. Error bars in panels A and B represent SEM. (C) Representative false color images of the mean tumor luminescence for each group are shown as an overlay of the reference image of the whole mouse. (D) Survival analysis of the BJAB-bearing mice; Kaplan-Meyer curves for the experiment are shown. The vehicle-treated (black line), rhApo2L/TRAIL-treated (blue line), rituximab-treated (green line), and rhApo2L/TRAIL and rituximab–treated (red line) mice are shown.