Figure 3.

The in vivo activity of lintuzumab (SGN-33) in a disseminated disease model of AML is dependent up the presence of murine effector cells. In the HL60cy model, mice (n = 10/group) were treated one day prior or the same day with agents to deplete murine effector cells as described in Materials and Methods. Mice were injected with 5 million cells and dosed 1 d later with a single dose of 10 mg/kg lintuzumab or the mutant, SGN-33G1v1 (arrow, A). The anti-leukemic activity of lintuzumab is dependent upon the presence of murine macrophages (B, p = 0.0008, log rank test) and neutrophils (C, p < 0.0001) but less on NK cells (D, p = 0.13). Results shown for depletion of NK cells with anti-TM-β1 (TMB) was similar to that obtained using anti-asialo GM-1 (ASGM). The results shown are representative of data obtained from two separate experiments.