Figure 7. Tigecycline has in vivo activity in models of human leukemia in mice.

(A) Human leukemia (OCI-AML2) cells were injected subcutaneously into the flank of SCID mice. Seven days later, when tumors were palpable, mice were treated with tigecycline (50 mg/kg or 100 mg/kg twice daily by i.p. injection), bortezomib (1 mg/kg t.i.w.), daunorubicin (0.65 mg/kg t.i.w.) or vehicle control (n = 10 per group). Three weeks after injection of cells, mice were sacrificed, tumors excised and the volume and mass of the tumors were measured. The tumor mass and the mean volume are shown. **P < 0.005, as determined by Tukey’s test after one-way ANOVA analysis. (B) Tumors from two control mice, and three tigecycline-treated mice were excised after 5 days of treatment and total proteins were extracted and analyzed by immunoblotting for Cox-1, Cox-2, Cox-4, and tubulin. (C) Primary cells from 3 AML patients and Lin⁻ CD34⁺ enriched human cord blood cells (E) (Normal) were injected intra-femorally into irradiated female NOD/SCID mice. Three weeks after injection, the mice were treated with tigecycline (100 mg/kg by i.p. injection daily) or vehicle control (n = 10 per group) for three weeks. Following treatment, human leukemia cell engraftment in the femur was measured by flow cytometric analysis of human CD45⁺CD19⁻CD33⁺ cells. **P < 0.005 as determined by student’s t test. (D) Cells from mice transplanted with one AML patient experiment were used to assess secondary engraftment in a second generation of NOD/SCID mice. Equal numbers of viable leukemia cells from the bone marrow of control and tigecycline-treated mice were pooled and aliquots injected into irradiated NOD/SCID mice, which were not treated with tigecycline. Six weeks later, human leukemia cell engraftment in the femur was measured by flow cytometric analysis for human CD45⁺CD19⁻CD33⁺ cells. Line represents median of engrafted human cells. *P < 0.05, N.S. not significant P > 0.05 as determined by student’s t test. Error bars represent mean +/− S.D. See also Figure S5.