Effects of HIF inhibition on patient-derived T-ALL xenografts. (A) Survival of recipient NSG mice after transplantation with xenograft-expanded primary human T-ALL leukemias transduced by lentivirus encoding shRNAs against HIF1α or scrambled shRNA control. Leukemia cells were transduced with virus, cultured on MS5-DL1 feeders for 3 days, FACS-sorted for the viral GFP marker, and then injected into each of 4 recipient animals (n = 4) at a dose of 1 × 10⁴ cells per mouse. Results are depicted for 2 different patient leukemias (M71 and F1313) in each experiment. **P < .01 (log-rank test). (B-C) Cell growth/viability assays. Xenograft-expanded primary human T-ALL cells were transduced with 2 different lentiviral shRNAs against HIF1α or scrambled shRNA control. In (B), transduced (GFP⁺) cells were FACS-sorted 2 days after transduction and cultured in vitro on MS5-DL1 feeders. Cell viability was tracked daily by flow cytometry for PI dye exclusion. In (C), cells were cultured in vitro on MS5-DL1 feeders following viral transduction. Absolute numbers of viable GFP⁺ cells from the unsorted culture were tracked daily by flow cytometry for PI dye exclusion with admixed polystyrene counting beads. Mean ± SD values are plotted. ns, not significant.