LUSV exhibits direct antileukemic efficacy in ALL cells. Treatment effects of LUSV and IL-7 on leukemic cell survival (A) and proliferation of 2 representative T-ALL PDX specimens (36.2% and 84.1% CD127⁺ cells, respectively) (B). (C) Effect of LUSV treatment on the level of IL-7 induced STAT5 phosphorylation (P-STAT5) in leukemic cells, identifying IL-7 responsive and unresponsive T- and BCP-ALL cell lines and PDX cells, as indicated (also compare supplemental Table 2). (D) Immunodeficient mice were transplanted with PDX cells from an TCF3::PBX1⁺ patient (83.4% CD127⁺ blasts) and treated with LUSV (5 mg/kg) or a control vehicle (n = 10, respectively) starting when 1% PDX cells were detected in the PB (IV treatment on day +1, +3, +7, +14 and every 14 days thereafter). Survival was analyzed using the Kaplan-Meier method and log-rank statistics.