In these first studies, ruxolitinib initiation at day 7 (Fig. 3A–C, blue) after TSLPRCART treatment of MUTZ5 xenograft mice resulted in greater TSLPRCART expansion and IFN-γ production in peripheral blood compared to simultaneous (day 0) co-treatment with concomitantly improved ALL clearance (Fig. 3A–C, green; Supplementary Fig. 3). Here, IFNG is linked to acute lymphoblastic leukemia.