Fig. 3: Ruxolitinib-induced inhibition of TSLPRCART is improved with delayed co-administration and is reversible.

A Luciferase-transduced MUTZ5 cells were injected IV into NSG mice. Once engraftment was documented by bioluminescent imaging (BLI), cohorts of 5 mice were randomized to IV treatment on day 0 with saline, 1e6 untransduced T cells (UTD), or lower-dose (1e6) or higher-dose (5e6) TSLPRCART. Ruxolitinib chow (rux) ad libitum was administered simultaneously at day 0 (green) or day 7 after T cell treatments (blue) and continued to day 42. Leukemia burden was measured weekly by BLI. Human CD3+/CD45+ T cells were quantified weekly by flow cytometry analysis of peripheral blood of mice treated with B lower-dose or C higher-dose TSLPRCART. Statistical analysis was performed by two-way ANOVA with Tukey post-test for multiple comparisons with differences indicated at relevant timepoints. D Ruxolitinib was then removed at day 42 (striped green bar) for relevant cohorts, and mice continued to be followed by BLI to monitor potential re-emergence of leukemia. After 49 additional days without ruxolitinib exposure (day 91), mice were injected IV with 1e7 luciferase-expressing TSLPR + MUTZ5 cells to simulate relapse (week 0 antigen rechallenge) and followed by BLI. D Summary BLI radiance data following MUTZ5 rechallenge are displayed graphically for the 5e6 TSLPRCART/original ruxolitinib day 7 cohort shown in the lower right aspect of (A) with (E) enumeration of human CD3+/CD45+ T cells in murine peripheral blood at these same time points by quantitative flow cytometry. TSLPRCART with prior day 7 delayed-ruxolitinib exposure expanded robustly following MUTZ5 rechallenge, and low or undetectable leukemia burden was maintained. Statistical analyses were performed for (B) and (C) with one-way ANOVA and Tukey post-test for multiple comparisons. *p < 0.05, ****p < 0.0001.