Fig. 6: In vivo ruxolitinib and TSLPRCART sensitivity of CRLF2-rearranged Ph-like ALL is recapitulated in Down syndrome-associated ALL. | Leukemia

Fig. 6: In vivo ruxolitinib and TSLPRCART sensitivity of CRLF2-rearranged Ph-like ALL is recapitulated in Down syndrome-associated ALL.

From: Co-targeting of the thymic stromal lymphopoietin receptor to decrease immunotherapeutic resistance in CRLF2-rearranged Ph-like and Down syndrome acute lymphoblastic leukemia

Fig. 6

A NSG mice were engrafted with 5e5 DSALL47 (left) or 1e6 DSALL515 (right) PDX model cells. Once >1% CD10+/CD19+ human ALL cells were detectable in murine peripheral blood, cohorts of 5 mice were randomized to treatment with control (orange) or ruxolitinib (purple) chow ad libitum. Leukemia burden was monitored weekly by quantitative flow cytometric analysis of human CD10+/CD19+ALL cells in peripheral blood (top panels) and in end-study spleens (bottom panels), which was determined by rate of leukemia progression in control mice for each model. Significant reduction of DS-ALL cell numbers in peripheral blood and spleens was detected in both tested models with near-curative effect after 4 weeks of ruxolitinib treatment. B Flow cytometric quantification of TSLPR surface antigen density demonstrates similar ranges of expression in CRLF2-rearranged Ph-like and DS-ALL PDX models, suggesting similar potential for therapeutic activity of TSLPRCART. CRLF2 wild-type NALM-6 and CRLF2-rearranged MUTZ5 ALL cell lines were used as negative and positive controls, respectively. C NSG mice were engrafted with 1e6 TCHK150 ALL PDX model cells. Once >1% CD10+/CD19+ human ALL cells were detectable in murine peripheral blood, cohorts of 5 mice were randomized to IV treatment with saline, 2.5e6 UTD, or 2.5e6 TSLPRCART. Additional cohorts of TSLPRCART-treated mice (n = 5) were also randomized to simultaneous (day 0, green bar) or delayed (day 7, blue bar or day 14, purple bar) administration of ruxolitinib chow ad libitum. Animals were monitored weekly by quantitative flow cytometry analysis of human CD45+/CD10+/CD19+ ALL cells in murine peripheral blood and (D) end-study spleens. Delayed ruxolitinib co-treatment with TSLPRCART improved leukemia clearance compared to monotherapy or simultaneous co-treatment in this DS-ALL model. TSLPR surface expression remained unchanged by quantitative flow cytometric analysis in residual ALL cells in TSLPRCART-treated animals where applicable (data not shown). E Flow cytometric quantification of CD45+/CD3+ T cells in murine peripheral blood demonstrated no inhibition of TSLPRCART proliferation in vivo with day 14 ruxolitinib co-administration (lavender) compared to TSLPRCART monotherapy (light orange), whereas day 0 (light green) and day 7 (light blue) ruxolitinib exposure significantly impaired T cell numbers. F ELISA was performed to quantify human IFN-γ in murine plasma prepared from weekly peripheral venous blood. Significant dampening of IFN-γ production was detected with TSLPRCART and day 0 ruxolitinib co-treatment compared to TSLPRCART monotherapy (light green versus light orange). Statistical analyses were performed for (A) with unpaired t-tests and for (C), (D), (E), and (F) with 2-way ANOVA/mixed effects analysis and Dunnett post-test for multiple comparisons using the TSLPRCART condition as the comparator. ns not significant, *p < 0.05, **p < 0.01, ****p < 0.0001.

Back to article page