Fig 1: In vivo treatment of a patient-derived T-ALL xenograft with ruxolitinib combined with dexamethasone. (A) Timeline of PDX X11 treatment. 106 luciferase and GFP positive PDX X11 cells were injected in the tail vain of 6 to 12-weeks old NSG mice. After two weeks, we assessed disease burden by performing bioluminescent imaging (BLI). All mice had reached a total flux of >107 photon/sec. Treatment with dexamethasone (Dexa) and ruxolitinib (Ruxo) was started 18 days after injection. Ruxolitinib was given at a dose of 50 mg/kg for 14 consecutive days. Dexamethasone was given in the drinking water at a dose of 4 mg/L for 3 days, followed by 2 days without dexamethasone. Five and 12 days after start treatment BLI was performed and mice were sacrificed after two weeks of treatment to assess organ infiltration by leukemia cells. N = 8 for placebo and ruxolitinib and n = 7 for dexamethasone and combination. (B) Bioluminescent imaging of PDX X11 at different time points during treatment. Images were taken at the start of the treatment, after 5 days and at the end of treatment. The images shown are of representative mice. Mice were imaged with the IVIS Spectrum in vivo Imaging System (PerkinElmer). (C) Overview of the BLI flux evolution. Average of the mean total flux (photon/sec) over time is shown for the different treatment groups. (D) Percentage of GFP positive cells in the peripheral blood for each treatment group. Peripheral blood withdrawal was performed before sacrificing the mice. GFP percentage was measured via flow cytometry on a MACSQuant Vyb (Miltenyi). (E) Spleen weight (mg) after indicated treatments. (F) Single cells were made from total spleens after which we measured the percentage leukemic GFP positive cells in the spleen via flow cytometry. (G) Leukemic bone marrow cells were flushed from the bones and percentage GFP analyzed via flow cytometry. (H) Overview of leukemic infiltration in the blood after injection of 389E PDX in vivo in NSG mice. Average of the percentage hCD45 over time is shown for the different treatment groups. Grey box indicates the treatment period (n = 5). (I) Spleen weight (mg) of mice injected with 389E PDX after indicated treatments. p values were calculated with graphpad Prism using the Student t test.