LDK treatment inhibits tumor progession in 2 in vivo models of T-ALL. (A-D) Adult rag2:cMYC-ER/lck:EGFP transgenic zebrafish with T-cell leukemia infiltration (outline) were treated with DMSO vehicle (n = 10) or 250nM LDK (n = 20) dissolved in E3 fish water over a 2-week period. As continuous exposure to LDK had toxic side effects, fish were subjected to a well-tolerated 2-day on drug/1-day off drug treatment regimen before being taken off drug altogether after day 14. (A) Fluorescence (left) and bright field (right) imaging of normal healthy adult rag2:cMYC-ER/lck:EGFP transgenic fish (arrow indicates normal T-cell fluorescence in thymus). (B) Treatment outcome of leukemic zebrafish incubated in DMSO vehicle only or 250nM LDK. One representative fish shown per treatment. (C) Vehicle control (left panels) and LDK treated (right panels) leukemic fish were sectioned and stained with H&E (top panels) as well as immunohistochemistry staining for GFP (bottom panels). Scale bars, 10 μm. (D) Kaplan-Meier survival plot shows superior survival of LDK-treated fish. Although all vehicle-treated fish (10/10) had expired by day 40, 67% of LDK-treated fish (13/20) were alive at day 270 (256 days after treatment). Three LDK-treated fish expired of unknown causes. Arrows indicate start and end time points of treatment. (E-G) LDK treatment inhibits tumor growth in a mouse xenograft model of T-ALL. Thirty male NOD-SCID mice were injected in each flank with 5 × 10⁵ luciferase-transduced CCRF-CEM T-ALL cells. Cells were then allowed to engraft for 3 days before first bioluminescence measurement. The mice were then divided into 2 groups of 15 mice each and treated twice daily via intraperitoneal injection with either LDK (16 mg/kg) or vehicle only. Bioluminescence was assessed weekly with a CCD camera. (E) Representative pictures for tumor progression in vehicle control (top) versus LDK-treated (bottom) mice. (F) Increase in tumor bioluminescence of vehicle and LDK-treated mice, normalized to baseline. (*P = .0265, **P = .0006, ***P = .0304). (G) Average weight of LDK-treated (red line) versus vehicle only (blue line) treated mice. Error bars = SEM. (A-B) Images were acquired at room temperature using the Olympus MVX10 microscope with MV PLAPO 1× lens (Olympus). Camera used was Diagnostic Instruments model 14.2 Color Mosaic Insight FireWire SPOT. SPOT Alias Version 4.6 acquisition software was used, 2000 ms exposure with no binning, γ = 1.0. Fluorescence excitation light source was EXFO X-Cite Series 120. (C) Images were obtained using automated immunostainer (BenchMark XT; Ventana Medical Systems) followed by IView DAB detection (Ventana Medical Systems). (E) Mouse images and tumor emittance data were collected at 37°C using the XENOGEN IVIS 100 imaging system (Caliper Life Sciences) with Spectral Instruments 600 Series camera controller. Mouse images were processed and analyzed for quantitative emittance using Living Image Version 2.50.2 software (Caliper Life Sciences).