STF-083010 and its decomposed product, A-I06, stall growth of CLL cells by inducing apoptosis. (A) Eμ-TCL1 CLL cells, (B) MEC1 cells, (C) MEC2 cells, and (D) WaC3 cells were untreated or treated with STF-083010 (50μM), A-I06 (50μM), or A-I07 (50μM) for a course of 3 or 4 days, and subjected to XTT assays at the end of each day. Percentages of growth were determined by comparing treated with untreated groups. Each data point derived from 4 independent groups receiving exactly the same treatment was plotted as mean ± SD. (E) MEC1 cells were untreated or treated with A-I06 (50μM), fludarabine (30μM), or the combination of both for a course of 4 days, and subjected to XTT assays. Data derived from the same experimental settings were plotted as mean ± SD. (F-G) Primary human CLL cells isolated from patient 1 and patient 2 were untreated or treated with STF-083010 (50μM), A-I06 (50μM), or A-I07 (50μM) for a course of 3 days, and subjected to XTT assays. Data derived from the same experimental settings were plotted as mean ± SD. Results are representative of 3 independent experiments. (H) Eμ-TCL1 mice with high percentage of CLL cells in the peripheral blood were identified and injected intraperitoneally with vehicle (n = 9) or A-I06 (60 mg/kg; n = 5) on day 0, day 1, day 12 and day 13. The percentage of CLL cells in PBMCs for each mouse was determined by flow cytofluorometry on day 2, day 7, day 14, and day 21, and compared with the CLL burden data of the mouse on day 0 (100%). Data derived from multiple mice receiving exactly the same treatment were plotted as mean ± SEM. (I) PBMCs isolated from Eμ-TCL1 CLL mice injected with vehicle for 24 hours were stained with CD19-APC-Cy7, IgM–Alexa 568, CD5-APC, B220–Alexa 488, annexin V–PE, and DAPI. CD5⁻/B220⁺ B cells and CD5⁺/B220⁺ CLL cells were analyzed on gated CD19⁺/IgM⁺ B-cell populations (left panel). CD5⁻/B220⁺ B cells and CD5⁺/B220⁺ CLL cells were further gated, and analyzed for the presence of annexin V⁺ and DAPI⁺ populations (middle and right panels). Data are representative of 4 independent experiments. (J) PBMCs isolated from A-I06–injected Eμ-TCL1 CLL mice were stained with CD19-APC-Cy7, IgM–Alexa 568, CD5-APC, B220–Alexa 488, annexin V–PE and DAPI. CD5⁻/B220⁺ B cells and CD5⁺/B220⁺ CLL cells were analyzed on gated CD19⁺/IgM⁺ B-cell populations (left panel). CD5⁻/B220⁺ B cells and CD5⁺/B220⁺ CLL cells were further gated, and analyzed for the presence of annexin V⁺ and DAPI⁺ populations (middle and right panels). Data are representative of 4 independent experiments.