Enhanced apoptosis of ABT-737 (A) combined with bortezomib (B) in CLL primary cells and lack of enhanced toxicity in PBMC. (A) Primary cells from 2 representative patients with CLL were treated with bortezomib and/or ABT-737 at 2.5 or 5 nM for 24 hours. Each combination group resulted statistically significant compared to the single drugs and control (P < .02). (B) PBMCs were treated with bortezomib at 2.5 or 5 nM and/or ABT-737 at 0.01, 0.1, or 1 μM ABT-737 for 24 hours. Each combination group was not significantly more cytotoxic then ABT-737 given alone (P < .36). Apoptosis was evaluated by cytofluorimetric analysis of yo-pro-1 and propidium iodide. Results represent the means plus or minus SD.