CR increases the lifespan of mice that receive ABT-737 treatment. (A) Syngeneic C57BL/6 mice were intravenously injected with lymphoma cells that were isolated from Eµ-Myc/WT mice and fed ad libitum or under CR for 17 days. Seven days after intravenous injection, mice were treated or not for 10 days with 75 mg/kg ABT-737. Next, all mice were fed ad libitum until the time of ethical euthanasia (see the experimental procedure scheme, left panel). Lifespans of the mice from the beginning of each treatment regimen are indicated for each group (control vs CR + ABT-737: median survival, 30 and 41 days, respectively; n = 10; P = .00005; CR vs CR + ABT-737: median survival, 30 and 41 days, respectively; n = 9 and n = 10, respectively; P = .0061; ABT-737 vs CR + ABT-737: median survival, 33 and 41 days, respectively; n = 8 and n = 10, respectively; P = .00048). (B) Numbers of platelets were measured in each group at 14 days after the intravenous injection of Eµ-Myc cells (control, n = 5; CR and CR + ABT-737, n = 4 for ABT-737). (C) Numbers of WBCs were analyzed in each group 21 days after the intravenous injection of Eµ-Myc cells (control, n = 7; ABT-737 and CR + ABT-737, n = 8; CR, n = 9). In vivo experiments were conducted twice with similar results. **P < .01; ***P < .001. i.v., intravenous.; ns, nonsignificant