(A) Schema of adoptive transfer of Eμ-TCL1–derived splenocytes into immunocompetent CD45.1 or immunodeficient NSG recipients. (B) Representative spleens of 5 vehicle control-treated and 5 E7107-treated animals, as harvested at the end of treatment. Scale bar: 1 cm. P value was calculated by Mann Whitney U test. (C) Flow cytometry analysis of peripheral blood (PB), spleen (SP), peritoneum (PC), and bone marrow (BM) to measure the percentage of B220⁺CD5⁺Igκ⁺ CLL cells from mice treated with vehicle control or with 2 mg/kg E7107. P values were calculated by Mann Whitney U test. (D) Western blot analysis of MCL1 protein levels in the splenocytes of 3 CD45.1 animals/group, as analyzed at the end of treatment with 2 mg/kg E7107. β-Actin is used as loading control. Molecular weights (in kDa) are indicated. (E) Representative spleens of 3 CD45.1 mice per group treated with vehicle control, single-agent 100 mg/kg venetoclax, single-agent 1 mg/kg E7107, or the combination of both, as harvested at the end of treatment (n = 7/group). Scale bar: 1 cm. Reported P values were calculated by 1-way ANOVA with Scheffé’s correction for multiple comparisons. (F) Flow cytometry analysis of the percentage of B220⁺CD5⁺Igκ⁺ CLL cells in spleens from mice belonging to the 4 treatment groups, as analyzed at the end of treatment. Reported P values were calculated by 1-way ANOVA with Scheffé’s correction. (G) Representative spleen sections (1 mouse/group) of CD45.1 transplants stained with H&E, anti-PAX5 (brown), and anti-CD5 (red) antibodies or anti-Ki67 at the end of a 2-week treatment with E7107 or venetoclax alone or in combination, as indicated in the figure. White dotted lines demarcate CD5⁺PAX5^– T cell areas. The CLL infiltrate is composed of cells coexpressing cytoplasmic CD5 and nuclear PAX5. The first and second rows display images captured using a ×5 objective (scale bar: 1 cm), the third and fourth display images captured using a ×40 objective (scale bar: 100 μM). (H) Survival curve of NSG mice transplanted with TCL1 splenocytes and then treated with vehicle control (n = 11), 25–50 mg/kg venetoclax (n = 10), 2 mg/kg E7107 (n = 10), or the combination of venetoclax and E7107 (n = 11) for 2 weeks, followed by observation for survival. P values were calculated using the log-rank test with Bonferroni correction. The gray shaded area indicates treatment period.