Assessments of activity relative to vehicle control following treatment with vecabrutinib or ibrutinib in the murine Eμ-TCL1 model. Differential cell counts for granulocytes, lymphocytes, and monocytes (A), platelet count (B), red blood cells (RBC) and hemoglobin levels (C), WBC count (D), and spleen and liver weights (E) upon BTK inhibitor treatment vs vehicle for 10 days. (F) Representative flow cytometry plots showing changes in the CD19⁺CD5⁺ population in spleen. (G) Change in tumor load (percentage of CD19⁺CD5⁺ cells) in blood, spleen, and bone marrow (G) and absolute number of CD19⁺CD5⁺ tumor cells per spleen (H). (I) Representative flow cytometry plots showing relative changes in Ki67-expressing tumor cells. (J) Tumor cell proliferation in blood, spleen, and bone marrow. *P ≤ .05, **P ≤ .01, Mann-Whitney U test. ns, not significant (P > .05).