Venetoclax treatment restores glycolytic switch and proliferation in CD4 T cells. Patients with CLL who underwent 12 cycles of venetoclax had donated PBMCs before and after venetoclax plus obinutuzumab (Ven + Obi) treatment. (A) These PBMCs as well as PBMCs from HDs were thawed, after which we stimulated CD4 T cells and analyzed expression of CD25 and GLUT-1 before and after Ven + Obi treatment. (B) In this same experiment, glucose uptake (2-NBDG) was measured. (C) Presence of Tregs after Ven + Obi treatment. (D) Dynamic analysis of CD4 T-cell activation revealed a substantial improvement of CD4 T-cell activation after Ven + Obi treatment. (E) T cells from patients with CLL obtained before and after Ven + Obi treatment and from HDs were stimulated with CD3 plus CD28 antibodies and allowed to proliferate for 10 days. Proliferation was measured by flow cytometry using 123count eBeads. Each point represents a different HD or patient with CLL. Data are presented as mean ± standard error of the mean. *P < .05, **P < .005, ***P < .001, ****P < .0001. ns, not significant.