Healthy human B cells undergoing venetoclax treatment have increased BCL-2 expression. (A) Schematic representation of the study design. PB samples from 4 breast cancer patients were collected at screening and during venetoclax treatment (all patients received 800 mg venetoclax). (B) Change in lymphocyte concentration (cells per μL) during venetoclax treatment in each patient after 31 days of treatment. (C) Concentrations of BAFF and APRIL (pg/mL) detected in the serum samples of the breast cancer patients using a Luminex assay at screening and 15 days after venetoclax treatment. (D) Histograms of BCL-2 protein expression by flow cytometry in B cells in patients before and after venetoclax treatment (BC_01013 after 201.7 weeks, BC_01014 after 61.1 weeks, BC_01026 after 67.4 weeks, BC_01029 after 112.1 weeks). (E) Geometric mean of the BCL-2 levels of B cells in 4 patients. (F) KEGG enrichments analysis of differentially expressed genes in single-cell cellular indexing of transcriptomes and epitopes sequencing data from 5 paired samples under long-term venetoclax treatment. Student 2-tailed paired t test was used to calculate P values. ∗P < .05; ∗∗P < .01. APRIL, a proliferation-inducing ligand (also known as TNFSF13); KEGG, Kyoto Encyclopedia of Genes and Genomes; TNF, tumor necrosis factor.