TGFB1 and B-cell chronic lymphocytic leukemia: Monoclonal antibodies targeting TGF-β or PD-L1 notably suppressed tumor growth and reduced the number of Breg cells in mice.887 Treatment with ibrutinib was shown to improve the immunosuppressive TME of chronic lymphocytic leukemia (CLL) via the STAT3-mediated suppression of Breg cells and the PD-1/PD-L1 pathway.889 Taken together, selectively targeting Breg cells in the TME appears to be a hopeful strategy for tumor immunotherapy.