BCL2 and Tumor Lysis Syndrome: SMI toxicity varies by type: pan BCL-2 homology domain 3 (BH3) mimetics (AT-101) tend to be more toxic, causing dose-dependent thrombocytopenia [17, 46, 47], selective BCL-2 BH3 mimetics, although platelet sparing, induce resistance and increase the risk of tumor lysis syndrome [17, 48, 49].