Disruption of aneuploidy and senescence induced by aurora inhibition promotes intrinsic apoptosis in double hit or double expressor diffuse large B-cell lymphomas

Abstract

Double hit (DH) or double expressor (DE) diffuse large B-cell lymphomas (DLBCL) are aggressive non-Hodgkin's lymphomas (NHL) with translocations and/or overexpressions of MYC and BCL-2, which are difficult to treat. Aurora kinase (AK) inhibition with alisertib in DH/DE-DLBCL induces cell death in 30%, while 70% are aneuploid and senescent cells (AASC), a mitotic escape mechanism contributing to drug resistance. These AASCs elaborated a high metabolic rate by increased AKT/mTOR and ERK/MAPK activity via BTK signaling through the chronic active B-cell receptor (BCR) pathway. Combinations of alisertib þ ibrutinib or alisertib þ ibrutinib þ rituximab significantly reduced AASCs with enhanced intrinsic cell death. Inhibition of AK þ BTK reduced phosphorylation of AKT/mTOR and ERK-1/2, upregulated phospho-H2A-X and Chk-2 (DNA damage), reduced Bcl-6, and decreased Bcl-2 and Bcl-xL and induced apoptosis by PARP cleavage. In a DE-DLBCL SCID mouse xenograft model, ibrutinib alone was inactive, while alisertib þ ibrutinib was additive with a tumor growth inhibition (TGI) rate of 25%. However, TGI for ibrutinib þ rituximab was 50% to 60%. In contrast, triple therapy showed a TGI rate of >90%. Kaplan–Meier survival analysis showed that 67% of mice were alive at day 89 with triple therapy versus 20% with ibrutinib þ rituximab. All treatments were well tolerated with no changes in body weights. A novel triple therapy consisting of alisertib þ ibrutinib þ rituximab inhibits AASCs induced by AK inhibition in DH/DE-DLBCL leading to a significant antiproliferative signal, enhanced intrinsic apoptosis and may be of therapeutic potential in these lymphomas.