Synergy of NVP-BEZ235 and enzastaurin in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a neoplasm classified as a B-cell malignancy, that accounts for approximately 3 to 8% of Non-Hodgkin’s lymphoma (NHL) cases diagnosed annually. MCL is difficult to treat and seldom considered cured. The pathobiology of MCL is complex and includes alteration in the cell cycle, abnormalities in the DNA damage response, and constitutive activation of key antiapoptotic pathways including phosphatidyl-inositol 3-kinase (PI3K)/Akt and nuclear factor-kB. This has promoted the identification of new targeted treatments and new agents that have shown promising efficacy for future MCL therapies. The phosphatidylinositol 3-kinase (PI3K) mammalian target of rapamicin (mTOR) pathway mediates proliferation, survival, and drug resistance in lymphoma cells. NVP-BEZ235 (BEZ235) is a new, orally bioavailable inhibitor of PI3K and mTOR and a representative of a new class of anti-tumour agents. In this study, we analysed the in vitro inhibitory effects of NVP-BEZ235 on mantle lymphoma cell lines (GRANTA-519 and JeKo-1) and its effects in combination with enzastaurin, everolimus and perifosine. Our data suggest that in mantle lymphoma cell lines, BEZ235 in combination with enzastaurin elicits its antitumour effect better than combined with perifosine and everolimus. Our data reveal that the drug combination targets phosphorylation of PI3K/Akt/mTOR pathways and induces both intrinsic and extrinsic apoptosis pathways. Furthermore, inhibition of Bcl-2 anti-apoptosis family members may, in part, explain the efficacy of signalling blockade in lymphoma cells and suggests an additional therapeutic targeting strategy. Therefore, these preclinical data support the potential use of BEZ235 in patients with mantle lymphoma, and in particular provide rationale for combination with enzastaurin