ABT-199, a BH3 mimetic that specifically targets Bcl-2, enhances the antitumor activity of chemotherapy, bortezomib and JQ1 in "double hit" lymphoma cells.

Double hit lymphoma (DHL) is a recently recognized lymphoma with a survival of less than 2 years. Both ABT-737, a Bcl-2/Bcl-XL inhibitor, and ABT-199, which selectively targets Bcl-2, were potently cytotoxic against DHL cell lines Sc-1 and OcI-LY18, the RL cell line and primary human DHL cells, but not Ramos cells, which lack Bcl-2 expression. ABT-199 was more potent than ABT-737, and is the most promising of the BH3 mimetics to date. The DHL cell lines were also sensitive (< 200 nM) to doxorubicin, methotrexate, cytarabine and the proteosome inhibitor, bortezomib. The combination of chemotherapy with ABT-199 and doxorubicin or cytarabine, bortezomib, YM-155 and JQ1 produced synergistic cell kill against the DHL cell lines. Cells from a patient with DHL were also sensitive to JQ1 and bortezomib, providing a rationale for a clinical trial of these combinations in patients with relapsed DHL.