Mantle Cell Lymphoma (MCL) is a highly aggressive B-cell lymphoma resistant to conventional chemotherapy. Although defined by the characteristic t(11;14) translocation that results in overexpression of the cell cycle proliferation gene cyclin D, a variety of genetic aberrations have been identified in MCL and may contribute to its pathogenesis and chemoresistance. Of particular interest are frequent gains of anti-apoptotic BCL-2 as well as deletions of pro-apoptotic BIM. Therefore, this proposal will explore the synergistic cytotoxicity of simultaneously activating two pro-apoptotic pathways in MCL. First, small molecules modeled after the BCL-2 Homology 3 (BH3) death domain, known as BH3- mimetics, will induce the intrinsic pathway of apoptosis. Second, cytotoxic T cells reprogrammed with chimeric antigen receptors (CARs) that target CD19 will induce the extrinsic pathway of apoptosis. Although CAR-T cells have displayed impressive efficacy toward previously unresponsive B cell malignancies, they are vulnerable to other cytotoxic chemotherapies and apoptotic stimuli - limiting their efficacy in combination therapies. Therefore, in order to maximize synergy, we will test the ability of various genes to impart a survival advantage to the CAR-T cells while in the presence of BH3 mimetics.
Aim 1 will test the use of various anti-apoptotic BCL-2 family members to protect CAR-T cells from BH3 mimetic-induced cell death. We hypothesize that anti-apoptotic proteins not targeted by select BH3 mimetics will confer protection to the CAR-T cells.
Aim 2 will test the use of a self-stimulating cytokine- cytokine receptor to promote T cell survival in the presence of BH3 mimetics.
Aim 3 will explore the combination of BH3 mimetics and CAR-T cells, fortified by both the anti-apoptotic and cytokine factors, in an MCL xenograft model in vivo. To avoid potential complications of expressing anti-apoptotic and proliferative genes in a T cell, they will be introduced in a transient fashion as mRNA molecules. mRNA reprogramming has numerous advantages over DNA including, among others, the ability to introduce multiple genes in a single rapid step. By integrating successful approaches from chemistry, immunology and apoptosis we are well positioned to significantly improve CAR-T cell technology in a manner that enables a more robust, calibrated cytotoxicity with additional modes of targeted therapeutics.
Harnessing a patient's own immune system to attack cancers has recently enjoyed remarkable success. Building on this general foundation, we have developed a novel approach that reprograms T cells, by using multiple mRNA molecules to optimize their ability to kill B cell cancers. Here, we pave the way for modulated, synergistic combination therapies by not only reprogramming T cells to attack aggressive B cell cancers, but by fortifying the T cells to withstand the small, cell-permeable molecules that are used in complementary, targeted therapy to promote apoptosis.
|Gross, Atan; Katz, Samuel G (2017) Non-apoptotic functions of BCL-2 family proteins. Cell Death Differ 24:1348-1358|