Identifying novel epigenetic modifiers that sensitize T cell malignancies to CD8+ T cell mediated cytotoxicity by high throughput drug screen

Abstract

Abstract T Cell Lymphomas are a rare subtype of Lymphoma, occurring in ~1% of all cancers and response rates to current therapies reach only ~23%. The lack of unique targetable T cell antigens as well as their tendency to overcome chemotherapies results in a high incidence of relapse in most patients leading to remission rates of approximately two years. Immunotherapies, especially immune-checkpoint blockade, have slightly improved outcomes in refractory disease, but there remains a need for stronger and more durable responses. The chemotherapeutic potential of epigenetic modifiers is just beginning to be explored. HDAC inhibitors, DNA demethylating agents, and histone methyltransferase inhibitors reshape the transcriptome, potentially altering the expression of immune modulatory pathways. We hypothesized that pretreating T cell malignancies with epigenetic modifiers will alter key genetic signatures that sensitize them to CD8+ T cell-mediated cytotoxicity. We pretreated five T cell lymphoma cell lines, representative of different T cell malignant diseases with compounds from an FDA-approved 700+ epigenetic modifying drug library at four different concentrations and then co-cultured them with a tumor-reactive HLA-A2-matched primary (derived from PBMCs) cytotoxic CD8+ T cell line. Changes in T cell mediated cytotoxicity and alterations in immune modulating surface markers and potential CAR-T cell targets (CD30, CCR4, and CD47) were assessed by flow cytometry. Several promising compounds were identified by their ability to improve T cell mediated cytotoxicity, increase expression of immune stimulatory markers, decrease expression of immune inhibitory markers, and augment expression of existing CAR-T target antigens. Supported by NIH and the Colorado Clinical and Translational Sciences Institute (CCTSI)