Sarcomas pose a significant therapeutic challenge as even intensifying chemotherapy has produced little improvement in the survival of patients with metastatic sarcoma. Therefore, a new approach to treating these tumors is desperately needed. T cells provide a highly targeted therapy with low intrinsic toxicity and the potential to persist long-term providing life-long protection against disease. Indeed, virus-specific T cells (VSTs) can safely and successfully treat virus-associated cancer. The use of T-cells for non-viral cancers has recently been facilitated by the use of chimeric antigen receptors (CARs), which combine the extracellular antigen binding domains of antibodies with intracellular signaling domains from the T-cell receptor and from costimulatory molecules, that when introduced into T cells, can render them tumor-specific. CAR-modified T cells have shown promise in the treatment of hematological malignancies and neuroblastoma, but potent tumor responses are still uncommon. Major reasons for this failure include a lack of proliferation and persistence after infusion of the T cells as well as the targeting of a single antigen leading to antigen escape variants. To address these obstacles, we have developed a method for engrafting a CAR on varicella-zoster virus (VZV) specific T cells, and we propose that stimulation of VZV T cells through their native T cell receptor using a commercially available VZV vaccine will promote extratumoral proliferation of the CAR-modified VZV T cells in vivo, and we now hypothesize that engrafting VZV T cells with two CARs targeting two different sarcoma antigens will provide superior antitumor activity by preventing antigen escape of these heterogenous tumors. GD2 and EGFR are antigens expressed on multiple sarcoma subtypes and can be targeted by CARs. In Aim 1 of this proposal we will generate VZV-T-cells expressing two different CARs (GD2.CAR or EGFR.CAR) by double transduction with the two vectors so that each T-cell expresses both CARs (BiCARs) or by transduction of a single vector for the generation of separate VZV-T-cell populations each with a different CAR (UniCARs). We will then compare their in vitro proliferation and function. In Aim 2 we will utilize in vivo bioluminescent and fluorescent imaging to investigate the proliferation, persistence and anti-tumor activity of BiCAR (GD2/EGFR) VZV T cells versus UniCAR (GD2 or EGFR) VZV T cells in an NSG mouse model of sarcoma. Success in these studies could lead to a highly potent, but less toxic, therapy for multiple sarcoma subtypes.
Cliona Rooney, PhD, Baylor College of Medicine
Recipient of the: $50,000 Sarcoma Foundation of America Research Award