T lymphocytes targeting native receptors

Abstract

The adoptive transfer of T cells specific for native tumor antigens (TAs) is an increasingly popular cancer treatment option because of the ability of these cells to discriminate between normal and tumor tissues and the corresponding lack of short or long-term toxicities. Infusions of antigen-specific CD4(+) and CD8(+) T cells targeting viral antigens derived from Epstein-Barr virus (EBV) induce sustained complete tumor remissions in patients with highly immunogenic tumors such as post-transplant lymphoproliferative disease, although resistance occurred when the infused T-cell population had restricted antigen specificity. T cells specific for EBV antigens have also produced complete remissions of EBV-positive nasopharyngeal carcinomas and lymphomas developing in immunocompetent individuals, even though in these patients tumor survival is dependent on their ability to evade T-cell immunity. Adapting this strategy to non-viral tumors is more challenging, as the target antigens expressed are less immunogenic and the tumors lack the potent danger signals that are characteristic of viruses. The goals of current studies are to define conditions that promote expansion of antigen-specific T cells ex vivo and to ensure their in vivo persistence and survival by combining with maneuvers such as lymphodepletion, checkpoint inhibition, cytokine infusions, or genetic manipulations. More pragmatic goals are to streamline manufacturing to facilitate the transition of these therapies to late phase trials and to evaluate closely histocompatibility antigen (HLA)-matched banked antigen-specific T cells so that T-cell therapies can be made more broadly available.