(125a) Engineering T-Cell Receptor Signaling Dynamics for Cell-Based Immunotherapy

Adoptive transfer of T-cells expressing chimeric antigen receptors (a fusion of tumor specific single-chain antibodies and intracellular signaling domains from the T-cell receptor (TCR) signaling pathway) has shown promise as an anti-tumor therapy. However, their efficacy is limited because of limited in vivo activity, T-cell exhaustion after ex vivo expansion, low persistence inside the host, and potential safety concerns. Here we are applying synthetic biology approaches to engineer and optimize the behaviors of these tumor targeted T-cells. By engineering synthetic positive and negative feedback loops in T-cells, we show that we can precisely tune the amplitude and dynamics of the T-cell response. We have demonstrated that expression of bacterial effector proteins can be used to shut down and attenuate the response. Conversely, we have also shown that we can amplify output by expressing fusions of signaling proteins that mimic an activated signaling complex. The modularity of these circuits should allow us to construct and search for altered response profiles that improve the persistence and anti-tumor activity of engineered T-cells. Our approaches complement ongoing work on chimeric antigen receptor engineering. Furthermore, this work has yielded a new set of genetic tools to control the T-cell signaling dynamics.