Interrogating the Effects of T Cell Receptor Engineering Strategies on TCR Specificity

The hallmark of the adaptive immune system is the ability to discriminate between “self” and “non-self”. A crucial component that allows for this discrimination are T cell with their specialized T cell receptors (TCR) and the peptide major histocompatibility complex (MHC) proteins that they recognize. Through the interrogation of peptides derived from intracellular proteins displayed on MHC complexes, T cells are able to interrogate the health of the cells in the body. The ability of T cells to identify compromised cells, whether due to viral infection, bacterial infection, or cancerous mutation, has therefore been leveraged for the development of immunotherapeutics for treatment of various diseases.

Early studies of adoptive transfer of T cells engineered to express T cell receptors specific to tumor antigens have shown promising results in both solid and hematological cancers. However, there are ongoing questions about TCR-engineered T cells, most notably whether efficacy can be enhanced without increasing risk. Prior efforts to enhance efficacy via enhancing affinity have resulted in significant off-target cross-reactivity. This has led to efforts to enhance specificity both alongside and separate from affinity.

Through the biochemical and functional interrogation of the 868-Z11 high affinity TCR, I aim to understand the impacts on specificity upon the introduction of mutations located both within and outside of the TCR pMHC binding interface. Through affinity measurements and T cell recognition assays using positional scanning peptide libraries, I aim to identify the magnitude of perturbation each mutation imposes on the specificity of the 868-Z11 TCR. The exploration of mutations outside of the TCR pMHC interface may provide an alternative approach to modulate affinity while minimizing or eliminating perturbations to specificity.