Project Summary/Abstract
Adoptive cell therapy (ACT) is a promising therapeutic approach for the treatment of cancer. However,
the initial success of ACT has been limited to chimeric antigen receptor (CAR)-T cell therapies for hematological
malignancies. Applying this cell therapy to solid tumors is challenged by the lack of targetable tumor antigens,
the severe systemic toxicity and the suppressive tumor microenvironment. T cell receptor (TCR) gene therapy
can overcome some of these challenges because it enables targeting of intracellular proteins presented as
peptide antigens on the human leukocyte antigen (HLA) complex. However, the majority of naturally occurring
TCRs are of low-affinity to their peptide-HLA targets. Engineering these TCRs via phage display or yeast display
for higher affinity is complicated by the introduction of unwanted cross-reactivity and the poor association
between affinity and function. This project seeks to tackle each of the major challenges of ACT in order to
effectively reprogram the immune system to combat solid tumors.
The F99 phase is focused on a TCR engineering platform for the creation, modification, and profiling of
TCRs that can target tumor-associated self-proteins with minimal toxicity profiles. In this approach, I first raise T
cells from the natural repertoire that recognize a related ‘foreign’ peptide that differs by one amino acid from the
self-peptide. Then, I modulate the fine specificity of the TCR by directed evolution of the peptide binding region
to switch its specificity towards the tumor self-antigen of interest. I demonstrate the value of this approach by the
creation of libraries of viral-specific TCRs and the subsequent in vitro selection of TCRs that switched specificity
to a closely related epitope. The engineered TCRs showed robust T-cell activation after ligand recognition and
are of equal or higher efficiency than the parental receptor. Importantly, the engineered TCRs displayed no
additional promiscuity or off-target specificities as compared to the parental TCRs. The goal for the remainder of
my dissertation project is to apply this approach to the generation of cancer reactive TCRs. By controlling the
fine specificity of TCRs, this approach will overcome two of the major challenges of ACT, namely increasing the
breadth of antigens that can be used for ACT while also minimizing cross-reactivities.
For the K00 phase, I will shift my focus to addressing the suppressive tumor microenvironment that
surrounds solid tumors by developing novel synthetic receptors and testing them in mouse models. I plan to build
upon my synthetic biology background to implement novel high-throughput screens, learn new statistical analysis
methods, and gain experience working with in vivo mouse models of cancer. These new approaches, coupled
with my already strong background in genetics, molecular biology and biochemistry will allow me to address the
most pressing and challenging issues facing targeted immunotherapies. With the aid of this award, I intend to
continue my research contribution to become a leader in the field of cancer immunotherapy.