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IMMUNO-REACTIVE CANCER ORGANOID MODELS TO EXAMINE MICROBIOME METABOLITE EFFECTS ON IMMUNE CHECKPOINT BLOCKADE EFFICACY

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title
IMMUNO-REACTIVE CANCER ORGANOID MODELS TO EXAMINE MICROBIOME METABOLITE EFFECTS ON IMMUNE CHECKPOINT BLOCKADE EFFICACY
author
Willey-Shelkey, Ethan
abstract
As the number of available immunotherapies for solid tumors increase, their prevalence in the clinic continues to rise as well. While the results are promising and immunotherapies have benefits over traditional chemotherapeutics, a sizable percentage of patients are non-responders to all types of immunotherapy as a treatment option. These differences in sensitivity can be either innate or acquired. Yet, there has been limited use of 3D in vitro models to assess tumor immune-reactivity and explore why different patients have such variable responses. These systems are ideal for isolating specific molecular mechanisms that dictate cell behavior and interactions. One such mechanism that is being increasingly evaluated as a source of variability in immunotherapy response is the composition and effects of the host microbiome. Our goal was to create an organoid model containing cancer cells paired with cytotoxic T-cells to model immune checkpoint blockade (ICB) efficacy. Specifically, we examined ICB in triple negative breast cancer (TNBC) because the lack of targeted therapy and relatively high mutational load makes it an ideal target. To achieve this goal, we created organoids consisting of matched tumor and immune cells, embedded in extracellular matrix (ECM)-like hydrogels. Organoids were exposed to physiologic concentrations of bacterial metabolites and further treated with therapeutic equivalent doses of anti-PD-1 and anti-CTLA-4. Results showed that ICB therapy stimulated internal localization of T-cells, inducing T-cell-mediated tumor cell killing. ICB and metabolite co-treated organoids showed greater tumor cell killing. RT-qPCR and flow cytometry demonstrated increased expression of CD-8 T-cell co-receptor, increased cytokine production, and increased effector T-cell viability due to bacterial metabolite and ICB co-administration. A qPCR panel on two of the metabolites demonstrated that microbiome metabolites can significantly alter gene expression. This novel model demonstrated the effects of specific bacterial metabolites paired with ICB to help determine how the microbiome can influence ICB. The translational value of this model was then assessed by utilizing different cancer types and therapies in the same organoid system. This model could be further used to examine novel microbiome-ICB interactions shown by recent research to alter therapeutic response levels in patients.
subject
Immunotherapy
Microbiome
Organoid
Triple Negative Breast Cancer
contributor
Soker, Shay (committee chair)
Almeida-Porada, Graca (committee member)
Cook, Katherine L (committee member)
Votanopoulos, Konstantinos I (committee member)
date
2022-05-24T08:36:19Z (accessioned)
2022-05-24T08:36:19Z (available)
2022 (issued)
degree
Physiology and Pharmacology (discipline)
identifier
http://hdl.handle.net/10339/100783 (uri)
language
en (iso)
publisher
Wake Forest University
type
Dissertation

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