TRANSLATION AND VALIDATION OF MYELOID DERIVED SUPPRESSOR CELL PROTEOMIC TARGETS IN LIVER AND LUNG TUMORS

Advancements in technology have made possible the development of highly personalized and efficacious medicines. Various forms of immunotherapy have demonstrated clinical utility in the treatment of blood-based cancers (e.g., leukemia, lymphoma, etc.). Cells in the tumor microenvironment (TME) of solid tumors can suppress the immune response of T cells, therefore hindering the efficacy of T-cell immunotherapies. Consequently, a growing number of studies are investigating methods of modulating the TME for improving immunotherapeutic outcomes in this context. Myeloid-derived suppressor cells (MDSCs) are one such cell responsible for diminishing the activity of immune cells by secreting immunosuppressive cytokines. Recent studies show that the glycoprotein, CD38, and Wnt-pathway triggering protein, β-catenin, are differentially expressed in MDSC populations of murine lung and liver metastases, respectively. MDSCs, chemically differentiated from the PBMCs of healthy human donors (hMDSCs) can be treated with small molecule inhibitors for validating the immunomodulatory roles of these targets. Successful candidates from these studies can be further evaluated in silico for predicting their pharmacokinetic characteristics, specificity in vivo, and most likely modes for target binding. Chapter 1 will describe the current state of cancer and the efficacy of its treatment with immunotherapy. Immunosuppressive cell types and current theories for their modulation by small molecules and biologics are also introduced. Finally, “omics” approaches for identifying pharmacologic targets in the TME and the preclinical models typically used for their translation and validation are discussed. In Chapter 2 of this thesis, the cytotoxic ranges of synthetic and flavonoid CD38 inhibitors are determined for hMDSCs and autologous T cells. Their influence on hMDSC production of key immunomodulatory cytokines is also evaluated, demonstrating the utility of 78c for decreasing the production of immunosuppressive IL-10, CCL17, and MMP7 while inducing release of CCL4 and IL-1β. Lastly, various in silico analyses are utilized to predict protein-ligand interactions, pharmacokinetic characteristics, and in vivo specificity of the tested CD38 inhibitors. Based on the data from these experiments, synthetic CD38 inhibitor, 78c, represents a promising candidate for further evaluation of its immunomodulatory potential of in vivo TMEs. Similarly, Chapter 3 involves the determination of cytotoxic ranges for various inhibitors of the Wnt/β-catenin pathway, each with unique mechanisms of intervention. With reference to these ranges, test compounds were again evaluated for their influence on key immunomodulatory cytokines in hMDSCs where ICRT14 diminished CCL17 and IL-1β while increasing CCL4. When assessed for their ability to decrease IL-10, FH535 was the only Wnt/β-catenin inhibitor capable of repeatedly decreasing the production of IL-10 in hMDSCs. Like Chapter 2, an in silico analysis was used to predict the physiological parameters and absorption, distribution, metabolism, and elimination (ADME) characteristics of test compounds. Based on these findings, both FH535 and ICRT14 demonstrate attributes that encourage further evaluation in the context of improving immunotherapy outcomes in solid tumors