novel-protocol-for-generating-physiologic-immunogenic-dendritic-cells

Novel Protocol for Generating Physiologic Immunogenic Dendritic Cells

Extracorporeal photochemotherapy (ECP) is a widely used cancer immunotherapy for cutaneous T cell lymphoma (CTCL), operative in over 350 university ...

Yale University School of Medicine

Extracorporeal photochemotherapy (ECP) is a cancer immunotherapy for cutaneous T-cell lymphoma (CTCL) operative in more than 350 centers worldwide. Although its efficacy and favorable safety profile have driven its widespread use, elucidation of its underlying mechanism has been difficult. In this study, we identify the principal contributors to the anticancer immunotherapeutic effects of ECP, with the goal of enhancing potency and broadening applicability to additional malignancies. First, we scaled down the clinical ECP leukocyte-processing device to mouse size. Second, we used that miniaturized device to produce a cellular vaccine that regularly initiated therapeutic antimelanoma immunity. Third, we individually subtracted key factors from either the immunizing inoculum or the treated animal to ascertain their contribution to the  antimelanoma response. Platelet-signaled monocyte-to-dendritic cell (DC) differentiation followed by sorting/processing/presentation of tumor antigens derived from internalized apoptotic tumor cells were absolute requirements. As in clinical ECP, immunogenic cell death of tumor cells was finely titrated by DNA cross-linkage mediated by photoactivated 8-methoxypsoralen (8-MOPA). ECP-induced tumor-loaded DC were effective immunotherapeutic agents only if they were spared exposure to 8-MOPA, indicating that healthy DC are required for ECP. Infusion of responder T cells into naïve tumor-challenged mice established the protective role of stimulated T-cell antitumor immunity. Collectively, these results reveal that selective antitumor effects of ECP are initiated by tumor antigen-loaded, ECP-induced DC, which promote potent collaboration between CD4 and CD8 tumor-specific T cells. These mechanistic insights suggest potential therapeutic applicability of ECP to solid tumors in addition to CTCL. These findings identify principal cellular contributors to the anticancer immunotherapeutic impact of ECP and suggest this treatment may be applicable to a broad spectrum of immunogenic malignancies. .

Extracorporeal Photochemotherapy Drives Monocyte-to-Dendritic Cell Maturation to Induce Anticancer Immunity.

Both targeted therapy and immunotherapy have been used successfully to treat melanoma, but the development of resistance and poor response rates to the individual therapies has limited their success. Designing rational combinations of targeted therapy and immunotherapy may overcome these obstacles, but requires assessment in preclinical models with the capacity to respond to both therapeutic classes. Herein, we describe the development and characterization of a novel, immunogenic variant of the BrafCdkn2aPten YUMM1.1 tumor model that expresses the immunogen, ovalbumin (YOVAL1.1). We demonstrate that, unlike parental tumors, YOVAL1.1 tumors are immunogenic in vivo and can be controlled by immunotherapy. Importantly, YOVAL1.1 tumors are sensitive to targeted inhibitors of BRAF and MEK, responding in a manner consistent with human BRAF melanoma. The YOVAL1.1 melanoma model is transplantable, immunogenic and sensitive to clinical therapies, making it a valuable platform to guide strategic development of combined targeted therapy and immunotherapy approaches in BRAF melanoma.

A novel immunogenic mouse model of melanoma for the preclinical assessment of combination targeted and immune-based therapy.

Tumors exhibit altered metabolism compared to normal tissues. Many cancers upregulate expression of serine synthesis pathway enzymes, and some tumors exhibit copy-number gain of the gene encoding the first enzyme in the pathway, phosphoglycerate dehydrogenase (PHGDH). However, whether increased serine synthesis promotes tumor growth and how serine synthesis benefits tumors is controversial. Here, we demonstrate that increased PHGDH expression promotes tumor progression in mouse models of melanoma and breast cancer, human tumor types that exhibit PHGDH copy-number gain. We measure circulating serine levels and find that PHGDH expression is necessary to support cell proliferation at lower physiological serine concentrations. Increased dietary serine or high PHGDH expression is sufficient to increase intracellular serine levels and support faster tumor growth. Together, these data suggest that physiological serine availability restrains tumor growth and argue that tumors arising in serine-limited environments acquire a fitness advantage by upregulating serine synthesis pathway enzymes.

Article	Year
Extracorporeal Photochemotherapy Drives Monocyte-to-Dendritic Cell Maturation to Induce Anticancer Immunity. Cancer research\| PubMed ID: 29764863	2018
A novel immunogenic mouse model of melanoma for the preclinical assessment of combination targeted and immune-based therapy. Scientific reports\| PubMed ID: 30718660	2019
Increased Serine Synthesis Provides an Advantage for Tumors Arising in Tissues Where Serine Levels Are Limiting. Cell metabolism\| PubMed ID: 30905671	2019

Katrina Meeth

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