In vivo cancer vaccination: Which dendritic cells to target and how?

Abstract

The field of cancer immunotherapy has been revolutionized with the use of immune checkpoint blockade antibodies such as anti-programmed cell death 1 protein (PD-1) and chimeric antigen receptor T cells. Significant clinical benefits are observed in different cancer types with these treatments. While considerable efforts are made in augmenting tumor-specific T cell responses with these therapies, other immunotherapies that actively stimulate endogenous anti-tumor T cells and generating long-term memory have received less attention. Given the high cost of cancer immunotherapies especially with chimeric antigen receptor T cells, not many patients will have access to such treatments. The next-generation of cancer immunotherapy could entail in vivo cancer vaccination to activate both the innate and adaptive anti-tumor responses. This could potentially be achieved via in vivo targeting of dendritic cells which are an indispensable link between the innate and adaptive immunities. Dendritic cells highly expressed toll-like receptors for recognizing and eliminating pathogens. Synthetic toll-like receptors agonists could be synthesized at a low cost and have shown promise in preclinical and clinical trials. As different subsets of human dendritic cells exist in the immune system, activation with different toll-like receptor agonists could exert profound effects on the quality and magnitude of anti-tumor T cell responses. Here, we reviewed the different subsets of human dendritic cells. Using published preclinical and clinical cancers studies available on PubMed, we discussed the use of clinically approved and emerging toll-like receptor agonists to activate dendritic cells in vivo for cancer immunotherapy. Finally, we searched www.clinicaltrials.gov and summarized the active cancer trials evaluating toll-like receptor agonists as an adjuvant.

Activation of CD8+ T Cell Responses after Melanoma Antigen Targeting to CD169+ Antigen Presenting Cells in Mice and Humans

“…To circumvent the laborious ex vivo DC vaccination therapy, DCs can also be targeted directly in vivo with specific antibodies (Abs) or ligands [16]. Both for ex vivo DC vaccination and in vivo targeting to DCs the selection of the optimal DC subset is important [17]. Classical cDC1 DCs are specialized in cross-presentation of cell-associated antigen (Ag) to CD8 + T cells and are identified by DNGR-1/CLEC9a, XCR1, CD8α or CD103 expression in mice and by DNGR-1/CLEC9a, XCR1 and CD141 expression in humans [18,19,20,21,22,23].…”

Transcutaneous delivery of DNA/mRNA for cancer therapeutic vaccination

“…Another approach for promoting antigen expression and presentation is the introduction of DC‐targeting ligands onto the polyplexes. DCs typically overexpress C‐type lectin receptor DEC‐205, Clec9A, Clec12, DC‐SIGN, mannose receptor and Toll‐like receptor, which are the commonly used DC‐targeting receptors. Mannose modification to polyplexes is mostly used in TCI .…”

“…DCs typically overexpress C-type lectin receptor DEC-205, Clec9A, Clec12, 95 DC-SIGN, 96 mannose receptor 97 and Toll-like receptor, 98 which are the commonly used DC-targeting receptors. Mannose modification to polyplexes is mostly used in TCI.…”

Mannan-Based Nanodiagnostic Agents for Targeting Sentinel Lymph Nodes and Tumors

“…More specifically, dendritic cells express not only DC-SIGN receptors, but also toll-like receptors. Some of the immunotherapeutic approaches use toll-like receptors agonists for dendritic cells targeting [ 22 ]. Each of the respective approaches possess its own strengths and also limitations.…”