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Extracellular Vesicle-Internalizing Receptors (EVIRs) for Cancer ImmunoGeneTherapy

Periodic Reporting for period 2 - EVOLVE (Extracellular Vesicle-Internalizing Receptors (EVIRs) for Cancer ImmunoGeneTherapy)

Reporting period: 2019-01-01 to 2020-06-30

In the last decade we have witnessed transformative results in the clinical application of both cancer immunotherapies and gene transfer technologies. Tumor vaccines are a specific modality of cancer immunotherapy. Similar to vaccination against pathogens, tumor vaccines are designed to elicit a specific immune response against cancer. They are based on the administration of inactivated cancer cells or tumor antigens, or the inoculation of antigen-presenting cells (APCs) previously exposed to tumor antigens. In spite of significant development and testing, tumor vaccines have largely delivered unsatisfactory clinical results. Indeed, while some patients show dramatic and durable cancer regressions, many do not respond, highlighting both the potential and the shortcomings of current vaccination strategies. Hence, identifying and abating the barriers to effective cancer vaccines is key to broadening their therapeutic reach. The goal of EVOLVE (EVirs to Optimize and Leverage Vaccines for cancer Eradication) is to propel the development of effective APC-based tumor vaccines using an innovative strategy that overcomes several key hurdles associated with available treatments. EVOLVE puts forward a novel APC engineering platform whereby chimeric receptors are used to both enable the specific and efficient uptake of cancer-derived extracellular vesicles (EVs) into APCs, and to promote the cross-presentation of EV-associated tumor antigens for stimulating anti-tumor immunity. EVOLVE also envisions a combination of ancillary ‘outside of the box’ interventions, primarily based on further APC engineering combined with innovative pre-conditioning of the tumor microenvironment, to facilitate the deployment of effective APC-driven, T-cell-mediated anti-tumor immunity. Further to preclinical trials in mouse models of breast cancer and melanoma, our APC platform will be used to prospectively identify novel human melanoma antigens and reactive T cell clones for broader immunotherapy applications.
In the first 36 months we have focused on 3 of the 4 Aims of the research program. Briefly, we have generated and validated a panel of extracellular vesicle-internalizing receptors (EVIRs) directed against EV-associated bait antigens, and established protocols for the generation of dendritic cells (DCs) with improved antigen-presenting capacity, as planned in Aim 1. We have tested an early version of the EVIR in the context of dendritic cell (DC) vaccination in mouse tumor models (Aim 2). Finally, we have developed protocols for the validation of our DC vaccination platform in the human system, using human DCs exposed to human melanoma-derived EVs and autologous T cells, as described in Aim 4.

In the reporting period we published several papers describing initial results of the project. In 2018 we have published a first paper describing the EVIR platform (Squadrito, Cianciaruso, Hansen & De Palma. Nature Methods, 2018). This work was initiated before the beginning of the project, but in the reporting period we undertook ERC-funded studies of the mechanism of antigen presentation by EVIR-engineered DCs (DC-EVIR), as planned in Aims 1 and 2 of the project. We obtained unexpected and exciting results indicating that the EVIR captures tumor-derived EVs and promotes cross-dressing of DCs with pre-formed tumor antigens in complex with MHCI. We also examined the effects of chemotherapy on tumor-derived EVs, which is relevant to applications of the DC-EVIR platform, as described in Aim 2 of the project, and published a paper reporting some of those findings (Keklikoglou*, Cianciaruso*, […] & De Palma. Nature Cell Biology, 2019). Moreover, we characterized by proteomics analysis various EV populations directly isolated from tumors; this is relevant to both exploring the antigenic repertoire of cancer-cell-derived EVs and identifying surface proteins that can be used to design new EVIRs (Aim 1). Some of the proteomics results have been published in 2019 (Cianciaruso*, Beltraminelli*, Duval*, […] & De Palma. Cell Reports, 2019). Finally, we published a Perspective article illustrating the state-of-the-art and prospects of engineering DC vaccines (Perez & De Palma. Nature Communications, 2019).
In addition to DC vaccination protocols, the EVIR platform may be exploited to identify EV-associated tumor antigens and cognate T cell receptors (TCR) through ex vivo cells assays, as described in Aim 4 of the project. This approach may help to select or identify tumor antigen-specific CD8+ T cells for adoptive T cell therapy applications.

We are currently exploring the possibility to initiate a start-up company for the pre-clinical and clinical development of our bioengineering platform.