Virus-based cancer vaccines are nowadays considered an interesting approach in the field of cancer immunotherapy, despite the observation that the majority of the immune responses they elicit are against the virus and not against the tumor. In contrast, targeting tumor associated antigens is effective, however the identification of these antigens remains challenging. Here, we describe ExtraCRAd, a multi-vaccination strategy focused on an oncolytic virus artificially wrapped with tumor cancer membranes carrying tumor antigens. We demonstrate that ExtraCRAd displays increased infectivity and oncolytic effect in vitro and in vivo. We show that this nanoparticle platform controls the growth of aggressive melanoma and lung tumors in vivo both in preventive and therapeutic setting, creating a highly specific anti-cancer immune response. In conclusion, ExtraCRAd might serve as the next generation of personalized cancer vaccines with enhanced features over standard vaccination regimens, representing an alternative way to target cancer.
Due to the high coverage of international vaccination programs, most people worldwide have been vaccinated against common pathogens, leading to acquired pathogen-specific immunity with a robust memory T cell repertoire. While CD8+ anti-tumor cytotoxic T lymphocytes (CTL) are the preferred effectors of cancer immunotherapy, CD4+ T cell help is also required for an optimal antitumor immune response to occur. Hence, we investigated whether the pathogen-related CD4+ T cell memory populations could be re-engaged to support the CTLs, converting a weak primary antitumor immune response into a stronger secondary one. To this end, we used our PeptiCRAd technology that consists of an oncolytic adenovirus coated with MHC-I-restricted tumor-specific peptides, and developed it further by introducing pathogen-specific MHC-II-restricted peptides. Mice pre-immunized with tetanus vaccine were challenged with B16.OVA tumors and treated with the newly developed hybrid TT-OVA-PeptiCRAd containing both tetanus toxoid-and tumorspecific peptides. Treatment with the hybrid PeptiCRAd significantly enhanced anti-tumor efficacy and induced TT-specific, CD40 ligand-expressing CD4+ T helper cells and maturation of antigen presenting cells (APCs). Importantly, this approach could be extended to naturally occurring tumor peptides (both tumor-associated antigens and neoantigens), as well as to other pathogens beyond tetanus, highlighting the usefulness of this technique to take full advantage of CD4+ memory T cell repertoires when designing immunotherapeutic treatment regimens. Finally, the anti-tumor effect was even more prominent when combined with the immune checkpoint inhibitor anti-PD1, strengthening the rationale behind combination therapy with oncolytic viruses. Research.
Recent approaches in the treatment of cancer focus on involving the immune system to control the tumor growth. The administration of immunotherapies, like checkpoint inhibitors, has shown impressive results in the long term survival of patients. Cancer vaccines are being investigated as further tools to prime tumor-specific immunity. Biomaterials show potential as adjuvants in the formulation of vaccines, and biomimetic elements derived from the membrane of tumor cells may widen the range of antigens contained in the vaccine. Here, we show how mice presenting an aggressive melanoma tumor model treated twice with the complete nanovaccine formulation showed control on the tumor progression, while in a less aggressive model, the animals showed remission and control on the tumor progression, with a modification in the immunological profile of the tumor microenvironment. We also prove that co-administration of the nanovaccine together with a checkpoint inhibitor increases the efficacy of the treatment (87.5% of the animals responding, with 2 remissions) compared to the checkpoint inhibitor alone in the B16.OVA model. Our platform thereby shows potential applications as a cancer nanovaccine in combination with the standard clinical care treatment for melanoma cancers.
Professor Satu Mustjoki has received honoraria and research funding from Novartis, Pfizer and Bristol-Myers Squibb (not related to this study). Professor Vincenzo Cerullo is cofounder and shareholder of the Valo Therapeutics LTD (not related to this study). All other named authors have no conflict of interest, financial or otherwise. Synopsis:Molecular mimicry can induce autoimmunity. By developing and using a bioinformatic tool to analyze molecular mimicry between tumor and viral antigens, the authors show this phenomenon can also play a role in antitumor immune responses.
Knowledge of clinically targetable tumor antigens is becoming vital for broader design and utility of therapeutic cancer vaccines. This information is obtained reliably by directly interrogating the MHC-I presented peptide ligands, the immunopeptidome, with state-of-the-art mass spectrometry. Our manuscript describes direct identification of novel tumor antigens for an aggressive triple-negative breast cancer model. Immunopeptidome profiling revealed 2481 unique antigens, among them a novel ERV antigen originating from an endogenous retrovirus element. The clinical benefit and tumor control potential of the identified tumor antigens and ERV antigen were studied in a preclinical model using two vaccine platforms and therapeutic settings. Prominent control of established tumors was achieved using an oncolytic adenovirus platform designed for flexible and specific tumor targeting, namely PeptiCRAd. Our study presents a pipeline integrating immunopeptidome analysis-driven antigen discovery with a therapeutic cancer vaccine platform for improved personalized oncolytic immunotherapy.
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