Oncolytic adenoviruses expressing transgenes targeting the tumor stroma to enhance the antitumor efficacy
[eng] Oncolytic virus (OV)-based therapies have an emerging role in the treatment of solid tumors, involving both direct cell lysis and immunogenic cell death. Nonetheless, tumor- associated stroma limits the efficacy of oncolytic viruses by forming a barrier that block efficient viral penetration a...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/134699 |
| Acceso en línea: | https://hdl.handle.net/2445/134699 http://hdl.handle.net/10803/667027 |
| Access Level: | acceso abierto |
| Palabra clave: | Oncologia Transformació cel·lular Immunotoxicologia Oncology Cell transformation Immunotoxicology |
| Sumario: | [eng] Oncolytic virus (OV)-based therapies have an emerging role in the treatment of solid tumors, involving both direct cell lysis and immunogenic cell death. Nonetheless, tumor- associated stroma limits the efficacy of oncolytic viruses by forming a barrier that block efficient viral penetration and spread. Another important hurdle for the efficacy of OVs is the antiviral immune responses, where virus-specific infiltrating T cells clear adenovirus-infected cells without compromising tumor burden. In this thesis, these hurdles have been addressed in separate chapters. We first hypothesized that arming an oncolytic adenovirus with a FAP-targeting bispecific T cell engager (FBiTE) could retarget infiltrated lymphocytes towards cancer-associated fibroblasts (CAFs), enhancing viral spread and favoring antitumor rather than anti-viral immune responses. The engineered ICO15K-expressing FBiTE virus showed similar infectivity and replication potency than the non-armed virus. FBiTE-mediated binding of CD3+ effector T cells and FAP+ target cells led to T-cell activation, proliferation, and cytotoxicity against FAP-positive cells in vitro. In vivo, FBiTE expression increased intratumoral accumulation of T cells and decreased the level of FAP, a marker of CAFs, in tumors. Finally, the antitumor activity of the FBiTE-armed adenovirus was superior to the parental virus. The data presented in this thesis strongly supports that the combination of viral oncolysis of cancer cells and FBiTE-mediated cytotoxicity of FAP- expressing CAFs might be an effective strategy to overcome a key limitation of oncolytic virotherapy, encouraging its further clinical development. Aiming to induce stroma disruption, we secondly generated a panel of oncolytic adenoviruses expressing FAP-targeting immunotoxins and a nitroreductase (NfrA)- activatable prodrug. During the development of these projects, we successfully rescued and characterized all the viruses. However, although immunotoxins molecules were properly expressed and secreted from modified-virus infected cells, no promising results were obtained. In contrast, NfrA-armed virus showed replication-dependent enzymatic activity on target cells, leading to increased oncolytic potency in vitro. These preliminary results indicate that this last strategy could be considered to foster viral spread in stroma-abundant tumors, encouraging its validation in an in vivo setting. |
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