Biohybrid Cloaked Nanovaccines for Cancer Immunotherapy

Immunotherapy is revolutionizing cancer treatment achieving durable and long-term responses in patients. However, only subsets of patients treated experience a positive outcome, due to immunotherapeutic resistance. Combinations of immunotherapeutics can overcome the drug resistance; the administration of a cancer vaccine or an oncolytic virus followed by immune checkpoint inhibitors is under investigation. Thereby, there is an unmet need for powerful, yet safe vaccines. Nanoparticles, in particular porous silicon nanoparticles, present ideal characteristics to formulate nanovaccines, thanks to their size-specific targeting to the lymphoid organs, to their intrinsic adjuvant effect, and to the possibility to simultaneously load adjuvants and antigens. Moreover, biohybrid cell membrane technology has been proposed as an innovative antigenic source. Thus, the aims of the current thesis were to develop a biohybrid multistage nanovaccine formulation and to evaluate its anticancer efficacy in murine tumor models. Firstly, the parameters affecting the formulation of the biohybrid nanosystems were assessed, along with the elucidation of the influence of the cell membrane coating on the colloidal stability in physiological conditions and on the biocompatibility in different cell types. Secondly, the effect of the cell membrane-wrapping on the cellular uptake was evaluated in the presence of inhibitors of selective uptake pathways, to assess the differences between naked and coated nanoparticles. Then, a multistage nanovaccine was engineered by glass capillary microfluidics, followed by the cloaking with the cell membrane. The immunological profile of the nanovaccine was investigated in vitro, assessing the expression of co-stimulatory signals and the secretion of proinflammatory cytokines. The efficacy of the biohybrid nanovaccine as a monotherapy and in combination with an immune checkpoint inhibitor was then evaluated in melanoma murine models. Finally, the adjuvant core was changed from synthetic nanoparticles to oncolytic adenoviruses to investigate the translatability of the technique, the influence of the cell membrane-coating on the viral infectivity, and the preventive and therapeutic efficacy of the vaccine in different tumor models. Overall, porous silicon and adenovirus-based biohybrid nanovaccines were developed, providing new insights on the structure and efficacy of these systems as therapeutic cancer nanovaccines.