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Browsing by Subject "onkolyyttinen rokote"

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  • Honkasalo, Oona (2018)
    Cancer immunotherapies aim to target the immune defence mechanisms of the body specifically and efficiently against the tumour tissue. Cancer vaccines and oncolytic viruses are forms of active immunotherapies, which require patients having a properly functioning immune system. The vaccines are based on the administration of tumour antigens into the body to which the immune system reacts. However, often the response is not robust enough. The oncolytic viruses in turn kill the cancer cells which causes the release of antigens from the tumour tissue. Viruses usually elicit a strong immune response but sometimes it is targeted too much against the virus instead of the tumour. Oncolytic vaccine is a composition of an oncolytic virus and a cancer vaccine. Tumour antigens can be coded to the genome of the virus therefore, when the virus invades tumour cells they start to produce the antigens. Eventually the cancer cells are also destroyed due to viral replication. The antigens can be tumour-associated that is, they are expressed in healthy tissues too. Their usage is not always efficient which is why an interest towards utilizing tumour-specific antigens has been increased. Considering the expression of antigens, tumour tissue is very heterogenous and distinctive between patients. Hence, utilizing mutated patient unique neoantigens would enable the development of personalized tumour-specific oncolytic vaccines. Genetic modification of viruses is complicated thus, an easier way to insert the neoantigens to the virus has been invented. The developed oncolytic vaccine platform is called PeptiENV, and it is designed to use with enveloped viruses. The idea is to fuse tumour-specific antigens onto the envelope of the virus and eliminate the need of gene insertion. The aim of this study is to investigate in vivo the efficacy of PeptiENV in preventing tumour growth and eliciting a tumour-specific immune response. An object is also to observe survival times of the treated animals. Furthermore, the preservation of infectivity is studied in vitro. The research was executed with two potential oncolytic viruses, vaccinia virus (VACV) and herpes simplex virus type 1 (HSV-1). The PeptiENV complex was formed by using an artificial tumour antigen, ovalbumin epitope SIINFEKL, which was attached to the viral envelope with cell penetrating peptide (CPP) or cholesterol anchor. The preservation of infectivity was examined by measuring cell viability of PeptiENV infected cells. Animal experiments instead were performed with a mouse melanoma model created with B16-OVA cells, which express ovalbumin and therefore the antigen epitope SIINFEKL. PeptiENV was compared to control treatments which were virus, SIINFEKL peptide and complexation medium only. Treatments were administered as intratumoural injections. Tumour growth was followed by measuring the size of implanted tumours every other day. With flow cytometry, tumour-specific immune response was assessed by acquiring the relative amount of SIINFEKL-specific CD8+ T cells in the tumour tissue. Euthanizing dates were registered in order to observe the survival of the mice. According to the in vitro results, conjugation of peptides to the virus does not affect infectivity. In addition, the in vivo studies show that PeptiENV VACV CPP prevents tumour growth the most. Difference in tumour growth between PeptiENV VACV CPP and control treatments is significant. Mice injected with the same treatment also lived considerably longer than mice injected with virus, peptide or medium only. Also, PeptiENV HSV-1 hinders tumour growth distinctly more than virus only and slightly more than SIINFEKL only, but unfortunately it did not have an evident impact on the survival time. In both experiments, the PeptiENV treatment elicits the largest proportional amount of SIINFEKL-specific CD8+ T cells. In other words, PeptiENV engenders a tumour-specific immune response. In the PeptiENV VACV study the difference to control treatments is clearer than in the PeptiENV HSV-1 study. At present, the PeptiENV platforms performs better with VACV than HSV-1. With further investigations however, the results can be verified and improved. All in all, the results are encouraging. The PeptiENV platform shows great promise for being a part of personalized cancer immunotherapy developments in the future.