abstract: Immunotherapy has been revitalized with the advent of immune checkpoint blockade treatments, and neo-antigens are the targets of immune system in cancer patients who respond to the treatments. The cancer vaccine field is focused on using neo-antigens from unique point mutations of genomic sequence in the cancer patient for making personalized cancer vaccines. However, we choose a different path to find frameshift neo-antigens at the mRNA level and develop broadly effective cancer vaccines based on frameshift antigens. In this dissertation, I have summarized and characterized all the potential frameshift antigens from microsatellite regions in human, dog and mouse. A list of frameshift antigens was validated by PCR in tumor samples and the mutation rate was calculated for one candidate – SEC62. I develop a method to screen the antibody response against frameshift antigens in human and dog cancer patients by using frameshift peptide arrays. Frameshift antigens selected by positive antibody response in cancer patients or by MHC predictions show protection in different mouse tumor models. A dog version of the cancer vaccine based on frameshift antigens was developed and tested in a small safety trial. The results demonstrate that the vaccine is safe and it can induce strong B and T cell immune responses. Further, I built the human exon junction frameshift database which includes all possible frameshift antigens from mis-splicing events in exon junctions, and I develop a method to find potential frameshift antigens from large cancer immunosignature dataset with these databases. In addition, I test the idea of ‘early cancer diagnosis, early treatment’ in a transgenic mouse cancer model. The results show that ii early treatment gives significantly better protection than late treatment and the correct time point for treatment is crucial to give the best clinical benefit. A model for early treatment is developed with these results. Frameshift neo-antigens from microsatellite regions and mis-splicing events are abundant at mRNA level and they are better antigens than neo-antigens from point mutations in the genomic sequences of cancer patients in terms of high immunogenicity, low probability to cause autoimmune diseases and low cost to develop a broadly effective vaccine. This dissertation demonstrates the feasibility of using frameshift antigens for cancer vaccine development. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2018