Browsing by Author "Mölsä, Riikka"

Lung cancer is the number one cause of cancer-related deaths in the world every year. Of all non-small cell lung cancers, lung adenocarcinoma is the most prevalent subtype. There is a great need for better treatment options for lung cancer, of which cancer immunotherapy is an attractive option due to the high mutational burden of lung tumors. Patient-derived lung cancer organoids (lung PDTOs) could provide a new testing platform for these studies as the 3D models better represent the original tumor and its microenvironment compared to often used 2D cell lines. One interesting field is immunopeptidomics, which focuses on discovering tumor peptides presented in the HLA-I molecule on the tumor surface that could elicit an immune response. Using lung adenocarcinoma PDTOs, this study aimed to analyze the immunopeptidome of five PDTOs to discover tumor-specific and immunogenic peptides using PeptiCHIP purification and LC-MS analysis. These findings could be used in PeptiCRAd, a novel cancer vaccine comprised of an oncolytic adenovirus coated with tumor peptides. To elucidate the applicability of PDTOs for virotherapy, three oncolytic adenoviruses, D102, Ad5/3Δ24 and Ad5Δ24-RFP, and their ability to infect, kill, and replicate in lung PDTOs was studied. PDTOs were characterized as epithelial, as they presented epithelial cytokeratin and epithelial layer structures, as indicated by cytoskeletal F-actin staining. The three oncolytic adenoviruses were studied by infecting PDTOs and a difference in killing capacity of the three viruses was shown, potentially due to differences in receptor interactions and expressed transgenes. In addition, D102 and Ad5Δ24-RFP were shown to replicate in PDTOs, which is necessary to induce a strong enough immune response against the virus for immunotherapy efficiency. HLA-I expression was high in all tested models, which indicated that antigens could be presented in the tumor cells. Immunopeptidome analysis did not result in a high yield of peptides, likely due to challenges in sample preparation and patient material being scarce. As the HLA-type of each patient was unknown during this study, more data analyses still need to be done to determine the best immunogenic peptides, which could then be further studied in vitro. However, peptides overexpressed in lung cancer and with cancer benefiting properties were found from PDTOs, which already gives promising results. In conclusion, though additional immunopeptidome studies with an increased yield of peptides are needed to select tumor-relevant immunogenic targets for therapeutical use, as well as additional testing on the optimal oncolytic virus for lung cancer targeted PeptiCRAd immunotherapy, this study proved that oncolytic viruses can infect and kill lung PDTOs, and that HLA-I expressed tumor peptides can be identified from them. This is also one step towards finding better and patient-specific research models for testing therapies and discovering and developing personalized cancer treatments.