MAGEA antigens as immunotherapeutic targets for advanced osteosarcoma

Osteosarcoma is the most common primary bone sarcoma. About 50% of patients develop metastatic disease and their 5-year survival lingers at around 20-30%. T cell checkpoint blockade immunotherapies have revolutionized cancer treatment in the last decade, but their impact remains limited in osteosarcoma. In order to reveal potentially novel immunotherapeutic strategies for advanced osteosarcoma, we conducted an immunogenomic characterization of a unique sample set comprising multiple osteosarcoma samples from seven patients, collected throughout the progression of the disease. We performed RNA-sequencing and imaging mass cytometry analysis on those samples to reveal the immunological landscape during osteosarcoma progression. Transcriptional and phenotypical hallmarks of cytotoxic T cell-driven anti-cancer immunity were enriched in metastatic lesions as compared to primary tumors. In parallel, we found a pronounced increase in the expression of cancer testis antigens, particularly MAGEA-related antigens, in osteosarcoma metastases. Their overexpression in metastatic lesions was confirmed at protein level and positive expression of MAGEA3 in primary tumors showed a significant association with metastasis free survival. Importantly, we demonstrated the presentation of MAGE-derived peptides in three osteosarcoma cell lines. These findings indicate a concurrent augmentation of cytotoxic anti-tumor immune responses and expression of MAGEA antigens from primary to metastatic osteosarcoma. This observation warrants the exploration of MAGEA antigens as potential targets for immunotherapy in the treatment of advanced osteosarcoma. To investigate transcriptome of osteosarcoma during the disease progression. For this, Primary tumors, recurrences and metastases of 7 patiens were collected