Ovarian cancer, notably high-grade serous ovarian cancer (HGSC), the principal cause of death from gynecological malignancies in the world, has not significantly benefited from recent progress in cancer immunotherapy. While HGSC infiltration by lymphocytes correlates with superior survival, the nature of antigens that can elicit anti-HGSC immune responses is unknown. Novel tumor-specific antigens (TSAs) shared by a large proportion of ovarian tumors are described herein. Most of the TSAs (>80%) described herein derives from aberrantly expressed unmutated genomic sequences, such as intronic and intergenic sequences, which are not expressed in normal tissues. Nucleic acids, compositions, cells and vaccines derived from these TSAs are described. The use of the TSAs, nucleic acids, compositions, cells and vaccines for the treatment of ovarian cancer is also described.