Neoantigens and the tumor microenvironment play important roles in the prognosis of high-grade serous ovarian cancer

Background: Despite the consistency of patient age, disease stage and treatment options, the prognosis of different high-grade serous ovarian carcinoma (HGSOC) patients is different. Here, we sought to measure predictive biomarkers for distinct responses to platinum-based chemotherapy and immunotherapy benefits. Methods: Sixteen HGSOC patients receiving debulking surgery and adjuvant first-line combination chemotherapy at Peking Union Medical College Hospital (PUMCH) were enrolled. Whole exome sequencing (WES) and RNA-seq were performed on tumor and normal tissues of these patients. Results: The tumor mutational burden (TMB) and intratumoral heterogeneity (ITH) of the platinum-resistant group were significantly higher than those of the platinum-sensitive group (P=0.0321 and P=0.0452, respectively). TMB, neoantigen and ITH had certain predictive value according to the area under the receiver operating characteristic (ROC) curve (AUC 0.7778 for TMB, 0.7619 for neoantigen, 0.7778 for ITH). The infiltration of other immune cells in tumor tissues was different between the two groups, but the difference was not significant. Univariate Cox proportional hazard analysis revealed poorer progression-free survival (PFS) for those patients who carried a higher number of neoantigens (P =0.0069), higher TMB (P =0.0083), and higher ITH (P =0.0249). Further Kyoto Encyclopaedia of Genes and Genomes (KEGG) analysis indicated the Differentially expressed genes (DEGs) in platinum-resistant and platinum-sensitive patients were mainly enriched in the phosphatidylinositol 3-kinase-Akt (PI3K-Akt) signaling pathway and focal adhesion pathway, which are associated with platinum resistance. Conclusions: Higher TMB, neoantigen and ITH may account for the worse prognosis of patients with platinum-based chemotherapy and higher TMB was observed in the platinum-resistant group, which could make the patients in the platinum-resistant group to be the better candidates for immunotherapy.