Germline PRDM1 Variant rs2185379 in Long-Term Recurrence-Free Survivors of Advanced Ovarian Cancer

Purpose: To identify the germline genetic characteristics of long-term recurrence-free survivors that can be applied to establishing a new strategy for curing advanced cancer, we investigated the whole-genome single nucleotide variants of ovarian cancer patients. Patients and Methods: DNA specimens were obtained from rare long-term recurrence-free survivors with FIGO stage III–IV ovarian cancer with no recurrence for 8–23 years after primary treatments for a whole-genome analysis of approximately 660,000 single nucleotide variants. We then established a mouse model with a notable gene alteration by CRISPR/Cas9 to confirm the biological role. Results: The long-term recurrence-free survivors more frequently had germline heterozygous variant rs2185379 of the PRDM1 gene exon than patients with early recurrence (6.8-fold, P=0.013) and the general population. In the mouse model, primary intraperitoneal disseminated tumors of allograft ID8 were significantly smaller in the germline heterozygous rs2185379 group than in the wild-type group (57.4% decrease, P=0.008). Immunohistochemistry showed that the area of distribution of infiltrating T lymphocytes with positive CD8 staining was significantly increased in the germline heterozygous rs2185379 group in comparison to the wild-type group. Conclusion: Germline heterozygous rs2185379 in PRDM1 is correlated with an excellent prognosis and can be used to establish a new strategy for treating advanced ovarian cancer.