970 Unveiling clinical insights and prognostic significance of CD73 in epithelial ovarian cancer

Introduction/Background CD73, an ecto-5'-nucleotidase, serves as a membrane-bound enzyme crucial for adenosine generation. The adenosine pathway plays a pivotal role in the immunosuppressive tumor microenvironment (TME). However, the clinical utility of CD73 remains undisclosed, necessitating a deeper understanding, particularly in the realm of gynecologic oncology. The study aimed to assess CD73 expression in the TME and its correlation with clinicopathological features, aiming to enhance comprehension of the CD73-adenosine pathway's role in epithelial ovarian cancer (EOC). Methodology A total of 51 patients with epithelial ovarian cancer were enrolled. For each patient, a retrospective review of medical records was conducted. Immunohistochemical staining for CD73 was performed using paraffin embedded tissue block. CD73 expression level were graded on a scale of 0 to 3 and divided two group; grade 0/1 to Low CD73 and grade 2/3 to High CD73 group. In addition, changes in CD73 grade were assessed in serially collected tumor tissues (treatment-naïve versus relapse). Progression-free survival (PFS) was compared according to the changes in CD73 grade. Results The majority of the patients were high-grade serous carcinoma (HGSC; 90.2%) and stage III-IV disease (94.1%). Median age was 55 years (range 38–81 years). Among the patients, 21.6% of patients (n=11) showed increased CD73 expression, whereas 39.2% of patients (n=20) showed decreased CD73 expression and other 39.2% of patients (n=20) showed no change. When comparing PFS between each group, the increased group showed better PFS compared to the decreased or unchanged group (median PFS, P=0.0308). Conclusion Our study suggested that increased CD73 expression after recurrence was associated with favorable survival outcomes in EOC. Further research is needed to investigate the role of CD73 in tumor immune microenvironment of EOC. Disclosures I have no financial relationships with ACCME defined ineligible companies to report.