High IL-17-positive tumor immune cell infiltration is indicative for chemosensitivity of ovarian carcinoma

Ovarian carcinoma in most instances is diagnosed in an advanced stage which cannot be cured by surgical tumor debulking alone. Standard adjuvant chemotherapy usually follows surgical procedures. Yet, few reliable predictive tissue markers exist for the response of ovarian carcinoma to chemotherapy. In this study, we evaluated the predictive value of IL-17- and FOXP3-positive tumor immune cell infiltration (TICI) for response to chemotherapy in ovarian carcinoma. Formalin fixed and paraffin embedded biopsies of mostly high-grade primary serous ovarian carcinomas and their matched recurrences were immunostained with IL-17 and FOXP3 on a tissue microarray. Chemoresistance was defined as tumor recurrence within 6 months of the completion of platinum-based chemotherapy. In 94 and 90 biopsies, conclusive data for IL-17 and FOXP3 were available, respectively. IL-17, but not FOXP3-positive TICI, displayed a significantly higher density in biopsies of chemosensitive tumors (p = 0.01). No significant difference in the expression of IL-17 and FOXP3 TICI was observed in all paired primary and recurrent biopsies without respect to chemoresponse (p = 0.77 and p = 0.87, respectively). However, significantly more IL-17-positive recurrences were encountered in the group of patients with chemosensitive tumors (p = 0.008). High IL-17-positive TICI is indicative for response to chemotherapy in ovarian carcinoma. Higher frequency of IL-17-positive TICI might persist in recurrent tumor tissues of chemosensitive biopsies, suggesting repetitive platinum-based chemotherapy as an appropriate therapy for patients with IL-17-positive recurrences.