e17033 Background: Calretinin (CRT) is a calcium-binding protein, controlling intracellular calcium signaling. Besides its prominent expression in neurons, CRT has diagnostic implications in cancer, particularly in mesothelioma. In a recent liquid biopsy approach, plasma CRT level has been suggested for pre-diagnostic detection of mesothelioma. CRT is also expressed in serous ovarian cancer in about 23% of cases; however, clinical relevance of serum CRT is completely unknown and shall therefore be analyzed, herein. Methods: Serum calretinin (sCRT) was determined by calretinin enzyme-linked immunoabsorbent assay (DLD-Diagnostika GmbH, Hamburg) in a total of 380 serum samples from 134 ovarian cancer patients (thereof n = 115 (86%) with FIGO III or IV), including samples at primary diagnosis and at 4 follow-up reading points in the course of adjuvant treatment. Results: sCRT levels were significantly increased in ovarian cancer patients compared to healthy controls (ED = 0.3ng/ml, p < 0.001) and enabled an accurate discrimination between ovarian cancer and controls (AUC = 0.85). High sCRT levels at primary diagnosis predicted suboptimal debulking surgery without achieving macroscopically complete tumor resection (p < 0.001) and were associated with advanced FIGO-stage (p < 0.001) and high volume of ascites (p < 0.001). Increased sCRT levels at primary diagnosis were an independent predictor of poor PFS (HR:1.99, p = 0.018) and also indicated poor OS (HR:2.49, p = 0.008). Increased sCRT levels before and after platinum-based chemotherapy were independent predictors of poor OS (HR:15.4, p = 0.01; HR:5.59, p = 0.026). Moreover, elevated sCRT levels at primary diagnosis indicated platinum-resistance (p = 0.002). Conclusions: This is the first study, suggesting sCRT as an innovative liquid biopsy marker for ovarian cancer by showing its independent prognostic relevance and its association with primary platinum-resistance.
RNA biomarkers from proximal liquid biopsy for diagnosis of ovarian cancer
