Thymidine kinase as a biomarker of chemoresistance in epithelial ovarian cancer using the KELIM model

Background Ovarian cancer (OC) remains the most lethal gynecological malignancy, with platinum sensitivity being a key determinant of treatment outcomes. The KELIM model, derived from CA-125 kinetics, is a promising biomarker for predicting chemosensitivity. Thymidine kinase 1 (TK1), a proliferation marker, has shown relevance in various cancers but its role in chemotherapy response for OC is unclear. Methods In this retrospective study, we assessed the association between TK1 protein (TK1p) and enzymatic activity (TK1a) and chemosensitivity (KELIM), platinum-free interval (PFI), and chemotherapy response score (CRS) in 28 patients with epithelial OC treated with platinum-based chemotherapy. Biomarker dynamics were measured at multiple timepoints. KELIM was calculated using CA-125 kinetics; relationships with CRS and PFI were evaluated. Results KELIM demonstrated robust predictive performance (correlating with favorable CRS rho = 0.731, p = 0.011 and longer PFI rho = 0.437, p = 0.007). TK1p and TK1a showed no significant correlations with KELIM, PFI, or CRS. ROC analysis for preoperative TK1p yielded an AUC of 0.6941, indicating moderate discriminative potential. TK1a increased postoperatively but lacked predictive value for chemoresistance. Conclusion Our findings reinforce the value of KELIM as a reliable predictor of platinum sensitivity in OC. TK1 dynamics reflect tumor proliferation but did not significantly predict chemotherapy response. Larger cohorts and further research are required to explore whether TK1 can complement established biomarkers.