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Validation of a UPLC-MS/MS Method for Quantifying Intracellular Olaparib Levels in Resistant Ovarian Cancer Cells
Szymon W Kmiecik1, Jennifer Lewis2,3, Jonas Schwickert2,3
1Internal Medicine IX-Department of Clinical Pharmacology and Pharmacoepidemiology, Medical Faculty Heidelberg, Heidelberg University Hospital, Heidelberg University, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
Pharmaceuticals (Basel, Switzerland)
|December 31, 2025
Summary
Ovarian cancer patients resistant to olaparib do not show altered intracellular drug levels, suggesting resistance stems from pharmacodynamic factors, not drug metabolism or efflux.
Area of Science:
- Oncology
- Pharmacology
- Biochemistry
Background:
- Ovarian cancer is a leading cause of female cancer mortality with significant unmet needs.
- Resistance to Poly(ADP-ribose) polymerase (PARP) inhibitors like olaparib is a major challenge in ovarian cancer treatment.
- Understanding resistance mechanisms is crucial for developing improved therapeutic strategies.
Purpose of the Study:
- To investigate the mechanisms of olaparib resistance in patient-derived ovarian cancer cells (OC12).
- To develop and validate a UPLC-MS/MS method for quantifying intracellular olaparib levels.
- To determine if altered drug levels contribute to olaparib resistance.
Main Methods:
- Induced olaparib resistance in OC12 cells through stepwise drug concentration increases.
- Developed and validated a UPLC-MS/MS assay for intracellular olaparib quantification (1-300 ng/mL) following ICH M10 guidelines.
- Compared intracellular olaparib concentrations in sensitive versus resistant OC12 cell lines.
Main Results:
- The UPLC-MS/MS method met all validation criteria for bioanalytical assays.
- No significant difference in intracellular olaparib levels was observed between sensitive and resistant OC12 cells.
- Efflux transporters or enhanced olaparib metabolism were excluded as causes of resistance in this model.
Conclusions:
- Olaparib resistance in OC12 cells is not mediated by altered intracellular drug concentrations.
- Pharmacodynamic factors are likely the primary drivers of olaparib resistance.
- The validated UPLC-MS/MS method is suitable for future studies on resistance mechanisms.
