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Biomarker-Based Prediction of OATP1B1 Activity in Clinical Routine-Investigating Coproporphyrins as Markers for
Leila Potzel1, Anina Zumtaugwald1, Anna Bollinger2
1Biopharmacy, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland.
Clinical Pharmacology and Therapeutics
|May 18, 2026
Summary
Coproporphyrin I (CPI) can identify drug-drug and gene interactions affecting the OATP1B1 transporter in clinical routine samples. This biomarker shows potential for safer medication management in complex patient cases.
Area of Science:
- Pharmacology
- Biomarker Discovery
- Clinical Chemistry
Background:
- Coproporphyrin I (CPI) is an endogenous biomarker for Organic Anion Transporting Polypeptide 1B1 (OATP1B1) mediated drug-drug interactions (DDIs).
- Previous studies on CPI primarily used controlled sampling in healthy volunteers, limiting understanding of its utility in real-world clinical settings with multimorbid patients.
Purpose of the Study:
- To evaluate the use of single timepoint CPI concentrations from clinical routine samples for assessing in vivo OATP1B1 activity.
- To integrate genetic and pharmacological data to understand CPI's role in complex patient populations.
Main Methods:
- Serum CPI levels were measured in patients undergoing pharmacist-led medication reviews.
- CPI concentrations were analyzed against genotype-predicted OATP1B1 phenotypes and exposure to OATP1B1-interacting drugs.
- In vitro transporter assays were used to further evaluate drug-OATP1B1 interactions.
Main Results:
- CPI levels correlated with drug intake and genotype-predicted OATP1B1 phenotypes.
- Phenoconversion was observed, where patients on OATP1B1 inhibitors showed CPI levels similar to those with poorer OATP1B1 function without inhibitors.
- These results suggest CPI can reflect combined genetic and drug effects on OATP1B1.
Conclusions:
- Single timepoint CPI measurements in clinical routine show potential for assessing OATP1B1 activity and identifying drug-drug-gene interactions.
- CPI may support safer and more effective drug therapy by aiding in the detection of interactions in clinical practice.
- Further validation in larger, diverse patient cohorts is necessary to confirm these findings.
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