Drug metabolism in the human body primarily takes place via enzymes known as cytochromes P450 (CYPs). This family of enzymes is also responsible for the detoxification of environmental and household chemicals we are unintentionally exposed to on a daily basis. These chemicals may interfere with CYP activity, causing an accumulation of therapeutic drugs above toxic levels or inducing CYP expression. This may lead to fast drug elimination and reduced therapeutic efficacy.
A microfluidic assay that measures CYP activity
Scientists of the EU-funded CUMTAS project wished to investigate the role of chemicals on CYP enzyme activity. As project coordinator Dr Tiina Sikanen explains, “the rate of drug clearance from one’s body is crucial as it may compromise therapy or cause toxicity.″ To study the interaction between different drugs and chemicals, her team developed a palette of novel and fast CYP assays, which are based on in vitro microfluidic technologies. The microfluidic assays enable the rapid screening of metabolic interactions while considerably reducing the cost and the consumption of biomaterials. At the same time, the use of through-flow immobilised enzyme micro-reactors allow the removal of reagents at precise moments, facilitating the monitoring and control of enzyme reactions, which is not possible in conventional static assays. Importantly, it enables the investigation of the time-dependent impact of chemicals on drug-metabolising enzymes as well as the mechanism of their interaction. Alongside microfluidic separation systems, researchers developed miniaturised sensor elements to enhance assay performance. New polymer-based materials, methods and enzyme immobilisation strategies further supported the technological development of the CYP assay. Scientists validated the method using commercially available, human-derived liver microsomes. “These real human-derived matrices helped us show how inter-individual variation in the expression of drug-metabolising enzymes impacts drug clearance,″ states Dr Sikanen.
The future of the CYP assay
The microfluidics-based technology was the most significant achievement of the project according to Dr Sikanen. “The multidisciplinary expertise of my team alongside their dedication helped overcome the technical challenges we encountered along the way,″ she emphasises. Dr Sikanen has received the ERC proof-of-concept grant for the PreMeDosE project to enable commercialisation of one of the technologies developed during CUMTAS. Although CUMTAS focused on CYP-mediated drug metabolism because of the critical role of CYPs in drug clearance, the assay can also measure the activity of other enzymes. It can also be used to investigate chemically induced inhibition of drug-metabolising enzymes as well as produce models for drug metabolism. Long-term, the technology has the potential to be applied in the drug discovery pipeline or for environmental screening purposes (e.g. clearance of drug residues in other species). In the drug development process, the assay can help eliminate chemicals with a high risk of metabolic interference, thus reducing unnecessary production costs. Drug metabolism depends both on genetic variation and on external factors such as diet, age, sex and disease state. The CUMTAS CYP assay will help determine the impact of both genetic and external factors on drug clearance capacity on an individual basis. Most importantly, it paves the way towards personalised drug dosing, which will improve patients’ quality of life, and reduce healthcare costs.
CUMTAS, cytochrome P450 (CYP), assay, enzyme, chemical, microfluidic, drug clearance, drug metabolism, toxicity