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Interview with Uwe Christians

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This month we hear from Uwe Christians, program leader of the Biomarker Working Group of the Immunosuppressive Drugs Scientific Committee. It’s inspiring to hear about developments at iC42, an academic laboratory that provides a wide range of bioanalytical services, from clinical trials to patient solutions. It is also the first time aptamer based analytics have been raised in an interview, in this case for biomarker assays. Exciting things are happening in Colorado.

 

Uwe Christians
Director, iC42: Integrated Solutions in Clinical Research and Development
University of Colorado, Colorado, USA


Can you tell us a little bit about your respective roles? What is a typical day like for you?

I am the director of a Clinical Pharmacology laboratory in the Department of Anesthesiology at the University of Colorado Denver Anschutz Medical Center in Aurora, Colorado. Our laboratory, iC42 Clinical Research and Development, is a University of Colorado Service Center. In addition to academic research projects, we also provide clinical therapeutic drug monitoring services, urine drug testing and carry out the bioanalytics for pre-clinical and clinical trials in collaboration with academic collaborators, the pharmaceutical and biotech industry including for GLP and pivotal studies for regulatory submission. The major foci of iC42 Clinical Research and Development include the assessment of pharmacokinetics, pharmacodynamics, and the development of clinical management tools for precision drug treatment. iC42 Clinical Research and Development is a unique entity that combines quantitative mass spectrometry (drugs, drug metabolites, other small molecules, large molecules, endogenous compounds) and metabolic and protein profiling technologies under one roof in a regulatory compliant environment. iC42 Clinical Research and Development is designed and uniquely qualified to carry out the bioanalytics for complex clinical trials involving drug quantification and molecular marker strategies. Accordingly, the expertise of iC42 Clinical Research and Development’s faculty ranges from medical and bioanalytical chemists, pharmacists, physicians, regulatory experts, data scientists to statisticians. In addition to bioanalytics, which is mostly mass spectrometry-based (we have 17 state-of-the-art LC-MS/MS and GC-MS systems), we also have quality assurance, PK/PD modelling and computational pharmacology teams and consult for the pharmaceutical and biotech industry.

The more interesting questions that may have come up by now is what iC42 means. “i” stands for “integrated solutions”, “C” for “clinical research and development” and the number 42 is inspired by the BBC radio and book series "The Hitchhiker's Guide to the Galaxy", in which it is revealed after 7 ½ million years of intense computing that the answer to the Ultimate Question of Life, the Universe, and Everything is simply “42”. So iC42 really stands for “I see the Answer”.

Is there anything that your laboratory does, or that is done at your hospital/center, that you would consider innovative?

iC42 Clinical Research and Development was designed to generate and inspire innovations. One of the things that makes iC42 Clinical Research and Development rather unique is that it is in its own separate facility in the Fitzsimons Biotech Park, operates in the same regulatory environment as a CRO, but is an academic laboratory with full access to the expertise, facilities, resources, shared instrumentation, clinical trial units and patient populations of one of the leading medical centers in the United States. While at most academic institutions mass spectrometry-based analytics is organized in separate core facilities, as aforementioned, iC42 Clinical Research and Development combines everything under one roof, which facilitates communication and thus the generation of new ideas. Among others, we have successfully worked in and contributed to the development of drug-eluting stents and balloons, novel clinical multi-analyte LC-MS/MS strategies for biomarker analysis, TDM and clinical toxicology, development of home-monitoring strategies in the fields of drug dependence and transplantation, the discovery and qualification of novel biomarkers for drug development and “pharmacodynamic/toxicodynamic TDM”, mostly in the fields of transplantation and nephrology, and, as almost unavoidable in the State of Colorado, we have been on the forefront of marijuana research.

What technological innovations have entered use during your career that have permitted a change, or evolution, in practice?

I scientifically grew up with mass spectrometers, which were the key to my doctoral thesis and have been at the heart of most of my research for 30 years. I learnt mass spectrometry from probably one of the best teachers in this field, Dr. H-M. Schiebel at the Technische Universität Braunschweig, starting out with a Finnigan/MAT sector field instrument, mostly using FAB ionization. Compared to the high-speed scanning, high-resolution mass spectrometers that we use nowadays, there has been tremendous progress. The same happened in the field of data processing. During my thesis work, I used two Hewlett-Packard 1084B HPLC instruments with a thermal paper XY printer. If peaks had to be reintegrated, we had to use planimeters, or easier, cut the peaks out of the thermal paper and weigh them. What a difference compared to cluster computing that we use nowadays to analyze “omics” data or for PK/PD modeling! One also should not forget the advantages of the internet. When I wrote my thesis, I spent weeks going through volumes of the Index Medicus, finding and copying articles from printed journals. Today, I can write the most extensive reviews or book chapters without having to leave my desk with most of the scientific knowledge in the world at my fingertips.

How did you become interested in your area of expertise?

The interest in TDM and clinical toxicology started from the first moment when I started the research work for my thesis. The first step of my thesis was to develop an HPLC/UV method for TDM of cyclosporine in transplant patients. We then isolated cyclosporine metabolites from the bile of liver transplant patients and expanded the HPLC/UV assay to also measure the metabolites. Since at the time, we were the only team besides Novartis, who had the full range of cyclosporine metabolites, we looked at the then important questions if the metabolites contribute to the activity and toxicity of cyclosporine. Then came tacrolimus, sirolimus and everolimus, metabolomics and proteomics and the question if metabolite/ protein biomarkers can be used for individualizing drug therapy and monitoring transplant patients.

Is there anything that you’ve seen or heard about recently and thought “I’d like to incorporate that idea at my center”?

In my opinion, the most promising development in recent years are aptamer-based proteomics technologies, specifically the SOMAScan assay. Aptamers were discovered 25 years ago, and are short single-stranded oligonucleotides, which fold into diverse molecular structures that bind with high affinity and specificity to proteins, peptides, and small molecules. SOMAmers are chemically modified aptamers and these chemical modifications greatly expand the repertoire of targets to which SOMAmers can bind compared to unmodified DNA. SOMAmers bind to proteins by folding into diverse and intricate shapes that interact specifically with protein surfaces. SOMAmers are selected in vitro from large libraries of randomized sequences. Once a SOMAmer is selected and its sequence is known, in contrast to antibodies, SOMAmer can be manufactured, thus avoiding the relatively large batch-to-batch variability inherent to antibody-based proteomics assays. Proteins in complex matrices such as plasma are measured with a process that transforms a signature of protein concentrations into a corresponding signature of DNA aptamer concentrations, which is quantified using a DNA microarray. SOMAmer-based proteomic technology for biomarker discovery is capable of simultaneously measuring thousands of proteins from small sample volumes (15 µL of serum or plasma). The current version of the SOMAScan assay measures 1310 proteins with lower limits of detection (1 pM median), 7 logs of overall dynamic range (~100 fM-1 µM), and 5% median coefficient of variation. Once the protein markers of interest are identified, more targeted versions of the SOMAScan assay for diagnostics can easily be developed. I strongly believe that the SOMAScan or similar modified aptamer technologies will revolutionize proteomics, clinical protein diagnostics and individualized medicine.

What sort of research do you have on the horizon that you think might influence clinical practice in the future?

First, there are many projects that we have been working on for many years and that will continue such as contributing to the development of drug eluting stents and balloons, studying the biological activity of “limus” drug derivatives and metabolites, and the development of new biomarkers strategies for drug development, clinical diagnostics and monitoring. One of the projects that we are working on in collaboration with Dr. Vinks’ group in Cincinnati is a project called “iCDrugs”, which is a novel home-monitoring system for patients in opioid treatment programs, which leverages a combination of novel communication tools, cutting-edge multi-analyte LC-MS/MS, and PK modeling. Another at the moment for us very important project is to study the cannabinoid PK/PD of marijuana users with free access to recreational marijuana. A problem that physicians in an environment of free marijuana access face is a lack of understanding the association between specific marijuana formulations, use patterns, doses of individual cannabinoids and behavioural and health outcomes. While routine standard questions estimate well alcohol and tobacco consumption with reasonably precise quantification of exposure, there is no similar way to estimate systemic exposure to marijuana’s active ingredients and the associated immediate and long-term risks. As of today, the PK of tetrahydrocannabinol (THC) and its key metabolites has been studied mostly in controlled clinical settings. However, actual cannabis users are a heterogeneous population, taking a range of potentially interacting other drugs, using a variety of marijuana-based substances, via various routes and means of administration (e.g., smoking, dabbing, vaporization of concentrates, and edibles) and with vastly varying doses; all of which make PK prediction in specific individuals a great, clinically highly relevant challenge.

What do you consider is the future for TDM and CT? What are you excited about? What are the challenges we face?

I believe that there are two important developments: TDM based on home blood collection using minimally invasive, small volume sampling technologies and the development of biomarkers strategies for precision drug treatment, basically personalized dosing and dose adjustments based on pharmacodynamic TDM. The challenges of the latter are that, although metabolomics, proteomics and gene array-based biomarker discovery technologies have been around for decades, they have resulted in disappointingly few new biomarkers that have been implemented in clinical practice. The problems are multi-factorial and include, but are not limited to, uncertainties and problems with quality control, study design, chemometric and statistical analysis, the regulatory environment and the limited resources and infrastructure of academic institutions that are required for taking promising biomarkers beyond the discovery stage to regulatory approval and clinical implementation.

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