Translational biomarkers: towards a better understanding of modern drugs

New medicinal compounds are proteins. These biopharmaceuticals can trigger immune responses causing side effects such as rash, fever, and fall in blood pressure. As long as these responses do not interfere with the effectiveness of the compound (e.g. via formation of anti-drug antibodies), or seriously hamper the patient’s well-being, the occurrence of these immune responses may be accepted by patients and pharmaceutical companies and regulatory bodies; the clinical development of the compound is not necessarily halted or terminated. For example, a monoclonal antibody like Herceptin, commonly used for the treatment of metastatic breast cancer, induces fever and inflammatory symptoms in 40-60% of all treated patients. As long as the benefit-risk balance for a drug is favorable, clinical use of the compound is defendable. However, it is remarkable from a scientific point-of-view that we administer compounds to humans when these inflammatory effects are poorly understood.

Some intravenously administered biopharmaceuticals reach a maximal plasma concentration at a time beyond the infusion duration. This phenomenon cannot be explained by conventional pharmacokinetic rules, and potential causes and consequences have only be speculated on so far.

These are examples of uncritical acceptance that certain drugs may behave ‘odd’. At CHDR we aim to optimally understand the behavior and effects of drugs, even if it concerns long-term marketed drugs. CHDR invests in the investigation of insufficiently understood drug behavior/effects. For example, we have recently demonstrated that therapeutic proteins non-specifically stick to the endothelium, which translates into delayed maximal plasma concentrations. Furthermore, we are relating inflammatory effects of biopharmaceuticals in vivo to drug responses observed in cell-based systems, aiming to develop in vitro methodology that better predicts drug effects in vivo. Importantly, a more extensive exploration of drug effects may exceed the level ‘nice to know’, as demonstrated by the first-in-human trial with anti-CD28 antibody TGN1412. All 6 healthy volunteers receiving this investigational compound experienced cytokine release syndrome, resulting in a potentially long-term disruption of the immune system. Evaluation of the TeGenero case by key opinion leaders led to the conclusion that the problems resulted from unforeseen biological drug action in humans, rather than from clinical misconduct. This case shows that drugs affecting previously unexplored pathophysiological pathways require careful exploration in tailored early phase clinical studies, with biomarkers that are fit-to-purpose.

CHDR advocates that recent evolutions in drug development require a more direct approach to monitor intended and unintended drug effects. For biopharmaceuticals and compounds with new mechanisms-of-action, biomarkers reflecting early/direct drug effects on cells or tissues should be selected. This will allow a more efficient, more rational, and safer translation between different stages in drug development: from animals to humans, from in vitro experiments on human cells to clinical studies, and from healthy volunteers to the targeted patient population. Such ‘translational biomarkers’ will play an increasingly important role in future drug development.

Matthijs Moerland

Research Director Translational Biomarkers

Forgotten players in glucose homeostasis?

It is highly likely that you learned at secondary school that the pancreatic hormones insulin and glucagon are important in the regulation of glucose metabolism. However, it is equally likely that during your further education more attention was given to insulin compared to glucagon, which at best got the role of bystander. Funnily enough both hormones were discovered around the same time (insulin in 1921 and glucagon in 1923) as was their role in glucose homeostasis. Insulin got all attention as new revolutionary medicine, possibly because Insulin Dependent Diabetes Mellitus (Type I DM) was such a lethal disease that could now be properly treated. In contrast, glucagon-deficiency was not recognized as a clinical entity let alone as a disease. This is all very understandable, but it remains enigmatic why insulin-based therapies also dominated the treatment of Non-Insulin Dependent Diabetes Mellitus (Type II DM). Especially in view of the observations in the 1960’s that Type II DM is not a disease of insulin deficiency, but a condition of insulin resistance which cannot be overcome by increased endogenous insulin release. Whatever the explanation for this enigma may be, we are currently witnessing a revival in glucagon-based therapies for the treatment of Type II DM.

At CHDR we have adapted and validated existing techniques to investigate the role of glucagon in glucose homeostasis and to evaluate glucagon-based therapies in humans. The development of these tools with our colleagues in industry and academia was and will be a hallmark of CHDR’s philosophy. This also regards the development of mathematical models that try to capture the complex interplay between insulin, glucagon and glucose. We are proud that all this work is now integral available as PhD thesis, which our colleague Marloes van Dongen will publicly defend on January 7, 2015 in the historical Academiegebouw of Leiden University.

An important role of the specialty of clinical pharmacology is to develop the tools of the drug development trade. We sometimes define new (and untested) medicines as extremely sophisticated technological innovation after evaluation with rather primitive methodology. The ongoing drug innovation wave has to be matched with equally sophisticated methodology to see the potential effects. These techniques have to be developed preferably ahead of a new innovation wave in a certain field[1].

Renewed interest in glucagon as one of the ‘forgotten’ players in glucose homeostasis, of which there are more[2], will lead to a potential wave of new products and devices. We are happy that our work is now available to support this, and make a difference in the attack on the Type II DM epidemic.

Koos Burggraaf

[1] Cohen et al. Annu Rev Pharmacol Toxicol. 2014 Oct 6. [Epub ahead of print]; PMID: 25292425

[2] ‘certain factors produced by the intestinal mucosa in response to nutrient ingestion that are capable of stimulating the release of substances from the endocrine pancreas and thereby reducing blood glucose levels’; see for instance Bayliss WM, Starling EH. Proceedings of the Royal Society of London[Biol] 1902;69:352-353 / Moore B, Edie ES, Abram JH. Biochem J 1906;1:28-38) and La Barre J. Bull Acad R Med Belg 1932;12:620-634.

Innovative drugs need innovative methodology!

In drug development it is important to try to answer as many questions as possible in as few drug studies as possible. If you expose humans –or other animals for that matter- to new and potentially harmful compounds, then not getting everything you can out of it, seems a waste. After a new drug has successfully passed the stage of animal studies, a “first in human” study is planned in which  -traditionally- pharmacokinetics of the new drug and potential side effects of the compound are determined. In this phase, however, it is likely that humans will be exposed to a broader range of drug doses than ever thereafter. An ideal opportunity to also try to determine the intended pharmacological effects of the new compound. To do that you need the correct methodology and this is often unavailable.

Luckily, more and more pharmaceutical and biotechnology companies are seeing the added value of this approach. CHDR’s self-funded research is focused on the development of new biomarkers and methodology to show pharmacological effects of new drugs in the earliest stages of clinical drug development. There is a new trend: co-funding of this type of research by a pharmaceutical company with a particular interest in the new method rather than just the new medicine.

Multiple Sclerosis is caused by inflammation that leads to demyelination -loss of the myelin sheath around neurons- in the brain and spinal cord. Existing therapies target inflammation and thus lead to inhibition of demyelination. However, new MS drugs are being developed, that target enhancement of the formation of new myelin and hence improvement of the function of demyelinated neurons. These targets are completely new and methods to quantify the effects of these innovative drugs therefore don’t yet exist. In collaboration with a biotechnology company, we developed and validated a method that uses labeling with deuterated water to estimate the speed at which new myelin is formed in the central nervous system. Healthy subjects drank 120 mL of “heavy water” per day for a period of 10 weeks and we performed repeated lumbar punctures to obtain cerebrospinal fluid over a period of almost half a year. We then extracted myelin breakdown products from the CSF and measured the rate of weight increase of the molecules, which was caused by incorporation of deuterium instead of hydrogen in newly formed molecules. These measurements, in combination with mathematical modeling, allowed us to estimate the rate of myelin formation.

Being able to quantify the rate of myelin formation will be essential in the process of developing a drug that is expected to positively influence remyelination. This may ultimately lead to a new treatment for patients with MS, which is much needed. But the method by which metabolic processes that occur within the confined space of the brain can be quantified using something as innocuous as water, may in turn contribute to the rational drug development of many other future CNS drugs.

Geert Jan Groeneveld

Cars & Clinical trials: driving simulators Vs. on-the-road-driving-tests

For many of us, driving a car represents freedom and independence and economical power. What has this to do with CHDR, you might ask? Well, many pharmacological agents that affect the central nervous system are of concern when it comes to driving safety. Those medications (and also drugs of abuse) can induce fatigue, impair vision and reduce vigilance leading to periods of inattention. This poses a risk for the operation of dangerous equipment like a car. Although those risks are often already known at a drug-group level, for clinical pharmacologists like us, it is important to estimate the dose response relationship for an individual investigative drug early in its development. Additionally there may be certain groups, like the elderly or the young drivers, which are much more at risk when impaired by medicines, alcohol or drugs.

The effect of investigative drugs on driving performances is often assessed by using a standardized on-the-road-driving-test, which was developed in the 1980s and has been applied extensively in over 50 studies since. In short, subjects are instructed to drive a car over a 100 km highway. The car is equipped with two camera’s that constantly monitor the position of the car within the traffic lane. The outcome is mainly measured by the alterations in the standard deviation of lateral position (SDLP), which has proven to be a suitable parameter for vehicle control and traffic safety.

However, the on-the-road-driving-test is inflexible, labor intensive and therefore costly, it may take weeks to complete a full study while testing a single dose only, making the test less suitable for the assessment of dose response effects and certainly not suitable for a quick adaption in the study design. Nevertheless, the on-the-road-driving-test is often required for registration purposes, but a negative study outcome may cause a significant restriction in its indication as specified in the SMPC. Therefore, an on-the-road-driving-test may not be the single most suitable tool for drug-induced driving risks.

Luckily, the SDLP can also be measured in an in- house driving simulator in a much more practical and reproducible manner. Other parameters that are of importance in driving a car safely -, i.e. alertness, memory, coordination amongst others – can be added effortlessly. Also, driving simulation makes it possible to study the temporal relationship between medication and driving performance and work out the pharmacokinetic dynamic relationships. Of course all tests are surrogate endpoints for the occurrence of accidents but this ‘real’ endpoint can never be assessed. The current generation of driving simulators have, however, been validated positively against real driving behavior.

At CHDR we are currently studying the sensitivity of a driving simulator test battery to the effects of ethanol and a benzodiazepine, trying to compare these results with those of the NeuroCart™, a validated and established test battery developed by CHDR that quantifies a large range of drug-sensitive CNS-functions that are also relevant for every-day performance. Results from this study will allow us to determine whether a driving simulator is suitable to assess impairment in performance due to investigative drugs in a laboratory setting. This will set the standard for future studies in the important area of drug effects on real life performance.

Rob Zuiker

Clinical trials now and then: 1983 vs 2014

Clinical 04- MQIn 1983 I administered my first new medicine to a human being in the department of clinical pharmacology at the Wellcome Research laboratories in Beckenham, UK. It was the antiepileptic lamotrigine (Lamictal) and it eventually reached a turnover of more than a billion pounds, but we were not so sure then. Lamotrigine killed dogs (due to a metabolite that we later found was only formed in the dog) and did nasty things to the kidneys of a certain species of rat.  After internal discussion we went ahead anyway probably to the benefit of many patients with epilepsy and depression, who are currently being treated with lamotrigine. This first in human study was also one of the first with an approval of an ethics committee. Before this we just went ahead after approval by one of the directors.

So the study went ahead. My boss came down from a meeting, had an iv cannula inserted and took the first capsule, returned to his meeting and occasionally walked down for an ECG and a blood sample. The second subject was the chemist who invented the molecule and was rather nervous about causing problems for ‘his’ molecule. This almost inevitably induced a nasty migraine attack. “Don’t winge Dave”, we said as he lay there with a bad headache and we injected anti vomiting drugs in him. The rest is history.

This story may cause severe distress in the modern quality assurance officer, trial monitor, or an attentive regulator. However it is real and by describing the past tries to highlight the contrast with the present.

When we started CHDR in 1987 we very quickly started to do studies for industry and our maiden first-in-human study was with an antiarrhythmic that prolonged the QT interval in the ECG. This cost about 80.000 Dutch Guilders and this would be in today’s terms about the same amount in euros. The protocol had 20 pages and the whole submission dossier to the ethics committee about 30.  The study was completed very quickly after the protocol was written and monitoring was done by one of the employees of the company. She visited us once or twice from Belgium and as a rule brought Belgian chocolates.

The real cost of such a study today is a factor 10 higher, the dossier would be about 20 times more pages and the staff involved in such a study is about tenfold. Of course this is excluding the internal cost of the company. Most likely they will employ an IT company for the study database, an ECG company to read the ECG’s, a central lab company to study the clinical chemistry and a monitoring company to meticulously go over all the blood pressures and side effects. Rules against conflict of interest have done away with the Belgian chocolates. Many of this is global so there is quite a CO2 footprint associated with such a study.

Some of this is good and I would not suggest that we go back to the informal studies of the last century. However, we have a duty to keep new medicines affordable to the whole world. The cost of current drug development is without a doubt unsustainable and the efficiency of the process must be increased. Innovating drug development and its methodology can do this. This is what we have been doing at CHDR for the past 27 years. This new blog series will be written by all our staff members and tell you about our views on this innovation and what we do about it. We hope you are going to read them and share your comments.

By: Adam Cohen