Clinical Trials Q&A

Learn about clinical trials

There are major clinical trials involving people with Huntington’s disease taking place in Australia and across the world. Here is some background information about what clinical trials are and what they set out to achieve.


What are clinical trials and why do we need them?

Clinical trials are carefully planned experiments that seek to determine whether new treatments, tests or other medical interventions are safe and effective when used to diagnose or treat people.

Trials provide an opportunity to see how people respond to a medical intervention, whether it does what is intended and whether it is safe and has no harmful side effects. Every effort is made to ensure that no harm is done to participants during trials.

Clinical trial interventions include:

  • experimental drugs
  • vaccines
  • medical devices
  • surgical and other medical treatments or procedures
  • preventative care strategies
  • diagnostic or screening tests

Researchers conducting clinical trials, who may be either from governments, pharmaceutical or bio-chemical companies, hospitals or universities will recruit clinical teams made up of doctors, nurses and other health care professionals to be involved.

Clinical trials in Australia are regulated by laws and codes of conduct. Approval from regulatory authorities is required before a clinical trial can begin.

Who can take part?

Trials can involve all parts of the population with all types and stages of a condition.

For each trial researchers will specify inclusion and exclusion criteria. Inclusion criteria are characteristics that each person must have if they are to be included while exclusion criteria are characteristics that disqualify people from participation.

For example, in drug trials involving people with Huntington’s disease, only those who are in the early symptomatic phase are eligible.

People who volunteer for a trial will often go through a pre-screening process to check their eligibility. Further screening tests such as a clinical assessment, physical examination or blood test will then be done on those found suitable to participate.

Each person whose screening tests meets the inclusion criteria will then be provided with participant information and consent forms which outline the objectives of the research, what is expected of them and any risks involved.

How does a trial work?

Participants are often divided into two groups. One group will receive the drug or other intervention over a set period of time. The second group will be the control and will receive a placebo (a substance with no medication) or an established intervention already in place.

In a single blind clinical trial, the participants do not know whether they are receiving the drug or intervention, or whether they are in the control group but the clinical team and researchers do.

In a double blind trial, the researchers, the clinical team and the participants do not know who is receiving the drug or intervention and who is in the control group. Blinding helps to reduce the effects of bias when comparing the outcomes of the interventions.

The aim of the trial will be to compare what happens in each group and to see whether there is enough difference to prove that it has not occurred by chance.

Anybody participating in a clinical trial will be closely monitored throughout and can withdraw at any stage. The names and personal information of trial participants are confidential and cannot be disclosed.

There is usually no cost to participate in a trial with the trial sponsor covering all testing and accommodation costs.


What if I miss out?

It can be very disappointing for people to miss out on a place in a clinical trial of a promising new drug that appears to have the potential to have a positive impact on a fatal disease like HD. But not meeting the specific eligibility requirements doesn’t mean someone will not have access to the drug if is proven safe and effective and eventually becomes commercially available and/or funded

There is also a community-wide benefit from clinical trials that provide an invaluable source of information for all researchers who are working in a field and may speed the development of other drugs or interventions to tackle a disease.

What are the phases of clinical trials?

Clinical trials are usually done in phases with specific goals/targets (called endpoints) in each. If a new intervention is promising, it may move to later phases of testing where more people are involved.

  • A phase I clinical trial is typically the first step after a drug or other intervention has been laboratory tested and proven to be non-toxic in animal studies. A small sample of volunteers (e.g. 20 to 80) are involved and the primary goal is to evaluate safety. In the case of a drug trial, that includes determining the safe dosage and whether there are any side effects.
  • A phase II clinical trial is done with a larger group of volunteers and will look at whether the intervention or drug works as it is intended and to further evaluate its safety.
  • A phase III clinical trial is done with an even larger group of volunteers (hundreds or thousands). It will likely involve many more trial sites and is a more comprehensive look at the effectiveness and safety of a drug or intervention. This is the last step before regulatory approval can be sought for a new treatment or intervention to be made publicly available.
  • A phase IV clinical trial occurs after an intervention or treatment has gone onto the market and helps to monitor its effectiveness with the population group that is using it and to look at whether there are any negative side effects of its extended use.

What happens after a clinical trial?

Depending on the results and whether a participant received the treatment or a placebo, there may be a therapeutic benefit to participating in a clinical trial. But even if there is not, an individual can take comfort from the fact they may be helping others in the future if the treatment or intervention is found to be safe and effective.

Depending on the results, participants in drug trials are sometimes given the opportunity to enroll in an extension study in which they are guaranteed to receive the drug.

All patient information is treated confidentially. Participants have the right to request that information about the trial’s results be given to them. Often the results will be published in reports or scientific journals.

From the point of view of the researchers conducting the trial, the close study of the results will lead to a decision about whether to proceed to another trial phase, to seek regulatory approval for the drug or intervention to go on the market, or to stop the research. It may also lead on to expanded research in other stages of the disease.