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Phases of clinical trials

A new treatment will go through several stages of development, from its initial design to becoming a standard treatment. There can be up to five phases of clinical trials

Clinical trials testing new treatments are divided into different stages, called phases. First, a treatment will go through several different phases and testing different things. Then, it can be approved for treating brain tumours.

What are the different phases of clinical trials?

Not all treatments go through a phase 0 trial.

Phase 0 clinical trials:
·       aim to speed up the development of promising drugs by testing them in people rather than animals, which subsequently gives more reliable results.
·       use small, therapeutic doses of a drug or treatment to see what it does in people.
·       use doses too small to treat your tumour, but you’re less likely to have side effects.

These are usually the earliest trial of a treatment in people, after testing in the laboratory
Phase 1 clinical trials tend to be carried out in specialised clinical research units rather than hospitals. And, they recruit only a few people and last several months.

Phase 1 clinical trials aim to find out::
·       whether the treatment is safe
·       what’s the right dose to use
·       whether it has any side-effects.

Treatment is:
·       initially, given at a low dose to a small group of people, who may be healthy volunteers
·       then, if the first group experienced no serious side-effects, given to another group at a higher dose.
·       other groups repeat this process until they determine the ‘maximum tolerated dose’ or MTD.

Additionally, patients will receive optimum care and attention while in the unit.

Not all treatments tested in phase 1 will make it to phase 2.

Phase 2 clinical trials use larger groups of patients (up to about 100) and can last for a couple of years.

They aim to find out:
·       more about the safety and side-effects of the treatment
·       whether the new treatment works well, for example, shrink the tumour, keep it away for longer, and make the patient feel better.

·       often compare the new treatment to an existing treatment or to a dummy drug, known as a placebo
·       may be a randomised trial – where people are put into the different treatment groups at random.

Most drugs unfortunately don’t make it to phase 3 because, they turn out to be ineffective, unsafe or have intolerable side-effects in phase 2.

Phase 3 clinical trials often take place in many hospitals across different countries. Larger groups (several thousand patients), who are usually ill receive these trials, and often last for several years.

Phase 3 trials aim to find out:
·       if the new treatment works better than the existing, ‘standard’ treatment
·       whether it produces fewer side-effects.

·       Compare 2 groups of patients with similar characteristics to see if the new treatment is better
·       Are often ‘randomised, blind trials’, also meaning that patients are not aware whether they are taking the new treatment or a placebo. This ensures that the trial results are not biased and can be trusted.

Read more about randomised trials.

If successful, the treatment can be put forward to the appropriate authorities for approval to be licensed for use. This approval process can take several years.

Phase 4 clinical trials are conducted after a drug has been shown to be effective and has been licensed to treat an illness.

The aim of the Phase 4 trials to find out :
·       what happens, while thousands of people have received the drug in the general community
·       assess any long-term risks and benefits and any rare side-effects of the drug.

Where can I find out more about trials?

First, speak to your healthcare team (such as, your neurosurgeon, oncologist or CNS) about, whether a clinical trial could be an option for you.

It can also help to understand more about what a clinical trial involves and why someone may choose to take part.

Make the right choices for you

Our Step by Step interactive guide outlines what happens following a diagnosis, to answer your questions and help you to understand what to expect.

Frequently Asked Questions:

You can ask your healthcare team and doctor to find out whether you are eligible to join the trial.

They aim to find new treatments which may help people with illnesses more effectively.

Clinical trials help professionals learn more about treating specific illnesses. Also, If you join and take part in a clinical trial, you may benefit from advancements in the treatment.

You may have some side effects as a result of the trial. Also a new treatment may not work better then standard treatment.

If you have further questions, need to clarify any of the information on this page, or want to find out more about research and clinical trials, please contact our team:
Support and Information Services
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