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Treatment-related clinical trials are usually carried out in a series of steps or phases. These steps or phases may not be needed for other types of trials.
New cancer drugs or treatments are first tested in the laboratory before they are given to people in trials. If it seems they may help to treat a particular cancer they are tested in phase 1 trials. If these are successful, the drug is entered into phase 2 trials, and then phase 3.
Manufacturers of drugs that have been shown to be safe and effective in phase 3 trials can apply for the drug to be granted a licence, known as a marketing authorisation. Licensed drugs are then available to be used in healthcare. Most licenses are granted by the European Medicines Evaluation Agency as the license covers all countries in the European Union. The Medicines and Healthcare Products Regulatory Agency can grant a license for a drug to be used just in the UK. Drugs that are licensed may be further researched in phase 4 trials.
People who run trials involving patients (trial researchers) have to offer a treatment they believe is at least as good as, and possibly better, than the best available treatment. The trials have to be conducted following strict rules and guidelines|.
Phase 1 trials test a new cancer treatment or drug which has already been tested on cancer cells in the laboratory. Phase 1is the first stage in which the drugs are used to treat people.
It’s not expected that the treatment will cure the cancer, but aims to find out:
Phase 1 trials usually involve a small number of patients. They are offered to people whose cancer has come back or spread where there is no other standard treatment that may help them.
The first patients are given a small dose of the treatment or drug that is expected to be safe. If none of the patients have any side effects, the next group will be given a higher dose. In this way the dose of the drug is increased until some people do have side effects. When side effects are seen that make it unsafe to increase the dose further, it’s known as the ‘maximum tolerated dose’ and the dose is not increased any more.
Sometimes, phase 1 studies include different ways of giving the new treatment; for example, patients may be given the same drug by injection, or as tablets.
It’s impossible to predict whether a new treatment will cause harmful side effects so people in this type of trial need to be monitored very carefully. Phase 1 trials are usually carried out in clinical research units at specialist hospitals, rather than in local hospitals. Sometimes this may involve a lot of travelling to and from the hospital.
Phase 1 trials may last several months to a year. At the end of the trial, the research team will know the major side effects of the treatment and whether it has some effect on the cancer.
If the treatment is safe and does have an effect, it will then be tested in phase 2 trials.
The aim of phase 2 trials is to find out:
Phase 2 studies have more patients, usually about 20–40 people, and may last a couple of years. These patients will be closely monitored to see whether their cancer is getting smaller. If the cancer shrinks, it’s known as a response to the treatment|. The trial will also look at any side effects caused by the treatment.
These follow phase 2 studies and aim to compare the effectiveness of newer treatments with that of standard treatments. They also give more information about the side effects that the new treatment may cause.
Sometimes a trial may test whether a new treatment will be as good as the standard treatment but cause fewer side effects. For example, a new way of giving radiotherapy may be tested and compared to the standard radiotherapy treatment used on patients.
Phase 3 trials are large and may include hundreds, or sometimes thousands, of patients from many different hospitals, often from several countries. They may take many years to complete. Researchers use these trials to find out:
Phase 3 trials usually involve randomisation|.
Phase 4 trials are carried out after a drug has been shown to be effective and has been granted a license. They aim to find out:
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