Clinical Trials Information Hub

Pronounced Phase "One", these trials test the safety and side effects of a new treatment. People who take part in phase I trials (up to 30 people) often have advanced cancers and have usually tried all the treatment options available to them. The first few patients to take part in the trial are given a very small dose of the drug. If they respond well, the next group have a slightly higher dose. The dose is gradually increased with each group. The researchers monitor the effect of the drug until they find the best dose to give. This is called a dose escalation study.

Pronounced Phase "Two", these trials test the new treatment on a larger group of people (more than 100) to find out more about the side effects, safety of the new treatment, and the effects on the cancer. These trials can last several weeks or months, and sometimes they can continue for years if the person is responding to treatment.

Pronounced Phase "Three", these trials involve more people (hundreds or thousands) and compare new treatments with the current treatment available longer-term.

Pronounced Phase "Four", these trials trials are carried out after a new drug has been shown to work and has been licensed to be used (a licence means the medicine can be made available on prescription). These trials aim to find out how well the drug works when it’s used on more people, the long-term benefits and risks, and more about the possible rare side effects.

In open label trials, both you and the researchers know the treatment you’re having. These trials usually compare two very similar treatments to test which treatment is the best, and usually happen in the early phases.

If you take part in a randomised clinical trial, you’ll usually be put randomly into either:

• the treatment group – where you’ll be given the treatment being trialled, or
• the control group – where you’ll be given the existing standard treatment, or a placebo (a treatment that has no effect) if no proven standard treatment exists. A placebo is only used if outside of the trial, there is no other treatment option available. This could be because the person has already tried all the available treatments. Nobody in the trial would be given a placebo if there was any other treatment option available to them, as this would be unethical.

If you take part in a randomised trial (most phase 3 and some phase 2 trials are randomised) a computer programme is usually used to randomly select which group you will be in. Your personal details, such as age, sex and state of health, are taken into account so that the groups in the trial are as similar as possible. This helps to make sure that the results of the trial are reliable and accurate.

A blind trial is a trial where the people taking part don’t know which treatment they are getting. You might get the new treatment. Or you could receive the standard treatment. So that you can’t tell which treatment you are having, everyone taking part will receive identical injections, tablets, or other forms of treatment.

In a double blind trial, you won’t know which group you’re in, and neither will the researchers, until the end of the trial. This makes sure that the results are more reliable as they will not be influenced by your expectations or the researchers’ expectations.