What types of clinical trials are there?

Find out about the different types of clinical trials for pancreatic cancer, which are known as phases.

Before any new treatment for pancreatic cancer is tested on humans in a clinical trial, it is thoroughly tested in a laboratory.

All clinical trials must also be approved by an independent ethics committee and by government agencies. They check that the trial will be carried out in a safe way. There is more information about this on the NHS website.

The new treatments being tested must then pass through several different types of clinical trials, known as phases. Each phase involves more people.

Click the links below to skip to the phase you want to read about.

Watch our video to find out about the types of clinical trials

Research nurse, Susie, explains the different types of clinical trials in this video.

Phase 1 trials

Phase 1 trials are the first stage in testing a new treatment on people. They usually involve a small number of people (around 10–30) who may have different types of cancer. The aim is to find out:

  • the safe dose of a drug and how often it can be given
  • what the side effects might be
  • how well people’s bodies cope with the drug
  • signs that the drug may have an effect on the cancer.

Phase 1 trials usually take place at specialist cancer centres. This may mean you need to travel to another hospital if the trial is not available in your local hospital.

There may be a waiting list to join the trial. Your doctor or nurse will be able to advise you on this.

Phase 2 trials

If the results of a phase 1 trial are good, the treatment will move to a phase 2 trial. A phase 2 trial usually involves more people – there may be as many as 100 people taking part.

In a phase 2 trial, the research team already know which dose to use from the phase 1 trial results. They now want to learn more about how effective this treatment may be for specific types of cancer.

A Phase 2 trial will also look at:

  • whether the new treatment works well enough to test it in an even bigger trial (a phase 3 trial)
  • more information about what dose to use
  • how the treatment affects people’s quality of life
  • more about the side effects and how to manage them.

If the results of the phase 2 trial are good, the treatment may move into a larger phase 3 trial.

Randomised controlled trials (RCT)

Some phase 2 and phase 3 trials are randomised. This means that there are at least two different groups in the trial. The people taking part are put into the groups at random, by a computer. One group will have the new treatment and the other group will have a treatment to compare it with. This could be a different dose of the new treatment, a standard treatment for pancreatic cancer, or a placebo (see below).

Blinded trials

Randomised controlled trials are sometimes blinded. People taking part in a ‘blinded trial’ will not know whether they are getting the new treatment or the standard treatment (or a placebo). The research team may not know either. They will give the best level of medical care to everyone in the trial. If they need to, the trial doctors can always find out whether someone is having the new treatment or the placebo.

A placebo

Sometimes phase 2 trials compare a new treatment to a placebo. A placebo is a ‘dummy’ drug that looks the same as the new treatment but does not do anything.

A placebo may be used in clinical trials if there is no standard treatment to compare the new treatment with, or if the new treatment being tested is being added to a standard treatment.

The placebo effect

Even though a placebo doesn’t actually treat the cancer, it can affect how some people feel. For example, they might feel better because they think they are getting a treatment for their cancer (even though they aren’t). This is called the ‘placebo effect’. The research team will consider the placebo effect when they look at the trial results.

Phase 3 trials

Phase 3 trials compare new treatments with the best treatment currently available. They can do this by directly comparing a new treatment with an existing one, or by comparing different doses or different ways of giving the treatment.

A Phase 3 trial will also look at:

  • how effective the treatment is
  • any side effects
  • the impact on a person’s quality of life
  • any other problems that could develop, to learn more about how to provide the treatment safely.

Most phase 3 trials are randomised controlled trials (RCTs) and usually involve many more people than phase 2 studies. Larger numbers of people are needed so that even small differences in results can be seen more easily, which means the results of the trial will be more reliable. Some phase 3 trials are blinded trials.

A new treatment usually has to show better results than the standard treatment before it can be introduced as a treatment on the NHS. Sometimes, a treatment needs to be tested in several trials before it is introduced. But if the trial is big enough and the results are good, several trials may not be needed.

Phase 4 trials

Phase 4 trials are usually carried out soon after new drugs have passed all the previous stages and have been licensed for use in the UK. Phase 4 trials aren’t needed for every drug.

Phase 4 trials aim to find out as much as possible about how safe the drug is by monitoring very large numbers of people. They also look at how well the drug works, learn more about side effects and what the long term risks and benefits are for people taking part. Phase 4 trials can also provide more information on the cost of the new treatment.

Published February 2022

Review date February 2025