- Laboratory research
- Phase 1Is it safe? What dose?
- Phase 2Does it seem to work?
- Phase 3Does it work in more people?
- Regulator review
Families often hear the word “trial” for the first time in the same week as the diagnosis. This page explains what a trial is, so that the conversation with the doctor is easier.
What is a clinical trial?
A clinical trial is a research study that tests a treatment in people. It follows a written plan, called a protocol, which sets out what will be done and why. A trial compares one treatment with another, or with no treatment, to find out whether it helps and whether it is safe.
Trials are not the same as care. A person in a trial is still looked after by their own team. The trial adds visits, tests and a treatment that is still being studied.
What do the phases mean?
New medicines are usually tested in stages.
- Phase 1 gives the medicine to a small group for the first time. The aim is to find side effects and a safe dose.
- Phase 2 tests it in a larger group of people with the illness, to see its short term effects.
- Phase 3 compares it with an existing treatment or a placebo in larger groups.
- Phase 4 watches the medicine after it is licensed and in use.
A placebo is a dummy treatment that looks like the real one. In many trials a computer decides who gets the new treatment and who gets the placebo or standard treatment. Often neither the person nor the doctors know who is getting which until the trial ends. This is called blinding, and it is done so that hopes and expectations do not colour the results.
Who can join?
Each trial has its own rules about who can take part. The rules are set by the people running the trial, called the sponsor, and they can be narrow: a particular diagnosis, a stage of illness, an age range, or a test result. Whether one person fits is a question for the treating team, who can read the current rules and the date they were set.
Before anyone joins, a doctor or nurse explains the trial, gives written information and answers questions. Agreeing to take part after that explanation is called informed consent. A person can leave a trial at any point without giving a reason, and leaving does not affect their care.
Who checks that a trial is safe?
Trials cannot start without approval. In the UK, an independent research ethics committee must approve research involving people, and the medicines regulator authorises trials of new medicines. In the United States, an institutional review board, an independent committee of doctors, statisticians and community members, reviews and monitors trials to protect the rights and welfare of participants.
What does this mean for prion disease?
There is no proven cure for CJD, and treatment aims at comfort. Research studies are under way, and in the UK the NHS points to clinical studies at the National Prion Clinic. Some studies are open only to a particular form of the illness, and some have been set up for family members at risk of an inherited form.
Useful questions for the treating team are: Is there a trial that this person could be considered for? What would it involve in visits and time? What happens if we stop? In the United States, the CJD Foundation helpline can also say what is being studied.
Current trials lists studies with their sponsor’s stated eligibility and the date it was checked. Genetics explains the inherited forms that some studies focus on, and Exposure and safety covers the questions families often raise alongside treatment. Whether a trial is right for one person is a decision for that person, their family and their doctors.