What is a clinical trial?

Ever wondered what’s involved in a clinical trial? Read on to find out…

Did you know it can take 12 years to develop one new drug before it becomes available to the public? The estimated cost to develop a new drug is £1.15 billion. This includes the cost of clinical trials, licensing fees and the inevitable costs of unsuccessful drug candidates.

Clinical trials are an essential step in developing a new drug and it potentially becoming a new standard treatment.

Aims of a clinical trial

Clinical trials are research investigations in which patients can volunteer to take part. They are intended to test new ways to treat and care for patients. Clinical trials can test the benefit of a new drug or combination of drugs, a new dosage, a new way to administer a known treatment or even look at how patient care or lifestyle can impact patient outcomes.

Clinical trials aim to find out if a new treatment is safe and effective for patients. There are different types and stages (or phases) of clinical trials. Each trial is designed to ask and answer specific questions to determine which treatment(s) should become available for patients.

Phases of a clinical trial

Phase 1

Phase 1 trials tend to be small trials with only a small number of patients (20-80 people). They are usually the first time the drug has been tested in humans.

The aim of Phase 1 trials are to determine what the best dose of treatment to administer. Researchers look at how the body copes with the drug, what the side effects are and how well it works.

The first patients to take part will be given a small dose of the treatment, with the dosage getting higher for each new group of patients. This is so that researchers can identify the safest and most effective dosage.

In cancer trials, patients involved in Phase 1 usually have advanced cancer and have already had all of the existing treatment options available to them.

Phase 2

Phase 2 trials are larger and can include over 100 people. These trials aim to test the dosage identified from Phase 1 in a larger group of people before it can be considered to test in very costly Phase 3 trials. In a Phase 2 trial, researchers may compare a new treatment to an existing treatment. This allows them to see if a new treatment is just as effective as or better than the treatment already in use.

Drugs can affect people in a variety of ways, therefore researchers can learn more about the safety and effectiveness of a new treatment from a larger patient group. Phase 2 trials can help to identify all the possible side effects.

In a Phase 2 trial, researchers may compare a new treatment to an existing treatment. This allows them to see if a new treatment is just as effective as or better than the treatment already in use.

Phase 3

In Phase 3 trials, the group of patients involved is even bigger and over 1,000 patients may be involved.

The aim of Phase 3 trials is to test whether the effectiveness and safety of a new treatment is beneficial enough so it can be licensed by drug approval bodies, such as the UK’s Medicines and Healthcare products Regulatory Agency (MHRA), the European Medicines Association (EMA), and the US Food and Drug Administration (FDA). These trials compare the new treatment against existing treatments to confirm that is it comparable or better than the currently available treatments.

Phase 4

Phase 4 trials can take place after a new treatment has been shown to work and has been granted a licence, and is being prescribed. Phase 4 trials are mainly run to find out what the long term risks and benefits of the new treatment are, learn about side effects after long term use, and see how well the drug works when used more widely in a ‘real world setting’.

If you would like to find out how to join a myeloma clinical trial, our Ask the Nurse blog post about clinical trials has lots of useful information. To find a clinical trial near you, have a look at our Myeloma Trial Finder.


  1. The Association of the British Pharmaceutical Industry (2019) Facts: A new medicine takes around 12 years to develop. Accessed at: https://www.abpi.org.uk/what-we-do/working-with-industry-and-academia/careers-in-the-pharmaceutical-industry/facts/a-new-medicine-takes-around-12-years-to-develop/
  2. The Association of the British Pharmaceutical Industry (2019) Research and Development: Clinical Trials. Accessed at: https://www.abpi.org.uk/what-we-do/working-with-industry-and-academia/careers-in-the-pharmaceutical-industry/working-in-the-industry/research-and-development/clinical-studies/clinical-trials/
  3. National Health Service (2019) Clinical Trials. Accessed at: https://www.nhs.uk/conditions/clinical-trials/ 

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