What is a
clinical trial?

About clinical trials

Before a medication can become available to patients at the hospital or from the pharmacy, it must undergo extensive medical testing to ensure it is safe to use and that it works to treat the condition for which it was designed to treat. This testing process is called a clinical trial. Most drugs go through multiple clinical trials that are split among different “phases”, with each phase including increasingly larger groups of trial participants.3


Clinical trials involve testing a new drug in humans. This step is only done after the drug has shown promising results in a laboratory and in studies involving animals.3

Clinical trials can have multiple purposes:2,3

  • To see if the drug helps people feel better
  • To see if the drug helps to improve a disease or prevent it from getting worse
  • To see if the drug is safe to use
  • To see if the drug causes unwanted side effects and how to manage those side effects
  • To see how well any side effects are tolerated by the people taking the drug
  • To see how much of the drug is needed to optimize the benefits of the drug while also reducing its risks

Clinical trials are necessary to provide enough evidence to ensure that a medication should become available more widely to other patients with the same disease or condition. Furthermore, the results of the clinical trial help doctors to make future informed decisions about how to prescribe the medication and which types of patients are most suitable to receive the medication.2,3

Why should I participate in a clinical trial?
Everyone participating in a clinical trial has their own individual reasons for joining.

Some of the most common reasons for joining a clinical trial are:3


  • To help future patients, so that one day there may be a treatment available
  • To know that the illness has had a positive effect on the lives of others, through the advancement of medicine
  • To try a new option, if no other treatments have previously worked
  • To have more access to specialized care and more frequent contact with doctors to ask questions and learn more about the condition or treatment
  • To monitor changes in health to hopefully address these changes more quickly

What can I expect during a clinical trial?
Clinical trials must be designed and organized in such a way as to ensure that the results will be trustworthy and reliable. For this reason, you can expect that you will be assigned to one group of participants and that there will likely be two (or more) groups:2,3

  • New drug versus standard treatment
    In some cases, one group will be given the new drug and the other group will be given the standard treatment that is already available to patients. In this scenario, the clinical trial will assess if the new drug is at least as good as (or possibly even better than) the standard treatment currently available.
  • New drug versus placebo
    If a standard treatment does not already exist, then the second group may receive what is called a “placebo”. A placebo is a treatment that looks and feels the same as the new drug, but it does not actually contain the drug. A placebo is used so that the researchers can compare whether the new drug is actually having an effect. If the new drug is not showing a benefit over the placebo, then the new drug is not working.

You will not be given the choice of which group you will be assigned. It is important to remember that during this process there is not yet proof that the new treatment actually works or is safe to use, which is why you will be randomly assigned to a group.


The decision to participate in a clinical trial is entirely up to you. If you choose to participate in a trial, you should know that you may leave at any time. A clinical trial is a big commitment, so when you are considering whether to join, you will be given more details about the specific process, the risks and benefits, and the requirements for that trial. During this stage, you will also be assessed to determine if you fill all the criteria needed to join the trial.3 Make sure to take the time to think about your choice and discuss it with your loved ones.


Once the clinical trial has been completed, you may be interested to see the results. Chiesi is committed to clinical trial transparency and data sharing.6 You can learn more about our policy on this here:

  1. Interventional Study to Assess Efficacy and Safety of Velmanase Alfa in Patients With Alpha Mannosidosis (SHAMAN). Available at: Last accessed: January 21, 2020.
  2. Learn About Clinical Studies. Available at: Last accessed: January 21, 2020.
  3. National Institutes of Health. NIH Clinical Research Trials and You. Available at: Last accessed: January 21, 2020.
  4. Borgwardt L, Stensland HM, Olsen KJ, et al. Alpha-mannosidosis: correlation between phenotype, genotype and mutant MAN2B1 subcellular localisation. Orphanet J Rare Dis. 2015;10:70.
  5. European Medicines Agency. New enzyme replacement therapy to treat rare genetic disorder alpha-mannosidosis in children and adults. Available at: Last accessed: January 21, 2020.
  6. Chiesi. Clinical Trial Transparency and Data Sharing. Available at: Last accessed: January 21, 2020.
  7. Malm D, Nilssen Ø. Alpha-mannosidosis. Orphanet J Rare Dis. 2008;3:21.
  8. Bavisetty S, Grody WW, Yazdani S. Emergence of pediatric rare diseases: Review of present policies and opportunities for improvement. Rare Dis. 2013;1:e23579.