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A clinical trial is a type of research study that involves human volunteers or participants. Clinical trials are designed to answer critical questions regarding the safety and efficacy of a specific intervention in order to determine whether it will be better, worse, or no different than current interventions at diagnosing, preventing, or treating a particular population or disease. The goal is to understand what intervention works best, taking into consideration factors such as age, sex, racial & ethnic background, stage and type of disease.
These interventions can include drugs, natural health products, lifestyle modifications (i.e., diet, exercise), rehabilitative practices, diagnostic or surgical procedures. Clinical trials can test novel interventions that have never been tested before or, repurposed interventions that have previously been tested in other health conditions. Often the intervention being tested is compared to the current standard of practice, to placebo or sham interventions that do not include the therapeutic ingredient or technique, or to no intervention.
A research question regarding a possible intervention for MS is often initially tested in a laboratory setting. This testing is done using cells and animal models of MS. One such model is called experimental autoimmune encephalomyelitis (EAE) in laboratory rodents. EAE animal models can replicate key features of MS in humans, including inflammation and demyelination, relapsing-remitting cycles, and chronic disability progression. Studies at this pre-clinical research phase allow for a preliminary evaluation of possible benefits as well as some indication of the safety and risks associated with the intervention. If the intervention is promising, it may then move further into clinical trials.
Clinical trials consist of four phases (Table 1). Each phase of a clinical trial varies based on the purpose and size of the group that is receiving the intervention. In general, early clinical trials focus on establishing the appropriate dose that is safe, tolerated in the body, and produces a positive response. Later clinical trial phases generally test the established dose in larger groups of people to determine if significantly more people will benefit from the intervention and to identify any adverse side effects. Extension trials assess the long-term safety and efficacy of an intervention and include people from earlier clinical trials who sign on to continue the intervention.
Each clinical trial is different depending on factors such as the type of intervention, who the intervention is intended for, what the intervention is trying to achieve, and how the intervention’s success is measured. The information gathered in each phase is used to build knowledge about the intervention and support the subsequent phases of the research process. A clinical trial only progresses to the next phase when positive results are received from the previous phase.
Purpose | Study Design | Participants | |
Phase I | To assess safety and tolerability of the intervention and determine its appropriate dosing in healthy people (may or may not include persons with MS). | Usually open label (1 year +) | 20-80 |
Phase II | To look more closely at safety and efficacy of the intervention and determine appropriate dosing in people with MS. | Usually includes control and non-control groups that are often double-blind (1-3 years +) | 100-300 |
Phase III | To confirm the intervention's efficacy, monitor potential side effects, and compare it to commonly used interventions or placebo in people with MS. After this phase, the trial is submitted to Health Canada for approval. | Randomized, double-blind, placebo/sham-controlled, often multi-centre trials (2-3 years +) | 1000-3000 |
Phase IV | Once Health Canada has approved the intervention, a post-market study is often done to identify long term effects, including risks, benefits, side effects, and optimal use. | Several hundred- several thousand |
To learn more about MS treatments in development in phase two and three clinical trials, click here.
Clinical trials have specific eligibility criteria outlining those who can participate in the study. Inclusion criteria outline factors that qualify a participant for a study, while exclusion criteria outline factors that disqualify a participant for a study. These eligibility criteria are based on participant characteristics including, age, sex, type/stage/duration of disease, treatment or medication history, and additional comorbidities.
People who are interested in participating in a clinical trial are encouraged to speak with their healthcare team to determine if they are eligible for a study and to ensure that participation will not hinder their current treatment and care.
Participation in a clinical trial is not complete without informed consent. An informed consent form detailing all relevant information about the clinical trial is provided to participants, with ample time to read and ask questions in order to make an informed decision. Upon agreement, the participant signs the form, but can still withdraw their consent at any point during the clinical trial.
A control is the standard against which experimental treatments are evaluated. In Phase II and III clinical trials, one group of patients will be given an experimental treatment, while the control group is given either a standard treatment for the illness or a placebo. A control is part of the criteria of evidence-based medicine.
For additional resources about participating in a clinical trial, visit the Clinical Trials Ontario page – here.
Whether or not a study can be considered credible and scientifically sound depends on many factors, including the following:
In an open-label study (usually phase I), both the researchers and participants know of the intervention the participant is receiving (i.e., experimental drug or placebo). In a blinded study (usually phase II-III), either the participants do not know (single-blinded) or both the participants and researchers do not know (double-blinded) the intervention the participant is taking, until the clinical trial is over.
Randomization is the arbitrary assignment of participants to different intervention groups of the study to avoid potential bias in the results. This usually occurs in phase II-III clinical trials, when two or more interventions are being compared (for example, a new intervention versus a current intervention approved for MS).
A control is the standard against which experimental interventions are evaluated. In Phase II and III clinical trials, one group of participants will be given an experimental intervention, while the control group is given either a standard intervention for the health condition or a placebo/sham. A control is essential to compare the effect of the new intervention against a standard.
A placebo is an 'inert' pill, liquid, or powder with no active pharmaceutical ingredients. In phase II and III clinical trials, experimental treatments are compared with placebos to assess the experimental treatment's efficacy and safety.
The placebo effect is a scientifically recognized, measurable reality. There are measurable changes that occur in the brain when someone is given a placebo that they expect or hope will benefit them. The effect tends to be the greatest in symptoms with a subjective component, such as pain, but it can affect physical function too.
A sham procedure is analogous to a placebo drug. A trial participant may receive a 'sham' or 'fake' surgery, injection, or other procedure that removes the therapeutic step of the procedure being evaluated, as part of the control group.
Disclaimer: The MS Society is an independent, voluntary health agency and does not approve, endorse, or recommend any specific product or therapy but provides information to assist individuals in making their own decisions. For specific information and advice, please consult your personal physician. Read our full privacy policy.