A clinical study is a study which is designed to evaluate the safety and efficacy of a new treatment in humans.
Before reaching the clinical study stage, the hypothetical treatment is first tested in the laboratory – in vitro and in vivo (on animal models) – to confirm the relevance and safety of the hypothesis. If the results are satisfactory, it is then tested on human subjects during clinical studies.
Clinical studies are conducted in three successive phases, of varying lengths, at research sites.
Phase I studies are the first studies on humans, and take place before the efficacy of a treatment is evaluated. They are conducted on a small group of healthy volunteers. The main aim of this phase is to evaluate the tolerability, the absence of side effects and the way in which the product is absorbed, distributed and metabolised by the body. This phase may, in exceptional cases, not need to be carried out.
Phase II studies are conducted on a larger group than phase I studies, comprised of volunteers suffering from the disease targeted by the test product. The aim of this phase is to study whether the expected beneficial effects are observed in the population affected by the targeted disease, as well as the side effects of the test product at the doses associated with beneficial effects.
Phase III studies involve a much larger group of patients. The aim is to formally test the nature and extent of the benefits of the new treatment versus a comparator in terms of safety and efficacy. From phase II, but more generally during phase III, the treatment is compared to a standard treatment, called a “reference” treatment, and/or a placebo treatment, that is, with no pharmacological properties.
At the end of phase III, the treatment may be submitted to the competent authorities and reimbursement authorities in order to obtain marketing authorisation. The competent authorities may be, for example, the European Medicines Agency (EMA) or the American Food and Drug Administration (FDA)
The sponsor initiates and finances the clinical trial and handles the organisation and execution thereof. The sponsor may be a legal person (non-governmental organisation, laboratory or business) or a physical person.
The investigator is a doctor who supervises the conduct of the clinical trial. He/She is the link between the sponsor and the patient who is participating in the study. The patient is, therefore, never in direct contact with the sponsor. The investigator supervises the clinical study in a hospital centre, or in a private or public establishment, which is called the investigating site.
The patients are the participants in the clinical study. They must meet certain eligibility criteria in order to be enrolled in the study.
The patient may benefit from several advantages by participating in a clinical study:
There are also some constraints and disadvantages:
In order to participate, patients must meet the eligibility criteria (also called inclusion criteria) required for the study in which they want to participate. These criteria may, for example, be based on age, diagnosis or the stage of progression of the treated disease.
Patients must be able to understand the requirements of the study and read and sign the informed consent document.
There are also exclusion criteria which exclude some patients from participating in the study. These may, for example, be associated with a list of particular treatments or diseases.
During the process of obtaining informed consent, the doctor ensures that the potential patient has received the necessary information regarding the trial (the aim, the treatment given, the duration and the protocol) and regarding the risks involved. Once the patient has received this information and if he/she is still interested in participating in the study, he/she will sign an informed consent document as proof of his/her consent.
Once the document has been signed, the patient can still withdraw from the study at any time, without having to give a reason or being subject to damages as a result of his/her withdrawal.