The World Health Organization (WHO) defines clinical trials as “a type of research that studies new tests and treatments and evaluates their effects on human health outcomes.”
These studies are performed on people with the aim of evaluating a surgical, biological, radiological, medical, or behavioral intervention.
Clinical trials are the primary means by which researchers determine whether a new treatment such as a new drug, medical device, or diet is safe and effective in humans.
Clinical trials can also be used to learn if a new treatment is more or less harmful or useful than the standard treatment. These trials may also be used to discover diseases in their early stages, sometimes even before the symptoms are apparent.
Clinical trials can also be used as a preventive measure and a way to make life easier for people living with a chronic health problem or a life-threatening disease.
Scientists perform laboratory tests and studies on animals to test for the safety and efficacy of a potential therapy. The U.S Food and Drug Administration (FDA) then approves a clinical trial to begin on humans if the studies carried out on animals show favorable results.
Phases of Clinical Trials
Phase 0
These are clinical trials carried out on people that aim to learn the effects and processes of a drug in the body. Small doses of the potential therapy are given to a group of about 10 to 15 people.
Phase I
This phase of the trial aims to find the best dose of the new drug with the fewest side effects. A group of about 15 to 30 people is tested with the drugs. Doctors begin by administering very low doses of the drug to some patients and higher doses to others until side effects become too severe or the desired result is observed.
The main goal of phase I is to test for the drug’s safety. If it is deemed safe enough, it proceeds to phase II for further testing.
Phase II
Phase II trials further assess the effectiveness and safety of the potential drug. This new phase involves testing the drugs on patients with a specific type of cancer. This phase of the trial involves a more extensive group compared to that of phase I. New combinations of drugs are often tested, and patients are closely watched to see if the new drug works. If the drug is found to work, it can proceed to phase III.
Phase III
The goal of this phase is to compare a new drug to the current standard-of-care drug. This phase of the clinical trials assesses the side effects of each drug and which drug is more effective. This phase often involves 100 or more patients.
The trials are often randomized, with patients put into treatment groups known as trial arms by chance. It is necessary to randomize to make sure that the people in the trial arms are alike. This lets the scientists know that the trial results are due to treatment and not differences between the groups.
Phase III trials often involve two or more treatment groups. The control group gets the standard-of-care treatment, while the other groups get a new medicine. All the patients in this phase of the trials are monitored closely.
The study will be stopped early if the side effects of the new therapy are too severe or if one group has much better results. Phase III clinical trials are usually required before the FDA approves the use of a new drug for the general public.
Phase IV
The goal of this phase is to test the new drugs approved by the FDA. This phase of the clinical trials typically involves several hundred or thousands of patients.
This allows for better research on short-lived and long-lasting side effects and safety. For example, some rare side effects may only be observed in large groups of people.
