Phases of clinical trials
After promising treatments are explored in animal and/or laboratory studies, researchers perform clinical trials. Once the drug, device or procedure enters the clinical trials process, it must go through several phases:
- Phase I trials determine the safety of a new treatment
- Phase II trials determine whether a certain kind of cancer responds to a new treatment
- Phase III trials study whether a new treatment is better than standard treatment
- Phase IV trials find more information about a new treatment that has been already approved for use in patients
Phase I Trials – Determine safety
The goal of a Phase I trial is to find the safest dose of a new drug that patients can receive without creating harmful side effects. During a Phase I trial, the researcher also examines the best way to give a new drug, such as by mouth or intravenously (through a vein).
Throughout Phase I trials, researchers monitor whether the new drug shows any effect against cancer. However, because these trials often are testing drugs for the first time in people, the goal is to find out how to give the drug in a safe way, and not how well it fights cancer.
Phase I trials usually include 15 to 30 people. Usually patients who have undergone standard treatments without success and have no other options are eligible to participate in a Phase I trial.
If the treatment successfully passes through a Phase I trial, then it will move forward to be studied in a Phase II trial.
Phase II Trials – Determine whether the new treatment works
The main goal of a Phase II trial is to examine how well the new treatment works to fight a certain kind of cancer. Less than 100 patients usually participate in a Phase II trial. Patients who volunteer for a Phase II trial may have been treated with chemotherapy, biotherapy, surgery or radiation and still need further treatment.
In addition to evaluating how well the treatment works against the cancer, doctors continue to monitor side effects. Since more patients participate in Phase II studies, some of them may experience side effects that patients in the Phase I clinical trial did not have.
If the new treatment seems to be effective against cancer in a certain percentage of patients, researchers may consider it successful enough to continue study in a Phase III clinical trial.
Phase III Trials – Study whether the new treatment is better than standard treatment
The goal of a Phase III trial is to compare the new treatment with the standard treatment. Researchers track whether a new treatment is better than, the same as, or less effective than the standard treatment.
Phase III trials may include hundreds to thousands of patients around the country or world. In general, each patient enrolled in a Phase III clinical trial has an equal chance of participating in one of two or more arms (groups) of the study. In a clinical trial with two arms:
The control group receives the standard treatment. The investigational or experimental group receives the new treatment being tested.
Neither the patient nor the doctor can choose whether the patient is in the control group or the experimental group. Regardless of which group a patient is assigned to, either he or she will receive the best standard treatment available or the new treatment that researchers believe is as good as, or better than, the standard treatment.
Single Blind versus Double Blind Trials
- Single blind studies: patients do not know whether they are in the experimental or control group
- Double blind studies: neither the patients nor the researchers know which patients are in each group (although this information is recorded and on file if needed)
Medicine and Healthcare Products Regulatory Agency (MHRA) Approval
The role of the MHRA is to make sure medical treatments are safe and effective for people to use. Researchers submit their clinical trial results to the MHRA, and based on the information, the MHRA may approve the drug or treatment. Then it becomes available to all patients and sometimes becomes the new standard treatment.
Phase IV Trials – Find more information about the new treatment
Phase IV clinical trials are not as common as Phase I, Phase II and Phase III trials. In Phase IV trials, researchers study drugs and/or treatments that have already received MHRA approval. The goal of Phase IV trials is to study how safe and effective a drug or procedure is over time.