What is a clinical trial?

A clinical trial is a scientific method for testing new treatments in people with a disease or medical condition, such as NHL, psoriasis, or asthma. New treatments studied in a clinical trial can range from new drugs, new biologics (such as monoclonal antibodies, like Rituxan), new surgical or radiological techniques, or new combinations of current therapies. Before a patient ever participates in a clinical trial the investigator explains to the patient the potential benefits if any, and risks, if any, of participating in the trial and asks the patient to provide his or her informed consent. New treatments under study have undergone preclinical testing in the laboratory with animals. If the treatment appears safe, it is then given to human patients in what is called a Phase I clinical trial. Typically, but not always, there are three phases of clinical trials—Phase I, II, and III—and each phase answers different questions about the new treatment.

Phase I
During this stage of the clinical trial researchers are looking primarily at two factors: 1) Is it safe or are there harmful side effects? 2) What is the largest safe dose? How often can the agent be given safely? A Phase I clinical trial involves a relatively small number of patients, typically ranging from 25 to 50 individuals, who would not be helped by any other treatments.

Phase II
With some insight into safety from Phase I, researchers turn their focus to learning if their treatment is clinically active. As in the case of an anti-cancer treatment, does it reduce the size of tumors significantly (i.e.: greater than 50%)? Does it shrink less than 50% but arrest tumor growth? Or does it have no effect on tumor size or tumor growth? Again, only a limited number of patients take part in a Phase II clinical trial—approximately 25-100 people—because of the unquantified risks associated with administering an experimental treatment to patients who are often in poor health.

Phase III
If treatment continues to show promising results, it will go into a Phase III clinical trial often involving hundreds of individuals. To avoid bias, researchers will put patients randomly into either a treatment group, which will receive the new treatment, or into a control group, which will receive the conventional therapy or a “no therapy” placebo in circumstances where no treatment is acceptable medical practice. In some cases, the new treatment may be compared to historical response rates to a standard treatment.