There are several phases of clinical trials in cancer immunotherapy. Because the overwhelming majority of immunotherapies are still in the experimental phase, this focuses on phases I, II, and III trials, the trials that occur before a treatment is approved. Each phase is designed to answer certain questions. As such, there are different factors related to each trial phase to take into consideration when choosing a trial that might be right for you.
Phase I trials are conducted to determine safety and to identify the optimal treatment dose. Many phase I trials represent the first time that a particular drug is being tested in patients. Although this entails some risks, there are always guidelines built into trials to ensure patient safety, such as provisions for conservative dose escalation and to terminate trials if there is evidence of serious adverse effects. Phase I trials are small and typically enroll 15 to 30 patients.
Phase II trials are larger trials to test for signs of clinical efficacy of a treatment, usually in a more defined cohort of patients, such as patients with a specific cancer type. Phase II trials are larger than phase I trials and may enroll up to 100 patients.
Phase III trials include large numbers of patients, often hundreds to several thousands, and are designed to test if a new treatment is better than the current standard of care. Often, phase III trials are randomized, which means that some patients will receive the experimental treatment and others, in the control group, will not. Regardless, all patients will receive the standard of care, whether they are in the treatment or control group.
New drugs must go through clinical trials before they can be approved by the U.S. Food and Drug Administration (FDA) and other regulatory agencies.