Clinical Trial Phases

For a new drug to be approved by the FDA for use on humans, it must first undergo rigorous testing. This drug development process is made up of four different phases. Each phase is designed to test a potential treatment’s risk, safety and effectiveness against standard therapies with hopes of improving on any of those markers. Multiple centers across the country are often involved in conducting each study to expedite development of a cure.

Phase I Trials:

Phase I is the most important step in the development of a new drug or therapy. During this phase, a treatment’s safety, dosage, and side effects are determined. Phase I trials involve a small number of patients (20-80) for whom standard therapies have proven ineffective or for whom alternative therapies are unavailable. Prior to being tested in a Phase I trial, a treatment has been tested at length in the lab on animals, and the drug has been deemed safe for use in humans. While Phase I trials may be beneficial for patients, their primary goals are to determine a drug’s safety and adequate dosing and schedule of administration. These trials often involve blood or tissue testing to evaluate the drug’s mechanism of action and pharmacology.

Phase II Trials:

A trial enters Phase II testing after it has been found safe during Phase I testing. Phase II trials determine the effectiveness of a treatment in a specific patient population at the dose and schedule determined during Phase I testing. The number of patients participating in a Phase II trial will be higher than in Phase I, and assuming Phase II trials are successful, the treatments will become standards of care or enter Phase III testing (100-200 patients.)

Phase III Trials:

These trials involve a much larger number of patients (several hundred to a thousand) and are the final stage of drug development leading to FDA approval and becoming a “standard of care therapy.” These trials serve as the primary basis of a drug’s approval for use in a given cancer. They are often conducted by large pharmaceutical companies across many countries and serve as a final test of a drug’s safety and efficacy.

Phase IV Trials:

Phase IV trials begin after a treatment has been approved by the FDA. In Phase IV clinical trials, the treatment will be given to a much larger group of patients and additional information will be gathered regarding its effectiveness, previously unidentified side effects and safety issues that may have been difficult to observe in a smaller sample of patients.


To learn more, please contact our Clinical Research Coordinator, Danielle Poliski at (616)-954-9800 ext. 2107
or the Clinical Research Coordinator, Penny Berger at (616)-954-9800 ext. 2041