How Long Do Clinical Trial Phases Take?

Before new therapies can be approved for use in the general public to treat cancer, they must go through several phases of clinical trials to ensure safety and effectiveness. In general, it usually takes around seven to ten years for a new study to go through all the phases of a clinical trial to approval, including clinical research before the trial is designed. So how long do clinical trial phases take?

Clinical trials move through phases 1-4. Phases 1-3 are the initial phases before the drug can be submitted for Food and Drug Administration (FDA) approval. After phase 3 is complete, pharmaceutical companies can apply for FDA approval. These applications can be a New Drug Application (NDA) or a biological license application (BLA). Once these applications are submitted, the FDA will review the results from the clinical trial and determine if the drug will be approved for use in the public.

How Long Do Clinical Trial Phases Take?

There are clinical trial phases 1-4, and each phase takes a different amount of time and requires a different number of participants.

Phase 1: In phase 1 of a clinical trial, about 20-80 healthy people participate in the trial who have no underlying health conditions. The reason for this phase is so that researchers can determine if the drug causes any severe side effects to participants. It also helps researchers determine the safe dose that can be given to participants. According to the FDA, 70 percent of medications move to phase 2.

Phase 2: Phase 2 of a clinical trial involves hundreds of participants who have the condition the medication is developed to treat. These participants are monitored closely for several months or years to understand the effect the medicine has on the disease and if any side effects develop in participants with the condition. According to the FDA, 33 percent of medications move on to phase 3.  

Phase 3: Phase 3 of a clinical trial usually involves a few thousand participants that have the condition the medication is meant to treat. This phase usually lasts for several years. The purpose of this phase is to evaluate the effectiveness of the drug in comparison to other treatments for the same condition. This phase is typically required before the new drug can be approved by the FDA. According to the FDA, 25 to 30 percent of medications move on to phase 4.

Phase 4: In phase 4, the drug has been approved by the FDA. The drug can be used commercially, but still requires additional long-term testing. This phase involves thousands of participants, takes place over several years, and is used to determine long-term safety and effectiveness.