Understanding Clinical Trial Phases

Tennessee Cancer Specialists offer Phase II and Phase III clinical trials. If your medical team suggests a clinical trial for you, you will be made aware of the phase and what you may want to consider before agreeing to participate. 

A clinical trial is categorized as one of four different phases. Most investigational cancer treatments are typically evaluated in Phases 1, 2 and 3 trials to determine if they are effective and well tolerated.

Some cancer treatments are tested in Phase 4 clinical trials after they have been approved by FDA to provide additional information about the treatment’s risks, benefits and optimal use. 

The use of a placebo, or inactive medications, are never used in place of the best-known standard of care. If they are used, they are given alongside an active medication. Patients can rest assured that they are receiving treatment when participating in a trial.

Phase 1:
First time testing mainly to evaluate its safety
  • Typically includes up to 60 people with a particular cancer diagnosis or cancer mutation profile.
  • Every patient will receive the investigational drug (there is no placebo).
  • Since less is known about the investigational drug, there are more frequent visits, including additional blood tests and procedures in order to learn about the effects of the investigational drug.
  • A Phase 1 trial may test:
    • Dosage range and schedule
    • Side effects
    • Early signs of effectiveness against the cancer
Phase 2:
Test safety as well as whether an investigational treatment is effective for a specific type of cancer
  • Study participants are typically assigned to different groups, where each group gets a different dose or schedule to provide information about which works best with tolerable side effects.
  • Phase 2 trials involve more study participants than the Phase 1 trials but usually include fewer than 100 people with cancer who meet specific requirements for entry into the trial.
Phase 3:
Compare an investigational treatment to the current treatment(s) available for that type of cancer
  • Much larger trial than a Phase 1 or 2 trial and can include thousands of study participants randomized to receive either the investigational treatment or the standard treatment that is already available for their type of cancer.
  • In most cases, neither the study investigators or the patient knows which cancer treatment they are receiving (called double-blind) so results cannot be influenced with conscious or unconscious bias.
  • Typically, a Phase 3 clinical trial needs to show that the investigation treatment is better than the existing treatments to obtain FDA approval.
Phase 4:
Tested after it has been approved by the FDA for a specific use
  • These trials are conducted to collect information about long-term effects on the patient’s quality of life, length of life and long-term side effects.
  • Phase 4 trials may also be used to test new combinations of approved therapies to determine if outcomes are better.