What is a Phase 0 Clinical Trial?

Researcher filling vials

Origins of Phase 0

In 2004, growing concerns surrounding slow and costly drug development led the FDA to introduce the Phase 0 clinical trial, a new mechanism to accelerate and streamline the drug testing and approval process. This new approach, unlike conventional Phases 1, 2 or 3 trials, bridges the gap between initial drug testing and definitive efficacy studies. Its goal is to quickly identify how a drug works in patients and whether it should be fast-tracked for further development.

The Ivy Phase 0 Clinical Trial

The Ivy Brain Tumor Center is home to the largest Phase 0 clinical trials program in the world and the first of its kind for neuro-oncology. We have adapted the Phase 0 strategy to brain tumor patients and incorporated a clinical trial ‘trigger’ that advances Phase 0 patients into a therapeutic study arm only if the drug is having an effect in an individual patient.

This approach addresses the two most common reasons most drugs fail in brain tumor patients:

  1. Most new drugs are incapable of reaching the brain.
  2. Laboratory animal studies of new drugs paint an incomplete picture of how the drugs will perform in humans.

In a conventional Phase 1, 2, or 3 clinical trials, a patient may be on an experimental drug for months before learning that the therapy is ineffective. At the Ivy Center, we understand that time is the most important commodity for our patients. Therefore, our Phase 0 clinical trials match patients to first-in-class drug combinations, confirm drug effects within days of exposure, and only treat patients when therapies are active in a patient’s own tumor.


Before a planned operation to remove a recurrent brain tumor, a patient is matched to an experimental drug combination based on the genetics of archival tissue from their first surgery. They then receive a small exposure to this drug combination in the days before surgery. This limited drug exposure is enough so  that, when we remove the tumor, we can ask two important questions:

  1. Did the drug penetrate the tumor?
  2. Did the drug have its intended effect?

If the answer to both of these questions is yes, then the patient moves forward with receiving the drug combination therapeutically for a longer period of time – advancing to the next phase of the trial.


If the drug combination has no effect on the tumor, the patient can enroll in another clinical trial without losing time or receiving an ineffective treatment.


Ultimately, Ivy Phase 0 clinical trials mean that patients, regardless of diagnosis, can have individualized treatment in a fraction of the time and costs associated with traditional drug research and development.

Discerning doctor speaking to her patient

Benefits of a Phase 0 Clinical Trial

Learn More
Man typing on a laptop

Have questions?

View FAQs