Skip to Content

What are Phase 1 Clinical Trials?

Developing new drugs involves four phases of clinical testing in cancer patients, ranging from Phase 1 to Phase 4. Phase 1 trials are the first stage of clinical testing and often involve drugs that have been tested extensively in the laboratory and on animals with encouraging results, but have not yet been given to humans. Patients in Phase 1 trials are sometimes the first to try new cancer drugs. 

clinical trials phases graph

Phase 1 trials only enroll a small number of participants, usually 15 to 100 patients, most of whom have advanced cancer that has not responded to standard cancer treatments. Trial participants are divided into small groups, known as cohorts. The first cohort receives a low dose of the new drug. Doctors may collect blood or urine samples to measure drug levels in the patients.

If the first cohort does not have any severe side effects, then a new cohort receives a higher dose of the same drug. The dose increases until the trial investigators find the best dose for future testing. With each increasing dose, doctors test each patient to see if he or she is responding to the treatment. If the doctors find that the treatment is safe, then it will advance to a Phase 2 trial.

The objectives of  Phase 1 trials include: 

  • Understanding the side effects of new drugs
  • Determining how the drug affects cancer cells in patients 
  • Observing patient response to the drug

At MD Anderson, drugs used in Phase 1 trials may have been developed by pharmaceutical or biotechnology companies. Some Phase 1 trials test new uses for drugs that have already been approved by the Food and Drug Administration, or test drugs given for the first time in combination. Drugs may also be administered in different ways, such as by regional therapy (infusing the directly into the liver for patients with liver metastases).

Some trials may be performed in collaboration with the National Cancer Institute (NCI) or the National Cancer Comprehensive Network (NCCN).  Many trials require frequent return visits to the Clinical Center for Targeted Therapy, mainly for safety monitoring. 

Request an Appointment

  • Call Yolanda Villanueva at 713-792-1160
  • Visit our Contact Us page for a checklist of information we'll need for your first appointment

Find Clinical Trials

Clinical trials are research studies that test new cancer drugs, diagnostic procedures and therapies on humans.


© 2014 The University of Texas MD Anderson Cancer Center