Clinical Trials: What You Need to Know

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Phase I clinical trials: Is the treatment safe?

Phase I studies of a new drug are usually the first that involve people. The main reason for doing phase I studies is to find the highest dose of the new treatment that can be given safely without serious side effects. Although the treatment has been tested in lab and animal studies, the side effects in people can’t always be predicted. These studies also help to decide on the best way to give the new treatment.

Key points of phase I clinical trials:

  • The first few people in the study often get a low dose of the treatment and are watched very closely. If there are only minor side effects, the next few participants may get a higher dose. This process continues until doctors find the dose that’s most likely to work while having an acceptable level of side effects.
  • The focus in phase I is looking at what the drug does to the body and what the body does to the drug.
  • Safety is the main concern at this point. Doctors keep a close eye on the people and watch for any serious side effects. Because of the small numbers of people in phase I studies, rare side effects may not be seen until later.
  • Placebos (sham or inactive treatments) are not part of phase I trials.
  • These studies usually include a small number of people (20 to 80).
  • Phase I trials may be reserved for those who have tried and failed current treatment options.
  • Often, people with different types of cancer can take part in the same study.
  • These studies are usually done in major cancer centers.
  • These studies are not designed to find out if the new treatment works against cancer.

Overall, phase I trials are the ones with the most potential risk. But phase I studies do help some patients. For those with life-threatening illnesses, weighing the potential risks and benefits carefully is key.

Here’s an example of how a typical phase I clinical trial might work:

Bruce was diagnosed with cancer 4 years ago. He was first treated with radiation therapy, but the cancer was later found to have spread to distant parts of his body. His doctor told him chemotherapy drugs A and B might help him. Bruce’s cancer shrank for a short time while he was taking drug A, but then it began to grow again. Drug B did not work for him.

Because Bruce is still fairly young, his doctor suggests he might want to consider trying a new form of treatment, “EX-1,” which is being studied in a phase I clinical trial at a nearby university hospital.

Bruce talks with the doctor conducting the study. The doctor explains that the drug being studied showed some promise in lab tests, but it is still unknown exactly how well it will work in people. What’s more, it might have side effects that haven’t been seen yet. After getting all of his questions answered and weighing his options, Bruce decides to take part in the study.

Because 3 people have already enrolled in the study and have had no major side effects, Bruce will be the first person to get a higher dose of the treatment. He will need to stay in the hospital overnight on the first night. This is both to watch for any unexpected reactions and to take blood samples every few hours so that doctors can figure out how long the treatment stays in his body. He will get to go home the next day, but must return regularly over the next few weeks to be watched closely until it’s time for the next treatment.


Last Medical Review: 09/25/2014
Last Revised: 10/31/2014