What are Phase 1 clinical trials?

Clinical trials are human studies designed to ethically evaluate new treatments. The assessment of new cancer treatments progresses through several phases, beginning with Phase I trials.

Phase I trials look at how well a new treatment is tolerated and are used to determine the highest dosage of a drug that can be safely given to patients. In general, Phase I trials evaluate new drugs that have shown promising activity in the lab and in animal models and/or new drug combinations. Phase I trial participation can be offered to patients who have advanced cancer that cannot be treated effectively with standard treatments or for which no standard treatment exists.

During a Phase I trial a new drug, combination of drugs or therapy is tested on humans for the first time following the laboratory studies, so these trials may be riskier compared to Phase II or III trials. For this reason, Phase I trials usually involve only a small number of people with cancer (about 15–30) who are not getting better with the standard treatment. Phase I trials are not always specific to one type of cancer and may involve people with different types of cancer. The first few patients on the trial will receive a very low dose of the treatment and will then be closely monitored. Based on the observed side effects, the next group of patients will receive a higher dose. This process continues until the right dosage is determined.

Phase I trials may also test an already approved drug or therapy to try and improve its effectiveness or see if it can be used in a different way. For example, a Phase I trial may test a drug or therapy that is already used for another disease or type of cancer. Phase I studies try to answer basic questions such as how should a treatment be given, how often should it be given, what is the safest and highest dose a patient can tolerate, what are the side effects and effects on the body.

The dose and schedule that researchers find most effective with tolerable and reversible side effects in a Phase I trial is then used to determine the dose and schedule of a Phase II trial.

Phase I trials are the first step towards finding a way to better the outcomes for cancer patients. They answer important questions and further the science and research behind cancer treatments.

Patient-Related Links

Find an Open Clinical Trial

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News & Events

World Cancer Day – Trevor's Story

Trial Terminology

Control Group / n. – a group of participants receiving the standard of care or treatment or a placebo whose results will be used as a comparison against the results of the participant group receiving the investigational treatment.