Phase 1 clinical trials have greater response rates than had been previously believed

A new study by the Department of Clinical Bioethics at the National Institutes of Health, has found that twice as many cancer patients testing medications in early, phase 1 clinical trials have positive response rates than had been previously believed. The response rates varied from zero to nearly 30 percent, and one in 10 study volunteers saw some improvement in their disease.

Previous studies have shown response rates in oncology trials are low, about 5 percent, and toxicity is high.This has prompted an ethical debate because the benefits are so low, said Christine Grady, head of the section on human subjects research. There is the contention that patients with advanced disease in risk-research studies, exploits a vulnerable population. Often patients enter clinical trials with a mixture of hope and fear.

Phase I clinical trials assess a drug's proper dosage, how the body metabolizes the medication and what side effects occur.

Cancer patients often enroll in phase I trials out of desperation because nothing else has worked.

The new research found response rates were much higher, toxicity was lower; the universe of phase I oncology trials is much more diverse than once thought.

Contrary to popular belief, most drugs used in phase I trials have been used in humans before. Many of the trials include drugs that are already approved by the FDA, but are being tested in a new combination.

The researchers looked for response rates and toxicity in each study. Responses rates were classified into three categories: complete response, which meant the disappearance of a tumor; partial response, which meant a 50 percent reduction in tumor size; stable disease or less-than-partial response.

Rates of complete and partial response went as high as 27 percent in some studies, but the overall response rate was 10.6 percent -- 7.5 percent with a partial response and 3.1 percent with a complete response.

Of 11,935 study volunteers, 58 deaths were thought to be related to trial medications -- a rate of 0.49 percent. The highest toxicity -- 0.77 percent -- was reported in trials that combined an investigational medication with an already FDA-approved medication.

The highest death rates still occur in chemotherapy trials.

Dr. Jay Brooks is chairman of hematology and oncology at the Ochsner Clinic Foundation Hospital in Baton Rouge, La.He feels the most important information for a physician referring patients to cancer trials, is the safety of the drugs. "We need to know that we're not killing patients with these drugs."

Some of the new medications being tested are having dramatic effects and response rates are improving.

Patients entering a phase I trial should have a clear understanding of the drug that's being tested and how many people already have already tried it. Expectations must be appropriate.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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