Drug, method show breast cancer promise

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SAN ANTONIO -- A novel way to speed cancer drug testing and quickly separate winners from duds has yielded its first big result: an experimental medicine that shows promise against a hard-to-treat form of breast cancer.

The method involves studying drugs in small groups of people and using advanced statistical techniques to analyze the results as they come in, instead of waiting for all the data to arrive.

Whether the drug, veliparib, ever makes it to market remains to be seen, but it has shown enough potential to advance to final-phase testing aimed at Food and Drug Administration approval.

Bringing a new cancer drug to market usually takes more than a decade and tests in thousands of patients, and it can cost more than $1 billion. Companies can't afford many studies such as that, and patients can't wait years for potentially lifesaving new medicines, said Don Berry, a biostatistician at the University of Texas MD Anderson Cancer Center. He helped design the novel analytical method discussed Friday at the San Antonio Breast Cancer Symposium.

Researchers testing a drug usually don't see results until they are all in, to prevent biasing the study. But several years ago, an unusual partnership decided to try a new way. It involves the National Cancer Institute, the FDA, drug companies, dozens of research centers and charitable foundations.

The study, called I-SPY 2, puts small groups of women on experimental drugs or combinations, then gives them surgery to see what effect the medicines had. The best result is a complete response, where no signs of cancer remain.

Each patient's results are analyzed as they come in, and advanced statistical methods are used to calculate probabilities that the drug would help in various situations, depending on which women had a complete response.

"This allows us to learn and adapt from each patient as the study goes on," and those results with early participants guide treatment that later ones get, said Hope Rugo, a clinical professor of medicine and director of the Breast Medical Oncology Clinical Trials Program at the University of California, San Francisco. When enough evidence indicates a high probability of success, the drug "graduates" to final-phase testing.

Researchers were able to determine the drug's potential after tests in only 71 women and just six months of treatment. They calculated that tests of only 300 women with triple negative tumors are needed to give a definitive answer, and that the drug has at least a 90 percent probability of success in such patients. If more types of cancer are included, the probability of success drops to 55 percent.


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