Patients whose breast cancer cells have lost their ability to express a protein called "tau" are twice as likely to have a good response to Taxol treatment, the researchers report at the annual San Antonio Breast Cancer Symposium meeting.

The finding makes sense because tau promotes the assembly of microtubules, which provide structure to the cell and help it divide. Taxol works by binding to microtubules to form an inappropriately stable structure which ultimately leads to cell death. "In the absence of tau, Taxol stabilizes microtubules more easily," says the study's lead researcher, Lajos Pusztai, M.D., Ph.D., an associate professor in the Department of Breast Medical Oncology.

If validated in larger studies, the finding suggests that tumor tissue could be screened to predict if it will respond to Taxol, says Pusztai. "If it doesn't, perhaps other chemotherapy regimens would work better."

The results also suggest a way to improve the use of Taxol, Pusztai says. "If you block the effect of tau with an agent, you could possibly increase the effectiveness of Taxol in more patients, making them super responders."

The researchers came up with their discovery after examining breast cancer biopsy samples taken from 82 patients, 21 of whom had a complete disappearance of their cancer after Taxol-containing treatment. They looked at the difference between these responders and non-responders in 22,000 genes, and found that tumors were highly sensitive to treatment that had low levels of tau messenger RNA (mRNA) expression in their cancer cells. This observation was confirmed by examining tau protein expression using a routine pathologi
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Contact: Nancy Jensen
nwjensen@mdanderson.org
713-792-0655
University of Texas M. D. Anderson Cancer Center
8-Dec-2004