Breast Cancer Drug from Evergreen Tree Has Promise

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The breast cancer drug paclitaxel (Taxol®) was originally derived from an evergreen called the Pacific yew, and now researchers have discovered a potent drug from another evergreen tree. Maytansine has shown promise in trials on metastatic breast cancer, according to two new studies just published.

New breast cancer drug is in clinical trials

Approximately 155,000 women and men in the United States have metastatic breast cancer, the deadliest form of the disease, according to the Metastatic Breast Cancer Network. The overall estimated number of new cases of breast cancer in the United States for 2010 is 207,090, according to the National Cancer Institute and about 40,000 deaths will be related to the disease.

A collaborative effort between scientists at University of California Santa Barbara and the pharmaceutical industry has uncovered how the drug destroys cancer cells. Because maytansine, a molecule found in an evergreen in the genera Maytenus, was originally found to be too toxic to healthy cells, scientists added a breast cancer-targeting antibody that significantly reduces this danger. The new result is a drug called trastuzumab-DM1.

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Researchers “discovered how the drug is taken up into the tumor cells,” according to Mary Ann Jordon, a professor in the Department of Cellular, Molecular and Developmental Biology. The drug is “metabolized by the cancer cells, inhibits the dynamics of cellular microtubules, and thus blocks the mitosis of the spindles in the cells, causing them to die.”

When the protein filaments called microtubules become unable to grow and shorten, they also become unable to do what is necessary for cancer cells to divide and spread. Results of early clinical trials indicate that the drug reduced tumor size in one-third of patients in the breast cancer study.

Jordan explained that “although the drug is not yet approved by the FDA, current clinical trials are open to new patients.” Additional tests of the drug are being conducted in other cancers, including multiple myeloma and B-cell lymphoma, and results are good thus far. Anyone interested in learning more about clinical trials can visit the clinicaltrials.gov website.

SOURCES:
Metastatic Breast Cancer Network
National Cancer Institute
University of California Santa Barbara

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