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Study Shows AstraZeneca's New Breast Cancer Drug Works Better

Posted on: Thursday, 9 December 2004, 15:00 CST

Dec. 9--A newer breast cancer drug that outperforms industry-standard tamoxifen should replace it as first-line therapy for postmenopausal patients, according to a new international study.

The University of Texas M.D. Anderson Cancer Center and other researchers reported Wednesday that women who took Arimidex were less likely to have their breast cancer come back, less likely to have it spread and less likely to have serious side effects.

"I hope with this new data doctors start using Arimidex as their new first choice," said Dr. Aman Buzdar, a professor in M.D. Anderson's department of breast medical oncology and the lead investigator for the North American portion of the study. "It's the better drug."

Buzdar, who presented the research Wednesday at the San Antonio Breast Cancer symposium, said he thought "the days of tamoxifen are gone." The findings of the study were also published online by the British medical journal The Lancet.

Tamoxifen, which revolutionized breast cancer treatment when it came out three decades ago, is taken by about three-quarters of postmenopausal women with breast cancer. The drug, which blunts estrogen's ability to fuel cancer growth, cuts in half the risk cancer will recur.

But the five-year study of more than 9,000 patients in 21 countries found Arimidex cut the risk of recurrence by 70 to 80 percent. In addition, women taking it had less bleeding and fewer blood clots, strokes and uterine cancers.

Arimidex, made by AstraZeneca, is one of a new class of breast cancer drugs called aromatase inhibitors (the others are Pfizer's Aromasin and Novartis AG's Femara). They work by preventing estrogen from being made in the first place.

The study included women who had cancer diagnoses that had not spread to the lymph nodes and that had been treated with surgery. The women were divided into three groups -- those who took tamoxifen, those who took Arimidex and those who took both. Three years into the study, the last group was disbanded because treatment showed no benefit.

The benefits for those on Arimidex versus tamoxifen included a 10 percent increase in the number of patients who remained disease-free; a 20 percent increase in the overall time until there was a recurrence; a 40 percent reduction in the spread of the cancer to the other breast; and a 14 percent reduction in the spread of the cancer to other sites in the body.

The study didn't show significant improvement in overall survival rates, even though 13 percent fewer cancer deaths occurred among Arimidex users (a number Buzdar said could have resulted from chance). Doctors said women in the study had such early-stage cancers that more time is needed to determine if one drug had better survival rates.

Arimidex only works on women whose breast cancer is hormone-receptor-positive, which amounts to about three-quarters of breast cancers. The other type is estrogen-receptor-negative.

In another promising breast cancer development at the San Antonio conference, M.D. Anderson researchers reported that a gene therapy reduced tumor size an average of nearly 80 percent in advance of surgery.

The therapy, known as Advexin, is injected directly into the tumor site. Researchers found evidence it replaced damaged tumor-suppressing p53 genes with healthy genes, and produced beneficial and possibly sustained local immune responses in the patients tested.

In the study, 12 patients with inoperable Stage 3B cancer who had injections followed by chemotherapy had their tumors shrink significantly.

The result meant many of the patients could have a lumpectomy (removal only of the tumor) instead of a mastectomy (removal of the breast). The study also found that tumors in lymph nodes decreased in size.

The World Health Organization says 1.2 million people will develop breast cancer this year. In the United States, 40,000 will die of it.

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AZN, PFE, NVS, NOVN,

Source: Houston Chronicle

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