Cancer Stats Don’t Add Up, But Numbers Do

Metastatic breast cancer drug eribulin fails to meet study objectives

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) By the time breast cancer spreads, women have usually had a number of different treatments. They may have been through more than one round of chemotherapy. A study of different chemotherapies has found somewhat puzzling results.

Eribulin mesylate (Halaven) is not more effective than capecitabine (Xeloda) in treating women with metastatic (has spread) breast cancer, a new study found.

This isn’t to say that eribulin isn’t useful for treating metastatic breast cancer. It is. The drug was particularly helpful for women with triple-negative breast cancer.

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Peter A. Kaufman, MD, associate professor of medicine at the Geisel School of Medicine at Dartmouth and the Norris Cotton Cancer Center, led the phase 3 multi-center study. He presented the results of this trial December 7 at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium.

“The study did not show a statistically significant benefit of eribulin over capecitabine, and it did not show a benefit in terms of progression-free survival [period of time the cancer doesn’t grow], so the overall study objectives were not met,” Dr. Kaufman said in a statement.

While the findings didn’t meet study objectives, the numbers tell a different story. Dr. Kaufman said, “Although we didn’t show a statistically significant superiority over capecitabine, which was our goal, numerically the overall survival with eribulin was better than with capecitabine.”

Breast cancer specialist, Christopher O. Ruud, MD, of the Austin Cancer Centers, told dailyRx News, “To frame the subject, metastatic breast cancer can be controlled for months to years. It is very useful to have another agent available when the tumor grows through prior treatment.”

For this study, 1,102 metastatic breast cancer patients were randomly assigned to receive eribulin or capecitabine. They had previously been treated with commonly used chemotherapy agents - anthracycline- and taxane-based therapy.

The study drugs were the first, second or third therapies the women received to treat their metastatic disease.

For women who received eribulin, median progress-free survival was 4.1 months vs. 4.2 months for capecitabine. Overall survival for those who got eribulin was 15.9 months, while those who received capecitabine lived a median of 14.5 months.

When researchers teased out the numbers and looked at women with aggressive breast cancers, eribulin showed positive results.

Researchers found that women with HER2-negative (HER2 protein not present in the tumor) the overall survival was better for women who received eribulin – 15.9 months vs. 13.5 months for women who took capecitabine.

The results for women with a particularly aggressive form of the disease – triple-negative breast cancer – were impressive. The median overall survival was 14.4 months with eribulin compared to 9.4 months for those taking capecitabine.

The authors put the somewhat confounding results into perspective. “In this Phase III trial, eribulin demonstrated a trend favoring improved OS [overall survival], compared with capecitabine, although this improvement does not meet the pre-defined criteria for statistical significance. This study confirms eribulin as an active drug in patients with MBC [metastatic breast cancer], and exploratory analyses suggest possible benefits of eribulin in specific subsets of patients, sufficient to warrant further study.”

Eribulin was approved by the US Food and Drug Administration in 2011 to treat metastatic breast cancer. All research is considered preliminary before it’s published in a peer-reviewed journal.

Reviewed by: 
Review Date: 
December 6, 2012
Last Updated:
December 10, 2012