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A new genomic test shows promise as a predictor of chemotherapy response and survival benefit in women with invasive breast cancer, according to research led by The University of Texas MD Anderson Cancer Center in Houston.1

The test combines multiple signatures, including a patient's estrogen receptor (ER) status, endocrine therapy response, chemotherapy resistance, and sensitivity. The findings may also help determine patients for whom standard therapy alone may not be enough, as well as identify those who may benefit from a clinical trial.

The multicenter study enrolled 310 newly diagnosed women with invasive stage II or III breast cancer (discovery cohort). All were human epidermal growth factor receptor 2-negative and received sequential taxane and anthracycline, followed by endocrine therapy if they were hormone receptor positive. Gene expression microarrays from the discovery cohort were used to develop predictive signatures for drug resistance and response.

The primary endpoint was distant relapse-free survival (DRFS) and absolute risk reduction (ARR). The median follow up was 3 years. The algorithm had a positive predictive value of 56%. In the 28% who were predicted to be treatment-sensitive, their 3-year DRFS was 92%, while their ARR was 18% with a 5-fold risk reduction of distant relapse.

When researchers analyzed ER status, treatment sensitivity was predicted in 30% of the ER-positive women and in 26% of those who were ER negative. After 3 years, DRFS and ARR were 97% and 11%, respectively, in the ER-positive cohort compared with 83% and 26%, respectively, in the ER-negative cohort.

Lajos Pusztai, MD, PhD, a professor in the department of breast medical oncology at MD Anderson and an author of the study, notes that treatment at diagnosis offers the greatest chance for cure and that many potential clinical trials using novel therapeutics and targeted agents are available for breast cancer. Physicians do not know, however, who they are curing with chemotherapy and who also would benefit from novel therapies, he adds.

If these findings are validated in future studies, they could be used as a guide to determine the selection of standard chemotherapy and clinical trials for those at greater risk of recurrence, Dr. Pusztai says.

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