FDA approves prognostic test for high-risk breast cancer

March 19, 2008

The Food and Drug Administration recently approved the TOP2A (topoisomerase 2 alpha) FISH (fluorescent in situ hybridization) pharmDx (Dako Denmark A/S, Glostrup, Denmark), a new genetic test that can detect alterations in the TOP2A gene in breast cancer cells derived from removed tumors; alterations signal an increased likelihood of tumor recurrence and decreased long-term survival.

The Food and Drug Administration recently approved the TOP2A (topoisomerase 2 alpha) FISH (fluorescent in situ hybridization) pharmDx (Dako Denmark A/S, Glostrup, Denmark), a new genetic test that can detect alterations in the TOP2A gene in breast cancer cells derived from removed tumors; alterations signal an increased likelihood of tumor recurrence and decreased long-term survival.

The test, which has been studied in 767 women at 21 centers in Denmark, is suitable only for premenopausal women and those with characteristics, such as tumor size or lymph node involvement, that suggest a higher likelihood of tumor recurrence or decreased survival.

The hope is that the information gleaned from the test, combined with other clinical data and laboratory test results, will better guide health-care professionals and their patients in choosing the most appropriate therapeutic course.

Commentary by Victoria L. Green, MD, MBA, JD, Associate Professor, Department of Gynecology and Obstetrics, Emory University, Atlanta, GA.

Specific proteins such as TOP2A, may help predict patient response to certain anthracyclines. Additionally, TOP2A appears to correlate with HER2 overamplification (another predictive marker). That said, we must wait for further research on the clinical value of this test procedure. Although in one study there was 100% concordance between TOP2A and HER2 overamplification, other studies have shown a 20% lack of concordance.