The last issue of The ASCO Post reports encouraging results with platinum-based treatment of triple-negative breast cancer (September 15, 2013).
We predicted these findings 4 years ago in a presentation at the 2009 Breast Symposium.1 We compared the activity of a series of agents (platinum, taxane, alkylating agent, and anthracycline) tested in cell cultures of fresh biopsy specimens of triple-negative breast cancer, in comparison with the activity in non–triple-negative breast cancer, previously untreated ovarian cancer, platinum-resistant ovarian cancer, and late-relapse ovarian cancer.
We reported the following conclusions:
1. Estrogen receptor (ER)-negative breast cancer is dramatically more sensitive to cisplatin than is ER-positive breast cancer.
2. HER2-negative breast cancer is slightly more sensitive than is HER2-positive disease.
3. ER-negative/HER2-negative breast cancer is more sensitive than is ER-negative/HER2-positive disease.
4. Poorly differentiated breast and ovarian tumors are more sensitive than are moderate and well-differentiated tumors.
5. Non–triple-negative breast cancer subsets are more resistant to cisplatin than are cases of platinum-resistant ovarian cancer.
6. Triple-negative breast cancer is equally sensitive to cisplatin as is previously untreated ovarian cancer, and cisplatin is the most active of the four tested drugs in triple-negative breast cancer.
It is gratifying to see the clinical validation for our prediction based on cell culture testing. With regard to the “exciting new assays coming down the pike to help us identify which patients may respond to platinum agents,” there is a very impressive peer review literature confirming the predictive value of fresh tumor cell culture assays with cell death endpoints to reliably predict for the clinical benefit of platinum agents in human neoplasms. These latter tests are already available from licensed clinical laboratories; however, in the absence of results from individualized cell culture testing, the markers that best identify breast cancer patients for platinum therapy are ER-negative, HER2-negative, and Bloom-Richardson Grade 9/9 (data shown in abstract.1) ■
—Larry Weisenthal, MD, PhD
Huntington Beach, California
Disclosure: Dr. Weisenthal reported no potential conflicts of interest.
1. Weisenthal L: Activity of cisplatin in triple-negative breast cancer in comparison to other cancer types in fresh tumor cell culture assay using a cell death endpoint. 2009 Breast Cancer Symposium. Abstract 61. Presented October 8-10, 2009.