MedicalResearch.com Interview with: Steven Jay Isakoff, MD, PhD Hematology/Oncology Department of Medicine Massachusetts General Hospital Medical Research: What is the background for this study? What are the main findings? Dr. Isakoff: Metastatic triple negative breast cancer remains a challenging clinical problem with no specific therapies targeted validated for this population.  From a number of preclinical studies and because of a link between BRCA1 associated breast cancer and triple negative breast cancer, platinum chemotherapy has emerged as a potential chemotherapy with activity in triple negative breast cancer.  However, it is not yet clear how to predict which triple negative breast cancer patients are more likely to respond to platinum chemotherapy.  We set out to answer several questions.

• First, what is the response rate to platinum chemotherapy in the first or second line for metastatic triple negative breast cancer?
• Second, can we identify biomarkers to predict response to platinum agents?  The results of our study showed that among 86 patients treated with platinum chemotherapy (either cisplatin or carboplatin), the response rate was about 25%.  We identified 11 BRCA mutation carriers in our population and the response rate among carriers was about 55% compared to about 20% in the non-carriers.  In addition, we found that a new assay called the Hologous Recombination Deficiency assay, which may identify tumors with a BRCA-like phenotype, seemed to predict which cancers were more likely to respond, whereas other biomarkers we looked at were not able to do so.
• Another exciting finding was that 6 patients who had major responses have become long term responders with no subsequent progression, some whom for over 5 years so far.  Surprisingly, none of the long term responders are BRCA mutation carriers.

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