Metastatic progression of breast cancer along with decreased mitochondrial cell death priming of breast cancer cells: a case report.

Metastatic breast cancer remains to be a major cause of cancer-related deaths in women. Exploring the molecular mechanisms to identify targetable alterations in progressing breast cancer and developing functional tools to predict therapy response in these patients are needed. In this report, we present a case of breast cancer patient who progressed following surgery and adjuvant endocrine therapy. Radiological and pathological analyses revealed metastasis to liver and brain. Paired liquid biopsies demonstrated acquired ERBB2 mutations in addition to TP53 and PIK3CA mutations, which were also present before progression. BH3 profiling test demonstrated decreased mitochondrial cell death priming in CTCs of the patient after progression. In conclusion, novel personalized treatment strategies are needed to monitor metastatic breast cancer patients for better clinical benefit.