Tumor BRCA1 Reversion Mutation Arising During Neoadjuvant Platinum-Based Chemotherapy in Triple-Negative Breast Cancer Is Associated with Therapy Resistance. Clinical cancer research : an official journal of the American Association for Cancer Research Afghahi, A., Timms, K. M., Vinayak, S., Jensen, K. C., Kurian, A. W., Carlson, R. W., Chang, P., Schackmann, E. A., Hartman, A., Ford, J. M., Telli, M. L. 2017


In germline BRCA1 or BRCA2 (BRCA1/2) mutation carriers, restoration of tumor BRCA1/2 function by a secondary mutation is recognized as a mechanism of resistance to platinum and PARP inhibitors, primarily in ovarian cancer. We evaluated this mechanism of resistance in newly diagnosed BRCA1/2-mutant breast cancer patients with poor response to neoadjuvant platinum-based therapy.PrECOG 0105 was a phase II neoadjuvant study of gemcitabine, carboplatin and iniparib in patients with stage I-IIIA triple-negative or BRCA1/2 mutation-associated breast cancer (n=80). All patients underwent comprehensive BRCA1/2 genotyping. For mutation carriers with moderate or extensive residual disease after neoadjuvant therapy, BRCA1/2 status was re-sequenced in the residual surgical breast tumor tissue.Nineteen patients had a deleterious germline BRCA1/2 mutation and 4 had moderate residual disease at surgery. BRCA1/2 sequencing of residual tissue was performed on three patients. These patients had BRCA1 1479delAG, 3374insGA and W1712X mutations, respectively, with loss of heterozygosity at these loci in the pre-treatment tumors. In the first case, a new BRCA1 mutation was detected in the residual disease. This resulted in a 14 amino acid deletion and restoration of the BRCA1 reading frame. A local relapse biopsy four months later revealed the identical reversion mutation, and the patient subsequently died of metastatic breast cancer.We report a BRCA1 reversion mutation in a newly diagnosed triple-negative breast cancer patient that developed over 18 weeks of platinum-based neoadjuvant therapy. This was associated with poor therapy response, early relapse and death.

View details for DOI 10.1158/1078-0432.CCR-16-2174

View details for PubMedID 28087643