Abstract P4-13-24: Impact of genomic medicine on clinical decision making in patients with advanced breast cancer at two academic medical centers

Background: A deeper molecular understanding of cancer biology has led to the development of therapies targeting driver mutations. Genomic profiling of tumors is commercially available and has become integrated into many clinical practices as part of a paradigm shift towards personalized care of cancer patients. The current impact of genomic profiling on clinical decision making for patients with advanced breast cancer is not well described. Methods: Patients with metastatic breast cancer (mBC) who had tumors submitted for commercial genomic analysis from 2013-2015 were identified consecutively at two large academic cancer centers with genomic basket trials open for the majority of the collection period. Demographics, tumor pathology, clinical, and treatment histories were extracted through medical chart review as per an IRB approved protocol. Data from genomic analysis reports was extracted including number and type of mutations, FDA approved therapies and clinical trials available. Genomic analysis was determined to have impacted clinical decision making if the next line of therapy was influenced either by accrual to clinical trial, or a decision to prescribe an FDA-approved therapy. The most frequent somatic mutations and their relative frequencies were determined. Results: A total of 82 patients with mBC who had undergone commercially available genomic testing were identified. The median age was 49 (range: 29-70). 42 patients (51%) had ER-positive HER2-negative disease, 33 (40%) had ER-negative HER2-negative disease, 4 (5%) had ER-negative HER2-positive disease and 3 (4%) had ER-positive HER2-positive disease. The median number of lines of therapy received prior to genomic profiling was 2 (range 0-15). Genomic analysis reports suggested that 61 (74%) of these patients had at least one FDA approved medication available for at least one somatic mutation, and 79 (96%) had at least one clinical trial available (39 (46%) in the same state, 11 (13%) in the same institution). Genomic testing influenced management in 8 patients (10%), with 6 patients (7%) experiencing a change in next line of therapy attributable to genomic information. In 74 patients (90%), genomic testing results did not affect clinical decision-making. The most frequently observed somatic mutations included: TP53, PI3KCA, MYC, CCDN1, FGF, ZNF703, GATA3, ARID1A, MCL1, PTEN, MYST3, and BRCA1. Conclusions: Genomic testing did not affect management in the vast majority of mBC patients treated at two major academic cancer centers. Furthermore, the most identified mutated genes found were not targetable. The real world clinical utility of genomic analysis remains limited in breast cancer but may influence clinical decision making in a minority of patients. Citation Format: Kruse ML, Santa-Maria CA, Raska P, Swoboda A, Jain S, Sohal D, Moore H, Budd GT, Abraham J, Montero AJ. Impact of genomic medicine on clinical decision making in patients with advanced breast cancer at two academic medical centers. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-24.