Abstract OT2-03-01: Measuring the Impact of MammaPrint on treatment in breast cancer patients: A prospective registry (IMPaCt)

Background: Gene expression profiling in breast cancer offers the potential to improve prognostic accuracy, treatment choice, and health outcomes in women diagnosed with early-stage breast cancer. Numerous gene-profiling assays are now available, which can be applied to a single tumor specimen to provide physicians with a more complete basis for treatment decisions. • MammaPrint is 70-gene profile to estimate whether patients are at high or low risk of developing metastases within the first 10 years after curative surgery. • BluePrint is an 80-gene molecular subtyping profile that discriminates between three breast cancer subtypes: Luminal, HER2, and Basal. • TargetPrint provides a quantitative measurement of estrogen receptor (ER), progesterone receptor (PR), and HER2. Trial design: IMPACT is a prospective, case-only, study to measure the impact of MammaPrint on treatment decisions in breast cancer patients. The primary objective will be to measure the impact of MammaPrint on treatment decisions in stage I and II Hormone Receptor (HR)-positive, HER2-negative breast cancer patients. As a secondary objective, the impact of MammaPrint on treatment will be assessed in patients with T1a/bN0/1 (up 1 LN) Triple Negative or HER2-positive breast cancer. Baseline clinical data and physician chemotherapy intention before knowing the MammaPrint result will be entered in CRF 1. After completion of CRF1, the MammaPrint result will be released. CRF2 will be completed after the final treatment decision has been made. This CRF will capture physician chemotherapy intention after the MammaPrint result and the impact of these results. Eligibility: The study will include women aged ≥18 years with histologically proven invasive stage I-II, HR-positive, and HER2-negative breast cancer, OR, T1a/bN0/1 (up to 1 node) triple negative or Her2-positive breast cancer who signed informed consent. Objectives: Primary objective: Assess the impact of MammaPrint on chemotherapy + endocrine versus endocrine alone treatment decisions in HR-positive, HER2-negative breast cancer patients. Secondary objectives: • Assess the impact of MammaPrint on treatment decisions in T1a/b, N0/1 (up to 1 node) triple negative or Her2-positive breast cancer patients • Assess concordance of TargetPrint ER, PR and HER2 results with locally assessed IHC/FISH ER, PR and HER2 • Compare clinical subtype based on IHC/FISH ER, PR, HER2 and Ki-67 (if available) with BluePrint molecular subtype Statistical methods: A sample size of 331 patients is required to detect a 25% overall treatment change (5% significance and 95% power) in stage I and II HR-positive, HER2-negative patients. In addition at least 50 T1a/bN0/1 (up to 1 LN) Triple Negative, and at least 50 T1a/bN0/1 (up to 1 LN) HER2-positive breast cancer patients will be enrolled. A McNemars test will be performed for the comparison of the two proportions of treatment intentions (before and after), both expressed as a percentage. Accrual: The study did not yet start accrual. First patient visit is expected in August 2015. Approximately 15-20 institutions in the United States will participate. Citation Format: Hart LL, Untch S, Stork-Sloots L. Measuring the Impact of MammaPrint on treatment in breast cancer patients: A prospective registry (IMPaCt). [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 OT2-03-01.