P3-04-06: Comparison of MammaPrint, BluePrint, and TargetPrint with Clinical Parameters in Patients with Breast Cancer: Findings from a Prospective United States Cohort.

Background: MammaPrint (MP) is a powerful predictor of disease outcome in early stage breast cancer. In addition, TargetPrint (TP), a quality approved microarray-based test that measures the mRNA expression level of ER, PR and HER2 and an 80 gene expression Molecular Subtyping profile BluePrint (BP) were developed. In the present study, MP, BP and TP were measured in a prospective U.S. breast cancer patient cohort. Methods: MP results were evaluated in fresh tumor samples from 141 breast cancer patients (T1-4N0-2; median age 62 [35-97 yr]) collected by core needle biopsy or from a surgical specimen between July 2008 and February 2011. We compared treatment advice as recommended by NCCN guidelines and classification according to MP. In addition, we compared IHC/FISHER, PR and HER2 assessments with TP. The MP and BP results were used to subtype the patients into molecular subgroups. Results: For the group of patients (n=69) for which NCCN recommends the use of a multi-gene signature for determining chemotherapy treatment recommendations, 50 patients were classified as High Risk and 19 as Low Risk by MP. Comparison of TP with IHC/FISH indicated a concordance of 98% for ER, 91% for PR, and 94% for HER2. For a subgroup of 63 patients combined MP and BP results were available; 22 patients were Luminal-type/MP Low Risk, 31 patients were Luminal-type/MP High risk, 1 patient was Her2-type/MP Low Risk, 2 patients were Her2-type/MP High Risk and 7 patients were Basal-type/MP High Risk. Conclusion: The multi-gene signature MammaPrint, as well as BluePrint and TargetPrint provides additional information for treatment guidance. By combining MammaPrint with the BluePrint molecular subtyping profile, specific groups of patients can be recognized that are at high risk of recurrence and that would possibly benefit from specific treatment. This study shows that TargetPrint provides high quality second opinion for local IHC/FISH assessment. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-04-06.