Abstract PS6-19: Comparing MammaPrint and BluePrint results between core needle biopsy and surgical resection breast cancer specimens

Abstract

Abstract Background: Pre-operative/neoadjuvant treatment utilization in early-stage breast cancer has been increasing, particularly during the COVID-19 pandemic. With goals of minimizing potential exposure to SARS-COV-2, as well as resource rationing, physicians are urged to triage breast cancer patients by identifying those that require urgent surgical care vs. those who may delay surgical treatment.1 Accurate risk assessment is an integral component of this triaging process, which has recommended that genomic testing on diagnostic core needle biopsy (CNB) samples be used to assist with the identification of patients with low risk tumor biology who may be candidates for surgical delay.1 MammaPrint (MP), a 70-gene risk of recurrence signature, and BluePrint (BP), an 80-gene molecular subtyping signature, have been routinely used in formalin-fixed paraffin embedded (FFPE) CNB and surgical resection (SR) samples since MammaPrint obtained FDA clearance for FFPE tissue in 20152. In addition, over 1,500 CNB tumor samples from patients enrolled in prospective neoadjuvant treatment trials (NBRST and ISPY-2) have received successful MP & BP testing. This study compares the gene expression results between CNB and SR specimens to better elucidate how these tests perform across specimen type. Methods: Routine diagnostic samples submitted to Agendia, Inc. (Irvine, CA) between Feb 2017 and May 2020 for MP and BP testing were processed according to standard FFPE microarray procedures. MP was used to stratify samples into Ultra Low Risk (UL), Low Risk (LR), and High Risk (HR). BP was used to classify samples into Luminal, HER2, or Basal-type. This study included 13,603 CNB and 25,684 SR specimens. MP Index (MPI) distribution on BP defined Luminal-type tumors were compared between CNB and SR samples. Comparative “logistics metrics” (average turnaround time [TAT] and success rate) were also assessed between these specimen types. Results: Of the 39,287 samples included in this analysis, 35% were CNB and 65% were SR (Table). BluePrint Luminal, HER2 and Basal-type distributions were 86%, 4%, and 10% respectively for CNB samples and 94%, 1%, and 5% respectively for SR samples. Within BP defined Luminal-type tumors, the frequency of UL, LR, and HR results were 18%, 58%, and 42% for CNB, and 16%, 60%, and 40% for SR, respectively. Overall, MP Index distributions were similar between samples tested from CNB vs. SR. Average TAT between CNB and SR were 4.52 and 4.55 days, respectively. For specimens that met the minimum tumor % threshold, successful testing rates for CNB and SR were 97.5% and 98.4%, respectively. Conclusions: MP and BP testing were successfully performed on both CNB and SR samples in approximately 98% of all eligible specimens with rapid TAT allowing for timely pre-operative decision-making. The frequency of each MP risk group as well as the distribution pattern of MP Index were nearly identical between CNB and SR specimens, indicating comparable performance regardless of specimen type. With no meaningful difference in MPI distribution, TAT or success rate between CNB specimens and SR specimens, pre-operative use of MP+BP genomic testing is feasible, in alignment with recent COVID-19 pandemic guidelines.