Comparing MammaPrint and BluePrint results between core needle biopsy and surgical resection breast cancer specimens

ABSTRACT

Goals The COVID-19 pandemic continues to strain healthcare systems globally. The ESMO COVID-19 adapted recommendations1 advocate for the use of pre-operative/neoadjuvant endocrine therapy as a strategy to defer surgery by 6–12 months in clinical stage I-II breast cancers to prioritize resources for patients that require urgent care. Accurate risk assessment is an integral component of this prioritization process. Adjuvant studies such as MINDACT showed that up to 46% of clinically high risk tumors were classified as genomic Low Risk with MammaPrint, and still have excellent outcomes at 8-yrs with endocrine therapy alone, highlighting the potential for overtreatment if using clinical-risk alone. Here, gene expression results with MammaPrint (MP) and BluePrint (BP) were compared between pre-operative core needle biopsy (CNB) and postoperative surgical resection (SR) specimens to evaluate test performance across specimen type. Methods: 10,574 routine diagnostic samples from outside the US submitted to Agendia between Jan 2017 and Oct 2020 were included in this study.MP and BP testingwere processed according to standard FFPE microarray procedures. MP was used to stratify samples into Ultra LowRisk (UL), LowRisk (LR), and High Risk (HR). BPwas used to classify samples into Basal, Luminal or HER2-type. MP Index (MPI) distribution on BP defined Luminal-type tumors were compared between CNB and SR samples. Comparative “logistics metrics” (avg. turnaround time [TAT] and success rate) were also assessed between these specimen types. Results: 10% of samples were CNB and 90% were SR (Table 1). BP Basal, Luminal and HER2-type distributions were 2%, 97%, and 1% respectively for CNB samples and 1%, 98.6%, and 0.4% respectively for SR samples. Within Luminal-type tumors (majority of the samples), the frequency of UL, LR, and HR results were 14%, 61%, and 39% for CNB, and 13%, 58%, and 42% for SR, respectively. Overall, MP Index distributions were similar between samples tested from CNB vs. SR. Average TAT and success rate % between CNB and SR were similar (Table 2).(Table Presented)Definitions Turnaround Time (TAT) is calculated from the time a specimen is received at the laboratory to the time a result is available. Success % excludes test failures due to insufficient RNA yield % and sub-optimal RNA quality, and evaluates the total number of specimens that have met the pre-requisite 30% minimum invasive tumor requirement that have a valid result. Conclusion(s) The frequency of each MP risk group as well as the distribution pattern of MP Index were essentially identical between CNB and SR samples, indicating comparable performance regardless of specimen type. With timely TAT and no meaningful difference in MPI distribution between CNB and SR specimens, pre-operative use of MP+BP genomic testing on CNB can be incorporated into the preoperative treatment decision making process. Conflict of Interest Employee of Agendia, equity/stock ownership interest.