On June 7, 2016 Agendia, Inc., a world leader in personalized medicine and molecular cancer diagnostics, reported that it has presented new prospective data for its MammaPrint 70-gene breast cancer recurrence assay at the 2016 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago, Illinois (Press release, Agendia, JUN 7, 2016, View Source [SID:1234513121]).

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Results from the Prospective study Of MammaPrint in breast cancer patients with an Intermediate recurrence Score (PROMIS) show that MammaPrint can provide clear guidance on whether a patient should receive chemotherapy, compared to the indeterminate results from 21-gene assay (OncotypeDx). MammaPrint provides a definitive, binary High or Low Risk result for a patient’s cancer recurring and thus whether the patient needs more aggressive, or less aggressive therapy.

Between 38-67% of women tested in different studies using the 21-gene assay were classified as having an intermediate/indeterminate Recurrence Score (between 18 and 30).1 PROMIS evaluated 840 estrogen receptor (ER)-positive, lymph node (LN) positive or LN negative women across 58 US institutions who had previously received an intermediate/indeterminate risk score from the 21-gene assay. Patient samples were re‑tested using MammaPrint to refine the risk classification and provide additional treatment guidance.

Of the 840 intermediate risk patients, MammaPrint reclassified 55% (466) of these patients as High Risk and 45% (374) as Low Risk of the individual’s cancer recurring. No correlation between definitive MammaPrint results or the indeterminate 21-gene assay Recurrence Score could be identified, reinforcing the discordance between these assays and inability to use the results interchangeably. MammaPrint was shown to provide additional prognostic information independent from clinicopathological factors to support the treatment decision.

Based on the outcome of the MammaPrint test, 34% (282/840) of physicians changed their treatment decisions, preventing both under and over treatment: 37% (171/466) of the high risk patients had chemotherapy added to their treatment recommendation and 29% (108/374) of the low risk patients had chemotherapy removed from their treatment recommendation. Of the MammaPrint Low Risk patients who were previously indicated to receive chemotherapy based on the 21-gene assay results, 76% of patients (108/142) decided to forego chemotherapy, preventing unnecessary overtreatment in this group.

Medical oncologist Dr. Michaela Tsai from the Virginia Piper Cancer Center, Minneapolis, MN and primary author of the PROMIS poster commented, "Of 466 intermediate patients reclassified as High Risk by MammaPrint, 342 have an Recurrence Score ≤25 and were not recommended for chemotherapy by St. Gallen Guidelines (Goldhirsch, Winer et al. 2013), risking up to a 73% chance of under-treatment." She also noted, "79% of physicians reported that they had greater confidence in their treatment recommendations with MammaPrint."

Dr. William Audeh, Chief Medical Officer of Agendia said: "The clinical performance of MammaPrint and its ability to accurately inform and guide treatment decisions has been definitively proven by the recent presentation of the MINDACT trial at the 2016 AACR (Free AACR Whitepaper) meeting. This unique phase III prospective, randomized, controlled study provides the highest level of clinical evidence to MammaPrint above any other genomic assay for making adjuvant therapy decisions in early-stage breast cancer."

MINDACT included 6,693 patients and is a phase III, prospective, randomized controlled, clinical trial comparing the use of MammaPrint 70-gene assay with clinicopathological criteria (current standard of care) for selecting early-stage breast cancer patients who should be treated with adjuvant chemotherapy.

"The PROMIS trial showed the positive impact a binary test could have in the clinical setting by providing a clear risk assessment of the patient to physicians" said Mark Straley, Chief Executive Officer at Agendia. "MammaPrint is the only FDA-cleared assay for early-stage breast cancer patients of all ages, further validating the quality and clinical utility of the test."

1 Lo, Mumby et al. 2011, Sulayman, Spellman et al. 2012, Stemmer, Klang et al. 2013, Sparano, Grey et al. 2015