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Veracyte's Prosigna IDs Breast Cancer Patients Likely to Benefit from Aggressive Chemotherapy

NEW YORK – A new retrospective study published in NPJ Breast Cancer on Monday suggests that Veracyte's Prosigna breast cancer prognostic gene signature assay can identify the subgroups of patients who are more likely to benefit from aggressive chemotherapy.

Veracyte obtained exclusive global diagnostic rights to NanoString Technologies' nCounter FLEX Analysis System last December, and with it gained the rights to the Prosigna test.

The 510(k)-cleared prognostic gene signature assay is intended to be used to gauge the 10-year recurrence risk in postmenopausal women with node-negative (Stage I or II) or node-positive (Stage II), hormone receptor-positive breast cancer. The recurrence risk provided by the test can be useful information for physicians trying to decide how aggressively to treat patients with hormone therapy.

The NPJ Breast Cancer study analyzed data from the DBCG89D trial — a randomized trial of 980 pre- and post-menopausal Danish women with early-stage breast cancer who were administered adjuvant chemotherapy regimens containing the anthracycline epirubicin, or cyclophosphamide/methotrexate/fluorouracil (CMF). The Prosigna 50-gene assay was successfully performed on 686 patients, of whom 38 percent had a basal-like breast cancer subtype, 32 percent had HER2-enriched subtype, 19 percent had luminal A, and 11 percent had luminal B.

Among the non-HER2-enriched, patients, 38 were clinically HER2-positive and 30 were TOP2A abnormal. HER2-enriched is a subtype of HER2-positive breast cancer that's characterized by high expression of ERBB2 and related genes. The HER2-enriched biomarker has also been associated with a higher likelihood of achieving pathological complete response following neoadjuvant anti-HER2-based therapy beyond hormone receptor status and chemotherapy use. 

The study found that among patients with HER2-amplified tumors, only those who simultaneously had a HER2-enriched subtype appeared to benefit from anthracycline-based treatment with epirubicin. The researchers further observed a benefit in substituting CMF-based chemotherapy with epirubicin in patients with HER2-enriched or basal-like subtypes.

However, the switch did not produce a benefit among patients with a luminal A or luminal B subtypes, which made up 30 percent of all patients in the study. Since anthracycline-containing chemotherapies can cause significant cardiotoxicity, patients with luminal breast cancer subtypes may do just as well on alternative treatments, therefore avoiding unnecessary side effects, the study proposes.

"These new data suggest that the Prosigna test may be able to offer new levels of individualized treatment for women with early-stage breast cancer, potentially enabling many to avoid more aggressive chemotherapy regimens," Veracyte CEO Bonnie Anderson said in a statement.