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Results from the IDEAL study demonstrate Breast Cancer Index® predicts benefit from extending aromatase inhibitor (AI) therapy

The largest Breast Cancer Index validation expands on previous evidence, establishing the biomarker as being agnostic to tamoxifen (TAM) or AI therapy in women with HR+, early-stage breast cancer.

STUDY DESIGN

  • 908 patients with HR+, early stage disease
  • Patients randomized to 5 vs 2.5 years of extended letrozole following an initial 5 years of adjuvant endocrine therapy:
  • Primary adjuvant AI (TAM/AI in sequence or AI monotherapy) - 87% (N=794)
  • Primary adjuvant TAM - 13%

Risk reduction and absolute benefit for patients whose primary adjuvant treatment included an AI:

BCI Yes (Likely to Benefit, H/I High)
was associated with a 66% relative risk reduction, 11.8% absolute benefit from a full 5 years of extended letrozole (P = 0.0036)
BCI No (Not Likely to Benefit, H/I Low)
was associated with no significant benefit from longer treatment (P = 0.7116)

BCI effectively stratified patients into those who would or would not be likely to benefit from a full 5 years of extended treatment for those treated with primary adjuvant AI therapy

Relative benefit of extended AI treatment by BCI (H/I) status

“Breast Cancer Index used a discovery gene analysis that was unbiased and the genes chosen had the highest correlation with endocrine response and outcomes. As such, Breast Cancer Index may prove to be drug class agnostic and a true biologic marker for extended endocrine therapy benefit."

- Mark Pegram, MD

Risk reduction and absolute benefit for patients in the overall cohort:

BCI Yes (Likely to Benefit, H/I High)
was associated with a 58% relative risk reduction, 9.8% absolute benefit from a full 5 years of extended letrozole (P = 0.0111)
BCI No (Not Likely to Benefit, H/I Low)
was associated with no significant benefit from longer treatment (P = 0.8354)

BCI effectively stratified patients into those who would or would not be likely to benefit from extended treatment in the overall cohort

Relative benefit of extended AI treatment by BCI (H/I) status

References: 1. Noordhoek et al. Clin Cancer Res. Oct 2020. DOI: 10.1158/1078-0432.CCR-20-2737
Mark Pegram, MD is a medical advisor for Biotheranostics, Inc.

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