The Breast Cancer Index assay is the only of its kind to be recommended in the National Comprehensive Cancer Network Guidelines for the treatment of breast cancer as being predictive of extended adjuvant endocrine therapy.
Breast Cancer Index (BCI), a molecular gene expression–based test used for determining which patients with early-stage, hormone receptor (HR)–positive breast cancer benefit from extended endocrine therapy, is now included in the National Comprehensive Cancer Network (NCCN) Guidelines for breast cancer, according to Biotheranostics, Inc.1
Per NCCN recommendations, BCI can be used for consideration of extended adjuvant endocrine therapy with a 2A category of evidence and consensus, which indicates uniform consensus from the organization that the recommendation is appropriate.
“Clinical guideline endorsement by the NCCN Panel marks an evidentiary milestone for the Breast Cancer Index underscoring its distinct clinical utility for women with HR[-positive] early-stage breast cancer, and a new paradigm for the use of genomic assays to aid in endocrine decision-making,” Catherine Schnabel, PhD, chief scientific officer of Biotheranostics, stated in a press release.“With NCCN Guidelines as the recognized benchmark for cancer policy, the positive recommendation of BCI as a predictive biomarker of extended endocrine benefit will allow increased patient access to this important genomic tool.”
The assay is the only of its kind to predict benefit of extended endocrine therapy in these patients and does so across 3 distinct groups. Appropriate therapy is grouped by patients benefiting from 5 years of tamoxifen followed by an additional 5 years of the same drug, those who should receive 5 years of tamoxifen followed by an additional 5 years of an aromatase inhibitor (AI), and those who will benefit from 5 years with an AI followed by an additional 5 years of the same drug class.
The guideline recommendation comprises both node-negative and -positive disease, and was based on data from the MA.17 (NCT00003140), Trans-aTTom (NCT00003678), and IDEAL clinical studies.
In MA.17, a prospective-retrospective, nested case-control design trial, patients with estrogen receptor–positive breast cancer were evaluated for prognostic performance of BCI for predicting late recurrence and treatment benefit from extended adjuvant letrozole. In such, BCI was able to accurately predict which patients who were disease free after 5 years of tamoxifen were at risk of late recurrence and likely to benefit from extended letrozole.2
Results of Trans-aTTom, a prospective-retrospective study, validated BCI’s predictive ability for extended endocrine therapy response in patients with node-positive disease. In it, 583 patients with HR-positive, early-stage disease were randomized to 5 years of extended tamoxifen versus stopping therapy after 5 years. BCI was able to effectively stratify patients by those who derive benefit from the extended use of the drug versus those who do not.3
The IDEAL study demonstrated the assay’s ability to predict benefit from extended AI therapy in the indicated patient population. Patients with HR-positive, HER2-negative early-stage disease were randomized to 5 versus 2.5 years of extended letrozole following an initial 5-year course of adjuvant endocrine therapy of either primary AI or primary tamoxifen. BCI was able to effectively stratify patients unlikely to benefit from a full 5 years of extended treatment with primary adjuvant AI.4
“We are thrilled that the NCCN has recognized Breast Cancer Index as the only biomarker to inform the decision of extended endocrine therapy,” Don Hardison, Biotheranostics’ president and CEO, stated. “This inclusion gives providers the added confidence to incorporate BCI into routine clinical practice. It also allows our organization to realize its goal to be standard of care for all early-stage HR[-positive] breast cancer patients faced with the difficult decision of the duration of endocrine therapy.”
1. NCCN. Clinical Practice Guidelines in Oncology. Breast cancer, version 1.2021. Accessed January 19, 2021. https://bit.ly/3nUeHUp
2. Sgroi DC, Carney E, Zarrella E, et al. Prediction of late disease recurrence and extended adjuvant letrozole benefit by the HOXB13/IL17BR biomarker. J Natl Cancer Inst. 2013;105(14):1036-42. doi: 10.1093/jnci/djt146
3. Bartlett JMS, Sgroi DC, Treuner K, et al. Breast Cancer Index and prediction of benefit from extended endocrine therapy in breast cancer patients treated in the Adjuvant Tamoxifen-To Offer More? (aTTom) trial. Ann Oncol. 2019;30(11):1776-1783. doi: 10.1093/annonc/mdz289
4. Noordhoek I, Treuner K, Putter H, et al. Breast Cancer Index Predicts Extended Endocrine Benefit to Individualize Selection of Patients with HR+ Early-stage Breast Cancer for 10 Years of Endocrine Therapy. Clin Cancer Res. 2021;27(1):311-319. doi: 10.1158/1078-0432.CCR-20-2737