bioTheranostics announced results from studies being presented at the 2015 American Society of Clinical Oncology (ASCO) meeting reinforcing the role its Breast Cancer Index (BCI) molecular test plays in informing decisions about extending endocrine therapy beyond five years post-diagnosis for patients with early stage, estrogen receptor-positive (ER+) breast cancer.

In the first prospective trial investigating the impact of BCI in clinical practice, BCI results led to changes in treatment decisions in 27 percent of patients tested, and significantly reduced patient anxiety regarding decisions about whether to extend endocrine therapy to 10 years.

Other studies further clarify the role of BCI in informing treatment decisions in clinically relevant subsets of patients (e.g., HER2 positive patients) and at various time points along patients’ breast cancer journeys.

In addition, new predictive data from the TransATAC randomized trial cohort build on the test’s predictive ability with tamoxifen shown in an adjuvant setting (Stockholm randomized trial cohort), and aromatase inhibitors in the extended endocrine treatment setting (MA-17 randomized trial cohort).

Nicolas Barthelemy, president and CEO of bioTheranostics, said these milestone studies demonstrate how the prognostic and predictive powers of BCI influence important decisions about duration of endocrine treatment.

In a prospective study of the decision-making impact of BCI led by Yale University Smilow Cancer Hospital, researchers evaluated how BCI testing in patients with early stage ER+ breast cancer impacted the decision of whether to extend endocrine therapy to 10 years versus five years.

Integration of BCI led to change in treatment recommendations for 27% of patients, with a majority of changes based on identification of patients with low risk of late recurrence and low likelihood of benefit from extended endocrine therapy.

In a retrospective study of patients from the prospective, randomized TransATAC trial, BCI Predictive was compared with quantitative estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expression in assessing the ability to predict benefit from anastrozole versus tamoxifen in 742 patients treated with five years of adjuvant endocrine therapy.

A large retrospective analysis in collaboration with Beth Israel Medical Center showed the clinical utility of BCI to stratify patients based on risk of late recurrence and likelihood of benefit from extended endocrine therapy.

Results showed that there was pronounced use of the test approaching the five-year anniversary, but also substantial use both earlier and later than the anniversary. In this large, real-world study, BCI identified a majority of patients as having a low likelihood of benefit from extended endocrine therapy.