bioTheranostics is reporting results from two new studies evaluating the performance of its Breast Cancer Index (BCI) biomarker assay in estrogen-receptor positive (ER+), early stage breast cancer. Study results showed that BCI predicts which women with early stage ER+ breast cancer are at risk for early and late distant recurrence, and which are most likely to benefit from continuing treatment with endocrine therapy after completing five years of tamoxifen. BCI is a combinatorial biomarker with a novel mechanism of action composed of Molecular Grade Index and the two-gene expression ratio HOXB13/IL17BR (H/I).
In a study published online in the Journal of the National Cancer Institute, tumor samples from 83 patients with breast cancer recurrence were matched to 166 patients without recurrence from the MA.17 trial, a landmark randomized clinical study that demonstrated improved disease-free survival with extended letrozole therapy in postmenopausal patients with ER+ breast cancer who were recurrence-free following an initial five years of tamoxifen therapy. Study authors concluded that the BCI assay identifies a subgroup of breast cancer patients, disease-free after five years of tamoxifen therapy, who are at risk for late recurrence, and that high H/I predicts benefit from extended endocrine therapy.
A second study, published online in Clinical Cancer Research, examined the ability of the BCI test to predict early (0 to 5 years) and late (>5 years) distant recurrence in ER+, lymph node-negative breast cancer patients. The study was a retrospective analysis of tumor samples from tamoxifen-treated patients from the randomized, prospective Stockholm trial and a multi-institutional cohort from two academic medical centers. The authors concluded that the ability of the BCI test to assess risk of both early and late distant recurrence has clinical utility for chemotherapy decisions at diagnosis and for decisions about extended endocrine therapy beyond five years. Read abstracts of the JNCI study and the CCR study.