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Breast Cancer Index predicts extended endocrine benefit to individualize selection of HR+ early stage breast cancer patients for 10 years of endocrine therapy
Purpose: Individualized selection of patients with early stage hormone receptor positive (HR+) breast cancer for extended endocrine therapy (EET) are required to balance modest gains in outcome with toxicities of prolonged use. This study examined the Breast Cancer Index (BCI) [HOXB13/IL17BR ratio (H/I)] as a predictive biomarker of EET benefit in patients from the Investigation on the Duration of Extended Adjuvant Letrozole (IDEAL) trial.
Experimental design: BCI was tested in primary tumor specimens from 908 patients randomized to receive 2.5 vs 5 years of extended letrozole. The primary endpoint was recurrence-free interval (RFI). Cox models and likelihood ratios tested the interaction between EET and BCI (H/I).
Results: BCI (H/I)-High significantly predicted benefit from extended letrozole in the Overall cohort (HR 0.42, 95% CI 0.21-0.84; P=0.011) and Any AI subset (HR 0.34, 0.16-0.73; P=0.004), whereas BCI (H/I)...
Show morePurpose: Individualized selection of patients with early stage hormone receptor positive (HR+) breast cancer for extended endocrine therapy (EET) are required to balance modest gains in outcome with toxicities of prolonged use. This study examined the Breast Cancer Index (BCI) [HOXB13/IL17BR ratio (H/I)] as a predictive biomarker of EET benefit in patients from the Investigation on the Duration of Extended Adjuvant Letrozole (IDEAL) trial.
Experimental design: BCI was tested in primary tumor specimens from 908 patients randomized to receive 2.5 vs 5 years of extended letrozole. The primary endpoint was recurrence-free interval (RFI). Cox models and likelihood ratios tested the interaction between EET and BCI (H/I).
Results: BCI (H/I)-High significantly predicted benefit from extended letrozole in the Overall cohort (HR 0.42, 95% CI 0.21-0.84; P=0.011) and Any AI subset (HR 0.34, 0.16-0.73; P=0.004), whereas BCI (H/I)-Low patients did not derive significant benefit (HR 0.95, 0.58-1.56; P=0.84, HR 0.90, 0.53-1.55; P=0.71, respectively); treatment to biomarker interaction was significant (P=0.045, P=0.025, respectively). BCI identified ~50% of patients with clinically high-risk disease that did not benefit, and with clinically low-risk disease that derived significant benefit, from an additional 2.5 years of EET.
Conclusions: BCI (H/I) predicted preferential benefit from 5 vs 2.5 years of EET and identified patients with improved outcomes from completing 10 years of adjuvant endocrine therapy. Findings expand the clinical utility of BCI (H/I) to a broader range of patients and beyond prognostic risk factors as a predictive endocrine response biomarker for early stage HR+ breast cancer.
Show less- All authors
- Noordhoek, I.; Treuner, K.; Putter, H.; Zhang, Y.; Wong, J.; Kranenbarg, E.M.K.; Duijm-de Carpentier, M.; Velde, C.J.H. van de; Schnabel, C.A.; Liefers, G.J.
- Date
- 2020-10-27
- Journal
- Clinical Cancer Research