HER2 Support Group Forums - HOXB13 levels correlates to Her2+ and predicts Tamoxifen response

Abstract
Introduction: The HOXB13:IL17BR index has been identified to predict clinical
outcome in the setting of adjuvant tamoxifen monotherapy of breast cancer. Further studies have shown that HOXB13 in particular can indicate benefit of prolonged tamoxifen treatment. Patients with high-expressing tumors did not benefit from prolonged treatment, suggesting that HOXB13 might be involved in tamoxifen resistance. No studies have been made regarding the HOXB13 protein levels in breast cancer. The aim of our study was to investigate whether tamoxifen benefit can be correlated to different levels of HOXB13 protein expression.

Methods: We used immunohistochemistry to analyze protein levels of HOXB13 in tumor samples from 912 postmenopausal node-negative breast cancer patients randomized to adjuvant tamoxifen therapy or no endocrine treatment.

Results: Tamoxifen treated patients with estrogen receptor positive tumors expressing none or low levels of HOXB13 had a clear benefit from tamoxifen in terms of longer distant recurrence-free survival (DRFS; hazard ratio (HR) = 0.38, 95% CI, 0.23-0.60, P = 0.000048). However, for patients with a high or intermediate HOXB13 tumor expression, tamoxifen did not prolong the DRFS compared to the untreated patients (HR = 0.88, 95% CI, 0.47-1.65, P = 0.69). Interaction between HOXB13 expression and benefit from tamoxifen was statistically significant for DRFS (P = 0.035). No prognostic value could be ascribed to HOXB13 among systemically untreated patients.