This is a clinical trial with a molecularly stratified parallel cohort, single arm design to explore the efficacy and safety of BKM120 in combination with tamoxifen in patients with ER/PR-positive, HER2-negative breast cancer with prior exposure to antihormonal therapy, and different biomarker profiles, two of them potentially indicative of constitutive PI3K pathway activation:~PIK3CA mutation/preserved PTEN expression~PIK3CA wildtype or mutation/ loss of PTEN expression~PIK3CA wildtype/preserved PTEN expression. This trial will explore, if the combination of BKM120 and tamoxifen can overcome resistance to antihormonal therapies. BKM120 is selective for class I PI3K enzymes with no mTOR inhibitory activity that has entered Phase II and III clinical trials. The tumor suppressor PTEN is the most important negative regulator of the PI3K signaling pathway. Therefore, in addition the trial will prospectively evaluate PIK3CA mutations and/or loss of PTEN expression as predictive biomarkers for clinical benefit from combined treatment with BKM120 and tamoxifen.
This is a clinical trial with a molecularly stratified parallel cohort, single arm design to explore the efficacy and safety of BKM120 in combination with tamoxifen in patients with ER/PR-positive, HER2-negative breast cancer with prior exposure to antihormonal therapy, and different biomarker profiles, two of them potentially indicative of constitutive PI3K pathway activation.