One clinical case study of a patient with refractory metastatic triple negative breast cancer (mTNBC) demonstrated a switch from high EGFR expression and PI3K pathway activation to a loss of EGFR and PI3K activation and increased MAPK pathway activation after treatment with single agent BEZ-235, a PI3K/mTOR, ATM, ATR, and DNA-PKcs inhibitor. The gene discussed is PIK3CA; the disease is triple-negative breast carcinoma.