It is of note, however, that the generally poor prognosis of patients with the combination of both PTEN deletion and HER2 amplification as determined in a historical breast cancer patient set predating the era of anti-HER2 therapies demonstrates that the poor success of trastuzumab in PTEN deleted cancers may also be driven by increased cancer aggressiveness irrespective of therapy response. The gene discussed is ERBB2; the disease is breast carcinoma.