Key exclusion criteria included prior palliative cytotoxic chemotherapy, prior treatment with mTOR (mammalian target of rapamycin)-inhibitors (prior treatment with exemestane was permitted), symptomatic visceral metastases, unstable skeletal metastases, medically uncontrolled cardiovascular diseases or diabetes mellitus, and known dihydropyrimidine dehydrogenase deficiency. Here, MTOR is linked to dihydropyrimidine dehydrogenase deficiency.