The results demonstrated the preferential activation of capecitabine to 5-FU in colorectal tumor, after oral administration to patients. This is explained to a great extent by the activity of TP in colorectal tumor tissue, (the enzyme responsible for the conversion of 5'-DFUR to 5-FU), which is approximately four times that in adjacent healthy tissue. In the liver, TP activity is approximately equal in metastatic and healthy tissue, which explains the lack of preferential activation of capecitabine in these tissues.

The pharmacokinetics of an orally administered valine ester of ganciclovir (GCV), valganciclovir (VGC), were studied. These were compared to the pharmacokinetics of oral and intravenous GCV.

This population pharmacokinetic model can predict trastuzumab exposure in the long-term treatment of patients with metastatic breast cancer and provide comparison of alternative dosage regimens via simulation.

Based on our data, we cannot recommend using serum HER2 ECD levels to make trastuzumab or other treatment decisions for individual patients with advanced/metastatic breast cancer.