Author(s): Bernhard C Pestalozzi, Sue Brignoli
Trastuzumab is a recombinant humanized monoclonal antibody used to treat breast cancer patients overexpressing the HER2 proto-oncogene. Its half-life in serum is 8.3 ± 5 days.1 It is unknown whether and to what extent trastuzumab can cross the blood-brain barrier. Therefore, we measured CSF and concomitant serum levels of trastuzumab in a 62-year-old patient with meningeal carcinomatosis treated with weekly intravenous trastuzumab. A few hours after trastuzumab infusion, serum levels achieved were as expected in the range of 10,000 to 100,000 ng/mL.1 Concomitant CSF levels were 300-fold lower (Table 1). Despite a possibly leakier blood-brain barrier in this patient with meningeal carcinomatosis, only minimal amounts of trastuzumab penetrated the CSF. Therefore, it is unlikely that intravenous trastuzumab would be useful to treat meningeal or cerebral disease of breast cancer.