The effect of increasing topotecan infusion from 30 minutes to 4 hours on the duration of exposure in cerebrospinal fluid

Background: The development of metastatic disease throughout the neuroaxis from primary central nervous system (CNS) tumors and non-CNS tumors suggests the cerebrospinal fluid (CSF) is an important source of exposure for chemotherapeutic agents. In non-human primates, a 4-hour, as compared to a 30-minute, topotecan (TPT) infusion prolonged TPT exposure in the CSF. Patient and methods: We evaluated this approach in a 51-year-old woman with breast cancer metastatic to the CNS. TPT was administered at 1.5 mg/m(2)/day (cycle 1) and 1.0 mg/m(2)/day (cycles 2 and 3) as a 30-minute infusion on days 0-4, and as a 4-hour infusion on day 5. Cycles were repeated every 21 days. Plasma, lateral ventricular CSF, and lumbar CSF samples were obtained after 30-minute and 4-hour infusions, and assayed for TPT lactone and total by HPLC. A three-compartment model was used to calculate area under the plasma (AUC(plasma)) and lateral ventricular CSF (AUC(CSF)) concentation-time curves. TPT CSF penetration was calculated as the ratio of AUC(CSF) to AUC(plasma). Results: Mean +/- SD values for TPT total CSF penetration in lateral CSF after 30-minute and 4-hour infusions were 0.25 +/- 0.15 and 0.29 +/- 0.02, respectively. TPT total lumbar CSF concentration was 3-fold greater after a 4-hour as compared to a 30-minute infusion. For TPT lactone and TPT total, time >1 ng/ml in lateral CSF was 1.8- and 1.7-fold greater, respectively, for a 4-hour as compared to a 30-minute infusion. Conclusions: Prolonging TPT infusion from 30 minute to 4 hours increases the duration of exposure in the CSF. This study demonstrates the ability to develop treatment strategies of systemically administered chemotherapy to enhance cytotoxic exposure in the CSF.