Topotecan-filgrastim combination is an effective regimen for mobilizing peripheral blood stem cells

We compared the efficacy, toxicity, and cost of topotecan-filgrastim and fi lgrastim alone for mobilizing peripheral blood stem cells (PBSCs) in 24 con secutive pediatric patients with newly diagnosed medulloblastoma. PBSCs wer e mobilized with an upfront window of topotecan-filgrastim. for 11 high-ris k patients (residual tumor greater than or equal to1.5 cm(2) after resectio n; metastases limited to neuraxis) and with filgrastim alone for 13 average -risk patients. All patients subsequently underwent craniospinal irradiatio n and four courses of high-dose chemotherapy with stem cell rescue. Target yields of CD34(+) cells (greater than or equal to8 X 10(6)/kg) were obtaine d with only one apheresis procedure for each of the 11 patients treated wit h topotecan-filgrastim, but with a mean of 2.3 apheresis procedures for onl y six (46%) of the 13 patients treated with filgrastim alone (P = 0.0059). The median peak and median total yield of CD34(+) cells were six-fold highe r for the topotecan-filgrastim group (328/mul and 21.5 x 10(6)/kg, respecti vely) than for the filgrastim group (54/mul and 3.7 x 10(6)/kg, respectivel y). Mean times to neutrophil and platelet engraftment were similar. Myelosu ppression was the only grade 4 toxicity associated with topotecan-filgrasti m mobilization and lasted a median of 5 days. Compared with filgrastim mobi lization, topotecan-filgrastim mobilization resulted in a mean cost saving of $3966 per patient. Topotecan-filgrastim is an efficacious, minimally tox ic, and cost-saving combination for PBSC mobilization.