title: Pilot study of topotecan and high-dose cyclophosphamide for resistant pediatric solid tumors.
abstract: BACKGROUND
  The recommended dosages of topotecan and cyclophosphamide in combination for prior-treated patients-3.75 mg/m(2) and 1,250 mg/m(2) in children, 5 mg/m(2) and 600 mg/m(2) in adults, respectively-are well below those of each agent when used singly. We tested the hypothesis that much higher dosing would meet critical goals of salvage therapy: antitumor effect and a lack of toxicity to key organs, so as not to preclude subsequent consolidative treatments needed for cure.
  
  
  METHODS
  Patients with resistant pediatric solid tumors received cyclophosphamide 4,200 mg/m(2) by 48 hr infusion, and topotecan 6 mg/m(2) by 72 hr infusion (HD-Cy/Topo). Mesna and granulocyte colony-stimulating factor were used. Cycles were repeated when neutrophil counts were >1,000/uL and platelet counts were >75,000/uL.
  
  
  RESULTS
  Twenty-eight patients, aged 2 to 33 years (median, 14), received one (n = 4), two (n = 15), or > or =3 (n = 9) cycles of HD-Cy/Topo. All patients had previously received > or =6 cycles of other therapy, high-dose alkylator-based chemotherapy, and/or etoposide- and doxorubicin-containing regimens. HD-Cy/Topo was given in an outpatient setting. Profound myelosuppression was the major toxicity, but retreatment was possible by day 28, and preliminary results with peripheral blood stem cell collections showed a sparing effect on hemopoietic stem cells. Mucositis was uncommon. After HD-Cy/Topo, cardiac, renal, hepatic, and pulmonary function remained within the normal range. Partial or minor responses were noted in neuroblastoma, desmoplastic small round-cell tumor, Ewing sarcoma, rhabdomyosarcoma, and osteosarcoma.
  
  
  CONCLUSIONS
  Its antitumor potential and limited toxicity make HD-Cy/Topo an attractive choice for inclusion in aggressive salvage programs aimed at achieving cures of resistant tumors. It may also merit incorporation into frontline treatment protocols.
authors.affiliation: Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. kushnerb@mskcc.org
authors.forename: B H
authors.initials: BH
authors.lastname: Kushner
authors.forename: K
authors.initials: K
authors.lastname: Kramer
authors.forename: P A
authors.initials: PA
authors.lastname: Meyers
authors.forename: N
authors.initials: N
authors.lastname: Wollner
authors.forename: N K
authors.initials: NK
authors.lastname: Cheung
mesh_terms: D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003520:Cyclophosphamide / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D009447:Neuroblastoma / Q000188:drug therapy; D010865:Pilot Projects; D016879:Salvage Therapy / Q000379:methods*; D012509:Sarcoma / Q000188:drug therapy; D019772:Topotecan / Q000008:administration & dosage
chemical_list: D019772:Topotecan; D003520:Cyclophosphamide