title: Weight-based dosing of Yttrium 90 ibritumomab tiuxetan in patients with relapsed or refractory B-cell non-Hodgkin lymphoma.
abstract: BACKGROUND
  Ibritumomab tiuxetan radioimmunotherapy produces durable remissions in patients with relapsed/refractory indolent non-Hodgkin lymphoma. The dosing of Yttrium 90 (90Y)-ibritumomab tiuxetan is based on patient weight and platelet count: 0.4 mCi/kg in patients with a count >or= 150 x 10(9)/L, to a maximum dose of 32 mCi. Patients weighing > 80 kg with platelet counts of >or= 150 x 10(9)/L receive a lower dose per unit of body weight. We evaluated whether this influences the safety or efficacy of treatment.
  
  
  METHODS
  Data on efficacy and safety in patients in 3 registration trials who were treated with 90Y ibritumomab tiuxetan at 0.4 mCi/kg (patients weighing <or= 80 kg) or 32 mCi (patients weighing > 80 kg) were collected.
  
  
  RESULTS
  Clinical responses were evaluated in 103 patients weighing <or= 80 kg (median, 70 kg) and 67 patients weighing > 80 kg (median, 95 kg). Sex (41% female vs. 73% male) was the only significantly different characteristic between the patients weighing <or= 80 kg and > 80 kg, respectively. The overall response rates were 79% (<or= 80 kg) and 70% (> 80 kg), and the complete response rates were 28% and 34%, respectively. Median times to progression were 8.9 months (<or= 80 kg) and 9.5 months (> 80 kg). There were no significant differences in efficacy measures or in the incidences of grade 3/4 nonhematologic adverse events, neutropenia, thrombocytopenia, or anemia.
  
  
  CONCLUSIONS
  The dose of 90Y ibritumomab tiuxetan was < 0.4 mCi/kg in 39% of patients, owing to the 32-mCi dose cap, but the efficacy or safety of 90Y ibritumomab tiuxetan in patients > 80 kg was not affected.
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Wiseman
authors.forename: Peter S
authors.initials: PS
authors.lastname: Conti
authors.forename: Katie
authors.initials: K
authors.lastname: Vo
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Schilder
authors.forename: Leo I
authors.initials: LI
authors.lastname: Gordon
authors.forename: Christos
authors.initials: C
authors.lastname: Emmanouilides
authors.forename: Dan H
authors.initials: DH
authors.lastname: Silverman
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Witzig
authors.forename: Mohamed
authors.initials: M
authors.lastname: Darif
authors.forename: Arturo
authors.initials: A
authors.lastname: Molina
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000009:adverse effects; D001835:Body Weight; D005260:Female; D006801:Humans; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D016499:Radioimmunotherapy; D019275:Radiopharmaceuticals / Q000008:administration & dosage* / Q000009:adverse effects; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; D019275:Radiopharmaceuticals; C422802:ibritumomab tiuxetan