Weight-based dosing of Yttrium 90 ibritumomab tiuxetan in patients with relapsed or refractory B-cell non-Hodgkin lymphoma.
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.
Wiseman
Gregory A
GA
Mayo Clinic, Rochester, MN, USA.
Conti
Peter S
PS
Vo
Katie
K
Schilder
Russell J
RJ
Gordon
Leo I
LI
Emmanouilides
Christos
C
Silverman
Dan H
DH
Witzig
Thomas E
TE
Darif
Mohamed
M
Molina
Arturo
A
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
D000911:Antibodies, Monoclonal; D019275:Radiopharmaceuticals; C422802:ibritumomab tiuxetan