title: Dosimetry of 90Y-ibritumomab tiuxetan as consolidation of first remission in advanced-stage follicular lymphoma: results from the international phase 3 first-line indolent trial.
abstract: The objective of this analysis was to assess the radiation exposure associated with (90)Y-ibritumomab tiuxetan when used as consolidation therapy in adults with low or minimal tumor burden after first-line therapy of advanced follicular lymphoma (FL).
  
  
  METHODS
  The patients who were enrolled in the phase 3 first-line indolent trial were 18 y or older, with CD20(+) grade 1 or 2 stage III or IV FL, and a partial response, complete response, or unconfirmed complete response to first-line chemotherapy. The patients were allocated randomly to receive a single infusion of unlabeled rituximab 250 mg/m(2) on day -7 and consolidation on day 0 with a single dose of (90)Y-ibritumomab tiuxetan, 14.8 MBq/kg, immediately after unlabeled rituximab, 250 mg/m(2), or no further treatment. On day -7, a subset of patients received an injection of 185 MBq of (111)In-ibritumomab tiuxetan immediately after unlabeled rituximab, 250 mg/m(2), for central dosimetry analysis. Correlations were assessed between organ radiation absorbed dose and toxicity, body weight, body mass index, and progression-free survival.
  
  
  RESULTS
  Central dosimetry evaluations were available from 57 of 70 patients. Median radiation absorbed doses were 100 cGy (range, 28-327 cGy) for the red marrow and 72 cGy (range, 46-106 cGy) for the whole body. Radiation absorbed doses did not differ significantly between patients who had a partial response or complete response to initial therapy. Progression-free survival correlated significantly with the whole-body (r = 0.4401; P = 0.0006) and bone marrow (r = 0.2976; P = 0.0246) radiation dose. Body weight was significantly negatively correlated with whole-body radiation dose (r = -0.4971; P < 0.0001). Neither the whole-body radiation dose nor the bone marrow radiation dose correlated with hematologic toxicity.
  
  
  CONCLUSIONS
  In patients with low or minimal residual tumor burden after first-line chemotherapy of advanced FL, whole-body and bone marrow exposure after (90)Y-ibritumomab tiuxetan consolidation showed a significant positive correlation with progression-free survival, whereas dosimetric data could not predict hematologic toxicity.
authors.affiliation: Department of Nuclear Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Angelika.BischofDelaloye@chuv.ch
authors.forename: Angelika Bischof
authors.initials: AB
authors.lastname: Delaloye
authors.forename: Cristian
authors.initials: C
authors.lastname: Antonescu
authors.forename: Thomas
authors.initials: T
authors.lastname: Louton
authors.forename: Jens
authors.initials: J
authors.lastname: Kuhlmann
authors.forename: Anton
authors.initials: A
authors.lastname: Hagenbeek
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D038622:Internationality; D008224:Lymphoma, Follicular / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011829:Radiation Dosage; D016499:Radioimmunotherapy; D011874:Radiometry; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; C422802:ibritumomab tiuxetan