Observational Retrospective Study of Altered Biodistribution of Tositumomab and 131I-Tositumomab.
The tositumomab/(131)I-tositumomab radioimmunotherapy regimen is administered as a dosimetric dose followed by a therapeutic dose. The biodistribution of the dosimetric dose is assessed by quantitative calculations of whole-body residence time (TBRT) and visual examination of whole-body γ-camera images, to determine the administered radioactivity dose and whether a therapeutic dose can be administered. We investigated whether altered biodistribution of (131)I-tositumomab could be identified using quantitative TBRT.


METHODS
BioClinica, Inc., provided γ-camera images to an independent reviewer to assess altered (131)I-tositumomab biodistribution in patients reported to a registry.


RESULTS
Of 2,649 therapeutic doses, 5 (0.2%) were cancelled because of altered biodistribution as determined by γ-camera images and TBRT. Of these, 3 γ-camera images were assessed by the independent reviewer; one showed altered biodistribution (0.04%) and was in agreement with the TBRT on-site calculation.


CONCLUSIONS
TBRT alone should be used to determine altered biodistribution and hence whether to administer the therapeutic dose.
Department of Medical Oncology, Johns Hopkins University, Baltimore, Maryland.
Richard L
RL
Wahl
Oncology Research and Development, GlaxoSmithKline, Collegeville, Pennsylvania; and thierry.j.horner@gsk.com.
Thierry J
TJ
Horner
Oncology Research and Development, GlaxoSmithKline, Collegeville, Pennsylvania; and.
Thomas S
TS
Lin
Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.
Mark S
MS
Kaminski
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007457:Iodine Radioisotopes; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging / Q000188:drug therapy; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D014018:Tissue Distribution; D051598:Whole Body Imaging
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D007457:Iodine Radioisotopes; C119496:tositumomab I-131
altered biodistribution; therapeutic dose; tositumomab