Radiation absorbed dose from indium-111-CYT-356.
Indium-CYT-356 is an agent developed by CYTOGEN Inc. (CYT) (Princeton, NJ) for the use in staging patients with prostate cancer. This investigation was performed to provide the human dosimetry needed for Food and Drug Administration approval for routine use in patients.


METHODS
Biodistribution data collected from three sites were obtained from prostate cancer patients who received diagnostic doses of 111In-CYT-356. Data included blood and urine collections, and the organ uptake value was measured from sequential conjugate whole-body and planar images over a 7-10 day period. Dose contributions from radioactivity in transit through the GI tract were estimated using a compartmental model. The calculations used the MIRD methodology and MIRDOSE 3.


RESULTS
The total-body dose observed was 0.14 mGy/MBq, and the effective dose was found to be 0.25-0.29 mSv/MBq. The largest organ doses were found for the liver (1.0 mGy/MBq), kidneys (0.67 mGy/MBq) and spleen (0.88 mGy/MBq).


CONCLUSIONS
The radiation dose to the patient from a typical 185 MBq administration of 111In-CYT-356 is comparable to the dose from other 111In-labeled whole antibodies used in the diagnosis and management of cancer patients. The inclusion of the GI tract as a source organ increases the effective dose by 18%.
Mardirossian
G
G
University of Massachusetts Medical Center, Nuclear Medicine Department, Worcester 01655, USA.
Brill
A B
AB
Dwyer
K M
KM
Kahn
D
D
Nelp
W
W
D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics; D006207:Half-Life; D006801:Humans; D007205:Indium Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011835:Radiation Protection; D011877:Radionuclide Imaging; D013997:Time Factors; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D007205:Indium Radioisotopes; C101315:Capromab Pendetide