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Title: Evidence of a saturable hepatic receptor for mouse monoclonal antibodies

Conference · · J. Nucl. Med.; (United States)
OSTI ID:5874887

Monoclonal antibodies (MAb) can be labeled with I-123 at high specific activities, so that large amounts of radioactivity attached to small amounts of protein can be injected for radioimmunoimaging. This conserves antibody and decreases the opportunity for foreign protein reactions and target tissue binding site saturation. In order to assess the effects on pharmacokinetics and imaging, the authors administered microgram amounts of I-123-MAb (Lyn-1, IgG2a or B6.01, IgGl with and following 4-5 milligram preloading with MAb on separate occasions to 4 patients with a target tumor (B cell lymphoma) and 2 patients without a target tumor (breast cancer). Pharmacokinetics were observed in blood and urine by counting whole samples and HPLC fractions of these samples and in organs by serial imaging. Early blood clearance and urinary excretion were faster after injection of microgram amounts of MAb, but subsequently were comparable to those obtained after preload. This paper concludes that the amount of administered MAb dramatically influences the pharmacokinetics of mouse MAb. Saturable hepatic Fc receptors are probably the source of these observations. Reports of accelerated deiodination of MAb are related to this phenomenon. Optimal imaging and treatment with MAb requires saturation of these hepatic receptors.

Research Organization:
Univ. of California, Davis Medical Center, Sacramento, CA
OSTI ID:
5874887
Report Number(s):
CONF-850611-; TRN: 87-039246
Journal Information:
J. Nucl. Med.; (United States), Vol. 26:5; Conference: 32. annual meeting of the Society of Nuclear Medicine, Houston, TX, USA, 2 Jun 1985
Country of Publication:
United States
Language:
English