Preparation and near-quantitative Y-90 labelings of monoclonal antibody-macrocylic chelator (MAb-DOTA) conjugates for radioimmunotherapy (RAIT)

Journal Article · Wed May 01 04:00:00 EDT 1996 · Journal of Nuclear Medicine

OSTI ID:447759

Govindan, S V; Griffiths, G L; Losman, M J ^[1]

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1. Immunomedics, Inc., Morris Plains, NJ (United States); and others

The importance of kinetically inert Y-90-DOTA chelate for RAIT is well recognized. The aim of this study was to adapt a published procedure to overcome long-standing problems related to practical preparation of DOTA-MAb conjugates and poor Y-90 incorporation, and further improve upon labeling efficiencies. Using monoactivated DOTA, we have prepared conjugates of a CEA MAb (MN-14), a lymphoma MAb (LL2), their humanized versions (hMN-14 and hLL2), and the respective divalent fragments, and systematically examined the Y-90-labeling parameters. The DOTA/Mab ratios in conjugates were in the 3.0-6.8 range. In competitive CEA-binding assays, unmodified MN-14, MN-14-DOTA (6.8 chelators) and hMN-14-DOTA (4.4 chelators) exhibited very similar binding patterns. Y-90 labeling yields of >90% were obtained using a labeling time of 2 h at 40-45{degrees}C, pH {approximately}5.5, and DOTA/MAb ratio >3. Incorporations (specific activities):>99%for hMN-14-DOTA (103-170 MBa/mg), 94-97% for hLL2-DOTA (107-185 MBa/mg), 93-98%for hLL2F(ab`){sub 2}-DOTA (111 MBa/mg), and >90% for MN14-DOTA (37-185 MBq/mg). Aggregate content was usually less than 5%. Observed high incorporations are due both to the higher temperature used and DOTA/Y-90 molar ratios which readily exceeded a threshold requirement of three. Labeling efficiencies also depended upon the level of trace metal contaminants in the Y-90 shipment. Incubations of Y-90 labeled DOTA conjugates of hMN-14 and hLL2 in serum and in 1 mM DTPA at 37{degrees}C showed no detectable loss of metal over a 10-day period. These results should allow us to routinely use Y-90-DOTA-MAb conjugates in future preclinical and clinical RAIT studies.

• OSTI ID: 447759
• Report Number(s): CONF-960659--
• Journal Information: Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 37; ISSN 0161-5505; ISSN JNMEAQ
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
55 BIOLOGY AND MEDICINE
BASIC STUDIES
CHELATES
EFFICIENCY
LABELLING
MONOCLONAL ANTIBODIES
RADIOIMMUNOTHERAPY
YTTRIUM 90