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Bioconjug Chem. 1991 May-Jun;2(3):187-94.

Backbone-substituted DTPA ligands for 90Y radioimmunotherapy.

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Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.


Four new bifunctional diethylenetriaminepentaacetic acid (DTPA) ligands were synthesized to provide an improved chelating agent for radioimmunotherapy with 90Y. The new DTPA ligands contained a 4-isothiocyanatobenzyl group (pSCNBz) substituted onto the carbon backbone of DTPA for use in linkage to immunoprotein. Methyl groups were strategically incorporated onto the backbone of the ligands via a peptide route to provide 2-pSCNBz-5-Me-DTPA (2) and 3-Me-6-pSCNBz-DTPA (3). Addition of these functionalities was expected to sterically hinder the release of radiometal from the chelate. A new monosubstituted ligand, 3-pSCNBz-DTPA (4), was also prepared in order to determine whether a shift in position of the linking group had an effect on the in vivo stability of the yttrium complex. Additionally, by modification of known methods, a disubstituted DTPA ligand, 2-pSCNBz-6-Me-DTPA (1), was prepared.

[Indexed for MEDLINE]

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