Development of anti-MUC1 di-scFvs for molecular targeting of epithelial cancers, such as breast and prostate cancers

H. Albrecht, Gerald L Denardo, S. J. Denardo

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Pretargeted radioimmunotherapy (RIT) is a promising approach to increase the therapeutic index of RIT for malignant solid tumors. For pretargeted RIT of epithelial cancers, such as breast and prostate, mucin 1 (MUC1), the epithelial mucin, was chosen as a target antigen (Ag). Overexpression, hypoglycosylation and loss of apical distribution on the cellular membrane distinguish the tumor associated MUC1 from normal MUC1. These characteristics of MUC1, best known in breast cancer, were validated in prostate cancer. The multivalent bispecific MUC1 pretargeting molecule under development consists of a tumor binding module and a radioactive hapten capturing module. The building blocks of each module were chosen as single chain antibody fragments (scFv) to be covalently attached to a multifunctional polyethylene glycol (PEG) scaffold. PEGylation studies with scFvs selected from anti-MUC1 libraries and engineered with a free thiol for site-specific conjugation showed that highest reaction yields were obtained with short monofunctional PEG molecules. To accommodate the use of a bifunctional PEG for covalent assembly of binding and capturing modules, the MUC1 binding module was developed into a di-scFv-SH format and optimized for linker length and location of the free thiol in respect to Ag binding and site-specific conjugation. Approaches under study to improve PEGylation yields with bifunctional PEG molecules include alkyne-azide cycloaddition. Assembly efficiencies, through PEGylation, of the binding and capturing modules and pharmacokinetics will influence the final valency of the MUC1 pretargeting molecule: anti-MUC1 di-scFv-PEG- anti-radioactive hapten scFv or di-scFv-PEG-anti-radioactive hapten di-scFv.

Original languageEnglish (US)
Pages (from-to)304-313
Number of pages10
JournalQuarterly Journal of Nuclear Medicine and Molecular Imaging
Volume51
Issue number4
StatePublished - Dec 2007

Keywords

  • Breast neoplasms
  • Drug labelling
  • Prosmtic neoplasms

ASJC Scopus subject areas

  • Medicine(all)
  • Radiology Nuclear Medicine and imaging

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