Recombinant full-length human IgG1s targeting hormone-refractory prostate cancer

J Mol Med (Berl). 2007 Oct;85(10):1113-23. doi: 10.1007/s00109-007-0208-z. Epub 2007 Jun 7.

Abstract

We have used a naive human single-chain fragment variable (scFv) library as a source of random shape repertoire to directly probe the altered surface chemistry of tumor cells. We reported previously the identification of more than 90 internalizing phage monoclonal antibodies targeting prostate cancer cells, including those that are hormone refractory. In this report, we describe the conversion of a panel of those scFvs into full-length human immunoglobulins (IgGs) and show that tumor specificity is retained. We have further shown that antibodies isolated from a naive phage display library can nevertheless be of high affinity towards target tumor cells. In addition, full-length IgGs retain the functionality of parental scFvs including the ability to rapidly enter target cells through receptor-mediated endocytosis and thereby to mediate efficient and specific intracellular payload delivery to tumor cells. We have used recombinant IgGs to immunoprecipitate target antigens and analyzed their molecular composition by mass spectrometry. We have identified one target antigen as activated leukocyte cell adhesion molecule (ALCAM)/MEMD/CD166 and have further studied tissue specificity of this internalizing ALCAM epitope by immunohistochemistry. Our study shows that cell type-specific internalizing human antibody can be readily identified from a naive phage antibody display library, characterized with regards to sequence, affinity, tissue specificity, and antigen identity, and modified genetically and chemically to generate various forms of targeted therapeutics.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activated-Leukocyte Cell Adhesion Molecule / immunology
  • Activated-Leukocyte Cell Adhesion Molecule / isolation & purification
  • Amino Acid Sequence
  • Animals
  • Antibodies, Neoplasm / administration & dosage
  • Antibodies, Neoplasm / immunology*
  • CHO Cells
  • Carcinoma / immunology*
  • Carcinoma / pathology
  • Carcinoma / therapy
  • Cell Line, Tumor
  • Cricetinae
  • Cricetulus
  • Endocytosis / drug effects
  • Humans
  • Immunoglobulin G / administration & dosage
  • Immunoglobulin G / immunology*
  • Immunoglobulin Variable Region / genetics
  • Immunoglobulin Variable Region / immunology
  • Immunohistochemistry
  • Immunoprecipitation
  • Immunotherapy / methods
  • Liposomes
  • Male
  • Mass Spectrometry
  • Peptide Library
  • Prostate-Specific Antigen / immunology*
  • Prostate-Specific Antigen / isolation & purification
  • Prostatic Neoplasms / immunology*
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / therapy
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / immunology

Substances

  • Activated-Leukocyte Cell Adhesion Molecule
  • Antibodies, Neoplasm
  • Immunoglobulin G
  • Immunoglobulin Variable Region
  • Liposomes
  • Peptide Library
  • Recombinant Proteins
  • Prostate-Specific Antigen