Induction of in vitro and in vivo NK cell cytotoxicity using high-avidity immunoligands targeting prostate-specific membrane antigen in prostate carcinoma

Mol Cancer Ther. 2011 Jun;10(6):1036-45. doi: 10.1158/1535-7163.MCT-10-1093. Epub 2011 Apr 27.


Cancer that might develop as host natural killer (NK) cells fail to detect ligands for their activating NK receptors. Immunoligands represent promising immunotherapeutic tools to overcome this deficit. These are fusion proteins containing a single-chain antibody fragment (scFv) to target an available tumor antigen and ULBP2 to activate host NK cells by targeting the activatory receptor NKG2D. Prostate-specific membrane antigen (PSMA) is an integral non-shed type 2 membrane protein that is highly and specifically expressed on prostate epithelial cells and strongly upregulated in prostate cancer. Here, we compare the impact of various anti-PSMA immunoligand formats on the therapeutic efficacy against prostate carcinoma cells by activating NK cells via NKG2D. Shortening of the linker separating the heavy and light chain antibody domain leads to the formation of dimers, trimers, and higher molecular mass oligomers. NK cells are most efficiently activated by multimeric immunoligands, thus showing an altered cytokine release pattern. The high avidity format is also superior in in vitro NK-mediated tumor cell targeting as shown in cytotoxicity assays. Finally, the efficacy of a multimeric immunoligand is shown in a prostate carcinoma mouse xenograft model showing a strong activity against advanced established tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody Affinity
  • Cell Line, Tumor
  • Cytotoxicity, Immunologic / immunology
  • GPI-Linked Proteins / immunology
  • GPI-Linked Proteins / metabolism
  • Humans
  • Intercellular Signaling Peptides and Proteins / immunology
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Male
  • Mice
  • Mice, SCID
  • NK Cell Lectin-Like Receptor Subfamily K / immunology
  • NK Cell Lectin-Like Receptor Subfamily K / metabolism
  • Prostate-Specific Antigen / immunology*
  • Prostate-Specific Antigen / metabolism
  • Prostatic Neoplasms / immunology*
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / therapy*
  • Receptors, Natural Killer Cell / immunology
  • Receptors, Natural Killer Cell / metabolism
  • Recombinant Fusion Proteins / immunology
  • Recombinant Fusion Proteins / pharmacology
  • Single-Chain Antibodies / immunology
  • Single-Chain Antibodies / pharmacology*
  • Xenograft Model Antitumor Assays


  • GPI-Linked Proteins
  • Intercellular Signaling Peptides and Proteins
  • NK Cell Lectin-Like Receptor Subfamily K
  • Receptors, Natural Killer Cell
  • Recombinant Fusion Proteins
  • Single-Chain Antibodies
  • ULBP2 protein, human
  • Prostate-Specific Antigen