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Oncoimmunology. 2017 Nov 13;7(2):e1393597. doi: 10.1080/2162402X.2017.1393597. eCollection 2018.

Enhancement of antibody-dependent cellular cytotoxicity of cetuximab by a chimeric protein encompassing interleukin-15.

Author information

1
Program of Immunology and Immunotherapy, Center for Applied Medical Research (CIMA), Pamplona, Spain.
2
Navarra Institute for Health Research (IDISNA), Pamplona, Spain.
3
Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain.
4
Servicio de Inmunología e Inmunoterapia, Clínica Universidad de Navarra, Pamplona, Spain.
5
Hematología y Área de Terapia Celular, Clínica Universidad de Navarra, Pamplona, Spain.
6
U3 Pharma GmbH, Planegg, Germany.

Abstract

Enhancement of antibody-dependent cellular cytotoxicity (ADCC) may potentiate the antitumor efficacy of tumor-targeted monoclonal antibodies. Increasing the numbers and antitumor activity of NK cells is a promising strategy to maximize the ADCC of standard-of-care tumor-targeted antibodies. For this purpose, we have preclinically tested a recombinant chimeric protein encompassing the sushi domain of the IL15Rα, IL-15, and apolipoprotein A-I (Sushi-IL15-Apo) as produced in CHO cells. The size-exclusion purified monomeric fraction of this chimeric protein was stable and retained the IL-15 and the sushi domain bioactivity as measured by CTLL-2 and Mo-7e cell proliferation and STAT5 phosphorylation in freshly isolated human NK and CD8+ T cells. On cell cultures, Sushi-IL15-Apo increases NK cell proliferation and survival as well as spontaneous and antibody-mediated cytotoxicity. Scavenger receptor class B type I (SR-B1) is the receptor for ApoA-I and is expressed on the surface of tumor cells. SR-B1 can adsorb the chimeric protein on tumor cells and can transpresent IL-15 to NK and CD8+ T cells. A transient NK-humanized murine model was developed to test the increase of ADCC attained by the chimeric protein in vivo. The EGFR+ human colon cancer cell line HT-29 was intraperitoneally inoculated in immune-deficient Rag2-/-γc-/- mice that were reconstituted with freshly isolated PBMCs and treated with the anti-EGFR mAb cetuximab. The combination of the Sushi-IL15-Apo protein and cetuximab reduced the number of remaining tumor cells in the peritoneal cavity and delayed tumor engraftment in the peritoneum. Furthermore, Sushi-IL15-Apo increased the anti-tumor effect of a murine anti-EGFR mAb in Rag1-/- mice bearing subcutaneous MC38 colon cancer transfected to express EGFR. Thus, Sushi-IL15-Apo is a potent tool to increase the number and the activation of NK cells to promote the ADCC activity of antibodies targeting tumor antigens.

KEYWORDS:

NK cell; antibody-dependent cellular cytotoxicity; apolipoprotein A-I; cetuximab; interleukin 15; scavenger receptor class B type I

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