Sensitization of B16 tumor cells with a CXCR4 antagonist increases the efficacy of immunotherapy for established lung metastases.

Abstract

Expression of the chemokine receptor CXCR4 by tumor cells promotes metastasis, possibly by activating prosurvival signals that render cancer cells resistant to immune attack. Inhibition of CXCR4 with a peptide antagonist, T22, blocks metastatic implantation of CXCR4-transduced B16 (CXCR4-luc-B16) melanoma cells in lung, but not the outgrowth of established metastases, raising the question of how T22 can best be used in a clinical setting. Herein, whereas the treatment of CXCR4-luc-B16 cells in vitro with the CXCR4 ligand CXCL12 did not reduce killing induced by cisplatin or cyclophosphamide, CXCL12 markedly reduced Fas-dependent killing by gp100-specific (pmel-1) CD8(+) T cells. T22 pretreatment restored sensitivity of CXCR4-luc-B16 cells to pmel-1 killing, even in the presence of CXCL12. Two immune-augmenting regimens were used in combination with T22 to treat experimental lung metastases. First, low-dose cyclophosphamide treatment (100 mg/kg) on day 5 in combination with T22 (days 4-7) yielded a approximately 70% reduction of B16 metastatic tumor burden in the lungs compared with cyclophosphamide treatment alone (P < 0.001). Furthermore, whereas anti-CTL antigen 4 (CTLA4) monoclonal antibody (mAb; or T22 treatment) alone had little effect on established B16 metastases, pretreatment with T22 (in combination with anti-CTLA4 mAb) resulted in a 50% reduction in lung tumor burden (P = 0.02). Thus, in vitro, CXCR4 antagonism with T22 renders B16 cells susceptible to killing by antigen-specific T cells. In vivo, T22 synergizes with cyclophosphamide or anti-CTLA4 mAb in the treatment of established lung metastases, suggesting a novel strategy for augmenting the efficacy of immunotherapy.

• Authors: Chih-Hung Lee, Takashi Kakinuma, Julia Wang, Hong Zhang, Douglas C Palmer, Nicholas P Restifo, Sam T Hwang
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 5 Issue 10 Pg. 2592-9 (Oct 2006) ISSN: 1535-7163 [Print] United States
• PMID: 17041104 (Publication Type: Journal Article, Research Support, N.I.H., Intramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• CXCL12 protein, human
• Chemokine CXCL12
• Chemokines, CXC
• Cxcl12 protein, mouse
• Peptides
• Receptors, CXCR4
• T22 peptide
• Cyclophosphamide

Topics

• Animals
• Antibodies, Monoclonal (administration & dosage, pharmacology)
• Antineoplastic Combined Chemotherapy Protocols (therapeutic use)
• Apoptosis
• B-Lymphocytes (immunology)
• Chemokine CXCL12
• Chemokines, CXC (pharmacology)
• Cyclophosphamide (administration & dosage)
• Cytotoxicity, Immunologic
• Drug Synergism
• Female
• Humans
• Immunotherapy
• Lung Neoplasms (immunology, secondary, therapy)
• Melanoma, Experimental (immunology, secondary, therapy)
• Mice
• Mice, Inbred C57BL
• Mice, SCID
• Neoplasm Transplantation
• Peptides (administration & dosage, pharmacology, therapeutic use)
• Receptors, CXCR4 (antagonists & inhibitors, genetics, immunology)
• T-Lymphocytes, Cytotoxic (immunology)