Enhanced tumor eradication by combining CTLA-4 or PD-1 blockade with CpG therapy

J Immunother. 2010 Apr;33(3):225-35. doi: 10.1097/CJI.0b013e3181c01fcb.


Tumor immunotherapy aims to break effector T-cell anergy and to block suppressive cell types and ligands allowing effector cells to exert tumor eradication. Previous reports demonstrate that cytotoxic T lymphocyte antigen-4 (CTLA-4)-blocking antibodies promote T-cell activation and render T effector cells resistant to T regulatory cells (Tregs) whereas programmed death receptor-1 (PD-1)/PD-L1 blockade results in loss of peripheral tolerance. Herein, we explored single or combined antibody blockade of CTLA-4 and PD-1 alone or combined with the toll-like receptor agonists CpG or bacillus Calmette-Guérin for treatment of murine experimental bladder cancer. In therapeutic studies, tumors were rejected by anti-CTLA-4 (aCTLA-4) while anti-PD-1 (aPD-1) suppressed tumor growth. The combination had no additive effect compared with aCTLA-4 alone. However, elevated levels of circulating CD107a expressing CD8 T cells were found in the aCTLA-4 plus aPD-1 group. In addition, levels of antinuclear antibodies correlated inversely with tumor size. Next, we combined CpG or bacillus Calmette-Guérin with aCTLA-4, aPD-1, or aPD-L1 and found that CpG in combination with aCTLA-4 or aPD-1 increased the survival of mice, with aPD-1 plus CpG being superior to either agent alone. CpG plus aCTLA-4 or aPD-1 increased the numbers of circulating tumor-specific CD107a expressing CD8 T cells as well as activated (CD25FoxP3-) CD4 splenocytes. Further, we investigated the numbers of Tregs in the tumor area of treated animals and detected decreased levels after aCTLA-4 or aPD-1 plus CpG therapy. Thus, the combination of CpG with CTLA-4 or PD-1 blockade improved long-term survival and led to increased levels of tumor-reactive T cells and reduced numbers of Tregs at the tumor site.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies / administration & dosage
  • Antibodies / immunology*
  • Antigens, CD / immunology*
  • Antigens, Surface / genetics
  • Antigens, Surface / immunology*
  • Antigens, Surface / metabolism
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / immunology*
  • Apoptosis Regulatory Proteins / metabolism
  • BCG Vaccine / administration & dosage
  • BCG Vaccine / immunology
  • CD4-Positive T-Lymphocytes / drug effects
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism
  • CTLA-4 Antigen
  • Cell Line, Tumor
  • Female
  • Flow Cytometry
  • Gene Expression Regulation, Neoplastic
  • Lysosomal-Associated Membrane Protein 1 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Oligodeoxyribonucleotides / administration & dosage
  • Programmed Cell Death 1 Receptor
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes, Regulatory / drug effects
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / metabolism
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism
  • Treatment Outcome
  • Tumor Burden / drug effects
  • Urinary Bladder Neoplasms / drug therapy*
  • Urinary Bladder Neoplasms / genetics
  • Urinary Bladder Neoplasms / pathology


  • Antibodies
  • Antigens, CD
  • Antigens, Surface
  • Apoptosis Regulatory Proteins
  • BCG Vaccine
  • CTLA-4 Antigen
  • Ctla4 protein, mouse
  • Lysosomal-Associated Membrane Protein 1
  • Oligodeoxyribonucleotides
  • Pdcd1 protein, mouse
  • Programmed Cell Death 1 Receptor
  • Transforming Growth Factor beta