CpG-based immunotherapy impairs antitumor activity of BRAF inhibitors in a B-cell-dependent manner

Oncogene. 2017 Jul 13;36(28):4081-4086. doi: 10.1038/onc.2017.35. Epub 2017 Mar 6.


Combining immunotherapy with targeted therapy has increasingly become an appealing therapeutic paradigm for cancer treatment due to its great potential for generating durable and synergistic antitumor response. In this study, however, we unexpectedly found that two types of CpG-based tumor peptide vaccine treatments consistently negated the antitumor activity of a selective BRAF inhibitor in tumors with BRAF mutation rather than showing a synergistic antitumor effect. Our further studies demonstrated that CpG alone was sufficient to dampen BRAF inhibitor-induced antitumor responses, suggesting that the impaired antitumor activity of the BRAF inhibitor observed in mice receiving CpG-based peptide vaccine is mainly dependent upon the use of CpG. Mechanistically, CpG increased the number of circulating B cells, which produced elevated amounts of tumor necrosis factor-α (TNFα) that contributed to the increased tumor resistance to BRAF inhibitors. More importantly, B-cell depletion or TNFα neutralization can restore the antitumor effect of BRAF inhibition in mice receiving CpG treatment, indicating that TNFα-secreting B cells play an indispensable role in BRAF inhibitor resistance induced by CpG. Taken together, our results strongly suggest that precautions must be implemented when designing combinatorial approaches for cancer treatment, because distinct regimens, despite their respective therapeutic benefit as monotherapy, may together provide antagonistic clinical outcomes.

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • B-Lymphocytes / pathology
  • B-Lymphocytes / physiology*
  • Cancer Vaccines / administration & dosage
  • Cancer Vaccines / adverse effects*
  • Drug Antagonism
  • Female
  • Immunotherapy / adverse effects
  • Indoles / administration & dosage
  • Melanoma / drug therapy*
  • Melanoma / pathology
  • Mice
  • Mice, Inbred C57BL
  • Oligodeoxyribonucleotides / administration & dosage
  • Oligodeoxyribonucleotides / adverse effects*
  • Protein Kinase Inhibitors / administration & dosage*
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Sulfonamides / administration & dosage
  • Toll-Like Receptor 9 / agonists
  • Tumor Cells, Cultured
  • Vaccines, Subunit / administration & dosage
  • Vaccines, Subunit / adverse effects
  • gp100 Melanoma Antigen / administration & dosage
  • gp100 Melanoma Antigen / adverse effects


  • CPG-oligonucleotide
  • Cancer Vaccines
  • CpG ODN 2216
  • Indoles
  • Oligodeoxyribonucleotides
  • PLX 4720
  • Protein Kinase Inhibitors
  • Sulfonamides
  • Toll-Like Receptor 9
  • Vaccines, Subunit
  • gp100 Melanoma Antigen
  • Braf protein, mouse
  • Proto-Oncogene Proteins B-raf