Lenalidomide overcomes suppression of human natural killer cell anti-tumor functions by neuroblastoma microenvironment-associated IL-6 and TGFβ1

Cancer Immunol Immunother. 2013 Oct;62(10):1637-48. doi: 10.1007/s00262-013-1466-y. Epub 2013 Aug 27.


Background: Treatment for children with high-risk neuroblastoma with anti-disialoganglioside mAb ch14.18, IL-2, and GM-CSF plus 13-cis-retinoic acid after myeloablative chemotherapy improves survival, but 40 % of patients still relapse during or after this therapy. The microenvironment of high-risk neuroblastoma tumors includes macrophages, IL-6, and TGFβ1. We hypothesized that this microenvironment suppresses anti-tumor functions of natural killer (NK) cells and that lenalidomide, an immune-modulating drug, could overcome suppression.

Methods: Purified NK cells were cultured with IL-2, neuroblastoma/monocyte-conditioned culture medium (CM), IL-6, TGFβ1, and lenalidomide in various combinations and then characterized using cytotoxicity (direct and antibody-dependent cell-mediated cytotoxicity), cytokine, flow cytometry, and Western blotting assays. Anti-tumor activity of NK cells with lenalidomide, ch14.18, or both was evaluated with a xenograft model of neuroblastoma.

Results: CM from neuroblastoma/monocyte co-cultures contains IL-6 and TGFβ1 that suppress IL-2 activation of NK cell cytotoxicity and IFNγ secretion. IL-6 and TGFβ1 activate the STAT3 and SMAD2/3 pathways in NK cells and suppress IL-2 induction of cytotoxicity, granzymes A and B release, perforin expression, and IFNγ secretion. Lenalidomide blocks IL-6 and TGFβ1 activation of these signaling pathways and inhibits their suppression of NK cells. Neuroblastoma cells in NOD/SCID mice exhibit activated STAT3 and SMAD2/3 pathways. Their growth is most effectively inhibited by co-injected peripheral blood mononuclear cells (PBMC) containing NK cells when mice are treated with both ch14.18 and lenalidomide.

Conclusion: Immunotherapy with anti-tumor cell antibodies may be improved by lenalidomide, which enhances activation of NK cells and inhibits their suppression by IL-6 and TGFβ1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody-Dependent Cell Cytotoxicity
  • Culture Media, Conditioned
  • Female
  • Humans
  • Interleukin-6 / immunology
  • Interleukin-6 / pharmacology*
  • Killer Cells, Natural / drug effects*
  • Killer Cells, Natural / immunology
  • Lenalidomide
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Neuroblastoma / drug therapy*
  • Neuroblastoma / immunology*
  • Neuroblastoma / metabolism
  • Thalidomide / analogs & derivatives*
  • Thalidomide / pharmacology
  • Transforming Growth Factor beta1 / immunology
  • Transforming Growth Factor beta1 / pharmacology*
  • Tumor Microenvironment / drug effects
  • Tumor Microenvironment / immunology


  • Culture Media, Conditioned
  • Interleukin-6
  • Transforming Growth Factor beta1
  • Thalidomide
  • Lenalidomide