RANKL Blockade Improves Efficacy of PD1-PD-L1 Blockade or Dual PD1-PD-L1 and CTLA4 Blockade in Mouse Models of Cancer

Oncoimmunology. 2018 Feb 14;7(6):e1431088. doi: 10.1080/2162402X.2018.1431088. eCollection 2018.

Abstract

Receptor activator of NF-κB ligand (RANKL) and its receptor RANK, are members of the tumor necrosis factor and receptor superfamilies, respectively. Antibodies targeting RANKL have recently been evaluated in combination with anti-CTLA4 in case reports of human melanoma and mouse models of cancer. However, the efficacy of anti-RANKL in combination with antibodies targeting other immune checkpoint receptors such as PD1 has not been reported. In this study, we demonstrated that blockade of RANKL improves anti-metastatic activity of antibodies targeting PD1/PD-L1 and improves subcutaneous growth suppression in mouse models of melanoma, prostate and colon cancer. Suppression of experimental lung metastasis following combination anti-RANKL with anti-PD1 requires NK cells and IFN-γ, whereas subcutaneous tumor growth suppression with this combination therapy is attenuated in the absence of T cells and IFN-γ. Furthermore, addition of anti-RANKL to anti-PD1 and anti-CTLA4 resulted in superior anti-tumor responses, irrespective of the ability of anti-CTLA4 isotype to engage activating FcR, and concurrent or delayed RANKL blockade was most effective. Early-during-treatment assessment reveals this triple combination therapy compared to dual anti-PD1 and anti-CTLA4 combination therapy further increased the proportion of tumor-infiltrating CD4+ and CD8+ T cells that can produce both IFN-γ and TNF. Finally, RANKL expression appears to identify tumor-specific CD8+ T cells expressing higher levels of PD1 which can be modulated by anti-PD1. These data set the scene for clinical evaluation of denosumab use in patients receiving contemporary immune checkpoint blockade.

Keywords: CD8+ T cells; RANK; RANKL; metastasis; tumors.

Grant support

M.J.S. was supported by a National Health and Medical Research Council (NH&MRC) Senior Principal Research Fellowship (1078671) and The Cancer Council of Queensland (1102242). E.A. and was supported by a University of Queensland (UQ) Australian Postgraduate Award (APA). H.H. was supported by a UQ International Postgraduate Research Scholarship, a UQ APA, and a QIMR Berghofer Top-Up award. J. S. O'D was supported by a UQ APA and a QIMR Berghofer Top-Up award.