| First Author | Tsukamoto H | Year | 2018 |
| Journal | Cancer Res | Volume | 78 |
| Issue | 17 | Pages | 5011-5022 |
| PubMed ID | 29967259 | Mgi Jnum | J:265564 |
| Mgi Id | MGI:6197295 | Doi | 10.1158/0008-5472.CAN-18-0118 |
| Citation | Tsukamoto H, et al. (2018) Combined Blockade of IL6 and PD-1/PD-L1 Signaling Abrogates Mutual Regulation of Their Immunosuppressive Effects in the Tumor Microenvironment. Cancer Res 78(17):5011-5022 |
| abstractText | Recently emerging cancer immunotherapies combine the applications of therapeutics to disrupt the immunosuppressive conditions in tumor-bearing hosts. In this study, we found that targeting the proinflammatory cytokine IL6 enhances tumor-specific Th1 responses and subsequent antitumor effects in tumor-bearing mice. IL6 blockade upregulated expression of the immune checkpoint molecule programmed death-ligand 1 (PD-L1) on melanoma cells. This PD-L1 induction was canceled in IFNgamma-deficient mice or CD4(+) T cell-depleted mice, suggesting that CD4(+) T cell-derived IFNgamma is important for PD-L1 induction in tumor-bearing hosts. In some patients with melanoma, however, treatment with the anti-PD-1 antibody nivolumab increased systemic levels of IL6, which was associated with poor clinical responses. This PD-L1 blockade-evoked induction of IL6 was reproducible in melanoma-bearing mice. We found that PD-1/PD-L1 blockade prompted PD-1(+) macrophages to produce IL6 in the tumor microenvironment. Depletion of macrophages in melanoma-bearing mice reduced the levels of IL6 during PD-L1 blockade, suggesting macrophages are responsible for the IL6-mediated defective CD4(+) Th1 response. Combined blockade of the mutually regulated immunosuppressive activities of IL6 and PD-1/PD-L1 signals enhanced expression of T cell-attracting chemokines and promoted infiltration of IFNgamma-producing CD4(+) T cells in tumor tissues, exerting a synergistic antitumor effect, whereas PD-L1 blockade alone did not promote Th1 response. Collectively, these findings suggest that IL6 is a rational immunosuppressive target for overcoming the narrow therapeutic window of anti-PD-1/PD-L1 therapy.Significance: These findings advance our understanding of IL6-PD1/PD-L1 cross-talk in the tumor microenvironment and provide clues for targeted interventional therapy that may prove more effective against cancer. Cancer Res; 78(17); 5011-22. (c)2018 AACR. |
