Antibody-mediated neutralization of soluble MIC significantly enhances CTLA4 blockade therapy

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Science Advances  17 May 2017:
Vol. 3, no. 5, e1602133
DOI: 10.1126/sciadv.1602133


Antibody therapy targeting cytotoxic T lymphocyte–associated antigen 4 (CTLA4) elicited survival benefits in cancer patients; however, the overall response rate is limited. In addition, anti-CTLA4 antibody therapy induces a high rate of immune-related adverse events. The underlying factors that may influence anti-CTLA4 antibody therapy are not well defined. We report the impact of a cancer-derived immune modulator, the human-soluble natural killer group 2D (NKG2D) ligand sMIC (soluble major histocompatibility complex I chain–related molecule), on the therapeutic outcome of anti-CTLA4 antibody using an MIC transgenic spontaneous TRAMP (transgenic adenocarcinoma of the mouse prostate)/MIC tumor model. Unexpectedly, animals with elevated serum sMIC (sMIChi) responded poorly to anti-CTLA4 antibody therapy, with significantly shortened survival due to increased lung metastasis. These sMIChi animals also developed colitis in response to anti-CTLA4 antibody therapy. Coadministration of an sMIC-neutralizing monoclonal antibody with the anti-CTLA4 antibody alleviated treatment-induced colitis in sMIChi animals and generated a cooperative antitumor therapeutic effect by synergistically augmenting innate and adoptive antitumor immune responses. Our findings imply that a new combination therapy could improve the clinical response to anti-CTLA4 antibody therapy. Our findings also suggest that prescreening cancer patients for serum sMIC may help in selecting candidates who will elicit a better response to anti-CTLA4 antibody therapy.

  • NKG2D ligand
  • soluble MIC (sMIC)
  • anti-sMIC antibody
  • anti-CTLA4 antibody therapy
  • cancer

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