Depletion of human regulatory T cells specifically enhances antigen-specific immune responses to cancer vaccines.

Journal Article (Clinical Trial;Journal Article)

CD4(+)CD25(high)FoxP3(+) regulatory T (Treg) cells limit antigen-specific immune responses and are a cause of suppressed anticancer immunity. In preclinical and clinical studies, we assessed the immune consequences of FoxP3(+) Treg-cell depletion in patients with advanced malignancies. We demonstrated that a CD25(high) targeting immunotoxin (denileukin diftitox) depleted FoxP3(+) Treg cells, decreased Treg-cell function, and enhanced antigen-specific T-cell responses in vitro. We then attempted to enhance antitumor immune responses in patients with carcinoembryonic antigen (CEA)-expressing malignancies by Treg-cell depletion. In a pilot study (n = 15), denileukin diftitox, given as a single dose or repeated dosing, was followed by immunizations with dendritic cells modified with the fowlpox vector rF-CEA(6D)-TRICOM. By flow cytometric analysis, we report the first direct evidence that circulating CD4(+)CD25(high)FoxP3(+) Treg cells are depleted after multiple doses of denileukin diftitox. Earlier induction of, and overall greater exposure to, the T-cell response to CEA was observed in the multiple-dose group, but not the single-dose group. These results indicate the potential for combining Treg-cell depletion with anticancer vaccines to enhance tumor antigen-specific immune responses and the need to explore dose and schedule of Treg depletion strategies in optimizing vaccine efforts.

Full Text

Duke Authors

Cited Authors

  • Morse, MA; Hobeika, AC; Osada, T; Serra, D; Niedzwiecki, D; Lyerly, HK; Clay, TM

Published Date

  • August 1, 2008

Published In

Volume / Issue

  • 112 / 3

Start / End Page

  • 610 - 618

PubMed ID

  • 18519811

Pubmed Central ID

  • PMC2481547

Electronic International Standard Serial Number (EISSN)

  • 1528-0020

Digital Object Identifier (DOI)

  • 10.1182/blood-2008-01-135319


  • eng

Conference Location

  • United States