Rapid Depletion of Intratumoral Regulatory T cells Induces Synchronized CD8 T and NK Cell Activation and IFN-γ-dependent Tumor Vessel Regression

Published in: Cancer Research

Authors: Yutaka Kurebayashi, Colleen P. Olkowski, Kelly C. Lane, Olga V. Vasalatiy, Biying C. Xu, Ryuhei Okada, Aki Furusawa, Peter L. Choyke, Hisataka Kobayashi, Noriko Sato


Tumor-infiltrating regulatory T cells (Tregs) were selectively depleted using anti-CD25 antibody fragment mediated NIR-PIT with ML7710 (50 J/cm2) in tumor-bearing mice. This induced transient IFN-γ expression in CD8 T and NK cells, which lead to efficient and rapid tumor vessel regression, intratumoral ischemia, and tumor necrosis/apoptosis and growth suppression. These results indicate the pivotal roles of intratumoral Tregs in maintaining tumor vessels and tumor growth by suppressing CD8 T and NK cells from producing IFN-γ.


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