CD25-Targeted Regulatory T Cell Depletion: Efficacy of Anti-CD25 Antibody Fragments in Near-Infrared Photoimmunotherapy
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- November 21, 2019
- 1 min read
Regulatory T (Treg) cells represent an immunosuppressive mechanism that enables cancer cells to evade immune surveillance. Depletion of intratumoral Treg cells may lead to tumor regression. However, complete elimination of Treg cells could also damage the immune system. Near-infrared photoimmunotherapy (NIR-PIT) is a treatment modality that causes selective cell death of specific cells within the tumor.
An antibody-photoabsorber (IRDye700DX) conjugate (APC) binds to the tumor and, upon irradiation with near-infrared (NIR) light, causes rapid death of these cancer cells. CD25-targeted NIR-PIT has been shown to induce depletion of Treg cells within the tumor microenvironment.
In this preclinical study, researchers compared the efficacy of the antibody fragment anti-CD25-F(ab')2-IR700 versus the intact antibody anti-CD25-IgG-IR700 in a mouse model. Four groups were evaluated:
- No treatment
- Anti-CD25-IgG-IR700 i.v. only
- Anti-CD25-F(ab')2-IR700 + NIR irradiation
- Anti-CD25-IgG-IR700 i.v. + NIR irradiation
While both CD25-targeted NIR-PIT approaches significantly suppressed tumor growth, anti-CD25-F(ab')2-IR700 demonstrated superior tumor growth inhibition compared to anti-CD25-IgG NIR-PIT. The absence of the Fc protein in the APC accelerated clearance and promoted more effective activation of T cells within the tumor.
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Source: https://bibgraph.hpcr.jp/abst/pubmed/31498995
Animal Study | Photoimmunotherapy | CD25 | Treg
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