‘Photobombing’ Tumor Immune Suppressors

Pairing an antibody with a light-sensitive dye is an effective way of targeting tumor cells and destroying them, researchers have found.

AsianScientist (Aug. 22, 2016) – Researchers in Japan and the US have found that an antibody-dye pair, activated by shining near-infrared light, can help to destroy immune-suppressing cells within a tumor. The report was published in Science Translational Medicine.

The research team, which consisted of members from Nagoya University Graduate School of Medicine in Japan and the National Cancer Institute in the US, used a method called near-infrared photoimmunotherapy, where an antibody is fused to a light-sensitive dye. The antibody-dye pair targets one common type of regulatory T-cells called CD25+ Tregs, which keep the immune system from recognizing and attacking cancer cells.

Shining near-infrared light on the tumor activates the antibody and targets only these Tregs for destruction. With the Tregs out of the way, the body’s usual immune cell defenders can enter and attack the tumor.

First author Dr. Kazuhide Sato and colleagues showed that the technique can shrink lung, colon, and prostate tumors in mice, and even help destroy untreated tumors of the same type throughout the body. The effect appears to last about a week, but its widespread effects may make it useful for treating metastatic cancer, and repeated treatments may give the immune system time to learn how to protect against recurrences of the cancer.

According to the research team, the findings offer a new way of selectively targeting the ‘brakes’ on the immune system that can keep the body from fighting off cancer, without widely affecting immune cells throughout the rest of the body and triggering harmful autoimmune responses.


The article can be found at: Sato et al. (2016) Spatially Selective Depletion of Tumor-associated Regulatory T-cells with Near-infrared Photoimmunotherapy.

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Source: Science Translational Medicine.
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