Light at the End of the Chemo

GETTINGTHE body’s immune system to fight cancer seems logical, since its job is to spot and attack foreign intruders. Trying to answer the question of why the immune system doesn’t readily eradicate tumor cells has led to the burgeoning field of immunotherapy. Progress has been stymied, but one researcher has seen the light. Minsoo Kim is using optics to boost the strength of immune therapy. According to a study in Nature Communications, this approach tackles a fundamental challenge: controlling the immune cells. Sometimes, the immune system overreacts and causes too much damage. Or the response may be too weak. And cancer is no easy foe. Tumor cells evade detection by immune cells, suppress the immune system and become resistant to treatment.

Kim, an immunologist at the University of Rochester, had an idea: Perhaps light could assist immunotherapy drugs in activating a response against cancer. Kim and his colleagues drew inspiration from algae, long known to respond to light. In the early 2000s, German researchers found genetic sequences that encoded a previously unknown molecule that algae used to bring positively charged ions into themselves. They called it channelrhodopsin. Kim and his team wondered if channelrhodopsin could be used to control how T cells responded to tumors in patients receiving immunotherapy. As a first step, they studied a group of mice with melanoma on their ears. Researchers infused T cells containing channelrhodopsin into the mice, so that this molecule would be active in their T cells. They also worked with a team of optics scientists to create an LED chip, which they implanted in the study animals.

Using tiny battery packs attached to the mice, the researchers triggered the LED to shine on T cells near tumors. When the light hit the channelrhodopsin in the T cells, they killed more cancer cells. Almost all the melanoma was obliterated. Kim hopes to begin human clinical trials soon.

The results, though preliminary, are intriguing because cancer usually suppresses the immune system so heavily. “Our light stimulation approach can help T cells overcome the immune suppression,” says Kim, “and kill tumors better.”