A cancer treatment called photoimmunotherapy involves injecting patients with an agent, then exposing their tumors to near infrared light. It was developed by a Japanese researcher who works at the US National Institutes of Health. Japan became the first country to use it on a patient in 2021. The agent that's injected contains cancer-specific antibodies, to which special chemicals are attached. After the antibodies bind to cancer, near infrared light is applied, killing the cancer cells.