For the first time ever, Chinese scientists have injected a person with cells that have been tweaked by the genome-editing technique CRISPR, Nature reports. The procedure was part of a clinical trial led by oncologist Lu You at the West China Hospital in Chengdu; it involved editing immune cells from a patient with aggressive lung cancer and then injecting them back into the patient to help defeat the disease.

Trials with modified cells have been run before. But this is the first time that scientists are using cells edited with CRISPR — a genetic copy-and-paste tool that makes modifying cells easier and cheaper. The technique can allow scientists to make cells grow and multiply faster, in addition to inserting instructions to kill cancer on sight. A trial with CRISPR-edited cells is expected to begin early next year in the US to treat various types of cancers.

The hope is that the edited cells will be able to defeat cancer

In China, the researchers took immune cells from the patient’s blood and then used CRISPR to disable a gene that slows down the cell’s immune response. Cancer takes advantage of that weakness to spread. The researchers then multiplied the edited cells and injected them back into the patient. The hope is that these new cells will help the patient defeat lung cancer. Lu told Nature that the first injection went well and the patient will receive a second one, but he didn’t provide more details.

Lu, who received ethical approval for the trial in July, says he plans to treat 10 people with CRISPR-edited cells. The patients will be monitored for over six months to see whether the injections are safe. Even if the trails are successful, they’re very small to determine whether the CRISPR-edited immune cells will be the new tool against cancer. But the research is promising.

Some have objected to altering human genes with CRISPR, but the cells edited in this clinical trial are considered less of an ethical gray area because they won’t be passed down to offspring. The patients will be the only one feeling the effects of the edited immune cells.