In a new step for Crispr, scientists have used the gene-editing tool to modify cancer patients' immune cells to fight their tumors. In a small study published today in the journal Nature, a US team shows that the approach is feasible and safe, but only in a few patients.

Cancer arises when cells become uncontrollable. Each person has their own immune cells that can differentiate cancer cells from normal ones, and they all have a set of genes that drive the disease. Patients don't have enough immune cells with these receptors in order to mount an effective response In this Phase 1 trial, researchers identified each patient'sreceptor, inserted them into immune cells lacking them, and grew more of them. Each patient's immune cells were unleashed into their bloodstream to destroy their tumors.

"What we're trying to do is really harness every patient's tumor-specific genes." The company collaborated with experts from the University of California, Los Angeles, the California Institute of Technology, and the Institute for Systems Biology in Seattle to create personalized therapies.

16 patients with solid tumors were separated from their T cells by the researchers. T cells are part of the immune system Each patient was identified with dozens of receptors that could bind to their own tumors. Crispr was used to add genes to the person's T cells in the lab.

More of the edited cells were grown by scientists, enough to make a therapeutic dose. They infused the edited cells back into each of the volunteers who had previously been treated for cancer. The edited T cells went to the tumors.

The tumors were frozen in six of the patients. The other 11 people had their cancer progress. There were two side effects related to the edited T cell therapy. The people in the trial were expecting the side effects of the treatment.

Mandl thinks the response to the therapy was limited because the patients were already very advanced. Some of the receptors the team chose did not have potent anti- cancer effects.

Bruce Levine is a professor of cancer therapy at the University of Pennsylvania. Picking the right ones is going to be a challenge. It's one thing to be able to get those T cells into a tumors. If they don't do anything, that's disappointing