Three cancer patients have become the first to be treated with a gene-editing technique called Crispr—but it’s not clear if it worked. “The good news is that all of them are alive,” said Dr. Edward A. Stadtmauer of the University of Pennsylvania Abramson Cancer Center. “The best response we’ve seen so far is stabilization of their disease.” Crispr is a tool that can identify and alter bits of DNA. In this study, which was meant to assess safety, doctors removed T-cells from patients’ blood, and deleted genes that could hamper the body’s ability to fight the disease.