"It's the most complicated genetic, cellular engineering that's been attempted so far," study leader Dr. Edward Stadtmauer, of the University of Pennsylvania in Philadelphia, told the AP. "This is proof that we can safely do gene editing of these cells."
Two to three months later, one patient's cancer has progressed and one is stable. The third patient was treated recently, so it is too soon to tell if it worked. Fifteen more patients will get the treatment, to test safety and efficacy, the wire service reported.
"It's very early, but I'm incredibly encouraged by this," Dr. Aaron Gerds, a Cleveland Clinic cancer specialist, told the AP.
This study is not aimed at changing the DNA within a person's body. Instead, the doctors used CRISPR to remove, alter and give back to the patient cells that are super-powered to fight their cancer - a kind of immunotherapy.
Chinese scientists reportedly have tried this for cancer patients, but this is the first such study outside that country. It's so novel that it took more than two years to get approval from U.S. government regulators to try it, according to the AP.
Preliminary findings were released by the American Society of Hematology, and more details will be presented at the society's annual meeting in December.