For the first time, researchers at West China Hospital in the city of Chengdu in Sichuan province have injected a patient with cells modified through the CRISPR-Cas9 gene editing technique, reports David Cyranoski at Nature. It’s an early step into a new age of gene editing, which promises to revolutionize health, agriculture, conservation and other fields of biology.
CRISPR is a gene editing technique derived from the naturally occurring immune systems found in a variety of bacteria, writes Sarah Zhang for Gizmodo. These species keep a “rogue’s gallery” of virus DNA in their genome so they can recognize it if it invades their cells. If the virus DNA is detected, the bacteria deploys CRISPR associated (a.k.a. Cas) enzymes that can find the invading virus DNA and precisely snip it out.
Researchers realized that if they could show the Cas proteins a slice of target DNA, the enzymes would patrol the genome, snipping out those bits of code. This ingenious method allowed them to hijack the system to precisely edit genes. The bacteria with the most efficient genetic homing device is actually Streptococcus pyogenes, which causes strep throat. Scientists are now working with the CRISPR-Cas9 technique to try and cut out the gene sequences that cause genetic diseases and even used it recently to partially restore vision in blind animals.
In this latest application, oncologist Lu You of Sichuan University and his team isolated a specific set of cancer-fighting T-cells from a patient with an aggressive form of lung cancer. These immune cells should attack abnormal cells like those found in cancerous tumors, but they don't always work. Some cancerous tumors exploit the T-cells' PD-1 receptor, which turns off the immune response. So the researchers snipped out the region of the DNA that codes for PD-1 proteins using the CRISPR-Cas9 system and cultured these modified T-cells before re-injected them back into the sick patient.
The hope is that by deleting the genetic code for PD-1 proteins, the T-cells will attack the cancer uninhibited.
The first injection went smoothly and the patient will receive a second dose, but patient confidentiality limits the amount of information the researchers could provide, reports Cyranoski. Ten other patients will undergo similar treatments, receiving two to four injections, and will then be monitored for six months.
Carl June, who researches immunotherapy at the University of Pennsylvania says this study will likely spur some healthy competition. “I think this is going to trigger ‘Sputnik 2.0,’ a biomedical duel on progress between China and the United States, which is important since competition usually improves the end product,” he tells Cyranoski.
Tracy Staedter at Seeker reports that June’s lab is currently the only one in the United States that has FDA approval to use CRISPR techniques on T-cells meant for humans.
But researchers in the U.S. are purposefully moving slow on the CRISPR front, Staedter reports. In 2015, researchers in Beijing used CRISPR to modify the genome of a human embryo, though they did not let it develop. That led to a heated debate over the ethics of using the nascent technology on humans and led the National Institutes of Health to create an advisory committee to oversee any proposals for using CRISPR on people.