In a world-first, CRISPR has been used to treat a patient who is HIV-positive. And while he has not been fully cured of the disease, researchers writing in the New England Journal of Medicine have shown that the procedure is safe – and describe it as "promising".
CRISPR is medically exciting but controversial. You may remember the doctor who late last year announced he had created the first gene-edited babies, two Chinese baby girls with a DNA adaption designed to protect them from HIV. Not to mention the public outrage (and investigation) that followed.
At the time, many said the procedure was unethical. Not only was it performed before it was known to be safe without any unintended side effects, but there are also other (perfectly safe) ways to protect people and babies from HIV transmission.
This time, however, scientists carried out the procedure on a 27-year-old man who already had HIV as well as a type of blood cancer called acute lymphoblastic leukemia. Using CRISPR, they edited stem cell DNA to damage the CCR5 gene – a gene needed in order for HIV to penetrate immune cells. The team then used chemicals and radiation to remove the patient's bone marrow so that it could be replaced by the edited stem cells, which entered the body via an IV.
The process was inspired by the Berlin patient, who in 2008 became the first person to be cured of HIV when doctors took him off antiretroviral drugs and administered blood cells from a bone marrow donor with a naturally occurring mutation that damages the CCR5 gene. The 41-year-old man was cured of his leukemia and his HIV.
In so far as the leukemia is in remission and there are no apparent side effects from the treatment, it's been a roaring success. Nineteen months later, the gene-edited cells are still in the body, there are no unintended DNA changes, and the procedure appears to be safe. While they were unable to reduce levels of HIV (the patient is still on antiretroviral medication), the study's authors believe that by improving the efficiency of the technique, they may be able to eradicate the virus from the body completely.
As it stands, only about 5 percent of the patient's white blood cells carried the edited gene variant. The researchers involved in the study want to increase that percentage so that it reaches 100. They hope to expand the trial once the efficiency has been improved but considering that only two months ago, they successfully eliminated HIV genomes in mice, it is a promising start.
And it's not just HIV. Researchers are investigating how CRISPR can be used to treat all manner of conditions from cancer to blood disorders to muscular dystrophy in dogs. As Carl June wrote in the accompanying editorial, "the genie is out of the bottle with genome editing."