There's been a lot of excitement lately that the powerful gene-editing technique CRISPR could offer a new way to treat health problems ranging from cancer to blindness.

But there hasn't been much direct scientific evidence in actual patients about whether it might work or would be safe — until now.

Chinese scientists have published the first report in a scientific journal of an attempt to use CRISPR-edited cells in a patient--a 27-year-old man who is HIV-positive.

While the treatment did not rid the man of the AIDS virus, the researchers and others are calling the report promising. That's because it indicates that so far the gene-editing technique seems to safely and effectively make the precise DNA change intended.

"It is a first step," says Hongkui Deng, a professor of cell biology at the Peking University, who helped lead the research. The case was published in the New England Journal of Medicine. "It is promising."

Others agree.

"It's not a home run at this point, but getting to first base is really critical for this technology," says Carl June , a professor in immunotherapy at the University of Pennsylvania.

June wrote an editorial accompanying the report that says the case means "the genie is out of the bottle with genome editing."

"It's a successful use of the technology, and it's the first one," June says. "It's a good first step."

Scientists in China have been trying to use CRISPR to treat a variety of forms of cancer, and two studies attempting to use the gene-editing technique to treat cancers recently started in the United States.

In addition, researchers have launched studies that are trying to use CRISPR to treat the blood disorders beta thalassemia and sickle cell disease. And later this year, scientists hope to use the technique to try to restore visionto people blinded by a genetic disorder later this year.

But none of the other researchers have yet published results in any peer-reviewed scientific journals.

In the new report, the researchers attempted to use CRISPR to recreate the experiences of two men known as the Berlin patient and the London patient. In those cases, HIV-positive men were declared effectively cured after they received stem cell transplants from people born with variations of a gene known as CCR5 that makes people naturally resistant to HIV. The variation disables a molecular gateway HIV uses to enter and destroy key immune system cells.

CCR5 also played a role in another recent CRISPR experiment. Another Chinese scientist, He Jiankui, sparked international outrage last year when he announced he had used CRISPR to create the world's first genetically modified babies — twin girls whose DNA he edited when they were embryos to try to protect them from HIV by editing their CCR5 gene.

But that was considered reckless and unethical because He performed the experiment before it was clear that it would be safe and would work. Many also question whether it was necessary, given there are other ways to protect people from HIV.

In the new case, Deng and his colleagues used CRISPR to edit the CCR5 gene on stem cells to recreate the naturally occurring protection against HIV. They then used the edited cells to perform a stem cell transplant for the patient. The man also had acute lymphoblastic leukemia, a form of blood cancer.

The transplant appears to have put the patient's leukemia into remission, the researchers reported. He suffered no apparent adverse side effects from the gene-edited cells, which have persisted in his body for more than 19 months, according to the report.

Both findings are important positive outcomes that suggest the approach is safe and could work, the researchers and others say.

In addition, the researchers reported that an intensive genetic analysis indicates the gene-editing didn't inadvertently cause any unintended changes in DNA, a key concern about the safety of gene-editing.

"So with this report we have partial success," Deng says. "It tells you the feasibility and the safety is quite promising for the gene-editing approach."

The approach did not reduce levels of HIV in the man's body because only about 5% of his white blood cells carried the edited CCR5 variation. So Deng says his team plans to focus on finding ways to boost that closer to 100%, which is what would be needed to eradicate the virus.

"In the future we will put a huge effort on this to optimize the efficiency and continue on this line of research," Deng says.

June agrees the report is promising.

"This says there will be blue skies ahead," June says. "We're going to see many, many applications now since they got to first base here on this one."

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