BEIJING — China could be just over a year away from clinical trials of a new gene-editing therapy with an unprecedented high level of safety, according to a team of Chinese scientists involved in the research programme.

The scientists said the research, based on groundbreaking work published in the journal Science earlier this month, could help save the lives of many patients battling deadly diseases including cancer.

The existing genome-editing method works like a shotgun, breaking up a large numbers of genome strands and sometimes missing its intended target, causing unnecessary damage to cells.

The new tool under development in China targets and swaps individual “letters” in the DNA with extreme precision, avoiding cuts to the strands and significantly reducing the risk of unexpected mutations.

The therapy could help cure two-thirds of the more than 50,000 diseases, including some of the deadliest cancers, caused by misplaced letters, the researchers say.

Dr Yang Hui, lead scientist of the programme at the Chinese Academy of Sciences’ Shanghai Institutes for Biological Sciences, said his group was racing to develop a new gene editor that would be safe for everyone.

Dr Yang, who left the Massachusetts Institute of Technology and returned to China four years ago after getting a huge grant from Beijing to support original research by young talented scientists, said: “Our goal is to launch clinical trials within a year or two.

“Many patients and their families are in despair. [These] diseases don’t leave them much time.”

Other groups are also testing gene-editing therapies on people. Boston-based CRISPR Therapeutics announced last month that it had started clinical trials, and more than two years ago Sichuan University in Chengdu claimed a world-first with a human gene-editing trial in which doctors injected edited white blood cells into patients with late-stage lung cancer.

But such work is rare because of scepticism in the medical community about the safety of the technology. Mutations caused by editing are extremely difficult to detect and some may trigger additional bouts of cancer.

In its Science paper, Dr Yang’s team detailed a technology that could catch editing-induced mutations.

The classic CRISPR technology, the most popular tool for gene editing, depends heavily on a cellular self-repairing mechanism to stitch up broken gene strands. But unpredictable problems can occur in the repair process.

A new variant of the CRISPR method, known as base-editing, does not sever the DNA strands but can still miss its target. The testing tool developed by Yang’s team confirmed this by recording a 20-fold increase in mutations in base-edited mice embryos.

Known as Goti, the new tool can mark the mutated genes and make them glow under a microscope like red florescent lights. With the technology, researchers can single out a few mutated genes in a pool of 6 billion pairs of DNA strands – a bit like listening for a raindrop in a thunderstorm, according to the team.

Goti also revealed what was causing the mutations in the existing base-editing method.

Dr Yang said the team’s next paper would offer a solution involving a modification of CRISPR’s protein structure to reduce or eliminate the off-target effect. That, he said, would be the therapy they hoped to test on patients.

“The United States has been a leader in gene-editing technology and there is still a significant gap between China and the US, especially in biomedicine,” he said. “But this technology originated in China, and we are coming up fast.”

Researchers from America and Europe have taken part in the China-led research.

Dr Yang’s research has had big support from the government and private investors, but it is not certain whether clinical trials will go ahead.

Last week, the National Health Commission in Beijing released a draft regulation requiring all gene-editing tests on people to be approved in advance by the central government; previously a local authority or even a hospital could approve the trial.

The tighter controls come after a controversial experiment by a research team in Shenzhen led to the birth of the world’s first two genome-edited babies earlier this year.

The new method also needs to get past a test on primates before it can be tried on human patients, according to Yang.

Dr Jiang Peng, a researcher who studies cancer metabolism at the Tsinghua University’s school of life sciences but was not involved in the Shanghai institutes study, said the research was an original piece of work and it might lead to a big leap forward in life science.

“Mutations are elusive. We are in great need of a good detection tool,” he said.

But Dr Jiang warned that experiments on humans should not be rushed without proper consideration of basic ethics, even if the patients and their families were willing to take the risk.

“Different sources of cancer require different treatments. Liver cancer, for instance, develops quite differently from lung [cancer],” Dr Jiang said.

So the advancement of the new technology from clinical trials to widespread application could take a lot of time, he said. SOUTH CHINA MORNING POST