More than 200 people have been treated with experimental CRISPR therapies

I watched scientists, ethicists, patient advocacy groups and others grapple with these topics at the Third International Human Genome Editing Summit in London earlier this week.

There’s plenty to get excited about when it comes to gene editing. In the decade since scientists discovered they could use CRISPR to edit cellular genomes, several clinical trials have sprung up to test the technology’s use for serious diseases. CRISPR has already been used to save lives and transform others.

But it wasn’t all easy. Not all trials went as planned and some volunteers died. Effective treatments are likely to be expensive and therefore limited to a wealthy few. And while these trials tend to involve editing genes in cells of the adult body, some hope to use CRISPR and other gene-editing tools in eggs, sperm and embryos. The specter of designer babies continues to loom over the field.

It was during the last summit, held in Hong Kong in 2018, that He Jiankui, then based at the Southern University of Science and Technology in Shenzhen, China, announced that he had used CRISPR on human embryos. News of the first “CRISPR babies,” as they became known, caused a huge ruckus, as you can imagine. “We will never forget the shock,” Victor Dzau, president of the US National Academy of Medicine, told us.

He Jiankui ended up in prison and was only released last year. And while hereditary genome editing was already banned in China at the time – it has been banned since 2003 – the country has since enacted a series of additional laws designed to prevent it from happening again. Today, hereditary genome editing is prohibited by criminal law, Yaojin Peng of the Institute of Stem Cells and Regenerative Medicine in Beijing told the audience.

There was a lot less drama at the top this year. But there was a lot of emotion. During a session on how gene editing could be used to treat sickle cell disease, Victoria Gray, a 37-year-old survivor of the disease, took the stage. She told the public how her severe symptoms disrupted her childhood and teenage years and shattered her dreams of becoming a doctor. She described bouts of severe pain that left her hospitalized for months at a time. Her children feared that she would die.

But then she underwent a treatment that involved editing the genes in her bone marrow cells. Her new “super cells,” as she calls them, have transformed her life. Minutes after receiving her transfusion of modified cells, she felt reborn and cried tears of joy, she told us. It took her seven to eight months to feel better, but after that, “I really started enjoying the life that I once felt was passing me by,” she said. I could see the typically stoic scientists around me wiping the tears from their eyes.

Victoria is among more than 200 people who have been treated with CRISPR-based therapies in clinical trials, said David Liu of the Broad Institute of MIT and Harvard, who has led the development of new and improved forms of CRISPR. Trials are also underway for a range of other diseases, including cancers, genetic vision loss and amyloidosis.