After 2 Deaths and Reports of Brain Tumors, How Dangerous Is Gene Therapy, Really?

The future of genetic medicine has perhaps never looked brighter than it does right now.

Remarkable recent cases like that of baby KJ have illustrated the potential for gene-editing therapies to treat and possibly even completely fix the genetic flaws that cause many debilitating health conditions. Such treatments are often bespoke, meaning they’re individualized to repair that patient’s specific genetic code. As of late, however, there have also been some unsettling incidents in the world of gene therapy revealed to the public.

First-Ever Custom CRISPR Therapy Saves Infant With Deadly Genetic Disorder

In late July, for instance, Science Magazine was the first to report that a six-year-old girl died last year after undergoing an experimental gene-editing trial performed by scientists in China—a trial that might have been rife with ethical shortcomings. Since then, the pharmaceutic company HuidaGene disclosed a second death likely caused by gene therapy in China, involving a young boy being treated for his Duchenne muscular dystrophy.

Both of these deaths occurred in trials run under China’s investigator-initiated trial pathway , or IIT, which allows doctors or hospitals to conduct early-stage clinical trials with less oversight from the country’s regulatory agencies.

ITT seems to have helped substantially speed clinical trial development in China. And as recently as this past June, lawmakers in the U.S. had pushed for implementing at least some of the elements in ITT to accelerate research stateside. China, however, has signaled that it intends to tighten up regulations governing the practice.

Speaking of the U.S., there have been recent reports of likely rare but potentially serious adverse events tied to gene therapy here as well. In May, researchers from Children’s Hospital of Philadelphia (CHOP) reported that a child developed a brain tumor probably fueled by the viral vector used to deliver his gene therapy four years earlier. Fortunately, the tumor was surgically removable, and the boy still appears to be doing well following treatment.

These incidents have arguably reopened a long-standing debate about how to balance the safety concerns surrounding gene-editing technology with the urgent need for such treatments. Notably, many patients receiving recently approved or experimental gene therapies are children with conditions that only progressively worsen over time and/or can dramatically shorten life expectancy.

For this Giz Asks, we reached out to biologists, pediatric doctors, and other experts to pick their brains on the overall safety of gene therapy as it stands currently and to ask whether these recent events should make us reevaluate how best to develop these life-changing treatments. The following responses may have been edited for clarity and grammar.

An assistant professor in the Biomedical Sciences Division at the University of California, Riverside.