"Theoretical concerns will continue to arise with regards to gene editing until the first substantial set of clinical data is generated given the interest and volume of preclinical work being conducted in the field, but do not see any direct concerns," he said in a note to clients. He has an equal-weight rating on Editas.

Companies respond

The three gene editing companies said they did not believe the potential p53 risk would affect their programs.

"We do not believe the theoretical risks described in these papers apply to Crispr Therapeutics' programs," company spokesman Christopher Erdman said in a statement. He said the company is using what are known as gene disruption and high-efficiency gene-correction methods, different than the ones used in the Nature Medicine studies.

Intellia "has not found this type of effect" in any of its animal or laboratory studies "despite extended observation," Jennifer Mound Smoter, a spokeswoman for the company, said in an email. Intellia's current work is focused on different cell types than the ones used in the Nature Medicine studies.

Editas Medicine can achieve "much higher targeted integration rates and gene correction without suppressing p53 than the authors of this paper saw in their experiment," Cristi Barnett, a spokeswoman for the company, said in an email.

Jussi Taipale, a cancer researcher at the University of Cambridge who is a senior author on one of the two studies, said that gene-editing research should "move forward cautiously" to look for any evidence that the methods the companies are using could be selecting for cancer-promoting traits.

"I would think the risk is relatively minor, but it would still be important to build in safeguards into studies," Taipale said. The study was done in conjunction with researchers at the Karolinska Institutet in Sweden.


The second Nature Medicine study is from scientists at Novartis who were investigating why it's harder to edit the genes in another type of cell, human pluripotent stem cells. They found that the cells die off after certain types of gene editing, triggered by functioning p53.

As a consequence, the process could leave more surviving cells with mutations, the Novartis researchers said in the study.

- with assistance from Tatiana Darie

Bloomberg