Gene editing not yet safe or effective enough for human use

Heritable Human Genome Editing

International commission concludes that gene editing in human embryos is not yet ready for human application.

Published 11 September 2020

A new report from a high-powered commission formed after gene-edited twins were born in China concludes that the editing technologies must be still be proven safe and effective before countries might approve their use in human embryos.

The risks from editing genes in human embryos, despite the potential for correcting serious genetic disorders, remain too high for current application, according to a consensus report from a high-profile commission.(1) The commission was convened by the US National Academy of Medicine, the US National Academy of Sciences and the UK Royal Society following the bombshell news from China of twins born following CRISPR-Cas9 intervention in the embryos (to prevent HIV infection) in 2018.(2)

A statement issued by the Royal Society warned that ‘human embryos whose genomes have been edited should not be used to create a pregnancy until it is established that precise genomic changes can be made reliably without introducing undesired changes — a criterion that has not yet been met by any genome editing technology.’(3) And once that point has been reached, adds the report, ‘initial uses should be limited to the prevention of serious monogenic diseases’.

The report goes on to summarise the potential benefits, harms, and uncertainties associated with genome editing technologies and defines a translational pathway from preclinical research to initial clinical applications - in the event that ‘a country decides to permit such uses’. The report also specifies preclinical and clinical requirements for establishing safety and efficacy, and for undertaking long-term monitoring of outcomes. ‘Extensive national and international dialogue is needed before any country decides whether to permit clinical use of this technology,’ advises the report, which also identifies essential elements of national and international scientific oversight.

These were largely the messages to emerge from the first gene editing summit in Washington in 2015 - organised by US National Academies – which nevertheless gave some cautious support to the CRISPR-Cas9 technique, but insisted any advance should be subject to strict oversight and only in an ethically approved research setting. The second summit, in Hong Kong in 2018, coincided with the news from China that the same technology had now been used not to cure or prevent an inherited disease but to introduce genetic resistance to HIV infection in the offspring. Most reactions were of outrage, describing the development as morally unacceptable – and one for which the culprit scientist, according to reports, was jailed in China for three years.

The commission now behind this latest report was formed in the aftermath of that 2018 summit in Hong Kong and the announcement that twins had been born following embryo editing. According to the Royal Society statement, it is hoped that the commission’s highly cautious report will now inform a WHO advisory committee presently developing governance recommendations for both heritable and non-heritable human genome editing research and clinical uses. The WHO advisory committee is expected to issue its guidance later this year.

Meanwhile, the commission’s co-chair Richard Lifton, president of the Rockefeller University, New York, reaffirmed that any initial uses of human genome editing ‘should proceed incrementally and cautiously, and provide the most favorable balance of potential benefits and harms’. He added that, based on the ‘responsible clinical translational pathway’ defined in the report, countries might then decide whether a gene editing application is permissible.

‘We think the bar should be high, and appropriately so,’ Lifton said in a press statement. ‘If you are going to be creating human beings, you want to know that you can reliably make the edits you’re intending. If you can’t do it reliably, without introducing unintended effects, you shouldn’t be going forwards.’


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