The New England Journal of Medicine carries a brief article about “Controlling CRISPR-Cas9 Gene Editing” (subscription required). The upshot: RNA used as a medicine, as in the case of “CRISPR” to edit genes, can hang around well after administration, and alter genes other than the ones intended to be altered. These “off-target” effects could lead to unwanted clinical side effects. You’d like to be able to shut the RNA medicine off. Pharmaceutical companies that make and develop medicines from short RNA sequences have been doing just that—creating “antidotes,” if you’ll pardon the expression (bad use of the word, really—an antidote is to a poison, and the medicines are not poisons)—to reverse unwanted off-target effects of their medicines, should such effects occur.
Using CRISPR for gene editing to treat known genetic disease raises a similar concern, and the NEJM article cites a recent experiment indicating that such a “reversing agent” for CRISPR, if needed, might indeed be feasible. So, suppose you are trying to treat someone with genetically-caused blindness, and there’s a risk that other genes might be affected. You could give the “reversing agent” to block that. Cool. You’d want to get it into the right tissues—the right parts of the body—but the work described in NEJM suggests that might all be reality eventually.
One challenge is: these RNA-based agents don’t always get into the parts of the body, or into cells, all that well. The NEJM writer says that this new work into “controlling” CRISPR-based gene editing “of course, depends on the [reversing agent] delivery problem being solved, but that is a topic for another day.”
It’s been some time since your correspondent worked for a drug company making RNA-based drugs, and I’m not close to the work these days, but I would say that is most definitely a topic for another day.
So, why bring this up in a bioethics forum? Because it’s one more matter that would need to be considered and addressed before charging into gene editing that can be inherited from generation to generation. This, as the present writer has repeatedly held, is something that that the human race should never do.
But it’s bowling along. The latest reports are that attempts to edit genes babies of deaf couples to prevent them from being born with genetic deafness are nigh in Russia. Understandable, laudable goal, but we should not think that control of the process is nigh. edium