What is the promise of gene editing?

For society as a whole, not much.

One of the unexpected findings of genomics is just how little our genomes matter to disease – particularly for chronic illnesses like heart disease and cancer. Not only are genetic contributions small compared to environmental ones, but their influence is spread out over dozens of genes. Fixing any one of them (or two or six) simply isn’t going to do much good.

If we want to reduce deaths from heart disease, cancer, stroke and COPD we already know what to do: stop smoking, reduce air and water pollution, get exercise, eat a varied diet with lots of plants, and drink in moderation. But nobody can get rich on that paradigm.

Some individuals – the tiny number who suffer from single-gene diseases – will benefit enormously from gene editing technology. An excellent list and explainer of single-gene diseases can be found here. The principal ones are cystic fibrosis (1/2500 Americans) and sickle cell disease (1/500 African-Americans). In these cases, fixing a single gene will cure the disease. Ideally this would be done at the embryonic stage, but a therapeutically meaningful effect can also be obtained by editing adult tissues, once the delivery technology gets better. Gene editing absolutely has the promise of curing and transforming the lives of people suffering from these diseases. But there just aren’t that many of them.

The other group that stands to benefit are investors. Although the number of patients who might benefit from gene editing technology is not large, the clinical value delivered to those individuals will be. We are already near a $500K price tag for Kymriah to treat (and apparently cure) some childhood leukemias, and I think a good case can be made for this price. I would not be surprised to see $1M price tags for some gene therapies. A cure for CF would be worth it.

Of course most gene therapy startups will fail, just like 90% of all other biotechs do. Most investors will lose every penny. Others will hit it big, and society as a whole will benefit. But not nearly as much as the gene boosters would have you believe.