Genetic Medicine: The Next Gene-eration

Good times indeed. But they’re long gone now. A perfect storm of a US biotech bear market, concerns about the efficacy and safety of treatments, and rather overhyped expectations have left gene therapy looking less like a silver bullet and more like a slightly leaky water pistol. And a very expensive one at that. The recent exit of Amicus from the gene therapy world is just one example of reality biting in this space.  

But the dream is still alive. New delivery methods, allowing better targeting and lower dosing, for example, are being investigated to address some of the big issues. Not to mention a much broader view of the types of diseases that might be addressable through genetic medicines, beyond the rare conditions that have attracted much of the attention. It’s also not fair to say that there’s been no progress in the area, with some recent in vivo gene editing success in amyloidosis.  

In our recent digging into the topic, we’ve been speaking to executives at a number of genetic medicine companies, and it’s clear that there is no shortage of belief in the future of the technology. There is, however, significant divergence in approach which is interesting. In fact, even the language starts to vary pretty quickly, from gene therapy to gene editing to perhaps the most ambitious, gene coding. Getting to grips with the differences between these three gets somewhat sticky, but we think it’s useful to try to pin down the definitions.  

• Gene therapy: delivery of a gene, usually via a virus, into the host. In the case of adeno-associated viral vectors, currently the most common approach, this sets up a copy of the gene in the nucleus that remains a separate entity to the host genome. The end goal is usually to produce a protein that is lacking in a particular disease.  
• Gene editing: there are two versions; in vitro where cells are taken out of the patient, edited and then put back in; and in vivo which involves directly editing the host genome - either by adding, removing or disabling a gene. Current thinking is that gene editing is a longer-lasting approach, but with more limited application than traditional gene therapy approaches. Gene editing methods include Crispr/Cas9 (and its more precise cousin, base editing), Zinc finger nucleases and Talens. 
• Gene coding: this is the bleeding edge of what is already cutting-edge technology and is a term coined by the early-stage private group Saliogen. Rather than editing the host genome, gene coding can, in theory, add any amount of DNA into the host genome. One good definition from Saliogen was “if Crispr is the cutting enzyme, think of us as the pasting enzyme”. 

Those who truly believe in the vision of gene therapy are of the opinion that one day it may become as common as other mainstream therapies. If that is true, there is a long and winding path between us and that brave new world. And the bricks to lay that road need funding by the very investors who have already started to get cold feet on the whole idea.  

The next few years need to show some solid progress to secure that investment. If these new approaches succeed, the potential impact on a huge number of diseases (not to mention the coffers of those who invest) will be almost immeasurable. If such successes do not materialise, even the most cutting-edge technology might not be able to revive the sector.  

The full report features interviews with Generation Bio, Saliogen, Code Bio, Verve, and Excision Biotherapeutics and you can read it here.