Gilmore O'Neill, CEO of Editas Medicine, reflects on the company's evolution from CRISPR pioneer to focused in vivo therapeutics developer. Two years into a strategic pivot, O'Neill shares the reasoning behind discontinuing the reni-cel cell therapy program in favor of lipid nanoparticle-delivered gene editing, and how EDIT-401, targeting severe hyperlipidemia, embodies that shift. He also discusses the investor response to Editas' recent public offering and his long-term vision for gene editing as a low-cost, globally accessible alternative to chronic disease management.
Can you start by taking us back to Editas Medicine’s founding and the mission that has shaped the company?
Editas Medicine was the first CRISPR company to be formed, established shortly after the Nobel Prize-winning work of Jennifer Doudna and Emmanuelle Charpentier was published. Over the following twelve years, the company invested heavily in developing the tools required to optimize CRISPR editing and enable its use in humans. Part of that effort produced tools that Editas made publicly available, including a computational tool called Calitas, which helps identify the optimal guide RNA selection for a given edit. In practical terms, that means making precise changes to the target sequence in the human genetic code while minimizing or eliminating the risk of unintended edits elsewhere.
About four years ago I joined as CEO, tasked with converting that significant body of innovation into a focused therapeutic company. It was an important inflection point, and we reframed the strategy around four objectives.
The first was to develop medicines that would be meaningfully more efficacious than the current standard of care, with no predetermined constraint on indication or therapeutic area. The second was to use CRISPR only for things CRISPR can uniquely do. If another modality, an siRNA, an antisense oligonucleotide, or a monoclonal antibody, could achieve the same result, we would not use CRISPR. That principle led us to our current focus of using CRISPR to make edits in non-coding DNA to functionally upregulate disease-mitigating proteins, something no other modality can do.
The third objective was to move our first wave of in vivo therapeutics into the clinic in indications where translation would be straightforward, with biomarkers that are easy to collect and can be rapidly read out, enabling us to identify and select doses efficiently and move programs forward with confidence.
The fourth, and critically important, objective was to develop commercially viable and accessible medicines, with a particular emphasis on keeping the cost of goods low and making the drugs easy to administer. That led us to focus on lipid nanoparticle delivery rather than cell-based or AAV vector-based approaches. Lipid nanoparticles (LNPs) are scalable in a way that AAV vectors and cell therapies are not, and the cost of goods comparison is stark, with LNPs offering reductions of multiple orders of magnitude.
EDIT-401 is probably the clearest embodiment of all four of those principles in a single program.
Can you expand on the uniqueness of an LNP approach compared to AAV vector approach?
Beyond the cost of goods, we wanted to make these therapies easy to use. Formulating the editing package into a LNP does not just reduce cost dramatically, it simplifies the entire patient journey. It is a single infusion. That single infusion makes a permanent change that benefits the patient and eliminates the need for chronic therapy or long-term follow-up.
It also simplifies infrastructure requirements considerably. Infusing a therapy once is far simpler than collecting cells, conditioning a patient, and performing a transplant. Patients can travel to a treatment center, receive the infusion, and go home. And because it is a simple infusion, the number of centers capable of delivering it is vastly greater than for cell-based therapies. You are also moving away from the infrastructure required to support chronic palliative care, which represents a significant reduction in long-term system burden.
The analogy I find most useful is the evolution of the telephone. What mobile phones did for communications, this approach to CRISPR editing could do for therapeutics. Suddenly, because you have simplified the technology and removed the cost and infrastructure barriers, access becomes possible in places and at a scale that was previously unimaginable. You do not need the equivalent of a long-distance telephone network built out in advance. You build a cell tower, and suddenly everyone can connect. That is the vision, and it is why we have built the platform the way we have.
Before moving on to EDIT-401, can you speak to the decision to discontinue reni-cel development and complete the pivot to an in vivo approach?
When we outlined our strategic vision four years ago, we already had human proof-of-concept data for reni-cel, and it was compelling. The potential to functionally cure patients from a devastating disease, where previously there had been little beyond palliative options, was an incredibly powerful proposition. So while our discovery group stopped all work on cell therapy and vector-based approaches to focus entirely on building the in vivo LNP platform, we continued the reni-cel program because we believed in its potential.
Two things happened that led us to accelerate the pivot and discontinue reni-cel entirely. The first was the pace of our own in vivo progress. We made substantial and rapid advances in delivering CRISPR extra-hepatically, specifically to hematopoietic stem cells, to the point where we had compelling data showing we could deliver the editing machinery with a single IV infusion and do so with high potency. We were moving faster than we had anticipated. In parallel, we had also identified new targets using our differentiated functional upregulation approach in liver delivery, giving us a meaningful pipeline of in vivo programs across multiple areas.
The second factor was harder to confront. The launch of Casgevy, the first approved CRISPR-based medicine, made clear how difficult commercializing a complex cell therapy would be. This was a company with deep expertise in launching complex therapies, and it was a challenging launch. Usability and access were the defining issues, which was precisely what our in vivo strategy was designed to solve. The investor community saw the same dynamic, and it became clear that continuing to fund reni-cel while advancing our in vivo pipeline was not sustainable. We had to make a very difficult decision to stop the program.
What made it particularly difficult was the nature of what we were stopping. We were discontinuing a medicine that had functionally cured the patients who had received it. We had also collected cells from patients enrolled in the trials, and we made the commitment that, notwithstanding the program’s cessation, we would complete manufacturing and treat every patient whose cells had been collected. We continue to follow those patients as required by the trial protocol. In total, over 50 patients with sickle cell disease or thalassemia were treated with reni-cel, and we believe they are doing well.
It was a very tough decision, but making it allowed us to fully commit to the in vivo vision. EDIT-401 is the medicine that demonstrates we can deliver on that promise.
What is the clinical use case for EDIT-401, and how does it compare to how hyperlipidemia is treated today?
EDIT-401 creates an edit in non-coding DNA to directly increase the production of LDL receptor in the liver, driving significant reductions in LDL cholesterol and Lp(a). In non-human primates we are seeing mean reductions of around 90 percent across both markers.
That level of efficacy is not incidental to the strategy. When we defined our approach, we were clear that we had to differentiate meaningfully from the current standard of care. Part of that reflects the reality of bringing a new technology to market. The computational biology and experimental data give us confidence that off-target editing risk is very low, but the true safety experience has to be characterized empirically in humans. The way you manage that is to ensure the potential efficacy is compelling enough that the benefit-risk profile is clearly favorable even before that full safety picture is established.
The potency of EDIT-401 also enables us to focus on a specific population of patients who cannot reach their LDL or Lp(a) targets despite current standard of care. That includes patients with heterozygous familial hypercholesterolemia who remain above target despite combinations of statins, CETP inhibitors, and PCSK9 inhibitors. It also includes patients with established cardiovascular disease who have had multiple events and still cannot reach target despite multiple therapeutic interventions. Both groups sit at very high cardiovascular risk, and critically, they know it. They have seen a family member have a sudden cardiac event, or experienced one themselves. That is a very different conversation from persuading a 35-year-old to take a daily pill for a risk they cannot feel. These patients are highly motivated, and they understand precisely what is at stake.
That population, between heterozygous familial hypercholesterolemia and patients with established symptomatic cardiovascular disease who remain above target, represents up to ten million Americans. It is not the full 70 million with hyperlipidemia, but it is a well-defined, high-need starting point. The broader application may come in time, but our near-term focus is on the patients where the clinical case for a one-time intervention is clearest.
The field is also moving in our direction. There is an increasing body of evidence that more aggressive reductions in LDL cholesterol and Lp(a) are necessary to meaningfully control cardiovascular risk, and clinical guidance has begun to catch up with where leading experts have been for some time. That trend toward more aggressive lipid lowering creates a favorable environment for a therapy that can achieve reductions no current approach can match.
How does the one-and-done model apply to a condition like hyperlipidemia, which has historically been managed through chronic therapy?
Chronic therapy places an enormous burden on patients and on the healthcare system. Taking pills every day, or injections every few weeks or months, requires constant adherence. The system has to ensure consistent supply, monitor whether patients are maintaining target levels, and support them in staying on therapy. And in challenging reimbursement environments, patients often face annual reauthorization requirements, creating real risk that someone who is managing well suddenly loses access to their medicine because of an administrative hurdle.
A one-and-done approach eliminates all of that. In the context of gene editing, particularly at this stage of the technology and in a population that is highly motivated and fully aware of their risk, a single intervention that makes a permanent change is a compelling proposition. That combination, durable efficacy, a simplified patient journey, and the removal of chronic therapy burden, is a strong justification for using gene editing in this population.
In terms of health system preparedness, how open are stakeholders like physicians and patients today to gene editing as a preventative or broader therapeutic approach?
If you look across healthcare providers, you can divide them broadly into early adopters, those who will wait and see, and those who will be more hesitant. There is genuine value in that distribution. Different risk tolerances serve a purpose in how medicine evolves.
What I see with EDIT-401 is a template for how gene editing will develop more broadly in therapeutics. The near-term focus is on patients with known, quantifiable, high risk and a clear unmet need that current standard of care cannot address. If there is an unknown component to the risk profile of a new technology, you optimize by starting with patients who have the most to gain. As the safety experience is characterized over time, you expand from very high risk to high risk, to moderate risk, and ultimately perhaps to a much broader preventative use.
That progression mirrors how medicine has always evolved. Hypertension treatment today is far more aggressive than it was in the 1940s. The approach to managing inflammation in multiple sclerosis today is unrecognizable compared to thirty years ago. In both cases, accumulating evidence and better tools moved the field toward earlier, more aggressive intervention, and outcomes improved. I expect the management of hyperlipidemia to follow the same arc.
The end state I believe in, and part of what drew me to Editas, is gene editing used prophylactically as a preventative intervention. If you have elevated cholesterol, being able to address it once, permanently, has enormous advantages for patients, for healthcare systems, and for access. The infrastructure requirements of an LNP-delivered gene edit are so much lower than chronic therapy that this technology could eventually reach patient populations in healthcare systems that could never support the chronic care model. That is the same dynamic that mobile telephony created in communications, and I think it is a realistic long-term vision for gene editing.
Getting there requires building the evidence base step by step, starting where the benefit-risk is clearest and expanding from there. That is a big ambition, but it is a feasible one.
What promise do in vivo platforms hold specifically when it comes to overcoming the infrastructure barriers of gene therapies?
It is no longer sufficient to use powerful new technologies simply to solve a biological or pharmacological problem. If we want to truly address a therapeutic or public health challenge, we have to do it in a way that is not just efficacious but effective. We have many highly efficacious medicines that are not effective in practice because the vast majority of patients cannot access them, whether because they are too expensive, too complex, or require infrastructure that does not exist in most of the world.
A stem cell transplant is hard to access in the United States. It is essentially impossible to access in most other parts of the world. An IV infusion is accessible in almost any healthcare setting globally. That difference is the promise of in vivo editing. We are combining over 20 years of lipid nanoparticle development, 30 years of nucleotide chemistry, and programmable CRISPR editing into a single IV infusion. That is the simplification that turns an efficacious technology into an effective one.
Where is EDIT-401 today, and what are the upcoming milestones?
One of the things worth noting is how short the timelines from target identification to clinic have become with CRISPR editing technology. We identified the LDL receptor as a potential target roughly two years ago and made the decision to advance it into development less than a year ago. We plan to file for approval to dose patients in the middle of this year and expect to have preliminary data from our first cohort by the end of the year.
This is a first-in-human phase one study with serial dose escalation cohorts. We expect to have fully enrolled the first part of the study in 2027 and to have top-line data across multiple dose levels that year. The near-term milestone we are tracking to is preliminary clinical data from the first cohort before the end of 2025.
What is the current investor sentiment around gene editing, and how has the Editas story been received?
Less than four weeks ago we completed a public offering that went extraordinarily well and has put us in a strong position to advance EDIT-401 through human proof of concept and beyond. What made it significant was not just the financial outcome but the change in investor sentiment it represented. The investors who came in were healthcare specialists with a long-term view, people who want to be part of the journey. That is a meaningfully different profile from perhaps the original investor base we started with.
A few things drove that shift. The first was a clearer understanding of where the risks in gene editing actually lie and how they can be managed. The second was a growing recognition of how well CRISPR editing translates from preclinical models to humans. The effect sizes seen in non-human primates have been replicated in humans across in vivo targets with unusual consistency. It is worth pointing out that CRISPR as a modality hits well above the average for achieving human proof of concept relative to the broader biopharma field. The third factor, and the one that was the tipping point for this specific raise, was our non-clinical data. When investors saw mean reductions of 90 percent in LDL cholesterol and Lp(a) in non-human primates, and combined that with the translational track record of in vivo CRISPR medicines, they wanted to be part of this program at this stage.
The final piece was the outcome measure itself. LDL cholesterol is one of the most straightforward biomarkers in medicine. In healthcare we have been measuring it for over 50 years. The onset of action is rapid, visible within days or weeks of administration in non-human primates, and we anticipate the same in humans. For investors assessing a phase one program, that combination of a well-characterized endpoint and a rapid readout is highly attractive.
How important is it for the science to be not just compelling but translatable into a clinically and commercially viable medicine?
Great science is the foundation, but it is not sufficient on its own. A meaningful therapeutic today has to work, and it has to be usable, accessible, and affordable. The technology has to solve multiple problems simultaneously. That is the lens we apply to everything we do at Editas.
That thinking shapes how we allocate capital as much as how we do science. When we had two compelling programs running in parallel, a hematopoietic stem cell editing program and EDIT-401, we made the deliberate decision to choose one and concentrate our resources behind it. We chose EDIT-401 because the path to human proof of concept was clearer and faster. It was local that getting to proof of concept quickly creates value for patients and generates the foundation from which we can advance other programs. Trying to do both at once would have slowed everything down and risked delivering neither.
That willingness to make difficult prioritization decisions, and to be disciplined about capital deployment, is something investors responded to strongly. In biotech, having compelling science is expected but having the organizational discipline to focus it effectively is now a differentiator.
Where do you want to take Editas in the long term, and what is the legacy you are looking to build?
In the near to medium term, we are entirely focused on being an innovative company that solves hard problems using CRISPR technology. That means maintaining our discipline around those four principles: differentiated efficacy from the current standard of care, using CRISPR only for things other modalities cannot do, moving programs into the clinic where translation is clear, and keeping cost and usability at the center of every development decision.
As EDIT-401 moves into the clinic, we are also building something beyond a single program. Every investment we make in the LNP delivery platform, the manufacturing processes, the analytics, the toxicology package, creates infrastructure that carries forward to the next liver target. When you move to a new target in the liver, you are essentially changing 20 nucleotides while everything else remains largely the same. That means the platform investment made for EDIT-401 dramatically reduces the cost and time required to advance subsequent programs. That is the compounding value of a platform approach, and it will become increasingly important as we expand the pipeline.
In the long term, I will say the idea of a fully integrated biotech is compelling, and I have worked in companies that have done it well. But commercializing a medicine requires a fundamentally different set of capabilities from inventing one. Those two things are completely compatible, but the transition creates its own distinct challenges. We are not afraid of that and we will take it on when the time is right. For now, our focus is on the innovation and the platform. That is where we can create the most value, and getting that right is the foundation everything else is built on.
What legacy do you want Editas to leave in the field of gene editing?
The legacy I would love to leave is of a company that used CRISPR to develop medicines that could not have been developed any other way, that made a significant impact on patients’ lives, and that were truly accessible. In essence, a company that used in vivo CRISPR platforms to take on previously unaddressable therapeutic problems while making the resulting medicines effective through low cost of goods, simplicity of use, and broad accessibility.
I have worked in healthcare systems where constraints on the public purse meant many efficacious therapies never reached the patients who needed them. I have also worked in systems like the US where those constraints were initially fewer but have grown significantly. That experience convinced me that efficacy alone is not enough. A medicine has to be efficacious and effective, and those are not the same thing.
What is exciting about this moment in gene editing is that we now have the technologies to solve both problems at once. The power of genetics has dramatically increased our ability to identify the right targets and predict meaningful therapeutic outcomes. And the evolution of in vivo delivery has given us the tools to make those medicines simple, affordable, and broadly accessible. We are no longer forced to choose between scientific ambition and real-world impact. The opportunity now is to pursue both simultaneously, and in doing so, to affect not just individual patients but public health at scale. That is what drew me to this field, and that is the standard I want Editas to be measured against.
What is your final message to the healthcare community about the future of gene editing?
These are exciting times to be working in gene editing. But there are misperceptions about the field that we have to address. The assumption that gene therapies are inherently expensive, applicable only to rare diseases, and carry significant risk is a picture that is rapidly becoming outdated, and I hope some of what we have discussed today illustrates why.
The broader point I would make is that as these technologies become increasingly real, we need to have an honest conversation with society about how therapeutics are changing. There is a tendency to assume that new technologies drive costs up. In gene editing, I believe we have a genuine opportunity to use technology to do two things at once. We can tackle therapeutic problems that were previously out of reach while actually bring costs down. That combination, if we execute on it, has the potential to change what is possible not just for individual patients but for healthcare systems as a whole. The conversation about how we get there needs to start now.
