A trio of scientists behind the first gene therapy approved in the United States have been awarded a Breakthrough Prize in Life Sciences. It’s arguably one of the most prominent recognitions yet for the field of gene therapy, which has suffered several ups and downs during the decades-long dream of curing diseases by replacing broken genes.
Jean Bennett, Albert Maguire and Katherine High shared the award, which is backed by Silicon Valley billionaires and comes with a $3 million prize, for their creation of Luxturna. The gene therapy, now owned by Roche, uses an engineered virus to provide a healthy copy of a gene called RPE65 that partially restores sight in people born with a rare form of vision loss.
Endpoints News
spent nearly three hours interviewing the scientists – all emeritus professors at the University of Pennsylvania – about the long road that led to Luxturna and the ongoing struggles in parlaying the still singular success into more therapies for hundreds of other forms of retinal disease. The conversations have been combined, condensed and edited for clarity.
Bennett:
In the 1980s, there was a publication showing that if you made a transgenic mouse with a growth hormone, you’d get a super mouse. And that just really intrigued me, and made me start thinking, why can’t you use a gene to treat a disease at its root? It hadn’t been done yet. But I wanted to be there when it was.
Maguire:
Our first attempts, we were getting uptake for 48 to 72 hours. But I realized this ain’t going to work for these diseases, which are lifelong.
Bennett:
As different recombinant viruses were identified, we tried them all. Adenovirus worked well, but expression waned and cells got cleared by immune responses. Some had really scary names — Mokola, Ebola, Lenti. Around 1996, people started describing a virus called AAV as able to target neuronal cells. The retina is made of neurons. We tried it, and it worked beautifully.
Maguire:
I want to sound smart, but Jean actually just kind of tricked me into all this. [
Editor’s note: Bennett and Maguire are married and both were professors of ophthalmology.
] There were no genes identified for any of the retinal diseases. But gene identification was coming so fast and furious, we figured it was just a matter of time.
Bennett:
We started working with transgenic mice and when I put a bioluminescent marker gene in photoreceptors, I could see it just by looking through an ophthalmoscope. And that really hooked me.
Maguire:
Then one day, Michael Redman identified a gene called RPE65, and then people identified it in humans and dogs. We had an animal model right here on campus. I knew how to do the surgery, we knew how to make the vector. It chose us; we didn’t choose it.
High:
For that disease, even though the biochemistry is broken from the beginning, the cells are still there, so we can go in and fix the cells. In a lot of other retinal diseases, you actually lose the cells, so we can’t fix it with gene therapy.
Maguire:
You look at one of these affected puppies (with RPE65 mutations) and it has bizarre nystagmus eye movements. It cowers and looks so different. Then you treat it, and all of a sudden it’s acting like a dog — wagging its tail, chasing squirrels. You see that and think, we’ve got to do this with people.
Bennett:
We were reversing blindness in puppies born blind from a spontaneous mutation. We treated them in July 2000 — right around the Jesse Gelsinger episode. [
Editor’s note: Gelsinger was an 18-year-old with a rare metabolic disease who died in 1999 after receiving an adenovirus-based gene therapy at the University of Pennsylvania.
] That basically shut down clinical trials, led to congressional inquiries and all the hype around gene therapy became ratcheted down. Our collaborators didn’t want to be tainted by the gene therapy death at Penn. We were left with no funding, no way forward.
High:
My group was doing clinical trials for hemophilia B. The first patient got a therapeutic level of clotting factor, but it only lasted for 10 weeks. So we had to figure out why that happened, and we did, but none of that was happening fast enough for the investors.
The biotech making our clinical-grade vector couldn’t raise money for gene therapy anymore, so they reoriented as a small molecule company. So I went to the CEO of the Children’s Hospital of Philadelphia and asked if he’d let us set up clinical-grade vector production in the hospital. All the news about gene therapy was bad. I was pretty sure he’d say no.
A week later, he said the most surprising thing in my career: “You keep telling me there are no problems here that cannot be solved. If that’s true, then gene therapy is going to be very important for children’s hospitals, because that’s where most genetic disease gets seen. I’m going to find the resources. But I have one condition. You can’t spend all the money on hemophilia.”
Bennett:
In July 2005, Kathy walked into my office and said, “Jean, how would you like to run a clinical trial for RPE65?” It came out of the blue. It took no time at all to say yes.
High:
We’d started a Phase 3 trial for Luxturna in the hospital. The CEO called me in: “What are you planning to do if it works? We’re a hospital. We don’t market products.” I was also getting cold calls — “Can we invest?” — which shocked me, after years of nobody investing in gene therapy. I didn’t want to out-license to any company not exclusively focused on gene therapy, because I was afraid they’d hit an obstacle and kill the program. We decided to start Spark Therapeutics in March 2013.
At first, I tried to be an advisor, because I didn’t want to give up my Howard Hughes (Medical Institute Investigator) position. I’d lie awake asking myself, am I more a businesswoman or an academic? The answer was always, an academic. Then I’d think, “You’ve spent your entire adult career on gene therapy. Now, when it really matters, are you going to hang back because you want what’s comfortable?” I didn’t want my kids to say that about me.
Bennett:
I was convinced from the beginning that it would work. But there were continual worries, continual obstacles. And a number of them were presented by the FDA. They didn’t like the outcome measure that we had proposed using for the clinical trial.
Maguire:
The eye-chart improvement the FDA would accept as clinically meaningful wasn’t where this medicine worked. It worked for side vision and night vision. During the day it’s almost pitch black for these people. Kids would have to go to a friend’s house and their parents would bring stage lighting so they could play — which doesn’t get you a lot of invitations back.
High:
One question that the regulators really try to get sponsors to answer is what is the clinical meaningfulness to the patient? We were perplexed and challenged by that question for Luxturna.
Bennett:
Everybody’s mired in visual acuity — the eye chart. That’s not all vision is. People appreciate dim light, contrast, side vision. But there are few approved outcome measures for those.
High:
I’m glad the regulators were tough about it, because it forces you to do some real thinking about what can they do that they couldn’t do before? With our multi-luminance mobility test, if you could only maneuver when the light was at 100 lux, and now you can at 10 lux, what does that mean? It means you can see your way around a train platform at dusk, and that may change your ability to commute to a job.
Bennett:
When Luxturna was approved in 2017, I was overjoyed. It was a huge celebration for the team, for sticking through it, for believing in something, not taking no for an answer.
High:
If you’d asked me in 2017: In five years, how many other approved retinal gene therapies will there be? I wouldn’t have said zero. Part of the issue is many of these diseases are ultra-rare, and the commercial aspects are challenging.
The great thing about both Luxturna and gene therapy for hemophilia is that it results in gain of function. You don’t need long to figure that out. But in some genetic diseases, all you’re going to do is stop further deterioration. That makes for long readouts, and that doesn’t work for a startup.
Bennett:
There are more than 340 genes identified that can cause blindness. Certainly some of them are going to be amenable. Some won’t, because they’re developmental in nature, and we’re not going to be able to treat an embryo or fetus in the first trimester with a gene therapy any time soon.
Maguire:
I get nervous when you’re going into children and infants and babies, but you need to for a lot of these childhood-onset diseases, because otherwise the brain’s visual system is not developing. And that, to a large extent, is your limitation.
Bennett:
The science has never been better. There’s so many exciting applications, and some of them are just science fictiony. But it’s taking a long time for the next set of approvals to appear.
Maguire:
Gene therapy has gone through a lot of rough patches. Every two or three years there’s another crisis. What I’d like to see is a more viable business model. When we started, people were willing to pay whatever, because it’s a first of its kind. [
Editor’s note: Luxturna costs $425,000 per eye.
] But the price has come down on making vector. People may not be making their multi-billion-dollar profits, but there’ll still be a reasonable return.
High:
Gene therapy emerged into a reimbursement system based on chronic medications — a system unfamiliar with it, for which valuing it was difficult. I don’t think we’ve fully traversed those challenges yet.
Bennett:
Groups joining the gene therapy bandwagon have tended to pick the same genes, which is kind of puzzling to me. And people have veered away from ultra rare diseases. Investors want to go for a huge possible payout. A lot of groups are interested in anti-neovascular gene therapy because of diseases like AMD (age-related macular degeneration) that affect millions of people.
Maguire:
I got into this because of the moral imperative. It’s heart-wrenching hearing people say I’m going blind and having nothing to offer. It’s been frustrating. We’ve started other companies, including Limelight Bio, and people walked away and collected their dividends and started new ones. Why don’t you stick with the mission?
High
: The challenge about gene therapy is you really do need a team to do it, because nobody can be an expert in everything that you need. The most common mistake people make when they try to do clinical trials is they overestimate what the vector can do, and they underestimate what the disease needs.
Bennett:
I think if the prices and the timelines could come down so that we can target these rare diseases, it would be a really great thing.
High:
I believe that genetic medicines are going to be very important over the next century. They’re going to be like monoclonal antibodies and recombinant proteins are now, but it’s going to take a while. I don’t think that they’re going to fade away. I think that they’re going to keep moving forward.
High:
I was advising Google Ventures’ life sciences practice when I saw a gene-agnostic technology from the Institute for Molecular and Clinical Ophthalmology in Basel. Amazing science. We’re developing it at RhyGaze, where I am CEO.
Bennett:
I retired from Penn. Now I’m working with companies, academics and nonprofit foundations to help fuel gene therapy development. There were a number of trials that failed over the past few years because they used visual acuity as their endpoints and not some other measure. I am pushing to get the FDA to approve other outcome measures that don’t require fancy equipment that reflect great improvements in vision but haven’t been adopted yet.
Maguire:
I recently retired. Now it’s painting and beekeeping — I’d advise against. It’s extraordinarily frustrating. Everybody says how cool it is. You do not want to get into this.