Using Gene Therapy to Help the Blind See

Pushkin. Think about the basic idea of gene therapy. You string together a gene, put the gene inside a virus, put the virus inside a patient, and then the virus delivers the gene to the patient, sells, and then that new gene, if everything goes according to plan, makes the patient get better. It sounds hard, it is hard, but after decades of research, gene therapy is starting to work. I'm Jacob Goldstein and this is What's Your Problem, the show where I talk to people who are trying to

So babies are born with the disease and usually within the first few months of life, their moms or dads notice that they're not looking at them directly, they're not fixating on objects. Oftentimes the babies will have a roving eye movement called nystagmus, and so they're diagnosed usually pretty quickly with this condition, and unfortunately, it's profound visual impairment, if not total blindness, and that remains with the patient

So it's one of the somewhat rare instances where there is like a single gene that maps to a single in this case, profound problem basically blindness or severe problems with vision, which is kind of you would think would be the first wave of gene therapy, right exactly, This is what the early two thousands, when you're and so the human genome has just been mapped, there's like a sense of oh, now we know all the genes, right, let's figure out how to help people with this new knowledge.

That's exactly right. This was sort of the step one in gene therapy was the simplest form, which is just gene replacement. Can we take a healthy copy of a gene and put it back into the patient's cells and then have that gene go on to make the protein it was supposed to make and then hopefully rett or the function to those cells.

And so what as a grad student are you trying to figure out?

The lab was studying the biochemical underpinnings of this disease, and they were using a chicken model to do this. That's kind of a unique thing in a lab. Usually research labs are using mice or rats, but there was a naturally occurring chicken model of this disease that had profound visual impairment and blindness.

So naturally occurring chicken model basically means this happens to chickens too, Yes, exactly, it is. That's right.

Yeah. So, at the same time that the lab was studying, you know, what was going wrong in this chicken and why it was happening, they wanted to ask the question would gene therapy be a reasonable approach for treating these chickens. Can we restore visions to these chickens with gene therapy. So this was a collaborative effort with my other grad students and I where we took a vector called Lenti

And so you injecting the non mutated form of the gene, the good form of the gene, if you will, encased in this virus, into the head of the chicken embryo. Yes, did it work?

For a while it did not, because again, it was difficult to manipulate a chicken embryo like that and actually have it to survive to hatch. But my fellow grad students and I did a lot of work to optimize that process, and eventually it actually did work. We had little chicks that were born, and I can distinctly remember them walking around on the lab bench and pecking at our jewelry or at Eminem's that we had laid out on the surface of the bench. Very different from the

It was so fun. We were all so so happy.

Okay, so that's two thousand and four as twenty years ago. Yeah, yeah, at that time, is it like, well, we did it in chickens, let's do it in people or what.

So that's actually where my thesis project comes in. So all of that chicken work was a really collaborative effort and it was exciting, but it had its drawbacks and it wasn't clinically translatable for a number of reasons. First and foremost, we were never going to do an embryonic injection and a patient. Maybe that'll happen one day, honestly, but it certainly wasn't close to happening in two thousand

Let's just pause for a moment and talk about this idea of a vector in gene therapy. So the basic idea, right, is like, you know what the good gene is, you know the gene you want to get into, in this case, the person's eye. But there's this weird question of how do you get it there, right, Like, you can't just put a string of genetic material randomly in someone's body, right,

That's exactly right.

But that's hard for a number of reasons. So like, tell me sort of the state of vectors at this time twenty years ago when you're figuring this out.

So there were a number of viral vectors that were being used to deliver genes, and each of them had their pros and their cons One was named adnovirus. This was a good virus because it's big, you can fit a lot of genetic material into it, and it was used in the early days of gene therapy and on. Fortunately it was discovered you know later on that it came with you know, some downsides. It's more immunogenic than the other viral vectors that are out there.

Meaning it generates an immune response. So the body's like, oh, that's a virus. I'm going to destroy it, and you're like, no, no, no, this is a virus that's going to help you exactly. It's like, I don't care. I've gotten rid of it.

Yes, yeah.

And then of course there was lenty virus, which is what we were using in the chickens. It is not the vector of choice, for instance, in the eye where I work, because it's not very good at delivering genes to developed cells in the retina. And then in the nineties some exciting work was going on evaluating a newer vector called Adno associated virus or AAV. Since the nineties early two thousands, AAV has become the gold standard gene delivery vector for essentially all of gene therapy.

And so at this time in two thousand and four, like, what was the state of gene therapy?

Oh, my gosh, it was the heyday. It was such a fun time and it was so it was so exciting. The my grad school days, my postdoc days, it was an extremely exciting time in the field that I would say it was filled with hope because there was so much proof of concept work going on in animal models of disease showing that gene therapy could restore vision, could restore muscular function, could restore clotting.

You know, you name it.

It was these successes were being seen across neuromuscular disease, CNS disease, ocular disease, but everybody was just really excited about it, and that extended beyond the scientists in the lab. That was true of the macro environment too, So you know, I mean.

Like in the media or like the industry, like the pharmaceutical industry.

Yeah, I'm talking more about like investors and big pharma. So I mean investors were keen to throw their money at gene therapy at the time because of how much promise it was showing in these pre clinical studies, and big Arma was keen to acquire, you know, startup companies that were in this space because of that promise it was showing. And I think their their reason at the

And then at some point, right there are these these strong results using gene therapy to treat a disease called LCA two, which is similar to LCA one, the disease you work on, and that's like a big moment in the field, right.

Yeah, the RP sixty five LCA two gene therapy trials were a huge success, and then they went on to form the basis of Luxterno, which is the first approved ocular gene therapy, and so everybody was super excited that, Okay, they got this approved. We're going to see this, you know, flood of other gene therapies getting approved on the heels of luxtern And I think that's I think that's when it got hard, and you know, there was a little bit of a reality check for the field.

What was that like for you? So you're working on LCA one, a very similar disease. Everybody is very excited about l c A two, are you like, yes, we got l c A two, I'm about to get LCA one. Like what what was your where were you at that? Oh?

I was I was super excited.

I was.

I was further behind obviously in my pursuit of l c A one, but I had, you know, high hopes that it would it would go, that it would work.

Why didn't it happen as fast as you thought?

So in twenty fourteen, I hit a stage where you know, the technology had been developed, I had done everything that I really could, you know, from the academic standpoint, to get this ready to move forward. But at that stage you hit what the NIH calls the valley of death, which is, you know, a period of time where you need a lot of capital and a lot of infrastructure to move a gene therapy from bench to bedside, and you can't do that in an academic lab.

So to put it to test it in people, basically testing it in people is obviously complicated and expensive and very at least some extent rightly so, right you're ingesting things into people's eyes.

Yes.

In twenty fourteen, my husband and I who I work with, we were very much in a pattern of developing technologies and then out licensing them to different companies. So in around twenty fourteen, we partnered with Genzyme, which was a company focused on developing gene therapies for rare disease, and

They let you go into people.

I INDA is an investigational new drug's exactly. So you're like doing all the work to say, like, look, this should be an investigational new drug that we can test in a very small number of people just to see if it's safe to start out with exactly.

Yeah.

So, and I'll be honest, that moved a little bit slower than I would have liked. But I mean, when you work with Big Pharma, and I will say they were an amazing, amazing team, excellent group of people, but Big Pharma is very siloed, and you know, it can take a long time for things to move. And then unfortunately, in around twenty eighteen, Cianna FI decided to pivot away from ocular gene therapy altogether, so they wanted to give the program away, and I was heartbroken. I remember the

It's like you want it more than anybody else can want it.

Yes, it was.

I mean one is my baby, right, and so are some of the other indications that I'm working on now. But yeah, I wanted to be the one to help usher them towards patients and keep it moving in the right direction.

And you mentioned your husband, So is he in the same field as you, like, is.

What's he doing?

Yeah, he's an AV vectorologist. When I was a grad student and I was tasked with my thesis project, which was okay, come up with a clinically relevant approach for treating this disease. So to do that, I needed to shift away from Lenti virus and start using ad no associated virus AAV. I needed to shift into a mouse model, a mammalian model of the disease, and so to get help on the AAV aspect of the project, I went to Bill Houseworth, who became my post docmentor, and he

Yes, it is a very nerdy meet cute, yes.

But yeah, we're very much in the same field. But we have very different skill sets, I would say, so we compliment each other.

Which is nice.

Obviously to get from, you know, doing this in chickens twenty years ago to doing it in people now. There were many, many, many things I'm sure that you had to figure out. There is there anything in particular that was a thing you figured out? Maybe that was a thing that people doing gene therapy more broadly were trying to figure out, just in the sense of, yeah, something you solved along the way.

In the early days, when I had first transitioned into testing the AV vector in the mouse, I did it over and over and over again, and it didn't work. And I think one big mistake that I made was that I was using the same gene, the same coding sequence that we had used in the chicken experiments, and interestingly, that gene was a bovine gene. In the early two thousands, it was a lot easier to generate bovine sequences for

So basically the versions of the gene exist in these different animals, but they're slightly different.

Exactly.

Yes, I have to say retrospectively out of my armchair ignorance. I feel like that one seems obvious in retrospect to me.

But it was strange to me because this bovine sequence worked in a chicken, so.

I think, and a mouse and a person who's more like a cow. Yes, okay, what's another one? What's another one? You had to figure out?

Another one was the flavor of AAV that we needed to use.

So the particular nature of the vector.

Yes, exactly.

So AV comes in a variety of flavors, and one flavor of AV might be good at infecting neurons, and another flavor of AV might be good at infecting skin cells, for instance.

Yes, and interestingly, in this point, you want it to infect, right, Infecting is delivering the gene exactly. Huh.

So we tested for the first time in non human primates a certain flavor of AV called AAV five, and we really for the first time showed that that flavor of AV was really useful in the rod and the cone foto receptors of the human of a primate retina rather, so that was the flavor of AV that we needed to figure out. And then I would say the third thing that we figured out was a specific regulatory sequence

And so just to be clear, just to unpack that a little bit, so the idea is, you don't just need to have the gene itself in this vector. You need to have the genetic information that tells it in what kinds of cells should this gene be expressed exactly, and in what kinds of cells should it not be expressed exactly.

And that's important from a safety standpoint, because ideally you don't want this gene expressing a protein in cells where it's not supposed to be.

In potent harm in your heart right exactly in a minute. What happened when Shannon's drug finally made its way out of the lab and into the eyes of patience. I asked Shannon how she got from figuring everything out in the lab and in animals to actually doing a clinical trial to actually testing her drug in patience.

So I will say that, fortunately, before Santafie let the program go, they did dose a couple of patients, so we did get them to start the trial thankfully, and they were absolutely critical and getting that off the ground. But when they handed it back to at Sina, obviously we had to build a clinical team and we worked closely with Santa fe during that transition period to make sure there were no bumps in the road, and then

So you have this virus that you have engineered to have this gene and this promoter, you inject it into the back of somebody's eye.

Then what happens, So the virus infects the photo receptors, it unloads the DNA inside, and then that DNA remains inside that cell over the lifetime of that living cell. So the gene will persistently remain inside that cell and express that protein that it needs to express. It does not integrate into the genome. It remains outside the genome. We call that episomal, but it leads to persistent expression of that gene and continuous production of that therapeutic protein.

And do cells Do those cells last forever?

It depends on the indication. So that's why LCA one with such an attractive target is because those patients retain their photoreceptor structure over their lifetime, So theoretically we could at persistent rescue over their lifetime.

So photoreceptor celves just stay there, they develop, and then they just hang out receiving photons forever.

Yes, in the syndication yep.

So like how many people are in this in this trial?

So we had.

Fifteen people total enrolled in this trial.

Okay, And how long does it take to find out if it works?

So with this condition, typically we saw responses by about four weeks post injection, and those responses get a little bit better up until about two or three months post injection, at which time the response is plateau. So it's a very quick, very quick readout.

And the patients are they completely blind? Like what is there before when they're coming to you? What is the state of their vision?

That's a good question. So there's a range, but we would consider all LCA one patients to be profoundly visually impaired, so ranging from twenty two hundred all the way to light perception only, so legally blind to folks that can only see light.

And so when do you first hear about the results, Like how do the results come into you?

Well, you have to be very careful as a you know, co founder and CSO of a company, I you know,

Yeah, So you're not spending your career trying to cure blindness in mice.

Nope, Nope.

So what was the outcome of that trial?

Sure, so it was a very positive outcome. We just published the results in the Lancet a few weeks ago, looking at all all fifteen of the Phase one two patients out to one year post treatment, and we showed that the gene therapy had a very very good safety profile. There were no you know, serious adverse events related to the medicine itself, and we showed a very profound efficacy.

And what is there like a median improvement.

Yeah, so the median improvement was about one hundredfold improvement, so really exciting and significant. And then you know, of course the anecdotes come in. We have one video of a little girl who saw snowflakes for the first time, so you know, it's more than the cold hard numbers like one hundredfold improvement in retal sensitivity. It's you're seeing a genuine improvement in the patient's quality of life, which is amazing.

So what's next?

So next will be phase three. Before you can get anything commercialized for broader use, you have to do a phase three trial. So we're fortunate because our LCA one program has received what's called an ARMAT designation, and put simply, that is a designation given to programs that cause a profound illness at birth and for which you have promising proof of concept data showing that you might have a cure. So we receive that designation and we need to align

How many people more or less have LCA one.

So there's about three thousand patients I would say in the US and the EU that have they indication.

So I mean a lot on a human level, but on a kind of population level, not a lot. It's very rare, that's correct. And so what does that mean? Well, what does that mean. I guess on the on the business side. Right on the science side, it sort of doesn't matter. It's the same science whether a million people have it or people have it. But what does it mean on the business side.

It's you know, the pendulum has swung back since the early two thousands where investors in big pharma were all very eager to throw money into this space, and they're less excited about rare disease obviously, But you know, as a scientist who sees the obvious impact it's having on these patients, I'm going to push it forward with full force. We've successfully raised money at SENA to keep this program going.

What else are you working on?

So we are working actively on another inherited retinal disease called X linked retinoskeesis or XLRS. We're also in a phase one two clinical trial and already showing structural and functional improvements in those patients using a novel flavor of AV, which has been interesting. So really excited.

So you have a separate indication where you're in clinical trials, yep, and anything else. I feel like remember seeing a couple more on the website.

Now, yeah, else.

Yeah.

So we're also working on a dual vector technology. So there are some indications caused by mutations in large genes that don't fit inside a standard AAV vector. So we've developed a technology wherein we split that large gene in half. We deliver the front half via one AAV in the back half via a second AV.

Those two. Yeah, it's really cool.

Say one gene, it's one gene and you're putting it into two different yes suitcases.

That's very sically Yeah, and.

Then dumb question, how does it get put back together?

So there's a complimentary sequence shared between the front and the back half. So when the two suitcases unpack their their respective front and back half genes, they find each other via that complementary sequence and then they recombine to form a full length gene.

That is wild. Have people done that technique in other other you know, indications of gene therapy and other domains they have.

Yes, there's a company recently that it is in the hearing space actually, but they use dual vectors to deliver a certain gene to patients that had hearing loss and restored hearing to these children.

So, and is the issue the gene is just too long, like it physically just doesn't fit inside. That's correct.

Yeah, So standard AV can only fit about five thousand base pairs of DNA, and some of these genes are are just too big to fit.

That is so clever. I love it when people are so clever. So let's let's zoom out. And you know, you've been working on gene therapy for twenty years ish, which is close to the life of gene therapy. Right of the field you got in or early, you've been there a long time. A lot has happened. Like when you zoom out, what do you see? Like where is the field now? You know? Yeah, where is it now? What's the big picture for gene therapy right now?

I think the big picture for gene therapy right now is we're a little bit bruised, right. You know, we have the success of Luxterna getting approved. Then you know you've got zulgensimo, which is a huge success story. And those were the successes. But we entered a period around that same time where I think, unfortunately, folks were taking

So like, so does that mean it's going to be hard every time? I mean it's going to be hard forever, And it's not like great, we figured it out and we can just put any gene into this vector and will cure everything.

Yeah, I mean I think it's somewhere in the middle, right, It's it's it's never going to be like just plug and play, right, But there are certainly tools that are being developed along the way that can be you know, used in one trial and used in another trial. But I think you always have to put a lot of thought into it. It can't just simply be Okay, if this worked for l c A two, then it's going to work for disease X, right. There always has to be a thoughtful process.

I mean, is it harder than you thought it was going to be?

Yes?

You know, in my grad school days it was hope, hope, hope, you know, excitement, excitement, excitement, and then forming my own company and being in charge of kind of the fundraising behind keeping these programs going. It's been it's been a lot of work, but I believe strongly in what I do and that it's having a positive impact on patient lives, and so it's it's worth that effort.

We'll be back in a minute with the lightning round. M hm hm. Let's finish with the lightning round. Okay, what's the best thing about working with your husband.

Oh, let's see. I think that at the end of the day, we can understand each other's stresses. You know, It's not like coming home and you know he has no idea what I'm talking about. It's like, if I have a problem, he can think through it very clearly because he understands it at its core and give me advice on how to navigate the situation and vice versa.

What's the worst thing about working with your husband?

Sometimes there's you know, evenings where I'm done talking about a vy. You know, I've done it all day long, and we're sitting over the dinner table with our kids and he's still talking about, you know, designing a vector to do whatever, and I'm like, Okay, we're done here, We're done for the night. But I mean it's with us all the time, and I think that's what makes us better scientists for it.

What's one interesting or surprising thing you've learned about the human eye?

The human eye, I would say most of all that you can be seventy years old and have had a congenital form of blindness since you were a baby and still benefit from gene therapy. And that's wild to me, Like, you know, I got my PhD and neuroscience, so I'm always thinking about you know, so what if we restore function to the retina, what's that going to mean in the brain? Is the brain going to be able to be receptive to that message if it's been turned off from that message input its entire life?

Right?

But we had a seventy year old patient in our LCA one clinical trial that showed some benefit following gene therapy, and that tells me that the brain is, you know, extremely plastic, more plastic than I gave it credit for before.

Huh, So it's not the eye but the brain. Like we're not really seeing with our eye. Our eye is just like the window and the brain is really where the seeing is happening.

That's right.

I read that you have a boat called wet Lab we do. H What was the runner up name? Oh?

I don't think we had a runner up. We've planned that one for years.

What's the biggest fish you ever caught? Oh?

My goodness. We go all the time and we catch big fish so often. I don't remember the biggest one that you catch.

So many big things to tell a first story. Thank you so much, for your time. It was very interesting to talk to you. I learned.

Thank you, Thank you. You're a great interviewer. This was a pleasure.

Jennon boy is a professor of genetics at the University of Florida and the co founder and chief scientific officer of Atsina Therapeutics. Just a quick note, the show is going to take a break. We'll be back with new episodes in a couple of weeks. In the meantime, please let us know who you'd like to hear on the show, who I should interview, were, just how we can make the show better. You can email us at at pushkin dot fm. Today's show was produced by Gabriel Hunter Chang.