WEBINAR: Inner Ear Gene Therapy – Recent Advances and Clinical Perspectives


Good evening, everyone. Thank you so much
for joining us tonight for Inner Ear Gene Therapy Recent Advances and Clinical Perspectives
with Dr. Lukas Landegger. Thank you so much, doctor, for joining us tonight. We appreciate
it. Before we get started, I want to say thank
you to Darcy Kriens of Alternative Communication Services for providing CART tonight. Everyone
should have captions available right now, if you click the closed caption button at
the bottom of the screen, it should turn green and you should see captions. Tonight, you can hit the raise hand button
if you have a comment or question, but I would really prefer that you use the Q & A if you
have a comment or question for me, and that’s the same place where you can pose a question
to Dr. Landegger at the end of his presentation, and I will post those questions verbally to
him so that becomes part of our CART transcript. Dr. Landegger earned his medical degree from
the Medical University of Innsbruck in Austria. He served as a military doctor in the Austrian
Army. He joined the Molecular Neuro otology Biotechnology Laboratory at Mass Eye and Ear
in 2013. Two days ago, Dr. Landegger completed the
Boston Marathon, so I’m anxious to hear more about that and I would not even be walking
if I did that two days ago, but I’m really glad that you’re here alive and well and you
finished, and I can’t wait to hear about that, too.
So go ahead, and I’ll let you get started.>>LUKAS LANDEGGER: First of all, good evening.
Thank you so much to everybody involved in the organization of this talk. Thanks to the
Hearing Loss Association of America for giving me this platform. While I was preparing this
talk, I kind of really had to figure out who the audience was, and so primarily it will
be patients from my understanding, however, there will be some professionals in the audience
as well, so what I try to do with these slides is that I have a lot of information in the
slides themselves. However, I really try to walk the patients through it and highlight
some of the most important information in red so that the professionals can kind of
follow up on this information and kind of go through the primary sources, so go to all
these papers that are mentioned on the slides. I still want to give guidance to the patients,
so as patients don’t be overwhelmed by the slides. I really will try to walk you through
it step by step. In this talk I’ll try to present, obviously,
inner ear gene therapy studies that have been done here in our lab and other labs around
the world. We’ll try to just present some of these most recent advances and give you
an idea where we stand and when these potentially could become available for clinical use.
So to give you an overview of the talk we’ll first start with the definition of hearing
loss and what the current standard of treatment is. Then we will talk about inner ear gene
therapy or gene therapy in general. Then we’ll briefly discuss different approaches and how
genes could be targeted, primarily viral vectors but also CRISPR Cas9. Some of them might have
heard about the gene scissors that have been mentioned in a lot of newspapers recently.
We’ll discuss certainly mouse models that have been rescued, so mouse models of human
disease that can be rescued with gene therapy, and we’ll briefly talk about stabilization
of cells versus restoration of cells, which is particularly important for age related
hearing loss. The last part is what are the hurdles on the way to the clinic as we said.
Hearing loss, as we all know not as we all know, but we know it’s a big problem and it’s
the most common sensory deficit in humans. Just last month the World Health Organization
released a fact sheet on deafness and hearing loss, and these numbers are really incredible
if you haven’t seen them before the estimate is over 5% of the world’s population has disabling
hearing loss, and this number is expected to basically double up until 2050 with about
900 million people being affected then. In addition to that, about 1.1 billion young
people are at risk of hearing loss. And the reason for hearing loss are multifold,
and can include genetic causes, complications at birth, infectious diseases and ear infections,
certain drugs especially chemo-therapeutic drugs such as cisplatin or aminoglycosides
which are certain types of antibiotics, noise, aging, et cetera. An overview of how many
patients are affected per life decade, you see newborns at about 0.2%, school children
goes to about 0.4% and then 16% in over 18 year olds, 34% in 65 to 69 year olds, and
eventually we go up to 72% in octogenarians, which is really remarkable.
To understand hearing loss, we have to first understand how hearing works in general. We
have sound that comes in through the external auditory canal, hits the eardrum, and the
sound is then transmitted through the ossicles, the smallest bones in the human body, to the
fluid filled inner ear, specifically the stapes or stirrup, that’s the smallest one in the
human body and connects to this oval window, and then a fluid wave is created, but it’s
mechanical transduction and kind of tilts or deflects the hairs of certain cell types
that are called hair cells. Once these hair cells or these hairs deflect,
the stimulus is changed from a mechanical stimulus to an electrical stimulus, and that
electrical stimulus is then forwarded by the auditory nerve to the brain where we then
actually hear. In this schematic, you see the cochlea where
we hear, which is the snail shaped structure here, and then we also have the vestibular
part of the human inner ear that is responsible like is the balance part of the human inner
ear and you see the semicircular canals here important for rotational movements, and we
can see the utricle and saccule, altogether five organs. They’re responsible for acceleratory
movements, either horizontally or vertically. Then we can, based on where the hearing loss
occurs, we can divide these types of hearing loss into either conductive or sensorineural
hearing loss. Conductive loss means everything to this oval
window here basically. So all the bones and canal, et cetera, and we have multiple treatment
options for that. However, the sensorineural part of the system, the cochlea or inner ear
and auditory nerve, right now it’s basically just the cochlear implant, although it’s a
really remarkable device and we’ll talk about the kind of a lot of pros, but the few things
that are not perfect yet regarding this device later in the talk.
Another thing that could be used is an auditory brainstem implant in case the nerve is missing,
but we won’t really talk about that in this presentation. So the current treatment options
are hearing aids. You’re all familiar with those and what they do. There’s a lot of models,
but we won’t talk about this in this presentation. Basically they simply amplify sound.
Then we can change the sound transmission itself and here so called middle ear prostheses
or middle ear active implants are important because for example, if we miss the ossicles,
we can replace them by titanium prostheses, so it’s relatively straightforward, or these
middle ear active implants. What they do is they have a little microphone
here behind the ear, and this microphone detects all the frequencies that come in and then
filters these frequencies and you have a little magnet in the middle ear that attaches to
the ossicles. And through the different frequencies that are detected, the number of vibrations
or kind of the vibration intensity itself is determined, and that can then, again, facilitate
hearing. Then cochlear implants, you might have heard
about them or even have one of them, and they’re really remarkable devices. What you have is,
again, this outside microphone that detects the different frequencies, and instead of
manipulating the ossicles, what this device does is that you have a coil that goes into
the snail shaped structure, so into the cochlea, and this device has certain outlets where
you can kind of shoot electricity out that directly stimulates the auditory nerve, and
so you kind of circumvent these hair cells that usually make the transition from the
mechanical stimulus to the electrical stimulus. It’s really great that this actually works.
What is gene therapy? So the idea is that you kind of introduce normal genes into cells,
and with those you can then replace missing or defective genes so that the cells work
again as they should. There’s about 100 genes that cause non-syndromic hearing loss that
could potentially be targeted with gene therapy. When we compare our field – the field of ENT,
you know, ears nose and throat, to ophthalmology it’s relative sad because right now there’s
about 30 gene therapy trials for 10 diseases of the retina (so the structure in the back
of the eye); however, there’s only one for severe to profound hearing loss going on.
The ophthalmologists already have one drug FDA approved since December of 2017. So we
really have to catch up in this way. This is an image that shows how a virus transduces
a cell, so how a virus gets taken up by a cell. This is an adenovirus. Most of the talk
is about an adeno associated virus, which is a relatively similar virus, and the main
difference is with adenovirus you can cause a transient expression of the gene, with adeno
associated virus usually the gene you want to replace stays there pretty much until the
cell dies, so pretty much forever. At least that’s the assumption right now – at the moment
we don’t really have the data in clinical trials that show how long. There have been
studies that have shown this expression for several years over the decades.
And this adenovirus attaches to the cell and is taken up by the cell, and the virus itself
cannot replicate or double itself basically so what it needs is the machinery of the cell
to actually kind of – yeah, replicate itself. So what it does is that it delivers the gene
that it has been loaded with into the inner part of the cell, and then the effects take
place that we could then potentially use for the gene therapy.
So what we briefly have to talk about genetics as well, because those have implications for
therapy, and so basically every human gets one gene, so it has two copies of a certain
gene. And one is received by the mother, and the other one is received by the father. And
if just one of those two has to be affected, then we are talking about a dominant disease.
So one of the two has to be affected so that the patient has the disease, and then it’s
a dominant disease. However, if both have to be affected, then it’s a recessive disease.
So dominant would mean my father gives me a faulty gene, my mother gives me a healthy
one=disease. Recessive disease means both my mother and my father have to give me the
faulty gene, so I have the disease. That is important because that means how we can or
that playing a role regarding how we can treat these diseases.
So the simple gene addition would be relevant for a recessive disease, because in recessive
cases, as we’ve just discussed, we basically have no functioning gene, and so the delivery
of a copy of a normal gene could then just kind of make the cell function again. That’s
what has been done in most animal studies so far.
However, in a dominant case we can also use so called gene we cannot use the gene addition
therapy or strategy, but here we’d have to use a gene disruption therapy because here
we have this dominant gene that will independently if there’s a normal copy will still produce
the faulty kind of protein, the faulty mechanism, and so we kind of have to target that somehow.
So by targeting that, the remaining gene can then take over.
And the last part is the gene editing part where with a recessive or dominant missing,
that’s a completely irrelevant mutation. If you have a minor part affected, you can then
use a so called CRISPR Cas9, so the gene scissors, again, to replace that specific part of the
gene. The functional gene addition is also something that we’ll skip for this talk.
So how would the gene therapy work specifically for the inner ear? Well, we’ve talked about
like how the hearing works, and so if we cut a piece of the cochlea out here and look into
it, then we see three fluid filled chambers. The names are irrelevant, but in the scala
media, we have the inner hair cells and three rows of outer hair cells. One row of inners
and three rows of outers. The inner hair cells make this transition from the mechanical stimulus
to the electrical stimulus, while these outer hair cells have more of an amplifying function.
And in one human ear we have about 15,000 hair cells, and it’s the same cell type in
the vestibular system, so the five organs we discussed before with the utricle and et
cetera. All of these have these stereocilia on top and the hairs give them their characteristic
look and name and we’ll see a few pictures afterwards.
What’s interesting in birds, for example, these cells regenerate without any problems,
while in mammals including humans they don’t. There’s just one exception. In 2014 researchers
found out in neonatal mice, newborn mice, some of these hair cells do regenerate, and
here supporting cells come into play. We’ll talk about them later. Those are the cells
right next to the hair cells here. And one potential surgical approach for gene
therapy is the round window here. That’s also the place where usually the cochlear implant
is introduced, at least nowadays is introduced. So that would be a relatively straightforward
process for the injection. We’ve talked about the success story of the
cochlear implant that has really enabled so many patients to actually learn language and
everything without any problems, however, there’s still some issues, namely the natural
sound perception (so sound perception in general is not that great), frequency sensitivity
(enjoying music, for example, is relatively hard), and speech discrimination in noisy
environments. In a bar, for example, with a lot of background noise, it’s really hard
with these devices to actually filter out that one voice. The goal of gene therapy is
to kind of restore natural hearing. And this is the mouse inner ear, the mouse
cochlea. It’s relatively similar to the human ear. We have the turns up here where we hear
with the hair cells, and we have the oval window here and the round window that could
be used for gene therapy and is being used for gene therapy by a lot of groups. It’s
right here. I’m sorry, I’m just trying to remove this bar here from my screen.
Okay. So the first study that I’m trying to or I’ll present is the VGLUT3 study, and it’s
one of the first rescue studies in mouse models. This VGLUT3 is a receptor in inner hair cells
and that’s what we discussed in the last few slides. It’s right there at the connection
between inner hair cells and the auditory nerve.
Mice lacking this transporter are actually deaf, and it’s only relevant in a few human
patients but what makes this model interesting or what made these models interesting is these
adeno associated viruses that I mentioned before actually specifically target these
inner hair cells, so that’s what needed here. What’s a relevant fact is these mice in general
usually develop hearing around two weeks after birth, whereas, humans are born with hearing.
So that is interesting in terms of timing afterwards because potentially that would
mean that if a mouse is injected immediately after birth, in humans we have to go into
the womb or like the baby would have to be injected in the womb.
And if we see that these mouse pups who are lacking the transporter are injected with
VGLUT3, then they actually did not go deaf. So this is a slide that or a figure that will
be used in several of these studies, and what you can see here on this Y axis is the loudness
level. Down here it’s like a whisper basically, and up here it’s like if a jet engine would
start right next to you, so very loud. These curves that you can observe are functions
of basically an objective hearing test, so once you see the curve, you can tell that
the mouse heard that. You can see in wild type mice, regular mice, healthy mice, we
have these curves somewhere around here. In knockout mice, the mice affected by this disease
where the transporter is not there, we don’t have any response at all, so those are basically
deaf. In these rescued animals where the VGLUT3 was injected with a virus, we can actually
get responses again. It means that these mice heard because the VGLUT3, the specific transporter,
was introduced into the inner hair cells, and in a different way that is depicted here,
you can see 95 decibels is really, really loud – no response at all while the wild type
animals and the injected animals are actually pretty good. So that was a really remarkable
paper that came out in 2012. What other functional rescue studies have
there been? Quite a few published in the last few years. However, what is common or what
is like the same in all of them is that they all talk about the inner hair cells and outer
hair cells are really hard to target and you can see that in these images where you can
appreciate that all of these viruses kind of just target the inner hair cells while
the three rows of outer share cells that should be out here somewhere remain dark. What is
that dark part? So everything that’s green lights up with so the lighting up means that
it’s GFP, green fluorescent protein. If a virus transduces a cell, gets into a cell,
you can tell what it expresses, and basically it expresses this green fluorescent protein
and then the cell lights up. That is something that researchers can use to determine where
the vector goes. For the rest of the talk, you can remember
green cells are good, because that means that the virus got into the cell, and we could
potentially deliver something into the cell including the healthy gene. So in this 2011
study, you can see that they tried five different serotypes, and for all these adeno associated
viruses, these inner hair cells were the most effectively transduced cochlea cell types.
So it’s good that it worked in this specific disease model before, but the difficulty is
to get these outer ear hair cells I mentioned before.
Here a virologist comes into play, Luk Vandenberghe and the institute affiliated with it comes
into play. His lab looked at a computer model, synthetic AAV, so they looked at the predicted
ancestor of adeno associated virus types 1, 2, 8, and 9 and those are commonly used viruses.
What they were looking for was that ancestor because everybody has had a cold, and this
adenovirus is actually the common cold virus. The adenovirus and adeno associated viruses
are relatively similar, so our immune system actually recognizes the similarities and neutralizes
some of these adeno associated viruses immediately before they can target the cells they should
target. His lab hypothesized that this novel ancestor,
predicted ancestor could actually circumvent this pre existing immunity. They did a lot
of high throughput screening, in vitro, in vitro means in the petrie dish, and injected
them into mice. So you can see AAV2, AAV8, so these conventional adeno associated viruses
in these columns, and Anc80 is the new virus and you can see expression in the liver, muscle
and retina, and Anc80 seems to outperform all these other conventional adeno associated
viruses. But nobody had tried that in the ear, so we
did that in the ear and we tried it on something called cochlear explants. These are like microdissections
of these mouse inner ears, and we can grow them and culture and add certain viruses or
whatever we want to them and see what they do.
Then in red, you can see hair cells, so a specific hair cell marker. In blue you see
a marker for neural structures, and in green we have, again, this GFP, so the green fluorescent
protein, which means that the virus went there. Every column here represents one of the conventional
viruses, and here the last two columns on the right are Anc80, so that’s this new virus.
What you can see is that Anc80, so this new adeno associated virus, really outperforms
all of the other adeno associated viruses, and we were very happy when we saw that for
the first time. Specifically, it was not only at the level of inner hair cells but also
outer hair cells and supporting cells. I’ll show that to you in a few slides later.
You can see that these micro-dissections are really tiny, so it’s really my thumb next
to it. You see these white, little dots, those are the explants. So mouse inner ears are
not really very big. We then also tried this together with or this work was primarily done
in Jeff Holt’s lab at Harvard Medical School. They injected mice with the virus, the most
promising vectors we identified in vitro in the Petri dish. Anc80 still outperforms all
the conventional viruses. They did a bunch of studies regarding how the uptake of the
virus would change the cells, and it was normal in terms of how the cells reacted and how
these animals then heard and then had these objective hearing tests in a way. Again, for
you to appreciate how tiny everything is, we have a mouse pup here, and that’s where
you the injections then take place, so you have to expose the round window back there.
It takes about 10 minutes per pup once you establish the approach.
Some more images of this GFP expression. You see along the whole length of the cochlea,
we get a lot of viral expression in inner hair cells and also the outer hair cells that
could not be reached with the conventional adeno associated viruses are finally transduced
with Anc80 with a maximum follow up up to a month and the expression was stable which
was interesting because mice live between 2 to 3 years, something like that. It depends
on the strain. So a month is a pretty substantial amount of time.
With the in vivo injections we showed that from the very apex or the very top of the
cochlea up until the very base of the cochlea, so up all the way to the bottom of the cochlea,
so throughout the cochlea we had a lot of expression of this virus, which is very promising,
and it was so strong that we sometimes even saw it on the other side of the ear. Then
we were wondering, how does it actually get there? For that we used brain slices of the
mice, so we cut the brain like this. You can see the A here, so the section is called an
axial section with this human head. For the mouse in front here, we have the snout while
here we have the cerebellum, which is the posterior part of the brain back here. You
can see that this is where we get the predominant GFP expressions of green fluorescent protein
expression, and you can see that these cells here take it up, and so what we think is what
happened is that the virus travels to the other side through a structure that’s called
the cochlear aqueduct, which is a connection between the fluid of the inner ear and the
cerebrospinal fluid – that’s the fluid where the brain and spinal column kind of swims
in it. That is actually known in rodents that this is relatively patent, so we have to figure
out how far that is translatable to larger animals, because that would be another hurdle
until it goes into clinic because you want to avoid that it actually goes into the brain.
We also looked at the vestibular system and what you see in mouse tissue that we get a
lot of green cells, so it’s very positive – we can actually reach them and what’s very
interesting is it was done by collaborators in London, we also got it into human tissue.
In some surgeries you actually have go through the inner ear, and what they do in this case
or to resect certain tumors you have to go through the inner ear and you can get access
to the precious human tissue. You see that we have this excellent expression also in
human tissue, so it seems to be a promising candidate for clinical studies. Excuse me.
This is another study that used Anc80 in adult animals. In 7 week old animals they were injected
through the posterior semicircular canal. That could be an approach used in humans,
specifically the lateral semicircular canal that seems to be accessible.
What you can see here is that, again, in these adult animals that couldn’t really be transduced
at all until now with this new virus, you get a lot of outer hair cells at the apex,
not so much at the base (not so much at the bottom of the cochlea). Still relatively promising.
Other collaborators at the Harvard Medical School used this virus in a model of Usher
syndrome. That was Holt’s group and Géléoc’s group. What Usher syndrome is, it’s the leading
cause of deaf blindness and is inherited recessively. Both genes have to be affected then. What
you can see in this figure is that it’s a scanning electron micrograph, so it’s the
highest resolution of the the highest resolution of basically the common microscopes that you
can see. What you can see on the left side here is
a wild type animal, so a healthy animal. What you see in the middle is a diseased animal,
so that’s an animal with Usher syndrome. What you see on the right side here is an animal
that has been injected with this Anc80 that had had protein that is missing had this gene
that is missing in these animals, and you can see that the hairs to the stereocilia
that give the hair cells their name, are really similar to these wild type healthy cells compared
to the Usher cells. So that was really remarkable these cells
could be rescued to such an extent. They performed many additional experiments and specifically
performed these hearing tests, objective hearing tests again and what you can see here is that
the control animal, so the Usher animal with the disease, did not show any thresholds at
all with the hearing, so the louder it gets, deaf animals no responses, while here on the
right side – the animals that were injected did actually have relatively nice hearing.
For some of them the hearing was as good as for wild type animals, as for healthy animals.
Several other studies have come out since then and like before them or around the same
time, and you they targeted different Usher models, so there’s a lot of different subtypes.
They all showed most of them showed rescue, however, none of them was as substantial as
with this novel virus presumably because the standard adeno associated viruses did not
target, or cannot target, the outer hair cells. Are there any other approaches that allow
viruses to target more hair cells? Yes. Another lab here at Harvard is working on
something called exosomes. They’re small vesicles, and for patients I would describe them as
“bubbles filled with information” and secreted from cells. They enable communication
between cells. These other cells then take exosomes up to process it, and these viruses
have hijacked this approach to actually get into the cells more easily.
What this lab is doing now, and a very clever strategy, is they package these conventional
adeno associated viruses into these exosomes and can target more cells with this approach.
Then this CRISPR Cas9, these gene scissors that we briefly had mentioned before, in a
very interesting study that was published at the end of the last year, they looked at
they had a mouse model that lacked Tmc1. That’s something I’ll explain in a minute.
I want to show you this here in this frog hair cell you see these stereocilia, so the
“hairs” of the hair cells. What you can see here is something called tip links. These
are the little bridges between the “hairs” of the hair cells and this Tmc1 and this transmembrane
channel-like gene family 1 is part of this gene complex here that is important to cause
the kind of or the movement of these hair bundles. In 2002 a study group created a mouse
with a TMC mutation, and it showed that it led to slow degeneration of the hair cells.
They named this mouse Beethoven mouse, which is not a great name because the composer had
a completely different type of deafness. This mutation is also relevant to humans and has
been described in a Chinese family. What these researchers did is they injected
so called Beethoven mouse pups and compared them to controls and this protein RNA complex,
so CRISPR Cas9, targets only the affected copy of the gene without influencing the other
gene. If we can get the affected copy of the gene, the diseased copy of the gene kind of
out of the way, then in theory the normal gene should take over and the cell should
be functioning again. That’s what these researchers hypothesized.
What you can see here on the right side, so again, we have inner hair cells here, and
then three rows of outer hair cells out here all along the length of the cochlea. On the
right side you see all the cells are still viable, while here on the left side the uninjected
animals, so these Beethoven mice, do have degeneration at the lower part of the cochlea
or the apex (or the top) is kind of still there. Then these injected animals actually
have preserved cells all throughout the cochlea. So it was a substantial rescue after the injection.
Then the researchers obviously again assessed the hearing, and what you can see here, again,
loudness on the Y axis – so loudest level up here, very quiet level down here. What
you can see is that these injected animals actually heard better than the uninjected
animals – deaf in some frequencies at least. However, the rescue was not as good as for
the uninjected animals, healthy animals. However, this study is really proof of concept that
this gene disruption be might be a potential strategy of treatments of some form of this
dominant hearing loss. So far we only talked about stabilization.
What about restoration actually? That is a different an interesting difference between
genetic hearing loss and age related hearing loss because for age related hearing loss,
we probably need a mix of gene therapy, molecular therapy and stem cell therapy or just focus
on yeah, there’s a lot of overlap between the three fields.
As I said before in some of these newborn mice, it is actually possible to make a transition
from the supporting cells to hair cells, some of these mice still regenerate hair cells.
And usually that’s through the switch of supporting cells into hair cells, and that’s been studied
extensively and several different signaling pathways have been identified by researchers
all over the world. In a relatively recent paper — and that is
lost after like the maturation of the mice – so in adult mice, you cannot transition
supporting cells to hair cells anymore. However, in a relatively recent paper that also came
out last year, a group actually tried to combine several of these factors, and then was able
to make the switch from supporting cells to hair cells, so you can see here in blue the
hair cells, the inner hair cells and three rows of outer hair cells and here after noise
damage they would be lost and could be regenerated after the mix of different factors. So this
group shows that for the first time in adult animals, which is very relevant for age related
hearing loss. The only clinical study at the moment that targets or that is focused on
gene therapy in the inner ear that I mentioned before is actually targeting ATOH1.
That’s a study that the lead investigator, the principal investigator is Hinrich Staecker
in Kansas, but they also have sites at Johns Hopkins in Baltimore and at Columbia in New
York. So to summarize, gene therapy is a potential
solution to restore kind of natural hearing and hopefully millions of people affected
by this hearing loss, especially hereditary hearing loss. Anc80 seems to be potent viral
vector for cochlear gene therapy and several mouse models that could be rescued and the
best results for the major deafness genes at the moment seem to be achieved with Anc80,
because with Anc80 you can also reach the outer hair cells and not just the inner hair
cells. Gene editing with CRISPR Cas9 is feasible
as this last study showed that was published at the end of last year, but now the really
important part for the patient and also for the physicians that are confronted with these
questions all the time: “What are the hurdles on the way to the clinic?”
As we saw in the mouse model with the expression in the cerebellum (so in the brain) – it’s
really necessary that there are studies in larger animal models, specifically for dosing,
because the inner ear is so much bigger in larger animals and humans compared to mice,
and also the safety issues that I mentioned before. It’s kind of the last step prior to
starting multiple independent human experiments. And what was interesting in the study that
also came out last year was that a group showed that they could actually inject a sufficient
volume into the inner ears of rhesus monkeys without worsening this objective hearing.
They have these ABRs where they can then detect the wave forms and see if the animal heard
it or not. I recently was attending a talk by an investigator
working in ophthalmology, and he said that the vector correlation, vector result correlation,
is under 30% between mice and humans, while it’s over 75% between monkeys and humans.
You can really see the result. Like, I’m also not a big fan of large animal
experiments, but if you look at these results, then it really seems to be necessary to have
a larger animal model to be sure that what goes into human studies that is, yeah, associated
with so much like risk, et cetera, can actually work and in vivo as well and humans as well.
Another question is can you specifically target certain cell types? A way to do that is to
give the vectors a kind of a different key. This key is called promoter scientifically,
because for some diseases you just want to target inner hair cells for some diseases
and you want to target outer hair cells for some diseases and you want to target neuronal
structures. If you have the keys for all the different cell types, it’s nice to be able
to kind of customize a treatment for every patient.
For these adeno associated virus vectors, the size of the gene you can actually put
into them, there are some approaches to try to circumvent that problem. Excuse me. Try
to circumvent the problem with very promising results that haven’t been published yet, but
I heard somebody talk about it the other day at a conference. Yeah, there’s several options
that hopefully can avoid this issue. And then the time window is another very important
thing that I was talking about. The degeneration of cells progresses in several
animal models or in many animal and human models, human diseases. So the question is,
do you really have to treat patients in the womb, or is it sufficient to kind of do it
after birth? Would the results be better in the womb, and if it has to be in the womb
it’s associated with a lot of risks and it’s really, really tricky to actually get that
into the inner ear. Then also the treatment of age related hearing
loss. Are these results from the one mouse study actually translatable, and what are
the results from this multi centered trial I mentioned before beyond the gene therapy
trial in humans at the moment. And what’s really exciting is most gene therapy labs
have now ordered this virus, and we really hope to accelerate the translational research,
and then there’s several more applications where definitely more research is necessary.
And with that, I’d like to thank all the collaborators that have worked with us on gene therapy projects
and all our funding agencies and as Nancy said, I did run the Boston Marathon two days
ago, and it was really horrible weather. If you want to support our research, then you
still have time until April 30th if you click on that link you can read some more about
me and why I decided to kind of try this marathon. It was my first marathon.
Yeah, I finished it. I was very happy with the time as well for these conditions, and
thanks a lot for your attention. I’m happy to answer any questions.
>>NANCY MACKLIN: Congratulations on that. There are a few questions that have come in
that are very interesting. Your presentation was very interesting. It provides so much
hope, so promising, this research. Lauren said, if you get a cochlear implant, are you
not a potential candidate for gene therapy?>>LUKAS LANDEGGER: That is an excellent question,
and that was also a big discussion about, yeah, 20 years ago or so. I wasn’t part of
that discussion, obviously, but back then people started to implant both ears, so in
Europe so primarily the first candidates only received one sided cochlear implants, and
then about 20 years ago or so in Europe primarily they started to implant both sides of the
both ears of the patient. When that first started, then some researchers
said this is madness, and you have to preserve one ear for gene therapy. Then the surgeons
asked, well, when will it be ready? Then they said, yeah, the maximum is five years or so.
That was 20 years ago. It’s really hard to make like any predictions when it will be
ready, so I am not sure how many questions I answered there, because that’s usually a
standard question that I get.>>NANCY MACKLIN: Right.
>>LUKAS LANDEGGER: Typically if there is a cochlear implant in place in that ear, you’d
rather not inject it at the moment at least. However, in the future if there still are
these supporting cells left, then potentially if these approaches worked to really make
the switch from supporting cell to hair cell, and then potentially they might be candidates,
but it’s a tricky question to answer. You look at the so in the slides I also posted
the link to this current gene therapy trial, and the criteria for the patient selection
are very strict. In the first studies you really have to determine what works in a very
small patient pool, and then if it works in those patients, then you can kind of expand
it and try to include more patients.>>NANCY MACKLIN: I think that’s probably
several people in the audience that would like to just become in the clinical trial
right now. Go from mouse to humans.>>LUKAS LANDEGGER: Also after the big paper
was published with the virus, I received a lot of e mails and all the collaborators received
a lot of e mails. People really appreciated that people are willing to really participate
in these trials, and hopefully we will be there soon. Right now, unfortunately, there’s
only this one trial with very limited criteria. You can definitely check out the website and
see if you are a candidate for this.>>NANCY MACKLIN: Okay. So we’ve identified
about 100 genes associated with hearing loss. Do these genes include both inner and outer
hair cell information?>>LUKAS LANDEGGER: It depends. It really
depends on the disease. So, as I said, this VGLUT3 is a specific inner ear hair cell problem,
and that’s why they fixed it with the AAVs and they target it. However, a lot of diseases
affect both inner and outer hair cells in that these conventional vectors seem not to
work so well. That’s why this new vector seems to be better specifically for these diseases
for the animal models.>>NANCY MACKLIN: Tony asked, he said, I have
hereditary hearing loss on my father’s side. I’m considering getting genetic testing to
identify the genes responsible for my hearing loss. Do you think getting the tests could
be beneficial at this time?>>LUKAS LANDEGGER: I mean, it might be beneficial
in terms of the prognosis for him. I mean, that’s personally, because based on the gene
that’s affected, it might tell you how will I hear in like ten years? How will I hear
in 15 years and so on? You can kind of see it from the father’s side already. Yeah, it’s
tricky to like say anything about it without seeing the patient, and I haven’t my clinical
training is very limited at this point, so I still have to finish my residency and so
on. So I’m kind of hesitant to answer this question and would rather recommend seeing
somebody who really has experience with hearing and genetics in the human background and geneticists,
specifically, like genetic counseling.>>NANCY MACKLIN: Fair enough. John says,
it is my understanding that for people who have lost hearing over a period of decades
that changes have taken place in the brain. For example, reduction of volume of gray matter
in the cortex. If you are successful in restoring hair cells, will the changes in the brain
gradually be reversed?>>LUKAS LANDEGGER: That is an excellent question
as well. The question regarding tinnitus, for example, the ringing in the ears and what
the current hypothesis of tinnitus basically is, is that if there’s not enough information
coming in from the ears, then the kind of central gain is just like amped up, and then
the brain kind of creates this noise itself. In tinnitus even if you cut the auditory nerve
that connects the inner ear and brain, then it still doesn’t go away. So it’s probably
not something that’s caused just by the inner ear itself. Again, from a limited clinical
experience, but in patients that receive hearing aids, they usually do better with the tinnitus
as well. So some of it might come back, but I think if you really have had have not done
anything about a hearing loss for decades, then it might be hard to actually do something
with this information that the brain all of a sudden receives.
>>NANCY MACKLIN: All right. Ken said, are patients with Meniere’s disease candidates
for gene therapy? I understand the hair cells die off in Meniere’s patients. Do they regenerate?
>>LUKAS LANDEGGER: That’s also a good question. We look at the vestibular system, so in some
of the genetic diseases the vestibular function is affected. So in these mouse studies, for
example, all of these mice were dizzy as well. So there’s some very interesting tests that
you can do with mice to figure out whether they’re dizzy. You can kind of film them from
the top of the cage and see how they run, or you can put them on a rotating rod called
the rotarod and determine how long they stay on top of the rod. Or have them swim and see
if they can keep the head out of the water. With this regeneration in Usher mouse models
and others, the vestibular function was it was like restored as well.
However, in these mouse models the hair cells kind of were still in there, and it was just
a gene that was lacking. The gene was lacking and reintroduced with this viral vector.
If the hair cells are gone, the vestibular hair cells are gone, it will be relatively
hard at the moment to kind of grow them back. However, also in the vestibular system you
have supporting cells that could regrow into the hair cells in the future. I mean, I’m
not we’re not talking about years here. It’s decades probably if I’d have to say anything
about a timeline. So, yeah. Tricky.>>NANCY MACKLIN: Okay. Katherine said, can
you talk about the role of deteriorated brain pathways in people with long term loss? Would
they be eligible for gene therapy or regeneration?>>LUKAS LANDEGGER: That’s kind of question
that I answered before where, yeah, it’s kind of the gain, et cetera.
>>NANCY MACKLIN: Okay. Got it. Is effectiveness of Anc80 versus AAVs specific to mouse inner
ear, or are there similar studies on other organs or organisms?
>>Organs, yes. There are different studies, so the initial paper I highlighted where they
showed it in the liver, muscle and retina, so everywhere there Anc80 seems to outperform
the other AAVs. It’s synthetic, so it’s the first of a class of synthetic AAVs, so in
different organs it works. Regarding different species, right now there’s nothing published
on that, whether it’s translatable. That’s why we’re so interested in having larger animal
models not just for Anc80s but AAVs in general.>>NANCY MACKLIN: Did male and female respond
equal to the therapy? The females did much better.
>>LUKAS LANDEGGER: That’s an excellent question, and the NIH requires us to analyze male and
female mice now because traditionally most of the studies were carried out in male mice
because they have fewer hormonal influences that play a role in noise exposure in general.
What we did for the in vivo studies is we tested it in male and female mice.
In vivo studies means the pups that were injected, we tested the male and female mice for the
so that was the same number, and pretty much the same effect. For the in vitro studies,
we don’t know. At postnatal day four it’s really hard to differentiate the sex. We don’t
specifically look for that. After a few weeks it’s relatively easy to
differentiate the sex in mice, but in the very small mouse pups it’s relatively hard.
>>NANCY MACKLIN: Okay. Has a gene been identified to explain cookie bite hearing loss?
>>LUKAS LANDEGGER: I have to admit I’m not familiar with cookie bite.
>>NANCY MACKLIN: With that term? I’m not either.
>>LUKAS LANDEGGER: Like the shape of the audiogram?
>>NANCY MACKLIN: I believe so.>>LUKAS LANDEGGER: Probably. Cookie bite
hearing loss. Yes, that’s the shape of the audiogram. I’m not familiar with some of the
clinical terms in English. This is not my native language.
That is a good question, and I’m, I mean, I’m sure there are one of like one of the
hundreds of genes or several of the hundreds of genes have such a form, but I like it’s
hard to give you a diagnosis now just based on this audiogram. So I don’t think that that’s
possible.>>NANCY MACKLIN: Okay. Would hearing loss
due to meningitis be similar to that of age related hearing loss discussed, or is that
totally different?>>LUKAS LANDEGGER: That is also a good question,
and, yeah. So it depends what is like what was inflamed. If there was actually a if the
inflammation took part in the ear as well or if it’s just the not just, but if it’s
primarily the central parts that are affected. If it is the central part, so the part of
the brain where the processing of the signals actually takes place, then I would say that
it would be different than the well, I’m not actually on this question, I’m not sure.
I don’t think I can answer this question. I’m sorry. I have to pass on that.
>>NANCY MACKLIN: Okay. All right. And last question. Is the talk about hair cell regeneration
in birds, mice, and fish applicable in nature or just in research clinical trials?
>>LUKAS LANDEGGER: No. For mice only in the very, very neonatal mice. But for birds and
fish, that’s applicable in nature. So they really regenerate their cells (their hair
cells) constantly basically.>>NANCY MACKLIN: Okay. Is there a reason
for the lack of therapy trials? Is it strictly because of funding, or you mentioned that
in the very beginning.>>LUKAS LANDEGGER: Right. That is a good
question. I mean, the eye is just way more accessible than the ear. The inner ear is
kind of encapsulated in one of the hardest bones in the human body and it’s really tricky
to deliver something there. In the eye you can use a syringe and inject it in there.
Yeah, it was just easier to kind of access that, and then funding for blindness in general
is or like hearing research is a relatively small community in general, whereas the blindness
foundations are definitely larger. So that might have played a role as well.
>>NANCY MACKLIN: Okay. And if you had to guess, when would you think that there would
be human clinical trials?>>LUKAS LANDEGGER: There is already one human
clinical trial.>>NANCY MACKLIN: For the mass you know, for
more people to get involved in the trials.>>LUKAS LANDEGGER: So I don’t think there
will be clinical trials for like everybody with deafness. It will be a clinical trial
for a certain disease, for Usher syndrome or that specific type for example with hearing
data and so on. I’d really hope that we’d have something to offer patients of like for
at least like one specific syndrome within the next two decades or so, but it’s really
hard to make these predictions. There’s one person from 20 years ago that said it would
only take them five years to translate into clinic. So you really have to be conservative
there.>>NANCY MACKLIN: It seems that the research
is so promising and on the verge of great discovery. I know everybody is anxious, and
we definitely like to keep up on this topic. So I welcome you to present again, even if
it is from Europe or wherever you may land from here. Thank you so much for doing the
webinar. It was rather short notice, I know, and you really did a great job.
Thank you again to Darcy, who provided CART tonight, and we’ll look forward to seeing
you next month when we talk about HLAA2018 in Minneapolis coming up in June.
Good night, everybody, and thanks again.>>LUKAS LANDEGGER: Good night. Thank you.

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