AADCd Family Workshop 1; AAV2-hAADC Gene Therapy in Poland & USA

AADCd Family Workshop 1: Transcript AAV2-hAADC Gene Therapy in Poland & USA

Professor Krystof Bankiewicz USA/Poland

Dr Toni Pearson USA

Transcript ...

Lisa Flint Hello everyone and thank you for joining today. I'm Lisa Flint Founder of The AADC Research Trust. Also mum to 23 year old Jake who has AADC. Together today with my colleague Julie, and all of you, we are celebrating 15 YEARS this year of patient advocacy, raising global awareness and funding critical disease research.

More than 14 countries are represented here today which is amazing.

The subject of Gene Therapy is of extremely high interest and we hope you find this workshop really helpful.

Before we start please can I ask you to keep your microphones on mute and message Julie throughout with your questions to ask them at the end.

So let's begin by introducing and welcoming our professionals.

Welcome Professor Krystof Bankiewicz. He is a Gene Therapist at Ohio State University and the University of California, San Francisco. He is the principal investigator for the AADC Gene Therapy Trial.

Also we welcome Dr Toni Pearson who is a child neurologist and child movement specialist as Washington University School of Medicine in St Louis. She is also the lead neurologist for the Gene Therapy Trial in the USA. Today they are co-presenting on Gene Therapy in Poland and USA.

Professor Krystof Bankiewicz Hi and thank you Lisa. I will be presenting for 20-30 minutes to provide you update on the Gene Therapy effort. I need to emphasise this is a clinical trial that I am conducting in the US, and Dr Pearson is the key principal investigator.

What it means is that we are investigating potential treatment for AADC via Gene Therapy.

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As such, this trial is limited to patients that we are able to enrol in the clinical trial in the USA, which is funded by the US government agency called NIH (National Institute of Health).

Dr Pearson will give you update on where we are with the follow up. We have number of patients now that we have been following for over three years.

As a consequence of conducting this clinical trial in the US, we are allowed to also offer the Gene Therapy on a compassionate basis. I donate the product, which is the viral vector, to the trial in Warsaw. We don't have separate through the clinical trial mechanism to pay for the procedure in Warsaw, therefore patients who underwent this treatment in Warsaw had to raise money to pay for hospital fees.

Having said that, let me share my screen with you.

Slide 1 Let me briefly give you a sense of what we are trying to achieve in this clinical trial, which has been ongoing now for a number of years.

As you are all aware there is profound loss of dopamine in the brains of patients with AADC deficiency.

The relevant pathway which is shown here. Food that you give your children contains Amino Acids, that need to be converted to different enzymes present in the brain called neurotransmitters.

A neurotransmitter is a substance that connects different pathways within the brain. Without this neurotransmitter, in this case it's dopamine, you witness all the clinical signs, that you are seeing in your children.

There are two principal neurotransmitters that are not working in the brains of patients with AADC deficiency; serotonin and dopamine. This is because of the mutation of this particular enzyme called Aromatic Dopa Decarboxylase.

As a consequence of that mutation compound called L-Dopa, a precursor that needs to be converted to dopamine is present in excess in the brain.

I'm showing you this because you will see in Dr Pearson's presentation that these biomarkers, these chemicals, we can measure in the cerebral spinal fluid, that we obtain from the patients before and after gene therapy. They are very important markers for us that tell us if gene therapy is working.

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Slide 2 AADC mutation affects dopaminergic cells very deeply within the brain. This region is called the Substancia Nigra & Ventral Tegmental Area. This is where the problem is. The other brain region affected by AADC mutation is in the brain stem. Thus far we have been trying to reverse the genetic mutation with Gene Therapy in the midbrain by delivering a small viral particle that correct genetic mutation. Gene therapy has to be delivered into substantia nigra and ventral tegmental area because that's where the dopaminergic neuronal projections originate. Not anywhere else.

It's very important that gene therapy is delivered right into these nuclei that are involved in dopaminergic projections. It's meant to rebuild it to normal function because we are delivering gene therapy into the part of the brain that is responsible for production of dopamine.

Our goal is to restore the dopamine and also relay on axonal transport to help distribute the dopamine and also AADC expression into these critical projection areas. The brain is wired with a lot of different connections and we specifically target this one by surgically intervening into the route cause of the problem seen on AADC deficiency.

Slide 3 Once we rebuild the genetic information in the Substantia Nigra & Ventral Tegmental area we rely on the existing neuronal wiring within the brain of your children to do the job. This is a very physiological way of transmitting the information as it is seen in normal brain.

Slide 4 We invented a surgical method to be allow us to operate on patients in what's called an MRI; Magnetic Resonance Imaging.

The patients are positioned in the magnet and we use devices shown on this slide and attach them to the patients skull to allow us to neuronavigate in real time, meaning that we can see what is happening while we operate. Thus, we are able precisely turn these knobs to confirm that we will put our delivery cannula right where it belongs.

Here is one of the children being operated on with this first-generation system that we invented at UCSF. This specific device allows us to infuse the gene very precisely into the target brain region.

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Slide 5 In order to perform this procedure we also invented a different device shown here that has a much smaller profile and it is much cheaper to use. That is the device that we are currently using in patients in Warsaw and we will soon use in patients in the US trial.

The operation requires that patient is being put to sleep, of course. Then the patient’s head has to be immobilised to allow us to attach these devices to the head.

Slide 6 Here are some of the pictures that you can see when the devices are being placed on the patients head.

Slide 7 Through that device we can very efficiently delivery the gene. The patient is then moved from the operating room into the MR scanner, then we move forward and start infusing the gene.

Slide 8 Here is the device itself that we can see on the scanner. We ensure very precise placement; this is what is called the trajectory. We aim through different array channels to pick the one that is the most safe in terms of trajectory. You can see the beginning of the gene delivery here. That white dot is actually the Gene Therapy being injected into the brain that we can see in the images obtained by MRI during the infusion.

Slide 9 Here is the example of gene delivery being done in a real time, in other words, while we deliver the gene we can actually observe how it is distributed within the brain by observing it on the monitor.

This is the area that I was telling you about. We can infuse the gene therapy on both sides of the midbrain, in both the substantia nigra and ventral tegmental area. This technique gives us very good precision but also allows to monitor where the gene transfer takes place.

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Slide 10 I told you about biomarkers and also the fact that we need to confirm that we are taking advantage of axonal transport, which we believe restores a lot of missing function in the children.

This is the part of the brain that we are trying to target. It is called the mid-brain.

Where I'm pointing, you don't see any signal. This examination is called Positive Emission Tomography (PET), that we have performed on many of our patients and there is no signal, nothing here that would indicate, that this part of the brain is functionally converting L-Dopa to dopamine. This is where we inject, here is the same part of the brain. And now you can see these red dots here that indicate that now functional gene has been restored.

What's more important for us is, that we are using this axonal transport to transport the dopamine into the part of the brain that is critically important for maintaining the motor control, but also some of the mood behaviours. Here is the pathway after administration of the gene, shown here.

Slide 11 In fact, PET exams show this in all the patients that we've examined. This is the projection area from our injection site. This region here is what controls motor behaviour, meaning that the children cannot sit or move, this part of the brain, it's called the caudate nucleus, the one here is called 'nucleus accumbens, and it can affect their mood. Without functional innervation shown here children with AADC deficiency cannot function very well, they cannot move but they also have problems with their mood behaviour. Remarkably, when we deliver AADC gene into this deep brain areas, we get very efficient restoration of this innervation in all the areas which are very important for their respective behaviours. So it is very important, that our hypothesis of restoring AADC gene within the part of the brain that requires production of dopamine, is actually functioning quite well.

Slide 12 You will hear in a minute about how many patients we've treated. We don't see any adverse events, serious adverse events related to gene delivery. All of the patients, have transient dyskinesias, as the brain adapts to the new message within the brain which is the dopamine.

A lot of the circuits have to adjust and one of them controls dyskinesia. It is being maintained and controlled by lowering some of the medication administered to the children. Usually within six to twelve months in the younger children, it pretty Page 5

much disappears.

The method of gene delivery that we have worked out and tested on twenty three, potentially twenty four, patients seems to be absolutely critical for the safe and accurate gene therapy. AAV is a nano particle that we use for gene therapy, is called Adeno Associated Viral Vector.

We really believe thus far, with all the subjects we've treated, there's very substantial increase in their clinical outcome, justifying the gene therapy further.

Dr Toni Pearson Slide 1 I'm going to share with you some of our results from the first twenty two patients who have had mid brain gene therapy.

Slide 2 First I'll summarise the different patients who have participated in either the clinical trial or an associated study. We have the first seven patients who were treated either in UCSF, San Francisco or Ohio State. Results from that part of the study will be published soon.

As Krys mentioned there's also been a cohort of patients who've also had compassionate use treatment, using a very similar approach in Warsaw, and that's fifteen of them.

I have followed thirteen families who have participated in a pre-surgery observational portion of this, which has given us extremely valuable information on understanding how symptoms fluctuate, how things change pre gene therapy.

Shout out to all those families who participated because that data has been particularly valuable as we've planned the next stages on this.

Briefly I will describe the makeup of these twenty two patients who have had the treatment so far. On the left of this graph is the ages of the first seven patients in the US. The youngest was four, the eldest nine. On the right is the ages of the subjects who were treated in Poland. The youngest was four, this has a larger range of ages. Included in this group are some teenagers, almost adults. 50/50 exactly male and female, just by coincidence. Almost all the patients had Oculogyric crises as one of their symptoms. That's something that we followed before and after.

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By in large most of these patients had pretty significant impairment of their motor function. Motor function meaning movement control, ability to reach for things, hold objects, speak. None of them were able to sit independently before gene therapy and only two of them had the ability to support their own head.

Slide 3 Krys mentioned that what we've been doing is a clinical trial which means we measure a lot of things before and after. I wanted to break it down into the three types of things that we are interested in measuring, because these are all things that tell us how the patient is doing and that we try to describe as a way of helping us to understand what the effect of gene therapy is.

In the first blue circle I've listed examples of the types of symptoms. These are things that we all experience, you experience twenty four hours a day, with your children. Things like crisis, involuntary movements, like dystonia, some children have problems with sleeping and mood, maybe feeding difficulties like vomiting or feeding intolerance. We are also interested in those.

We are also interested in function, so these are, given that AADC deficiency is present from birth, the impact is felt not only in the symptoms that children experience, but also what is the impact on their ability to develop and to function. So things we track, for example, during infancy like head control, sitting, standing, and walking, development of speech.

One example of a standard test we use, so we can score, is called the Gross Motor Function Measure or GMFM. Finally we do other tests like scans and lumbar punctures. We can measure the level of the dopamine metabolite in spinal fluid and we can also do specialised scans that show us AADC activity in the brain. Krys showed some examples of that.

Slide 4 So I'd like to show you some highlights of the main results and show you some videos of a couple of the patients, whose families kindly agreed to letting me describe what they've experienced today.

The first one of the results that we are most pleased with is that the mid brain gene therapy has had a big impact on OGCs. I mentioned before that almost all the patients treated so far had OGCs before surgery, twenty of them had them, and in some patients they had ten to twelve or more hours of crisis per week. In the vast majority of patients, we've observed that the crises have gone away completely. It usually happened within the first three weeks or so after surgery.

There are three who have not had them go away completely. In one case they Page 7

went away and then came back in a milder form, and in the other two patients they didn't go away but what they experienced was that their crisis became much shorter and milder, so not as severe.

Slide 5 The other thing that improved a lot and I won't go into the details of the graph which shows the results very detailed diaries of the first seven patients in the US kept to describe sleeping behaviour over a week, but most families noticed that sleep and mood after gene therapy improved a lot.

Slide 6 Let me show you some videos of a couple of patients now. The first one is Audrey, who was enrolled in the UCSF trials. She had her surgery in July 2018 and is now nearly three years after surgery.

This was her assessment before surgery. She is six and a half here and needs some support to sit. You can appreciate that her movements are slow, has trouble supporting her trunk and her head to sit up.

Slide 7 After gene therapy, here she is at two months. I'm using this to show some of the involuntary movements that all patients develop after surgery. You can already appreciate that she already has better head control, she's starting to actually hold her head by itself. You can see these movements, her legs and arms are involuntary, and that's a typical result that we see after the dopamine level increases in the brain after surgery. Another very common behaviour that we see in children after surgery, is this tendency to put their hands in their mouth.

This is her at her 18 month assessment. You can appreciate here she has gained a lot more ability to move and much better trunk control for sitting.

This is a home video her parents shared, at twenty one month’s where she started to be able to stand up and take weight through her legs, which was great to see.

Audrey's mum shared some recent videos. They show her walking around her school. She's able to take steps for shorter distances without a walker. Here she has become highly skilled at using a communication device.

Slide 8 So some comments on that series of events. I showed a brief video of her Page 8

involuntary movements at two months and that's something we observed in everybody, this onset of dyskinesia, it just means involuntary movements, that happens at about a month after gene therapy and takes a number of months to improve.

We typically taper off medications in that phase, and it helps the movements to calm down, but it's not in itself the only thing that's needed. Time is also needed.

We had a few patients need, at least temporarily some additional medications, while the brain adjusts.

I mentioned earlier many families described sleep getting much better.

Immediately after surgery it's very common for people to go through a period where their sleep is worse for a few weeks.

Slide 9 The next patient I want to tell you about is Rian, because she participated in a year of the observational phase of the study, this Natural History phase, before she had her surgery.

This video was taken in England in October 2018, and she had a baseline assessment done at that time, and then was followed a couple of times over the subsequent year before she had surgery. Here she is at age four at the baseline assessment.

Slide 10 Here she is almost a year later, right before surgery. You'll appreciate in terms of motor function, she is very similar. This assessment is being done at Washington University. Aaron is a Physical Therapist who works with me here. And then most recently, she had surgery eighteen months ago. This was her most recent assessment at 18 months after surgery. She has made a lot of progress. A lot more mobility, she can move around the floor, she sits really strongly on her own, she started to be able to hold a cup and drink and has been eating much better as well. You can appreciate that she has grown a lot and gained weight since she had her gene therapy.

Slide 11 I'll go through a couple of results really quickly for the group. We saw some examples there but what we have found, with a couple of milestones in particular, so head control, which most patients did not have at baseline, but almost all of them developed good head control within a year.

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I've broken this down, this is our initial cohort of USA subjects, who are all under age nine, and then the subjects who were operated on in Warsaw with an older group and younger group here. For head control you can see that both the younger and older patients did similarly.

Some patients developed head control very quickly within one or two months after surgery. In others it took longer. The range was somewhere from one to nine months.

For independent sitting, something that none of our patients were able to do before gene therapy, the majority of them were able to do this by a year. We see a small difference in the older groups of patients, who were operated on in Warsaw, some of whom had really significant motor impairment, had not had much motor development at all by the time they were operated on. That is a factor for all ages. It is emerging as something that effects the speed of making progress after surgery. We are gathering more information about that.

Overall two thirds of patients were able to sit by twelve months. Of those who were able to do it, the typical time for achieving that was six to nine months but it's very variable and some patients developed being able to sit later than that.

Everybody follows their own pace of development.

Slide 12 We saw a couple of the physical therapy examples of the therapist assessing the patient, doing the Gross Motor Function Measure, which is a way of us being able to measure function and then come up with a score, somewhere between 0-100, which is very useful for research studies. Although in day-to-day life the score is not necessarily the most important thing.

Slide 13 We measured, this is our cohort of the first seven patients in the US. They had two lumbar punctures before gene therapy to check neurotransmitter metabolites before and, then had three in the first year afterwards, and what we can see is, as a group, most patients have very low levels of the dopamine metabolite in their spinal fluid at baseline. The normal range is represented by the dotted line here and then we saw a nice increase in the group afterwards.

Slide 14 Here's another way of us looking at AADC activity in the brain. Areas where there is AADC activity that leads to dopamine production show up here as red. We can see in one of our subjects before gene therapy, there's almost no red, or the red Page 10

is very faint in all areas of the brain.

Three months after, we can see these two spots in the mid brain, which is the area where gene therapy was delivered, and then this is an area higher up in the brain called the Striatum, the Caudate, Nucleus (accumbens), the putamen and we can see the result of delivering the gene into the mid brain, which the only place it was infused, leads to all of this AADC and dopamine activity in areas that are connected to the brain.

Slide 15 For completeness I wanted to mention adverse events because it's a really important part of our monitoring for any clinical trial, is looking at safety and looking at any things that happen that are side effects of treatment or things that happen maybe unrelated to treatment. We follow all these things really carefully.

Two patients who participated in the gene therapy trial have passed away. In one case there was no illness associated with it. It was a subject who was doing very well at the six month visit, and then passed away suddenly one morning at seven months after therapy. We don't think that was in any way related to the gene therapy. It was something that was probably related to AADC deficiency itself. Another subject who had severe pneumonia about five weeks after surgery and passed away, in the context of that illness. Again something probably not directly related to the gene therapy itself, but certainly related to the illness.

We've had several subjects who have had chest infections that have led to hospitalisations, not necessarily related in the study, but during the course that we've been following them.

A couple of patients who after gene therapy have had seizures and that is something we are following. It's a new development and has happened in a couple of people and how much that's related to gene therapy verses something that the gene therapy might have connected to or patients being pre-disposed to seizures is something we are looking to learn more about.

Three patients, and I think this is a direct result of gene therapy as there isn't another explanation for it, but it's something we are also following, three people had either short term or longer term problems with diarrhoea after gene therapy.

A distinct change in their gastrointestinal function and that is something that we need to understand better.

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Slide 16 We have learned so far that mid brain gene therapy for AADC deficiency can be safely delivered.

We have seen significant benefits in the patients afterwards.

So in the twenty two patients treated so far 85% of them had their OGCs resolved completely and in the first twelve months after gene therapy we've seen head control developing 90% and the ability to sit independently in almost two thirds. We think this has the potential to definitely be a disease modifying treatment.

Q&A Lisa Can you conduct the US gene therapy after having the Taiwanese gene therapy?

Professor Krystof Bankiewicz We won't be able to consider that because there is a potential for the immune response to the gene therapy that has been delivered using a different route from what we are doing, so we would be unlikely we will be able to treat patients.

Lisa What's the youngest age for gene therapy either in the USA or on compassionate use in Poland?

Professor Krystof Bankiewicz So far four years of age but with the navigation system that I presented to you we will be able to drop two years of age for now.

Lisa How important is intensive therapy post-surgery to maximise the benefits of gene therapy?

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Dr Toni Pearson I think it is important. I think there is lots of different forms that can take because I think the reality is that people take part in lots of different types of therapy depending on their local resources. So there is not one prescribed course of therapy that needs to take place but definitely a period of regular therapy especially beginning as soon as possible, but given that I mentioned that that first period where there is maybe sleep disruption and involuntary movements and during that very initial phase, it might be hard to get the maximum benefit out of therapy, but immediately after that, once those things start to settle down a little bit. We've had several patients do blocks of intensive therapy where they might do daily therapy for two or three weeks and have some goals at the end of that for example, so there's many possibilities of what that can look like.

Lisa When will you begin gene therapy in Poland again, will it be compassionate use or does it have to be a trial?

Professor Krystof Bankiewicz We will restart in September. We had to run some tests on the vector that we are using so that's delaying things in addition to Covid. So that's for now and then the plan would be to hopefully open clinical site in Europe as well.

Lisa Would you ever consider gene therapy for children who show moderate symptoms?

Professor Krystof Bankiewicz I think from the cohorts of patients that we have treated there are couple of patients who had probably more moderate disease and I think they have responded quite well, so I think that would be something that we would consider.

Lisa Why is it important not to change the dosage of our of medications before surgery? We have been taking the same doses for two years.

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Dr Toni Pearson With our initial protocol we wanted people on stable regimens mostly so that when we see a change after gene therapy it's clear that the change that's being observed is due to the gene therapy, not to other changes in medications that might have been made beforehand, so the trial has had that requirement up until now to be on a stable regimen of therapy so that we establish what the baseline is.

Lisa Is the Poland method different to the US method? Dr Pearson said Poland is similar to the USA so what are the differences?

Professor Krystof Bankiewicz I think they are almost identical. In the last patient we treated in the US we used exactly the same method we had developed in Poland. Just so you understand the first seven patients were treated with 4 needle passes so we had to put two cannules on each side of the brain and deliver small volumes and that obviously increases the chance of surgical complications. In Poland we are placing just 1 cannula per hemisphere, and now we started doing exactly the same thing in the US. There are tiny differences in terms of some of the instrumentation but everything else remains the same in terms of how much vector is given and infusion volume. So it's very standardised right now between both centres.

Lisa Will all families who can afford gene therapy in Poland get a chance in September?

Professor Krystof Bankiewicz Well it's a difficult question. We can't really treat a large number of patients for a number of reasons. The logistical one will be the critical one. Again, we are doing it at cost, any funding that needs to go into treating patients in Warsaw, is to support your travel to Warsaw and whatever needs you may have and also to pay the hospital bill, hospital charges as for the operating room, for paying the salaries for all the personnel that is involved in the procedures. There is a travel cost for you as well. We donate as much as we can, again it's a compassionate use, this is not a clinical trial. We are doing everything to help the families but there is a limited number of resources available for that.

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Lisa So if they continue to raise money to cover those costs is every country accessible or are there countries that wouldn't be able to take part in Poland?

Professor Krystof Bankiewicz No I think with travel restrictions being lifted there is really no restrictions of any kind in terms of where the patient is coming from. We have operated on patients outside of the European Union as well.

Lisa Any new information or ideas about diarrhoea after gene therapy and how to treat. Is there any particular way that should be handled?

Dr Toni Pearson I think that the people who have had it have worked usually with a gastroenterologist and there may well be things that the gastroenterologist can recommend that effect gut motility and that can improve that. It's a little out of my area of expertise, how to fix that problem but I realise it's a significant one for daily life.

Lisa Is there any pre-tests that you can perform on children to see whether they have a predisposition to seizures prior to gene therapy. Are there any indicators that you can measure now across the board?

Dr Toni Pearson I think it's many children's experience that they get tested for that before their formal diagnosis is made. Many patients have seen a neurologist and have had some tests for example EEG, especially if there was any concern in the beginning that OGCs might have been seizures so, I think many patients have had that. I will say there is nothing that would necessarily come up on that test that would predict whether somebody is or is not at risk of getting the seizures afterwards.

We have many patients who have had EEGs that were normal and abnormal. I think both patients who have had the seizures afterwards had normal EEGs beforehand, so there would not have been a particular indication of risk and I will say actually we have other patients who have had abnormal EEGs beforehand, that have not had seizures and those patients did not get seizures Page 15

afterwards.

Julie Our son has G6PD deficiency, can we know which chelating agent is used for gene therapy? Aaron has a list of chemicals which he should not get as they may trigger haemolytic anaemia.

Dr Toni Pearson For GDP6 deficiency specifically the issue would be medication exposure. There's that list that we always follow of things that may trigger haemolysis and would not be a specific reason to make it impossible to do this, it would just be that we would follow procedures, like any doctor would for GDP6 deficiency to check that the medication is appropriate to be given.

Julie If the child has a history of an acute auto immune condition earlier in life would you use steroids/immune suppressants after gene therapy to ensure that the body does not fight or reject the virus. Aaron had one acute auto immune haemolytic anaemia at one year and two months. He is now seven and a half years old.

Dr Toni Pearson Right now our protocol does not include the use of steroids. Immune response is something that is being studied. Krys you may want to make any comments about that as well. Looking at immune response to the vector is a question that we are always evaluating.

Professor Krystof Bankiewicz I really don't have much more to add other than we are studying right now a lot of aspects of the immune responses to the single administration of this vector to the brain, or multiple courses, trying to truly understand if there is a need for immune suppressants. I mean one possibility that we are considering is that some of the mutations that may be affecting your children, may also cause some of the immune responses to the gene therapy, but it is unknown. The vector we are using is designed specifically to avoid immune presentation because it only infects the neurons. It's very controversial right now and a very intense research in the field.

Multiple studies in the gene therapy are facing the same issue, maybe not to the same extent as we do, but the immune responses to gene therapy are being studied. We may consider the use of steroids as well.

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Julie Can you operate on children like our son who has AADC but is a moderate phenotype or do you prioritise the more severe phenotypes?

Professor Krystof Bankiewicz I think we would like to concentrate on patients who require gene therapy because they are much more severe and they have chances of responding. That said we would not like to restrict the gene therapy to only very severe patients. So hopefully we will be able to operate on some more mildly affected subjects.

Julie What's the difference between gene therapy to the Substansia Nigra and gene therapy to the Putamen?

Professor Krystof Bankiewicz The gene therapy to the Putamen has been developed by my group for Parkinson's patients. There's a strong rationale why, in that disease, that has a different underlying cause was efficient. We never thought, and still do not believe, that the gene therapy delivered to the Putamen is the right approach, simply because of the type of cells that are being infected. The problem in AADC deficiency lies within the mid brain. The changes in the Putamen are consequences of that change in those cells that I was describing. So we go to the root cause of the problem which is the cell population within the mid brain. Also, the phenomenon which I pointed out to you, that relies heavily on the axonal transport, is responsible for the changes that we see in patients who responded well to gene therapy to the mid brain to be much more normalized. In other words, there are more physiological than what you have after the delivery to the Putamen.

Julie Have you seen children's immune systems improve after gene therapy?

Professor Krystof Bankiewicz I really don't think so. I mean we haven't really looked at very carefully.

Dr Toni Pearson I'll just make a brief comment, we wouldn't anticipate a change in their immune Page 17

system from gene therapy, what I think a number families have experienced is fewer serious illnesses requiring hospital stays, which I think is probably not an immune response but because, for example, the child has better head control, better ability to manage their oral secretions and so are at a lower risk of getting very sick when they get a respiratory virus or something like that for example. We have had many families experience fewer episodes of severe illness but I think that is more due to the neurological changes.

Lisa AADC kids taking the Covid vaccine, do you have any opinion on that?

Dr Toni Pearson Children of any age can have a Covid vaccine. It's something each of you should discuss with your doctor or paediatrician, specific to your child. There's not a specific reason that I can think of for someone with AADC deficiency to have an additional risk to another child from a Covid vaccine or another vaccine so there's very few things that would make it impossible to get a Covid vaccine but just check with your doctor.

Lisa Gene Therapy USA trial are you still taking patients?

Professor Krystof Bankiewicz Yes

Lisa Would you recommend gene therapy to older children or have some of the responses for the older children ruled out them as possible subjects?

Professor Krystof Bankiewicz This is something that we are studying right now. Generally speaking, older patients did not respond as well as the younger patients. We are not really certain of the age at this point. I think adults have not done collectively as well with gene therapy. It is probably too late for them to benefit from the treatment, so I think, given the experiences from the European and US trials, we feel that maybe fifteen years of age, fifteen or sixteen, is probably where you draw a line for expecting some more consistent results. That said, I think patients that we Page 18

have treated that were around nine years of age, have responded quite well. I think that seems to be an expectation right now for us.

Lisa We have lots and lots of families, now forty in China. Do you have any plans to launch gene therapy in China or will it be accessible for them in Poland and how can we help make that happen?

Professor Krystof Bankiewicz There are no plans to open a clinical trial in China. If Warsaw becomes an option that's the only one probably right now but that said, maybe at some point we may be able to operate on patients in Asia as well.

Unfortunately I have to run to another Conference. I'm sorry. Bye bye.

Lisa Thank you for your time Professor Krystof Bankiewicz, we really appreciate it.

Lisa The gene therapy in America, are you taking patients from outside of America?

Dr Toni Pearson That is something that is being discussed. I don't know for sure what the details of that will be. It's a possibility. Let me say it this way, it's not impossible at this point but the details are not figured out yet. We are still figuring that out.

Lisa Toni are there any questions that you would like to ask us?

Dr Toni Pearson Thanks to all of you who have contributed, I know there are many families who are here listening or will hear it later, who have helped us in some way or another, so thank you all very much.

Lisa Thank you Dr Pearson and thank you everyone for joining.

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AADCd Family Workshop 1 : Transcript Produced by Julie Ramsay Verified by Lisa Flint, Professor Krystof Bankiewicz & Dr Toni Pearson The AADC Research Trust would like to thank all involved.

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