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[00:00:06] Dr Dipak Ram : Hello everyone and welcome to our webinar. So I'm Dipak Ram, I'm a pediatric neurologist in Royal Manchester Children's Hospital in the UK, and joining me we've got Dr Mireia Del Toro. I'll let her introduce herself as well.
[00:00:24] Dr Mireia Del Toro: Hi, good morning. I'm Mireia del Toro. I'm also a pediatric neurologist working in Hospital Vall d'Hebron in Barcelona in Spain, thanks, and so we're going to do a joint effort, talking about current and upcoming treatments, but also how we manage the complex patients with MLD, and just a few things.
[00:00:45] Dr Dipak Ram: I think the real main housekeeping notes is to please not take any screenshots of the slides, because some of them may contain confidential information which can't be shared outside this for teaching information and also, if you have any questions and answers, please put them in the Q& A box and we'll aim to answer them at the end of both our talks. So, to kick off, we're just really going to start off talking about where we are at now with treatment options for MLD and really we are in the era of gene therapy, so we'll talk a little bit about that. How that is challenging because things are not straightforward. What the future holds, really to think about what the treatment options are, era of gene therapy and some of the challenges we are facing moving forward. Next slide, please. So MLD is a lysosomal storage disorder- this is just to recap- and it's caused by a mutation in the ARSA gene causing an enzyme deficiency, accumulation of sulfatides, and you end up getting CNS and peripheral nervous system toxicity. And these are the symptoms which all of you will recognize as classic symptoms of MLD. So I'm not going to go too much into that. The main things to know is that there are a couple of different categories which are really important to recognize because this informs us about eligibility for treatment. So in the early onset there are the late infantile patients, which is the commonest form which we see worldwide. But there's a caveat that there in some countries that is not the commonest form of MLD, but certainly in most of the world the late infantile form is the commonest form of MLD. And then we also have an early juvenile form, which happens later on, when the onset is between 30 months and six years of age, more insidious. And then there are the late juvenile and adult forms, which are very poorly understood, extremely rare, and we don't really even understand some of the natural phenomenon. They could even present with dementia and end up in a car home. So very, very difficult to sometimes diagnose this juvenile and adults. And this is just showing you the classic kind of phenotype. So here on the left you can see the trajectory of a child with late infantile MLD and the ones with early juvenile. So really awful kind of natural history which many of you may be aware of already. So thinking about a case. So this is a 25 month old girl and she was developing completely normal until her second birthday and her parents thought she was always clumsy. But then from 27 months of age, when she was seen by her pediatrician he found that she had some increased tone. The plan was to see her again in a few months time but within eight weeks she then started losing some of her speech, became very unsteady and was only walking with support and she had some dystonia emerging with some swallowing difficulties. And this is the brain scan which she had done, showing the classic tigroid pattern that we see in metachromatic leukodystrophy. So it was very clear that she had the diagnosis of late infantile MLD after she had enzyme and genetic testing. Unfortunately she was too late for any disease modifying therapies, which is the reality, and she only had symptomatic management and unfortunately will pass away. However, she has got a 12 month old sibling which has also been confirmed to have MLD. So this younger sibling of her is pre- symptomatic, which is why it's really important to think about what we can do now in the era of gene therapy for such children. So I'm going to pause on the case for a bit and come back to that younger sibling later, thinking about what has been tried before. Bone marrow transplantation, unfortunately in this cohort of children for late infantile and early symptomatic, early juvenile, has not been promising. What has happened is, unfortunately, although some of the central nervous system bits have been preserved, a lot of them continue to have significant peripheral nervous system problems. They still deteriorate, end up in a wheelchair and pass away. So it's not been helpful and what that has taught us is that perhaps just giving someone normal ARSA enzyme levels again- which is what a bone marrow transplant does- you're giving out someone else's transplant cells and putting a normal amount of ARSA in the body and that has not been helpful, clearly. So it's taught us that normal ARSA levels are not helpful. And therefore, we've only been really left with symptom management all this time. Until we are now in the era of gene therapy. And what does gene therapy do? Because this is very different from other forms of gene therapy. So this is a stem cell- based gene therapy. So essentially, you are harvesting the patient's own stem cells. You're then modifying it by inserting a working copy of the gene. You then also switch the gene on to deliver much higher enzyme levels. Because we know already that bone marrow transplant hasn't been helpful. So if you just deliver normal enzyme levels, it's likely the patient will still deteriorate and pass away. So with this, you can then target that and increase the number of enzymes being produced in the body. So normally switched on even 10 to 20 times normal to try and deliver lots more enzyme. We know that's something which is safe. And then you re- infuse that into the patients. And remember, this is an autologous procedure. So you are using the patient's own stem cells, not any donors. And why and how has this been helpful? I think it's always important to make sure that clinical trials. And the biggest clinical trial, which is the definitive trial which has been done, were by our colleagues in Milan, looking at the outcomes of these children in a trial. And many of our patients that we looked after went on to the trial too. And in that trial, you could see that, you know, they had a lot of pre- symptomatic late infantile children, but also early juvenile. And at follow up, 90% of them survived. One child had a stroke, which was not thought to be related to the transplant. Another child who was transplanted just at the cuff of deterioration, unfortunately continued to deteriorate and pass away. But most of the children who did well, who were selected carefully, did really well. And the pre- symptomatic patients, meaning that if they had gene therapy before they developed symptoms, they did extremely well. And you can see here that the scores are tremendously different. So two years down the line, the children treated with gene therapy continued to preserve their mortal scores compared to the ones who were not treated. And remember what I said, that classically between two to three years of age is when these children rapidly deteriorate. So between the second and third birthday, most children with late infantile MLD will deteriorate dramatically from going from walking or taking steps to being completely bed bound. So you can see here, even at year three, the outcomes have stayed really good for children who received gene therapy. So there's a huge benefit we've seen and also cognitive function they found had been preserved. Side effects, because this is autologous, so a little bit different. So it's not like giving other sorts of transplant, but there is chemotherapy because you still have to condition them to receive the stem cells again. So that is the side effects of chemotherapy and conditioning. There is no risk of cross versus host compared to bone marrow transplant. And this is removing the viral related risk you see in other kind of gene therapies, like in spinal muscular atrophy, where you see that kind of fever with hepatitis develop 48, 72 hours down the line. But, you know, nothing is without problems. So there is always a challenge, even if you are doing revolutionary things in medicine. And the biggest challenge is time. Is that, you know, time is so important and that these things which are done properly take about six to eight weeks. So it takes time for the stem cells to be modified in the laboratory before you can re- infuse it back. They need to have quality control to make sure the enzyme is being expressed sufficiently before you put it back in the patient. And then when you put anything in, since the same principles with bone marrow transplant, sometimes there is a lag period for full engraftment. So although ideally things start working immediately, there sometimes can be a delay in engraftment. And that's what our transplant colleagues say for all sorts of transplant. And there is that lag period sometimes. what we've learned from the trial, you know, if you give it to someone who has started developing symptoms in that six to eight weeks, like they did for a patient in the trial, that can actually accelerate the deterioration because you are giving them conditioning to put the stem cells back and sometimes that can cause the child to deteriorate very quickly. So you could end up doing more harm than benefit if you don't look at the cases carefully. And here we are in Manchester, you know, so we are one of the five sites currently in Europe delivering gene therapy and, you know, we've learned so much from our process so far. These are my colleagues who work with me for metabolic transplant, specialist nurses and psychology. So it's really truly a multidisciplinary team service when we make decisions about who is eligible for gene therapy because there are strict criteria and these are the same criteria internationally for LibMELDY. We know it can only be given for pre-symptomatic late infantile disease because, like I told you, late infantile disease is very aggressive. So when symptoms start, they tend to deteriorate within weeks and we don't have weeks in this situation to get the stem cells back. So unfortunately you can only give it in pre-symptomatic children. And then for early juvenile disease, they have to be either pre-symptomatic. The trial also showed us that in early symptomatic early juvenile patients, so if they were able to take some steps and had an FSIQ when they did cognitive testing which was greater than 85, that showed that in those children they managed to preserve them to an extent. So that is the criteria now which has come from the trial. So if we come back to that first case which I showed you, that little girl had a younger sister and she was also confirmed to have MLD. So in this situation, because she was pre-symptomatic and we know the older sister only developed symptoms about 25 months, so we have that window of opportunity now to offer her gene therapy. So she was the first child who had gene therapy but when we opened in February 2022 with our commission service, we were flooded with referrals and you know lots of referrals from all over the UK but also a few from across Europe. So it's truly an international service but you can see here the stark reminder that you know out of those 36 children, only six have been eligible for gene therapy and the sixth one here is out of the equation at the moment because they've only just been seen recently. So they're still awaiting their gene therapy but they are eligible. But so far we've only done gene therapy for five children and the vast majority are ineligible because they've presented too late. And reflecting our UK epidemiology, the majority are late infantile patients which means that they have already been symptomatic when they presented which is why they can't have treatment. And this is just to show you you're not expected to read this but to show you the stark reminder that you know most of the children are not eligible for gene therapy because they've already got neurological symptoms. So that is hard because for all these families this is a big big challenge. So thinking about the treated patients, so the pre-symptomatic patients here who are late infantile, they both had older siblings who unfortunately could not be treated and that's the only way we could diagnose these children at the moment. So it means that you are sacrificing an older sibling to treat a younger sibling. But that first girl who is the younger sibling of that case I showed you, she's now two years down the line walking independently, running around, excellent speech and language. You wouldn't be able to tell currently that she's got MLD because she's got no physical manifestations or cognitive manifestations of the condition. And remember her sister deteriorated dramatically between two to three years of age. She's now three and a half and doing really well. The second child, so this child was tested at birth because they had previously lost a child with MLD as well. And she has been doing well again. She's walking independently now. She's from a bilingual home, many single words, good comprehension. So so far very good outcome as well. The early juvenile patients, so a word of caution, you have to remember that we are giving gene therapy to someone who's already symptomatic and I told you that it takes time for the treatment to engraft. So sometimes these children who already have symptoms with ataxia may end up deteriorating and end up being wheelchair bound but then preserve their cognition and that motor skills in a wheelchair. And that is what the trial showed us as well. Many of the early symptomatic early juvenile patients who were walking but very ataxic ended up in a wheelchair but then stabilized for the rest of the years. So that's what we've seen with this patient and in fact you can see that we expedited his gene therapy and the fastest turnaround was for this child because we knew he was going to end up probably might end up going into a wheelchair but then stabilize and that's what happened. And the other child who was early symptomatic, early juvenile, she presented with ataxia as well. And she's still now two years down the line is walking independently with preserved cognition. She has got some cognitive difficulties, but they've been preserved and not deteriorated dramatically since. So how do we monitor these patients? I guess, of course, we are clinicians. So clinical monitoring is the best. But there are other things we do to make sure that they are not developing progressive leukodystrophy, monitoring them on their nerve conductions to make sure that their neuropathy has stabilized. We check their enzyme levels as well to make sure that that is super therapeutic. And what we found is that the ARSA levels have remained in the hundreds in all these children with normal levels for our reference range about 40. So really good levels. And neurofilament light chain is one of the biomarkers that a lot of centers are starting to use. It's a marker of inflammation and can be sometimes helpful to monitor disease activity. But I'm just putting this in bold again, pre-symptomatic children do the best. And pre-symptomatic children at the moment really can only be diagnosed if someone else has been diagnosed in their family, which is not good unless we can do something else. So this is the story of our family, you know, which has been broadcast internationally to show you that actually the older sister, who's the one I told you about, unfortunately cannot get treatment and she will pass away. But she saved her younger sister's life. And, you know, that really tells us that we need newborn screening for conditions like metachromatic leukodystrophy because we can't move forward. And we don't want 30 cases to then treat five children. We want to be able to treat these children and offer them therapy from the word go. So there are lots of things that we have been doing globally. We have an MLD initiative amongst the centers in Europe and some clinicians from across the globe, even in the US, have joined. And this is really trying to think about how we can brainstorm together and think about newborn screening. And we had to even think about what our consensus based recommendations would be based on having hypothetical patients being diagnosed on newborn screening and what their pathway of management would be down the line. So a lot of work has been done for this. And some of the centers have already started newborn screening, particularly in Germany and some states in the US. So there are centers which are ahead of the curve and starting to see these patients already. In the UK, we are also trying to spearhead this. So we have done a pre-pilot newborn screening study in Manchester. And in that 3,500 patients, there was actually this was just a validation study. But whilst the validation was being done, we picked up a patient with MLD. And that patient was found to have low ARSA activity and the genetics were consistent with late infantile. And this was just looking at random newborn screening of anyone under the age of 12 months who's consented. And this child was 10 months at that age that we found that. So he was a fast track and he had gene therapy at the age of 13 months. And he's taking a few independent steps now. He's got a little bit of swallowing dysfunction, probably from some mucositis after the gene therapy and the conditioning. But he's starting to improve. But motor wise, he's doing well. And again, this is a reminder about why it's so important for newborn screening. Whilst this child was picked up on our pre-pilot study, his first cousin presented with symptoms and his first cousin was 18 months of age. And the father of this patient diagnosed MLD in his nephew, saying that, you know, I think this is MLD. You need to go and see someone urgently.
[00:19:32] Dr Dipak Ram: And they did. But unfortunately, that child was too late for treatment. So again, tells us the importance of early diagnosis, recognition, trying to get that wider family history and offer testing as fast as we can. So we are nowhere near, you know, rolling out newborn screening everywhere in the world. But places are starting to to show the evidence of it. But these come with challenges as well in the future.
[00:19:58] Dr Dipak Ram: There might be cases that we pick up on newborn screening that we don't know when this person is going to manifest with symptoms, that they could have one copy of an adult gene and the other copy manifesting with late infantile MLD. So there are lots of challenges in future that we may not know. And we may have to have a treatment MLD panel, which is what we have at the moment, discussing all these complex cases globally. So, the main message we are trying to get out is please try and recognize MLD early. There are lots of webinars prior to this to talk about the recognition of MLD. But the reason recognition is early is because there are treatment options now and all patients should be referred to an MLD service in your region so that appropriate counseling can be given not just for that patient who may not be eligible for treatment, but also family counseling and if they are younger siblings or other people to be screened in the family ASAP because the therapeutic window is very, very narrow with gene therapy. So we need to really not just think about the child you're looking after, but also the wider MDT. And ultimately what we're doing is trying to change the natural history. So this is our first patient from the UK who went across for the trial in Milan back in 2014. And here he is like, you know, 11 years down the line, symptom- free and so far doing really well. No motor problems, no cognitive problems and, you know, really modifying the landscape of a condition which was previously devastating for everyone.
[00:21:41] Dr Dipak Ram: So on that note, I will stop and see if Mireia has any questions for me before I introduce and pass on to her.
[00:21:51] Dr Mireia Del Toro: Thank you, Ram. I have many questions, but because of time, I think I will do one or two at this time and then we will leave the other ones for the chat and we invite you to write the questions on the chat. Yeah. One of my first worries about this is, do you think this treatment will be life- longing? Because, yeah, it's a treatment. We know about immunology, about other problems that can become. So what's the experience in the earlier patients treated?
[00:22:29] Dr Dipak Ram: Yeah. So theoretically, when we speak to our transplant colleagues, because we've modified the stem cells, we would hope that they'd be delivering the supra-therapeutic enzyme levels forever. I mean, we so far have only 11 years of follow-up, even from the trial in Milan, but those patients biochemically are producing supra-therapeutic levels of enzyme. However, we need to make sure that they are not clinically manifesting with symptoms at any point in future to a milder extent. Now there are some children who are pre-symptomatic late-infantile who develop very subtle tone difficulties in their feet, needing some splints, but are still ambulant and walking with therapy. Why is that really interesting that in MLD, even in some newborns with MLD or very early infants of MLD who have nerve conduction tests done, they are abnormal even at three or four months of age, which tell us that the peripheral nervous system involvement of MLD could be very early and could explain some subtle motor difficulties in children. But so far, thankfully, we've not seen any progressive leukodystrophy and we've not seen any significant cognitive deterioration, but like with all therapies, we have to monitor them for life. So we have even in the transition service now, we have started to transition some children to adults and they are going to have to have lifelong monitoring of their ARSA levels and clinically with imaging and monitoring of their clinical function. But we hope that, you know, this is lifelong, but we don't know is the answer.
[00:24:08] Dr Mireia Del Toro: Okay. Thank you. Thank you. I think I will leave the other one in terms of time to the chat, because I have many other questions to ask you if there's no other questions.
[00:24:21] Dr Dipak Ram: Thank you so much. So Mireia, over to you and just for the audience listening. So this will really complement what we've talked about, because I've really heavily focused on the children we can treat and offer gene therapy to. But bear in mind, the large cohort cannot have that treatment and are struggling. So we need to also manage them. So Mireia is going to tell us a bit about the other side of the coin. Yeah.
[00:24:45] Dr Mireia Del Toro: Yeah. Thank you very much, Ram, for your kind presentation. Yeah, of course. Unfortunately, let me see how I can. As Ram said, and you all know already that this is a progressive neurodegenerative disorder and it's very, very aggressive in some of the types of the disorder. And although that we have just learned, and in the other talks also, that there's this very, very positive and very changing of prognosis therapy, that's ex vivo gene therapy, unfortunately and what we've learned from the talk of Ram is that not all the patients will be able to have the treatment and the treatment is reduced to the patients that are pre-symptomatic or very, very early symptomatic for the juvenile forms. And this, in the absence of newborn screening, is very, really very, very difficult. So unfortunately, a big part of the patients will still have no access to treatment and they will have to be followed by our other multidisciplinary units and taking care of all the different aspects of the disorder. And that's what I will try to summarise now with a clinical case. So there are many guidelines on treatment. These are the last ones. This one you see here from the United States group, but also with the help of many European participants and they are very nice to read and they are very easy to read so you can find them easily. And, but more or less, they all talked about the, sorry, because I'm trying, yeah, they all talk about the, well, about the needs of having a well-coordinated multidisciplinary team that takes care of all the different aspects that the patient needs and not only the patient but the family. And this means not only the medical specialist but also nurses that coordinate many times the communication between families and other staff, the therapies, psychologists, social workers, palliative care, educational, all the professionals that have to help this family and this patient to have a better quality of life with this devastating disorder. And, sorry, because I will try to go through all these needs with a clinical case. The part of the MLD is quite typical, so we will go through all the needs on the different stages, but it's true that the diagnosis was a bit special. That's why I think it's interesting. So this is a 20-month-old boy that is referred to an ER, an emergency service in another hospital because of an abnormal posture of the right superior limb in the, for one or two weeks.
[00:27:46] Dr Mireia Del Toro: He doesn't have any relevant family story or personal family story. The only relevant thing is that he has a monocorial twin, but the pregnancy and the delivery were uneventful and both of the children have a normal psychomotor development. So the parents take him to the ER because he's losing the, he's not using his left arm and the left arm is having sort of a dystonic posture and they are worried because this is worsening and also he's worsening, he's beginning to be clumsy and to need support to work. There's no infections history in the past weeks, there's only a vaccination sort of two or three weeks earlier. What the doctor in the ER saw was that he was irritable and he was a bit drowsy. He didn't want to stand or to walk in front of the doctors and he had a dystonic monoparesis of the left arm. The rest of the physical exam was normal except that he had bilaterally hyperreflexia also in the lower limbs and he had a Babinski sign in both lower limbs, more clear in the left one. So the child was, he went for a CT scan first. In this CT scan they saw this hypointensive lesion in the frontotemporal lobe. Then he went for an MRI. The MRI showed this big lesion again in the temporal frontotemporal lobe that was a bit bulky that affected cortical, subcortical and white matter with another lesion here in the corpus callosum as you can see here. So extension studies were performed and as you see here they were all normal except for a mild pliocytosis in in CSF and the autoantibodies for encephalitis were referred to another hospital. He was diagnosed of acute demyelinating encephalomyelitis. He started on prednisolone because the image is quite typical of this disorder and the antibodies came positive one week later to anti-MOC IgC positive in blood and in CSF and these antibodies normalized after the treatment with steroids. The patient also went quite well, he improved clinically at the control at four months after the treatment, he only had a mild gait disturbance. They performed, all this was in another centre in Spain, they performed an MRI, it was informed as normal, but if you check it and knowing what we are talking about, you can see that here in the occipital white matter is a bit more intense than it should be for a two- year- old. It's true that two- year- old children cannot be well, can have a bit of terminal myelination, but this is usually more in the frontal lobes and in the occipital lobes. And here it was shown as normal, but you can, knowing the diagnosis, you can see that there was a bit of hyperintensity in white matter. Four months later, the parents went again to the neurologist because the child was beginning to lose language and to walk with more difficulty. He was falling constantly, he was sort of clumsy and he was tripping a lot and the exam showed hypertonic paraparesis of both limbs with spontaneous Babinski and hyperreflexia clonus and he also showed the language regression. He was able to speak, but only the first syllable of words, he could not finish the words. He had a preserved comprehension and he was sad and he was a bit irritated because he was aware that he could not express himself properly. An MRI was performed and here you can see the typical images that showed us of MLD and also the extension study showed involvement of auditory and visual responses and also a sensory motor demyelinating polyneuropathy. So the enzyme testing was done and the genetics testing also and they both confirmed the diagnosis of MLD. At that moment and the moment of diagnosis, the second twin began with symptoms. He began to walk a bit clumsy also and had the mild hyperreflexia and he was diagnosed also of MLD. So after this first episode of acute demyelinating disorder, they finally had both of them diagnosed as MLD and because they were not candidates to gene therapy, because they were already symptomatic in a late infantile form of the disorder, they were referred for a multidisciplinary follow- up. So at two and a half years, they had a spastic paraparesia of lower limbs. They were able to manipulate without problem, but they began using orthosis, as you can see here, and also they were referred to the orthopedics and to the... the physical therapy. At the age of three, they were already unable to walk and they could sit with support. They began drooling and their language was less, was more difficult. They could say some syllables and try to communicate, but they were not fluent in language. They were referred to nutrition and speech therapy. They began a specific therapy, the swallowing was assessed by video fluoroscopy and by a study and it showed initial dysphagia and very mild dysphagia, so thickeners was added to liquids to improve their swallowing. At the age of four, the clinical progression continued, so they didn't have any language, but they had a good contact and they could show with the arm what they wanted. They were not able to sit by their own, they still were able to roll in the floor and as you see in the photo, they had clenched hands, so they were not able to grasp objects. They began coughing and they also showed some constipation. So they were put on dystonic and spasticity medical treatments. The more affected one began with botulinic toxin infiltrations and also they began respiratory physiotherapy, controlled by an pulmonologist and gastroenterology support for the constipation. And now they are seven years old, well they are eight exactly, their contact is still present. They like joking, they like between each other they laugh, they like playing with balloons. They are not able to roll or to sit anymore and they are losing head control, but they are quite happy in their very, very poor performance, they are wheelchair- bounded and they also have a sleep disorder. They go to a special school, they are followed also by, apart from all the other specialists, they are also followed up by the ophthalmologist, the ENT specialist and they are under melatonin for sleeping. So, as you can see in this clinical case, what we have to do as professionals in our multidisciplinary teams is to, in the early stages, try to maximise the developmental potential of the children and try to help them to communicate, to do things that they are able to do because they can think them, and in the later stage, any things that can help to improve quality of life of the patients and also of the families. So, apart from the neurologists that are involved from the beginning and with the specific therapies, with medical treatments for spasticity and dystonia and the orthesis, in the late stages we can need anti- epileptic drugs for epilepsy. Language that is affected in early stages is very important because they are able to think and they would like to communicate, so facilitating verbal, non- verbal or adaptive communication with the speech therapist is a very important point, as well as the follow- up as we see with the ENT and the ophthalmologists. sialorrhea, no? sialorrhea and drooling is another very uncomfortable symptom, so it also has to be considered, treated with a toxin, with botulinum toxin, with glycopyrrolate or with physical treatments. Dysphagia is a risky symptom for the airway, so it also has to be treated, and in the late stages you know that they will maybe need an nasogastric tube feeding or gastrostomies. Again, gastroenterologist for constipation, the orthopedic surgeon for scoliosis and hip dislocation and the pulmonologist. And last but not least, the palliative care or chronic care teams that are very involved with families and can help them very much in these late stages of the disease. Two things I would like to focus on, one is irritability, and irritability is a very disgusting sign and symptom for parents and for the children. In the first stages of the disorder, this irritability can come because of the frustration when they're not able to communicate or to perform, but they are quite connected, so we have to, again, as I said before, to ensure that we can help them in these aspects. And in later stages, irritability can come from pain, and we have to rule out pain coming from the same spasticity of the joint problems, gastrointestinal problems like constipation, urinary infections, gallbladder disorder, and I will talk of this in a few minutes, and as other children, ear problems or other problems that can cause pain in children. And the other thing that's very important to address is sleep disorders, because if the children don't sleep, the parents don't sleep, and the parents have to keep on taking care of the children, and they have to go to work, and they are tired, and this is sort of a wheel that never ends. So sleeping is another of the things that we have to take care of and to address. And sleeping disorders can come because of just behaviour, because they feel unsure and they want to be with the parents, because they don't have nice rules or good sleep hygiene, because of pain, of respiratory problems, or of temperature dysregulation that makes them hot or cold at night, so we have to try to rule out all the problems that can give sleep disorders. As I said, one specific thing we have to take care about in MLD is gallbladder involvement. It's not exclusive of MLD, but it's quite frequent, and some of the studies said that up to 60 or 80% of children, especially in children with MLD, will have gallbladder involvement in different forms, in thickening of the walls, polyposis, even carcinoma, and it can give place to pain or to cholecystitis, so yeah, it's something we have to rule out with ultrasonographies when they have symptoms, but even when they don't have symptoms to prevent gallbladder involvement to go worse. So, in this first part, I wanted to insist that multidisciplinary care, unfortunately, because we don't have treatment for all the patients, remains the main treatment for many patients. And these coordinated teams, we have to take care of medical, psychological, and social conditions to assure the best quality of life for patients and also for the families. And of course, as Ram said, a newborn screening is mandatory because we have a treatment that for the moment, it's also only recommended for presymptomatic and oligosymptomatic patients in some ages. So we have to, yeah, to try to fight for newborn screening to at least be able to treat this group of children. I was asked to finish my talk giving a perspective of what's the future in treatment for MLD and other lysosomal disorders. I will try to do this very shortly in a few slides. This is a very well- known picture of what happens in lysosomal disorders and where we can try to have treatments that are effective. It's by Parenti, by Giancarlo and his collab. It's an old paper, but it's a very nice picture. So because of the genetic mutation, that's the origin of everything, we can have gene therapy. These are the treatments that are approved at the moment. In gene therapies, we have MLD, as Ram explained very well. This gene mutation gives place to a dysfunctional mutated protein. And then there are some treatments that try to recover the form of the proteins, the chaperones and other regulators. We have approved treatments for Fabry disease that are chaperones. The mutated enzyme doesn't arrive inside the lysosome. That's why we have this defect on lysosomal proteins. And then we have many LSDs in which we can give the enzyme via intravenously, via intrathecal as in CLN2, or with a hematopoietic stem cell transplant and a cross- correction phenomenon that Ram also explained previously. When the enzyme doesn't work, then we have the accumulation of the storage and we could try and we will see that there are some approaches trying to eliminate this storage. And in the other place, we can try to block the via the metabolic pathway earlier so that the storage doesn't accumulate. And this we have approved treatments with Gaucher, with Eliglustat and with Niemann–Pick with Eliglustat. And when all this doesn't work, then we have all the secondary problems that are as important at least or more important even than the accumulation. this relates to mitochondrial dysfunction, inflammatory inflammation, autophagic cascades and all other problems that come when the lysosome doesn't work. And here we have just a few months ago, have approved for Niemann-Pick arimoclomol in the States. And this is a protein that improves the concentration of heat shock proteins and that prevent the cell from some of the effects of cholesterol and ganglioside accumulation. But we have a lot of unsolved challenges. One of them is that we have a lot of diseases that still don't have specific treatments, some of them because they are ultra- rare, some neurological and it's more difficult to find a neuro lysosomal treatments. And for some of the others, we have treatments like MPSs, but they are suboptimal. They change the course of the disease, but they are not curative. Nevertheless, they improve a lot the patient or the quality of life. And these suboptimal treatments are like this. One of the causes is because of the poor penetrance in some tissues, especially in brain and in bone. And here we have a lot of approaches, I will list them now, trying to get into the brain with nanoparticles or extracellular vesicles, with the ex vivo gene therapies that Ram commented and also with other gene therapies directly to the brain or intravenous that are directed to the brain. We also have the fusion proteins and other modification on enzymes that are trying to arrive to the brain and not only to the brain, but to the neurons. And in bone are the same. There are several ongoing investigations trying to make a gene therapy or enzymes go into the bone. We also have some other problems in therapies. One is immunogenicity with virus and with the enzymes and with the vesicles that we are learning a lot about immunosuppression regimes. And we also have to treat, as I said, these secondary pathways that are really activated even in very early stages of the disorder. And we know that doing only the enzyme replacement is sometimes not enough. So we have to treat or maybe combine with therapies that will treat other pathways. So my last slide is the what is under investigation and here you have the big list of things that are in preclinical or clinical trials. Most of them are preclinical, but some of them are already in clinical trials. We have gene therapies in very advanced preclinical stages for other therapies for MLDs, for Gaucher Fabry, for all the diseases that you have listed here. We have also chaperones that are being tested for Gaucher, Niemann- Pick and GM2. We have more enzymes that are improving enzymes for Fabry- Gaucher, the MPSs, Pompe, various CLNs and again MLD. We have therapies that try to to diminish the cargo of cholesterol for Niemann- Pick C, like cyclodextrin and for MPS. And we also have, as you see, many other things that are ongoing and hopefully we will surely have clinical trials to be beginning. Unfortunately, not all these not all these investigations will arrive to a good port. We know that only between 10% or 20% of all the investigations arrive to a clinical trial and not all clinical trials are effective at the end. So some of them will finish going around the tree and coming back, but hopefully have some of them, what we will learn from them to improve the treatment and to be able to to improve our treatments for neurometabolic patients. So maybe not in the next years, but I hope that in five or ten years, then we have a bright future. At least it's a very engaging future and very interesting. And thank you very much.
[00:47:24] Dr Dipak Ram: Thank you so much, Mireia. That was an excellent overview of all the challenges and the complexities of dealing with families and children with MLD. I guess one question is, you know, in the era of gene therapy, when you see a family of a child who's not eligible for treatment, how difficult can it be, you know, with this, you know, with these families pushing to get gene therapy, when you know that the child may not be eligible. What would you, how would you manage that?
[00:47:56] Dr Mireia Del Toro: We manage it with giving a lot of support, you know, a lot of psychological support, because many of these families are the ones that began to get involved with the pharmacist to try to find a cure for their children. So many of the older patients that are not candidates for treatment are the ones who began to fight for the treatment and invested their time and their money in the trials. And when the trial came, they were not able to participate. And we've had experiences of this, especially for San Filippo and for others. And yes, it's very difficult. And you know that when we begin a trial, even if the inclusion criteria are quite clear, we see families from all over the world trying to come, and they are quite desperate. And it's really, I think it's really understandable. But yeah, we usually treat them with as well as we can, giving them the support and psychologists and also the rest of the family are quite important, giving support. I had if there, I don't know if there are questions from the audience. If not, I wanted to ask you another question. What do you think, because the problem with some trials, and MLD is one example, is that in the trial is that the possibility of stripping is restricted to the patients in which treatment has been tried, no? So we find that maybe older patients with milder forms of the disorder that could be good candidates are not able to be treated. And this is also something families come to us and say, why not? And I wanted to know about your thoughts on this.
[00:49:52] Dr Dipak Ram: Yeah, completely. I think that is an unanswered question so far, but I think completely agree. So if we are saying that we are delivering super therapeutic levels of the enzyme, and it's helping with late juvenile and early juvenile cases, there's no reason why it shouldn't be helping with late juvenile and adult onset patients. I guess because the trials were only done in those criteria of patients so that, you know, they could get their outcomes quicker. That's always the difficulty when you put things with clinical trials into practice. But I generally think that over time when we see and monitor these children for a longer period of time, and we see that it's safe and sustainable, then I think that these therapies may, we will need to push for these therapies to be given for other aspects of MLD like the juvenile and adult onset because there's no reason why it wouldn't work. And it should be technically more effective than bone marrow transplant, which is now the only thing out there for them. So I think it will take time because at the moment.
[00:50:54] Dr Mireia Del Toro: I think they were beginning. I think they were willing to try in a few patients in Milan. I don't know if they did, but you are the second most important centre for this. So yeah, I wanted to know your opinion.
[00:51:08] Dr Dipak Ram: Yeah, they really. I think they struggled to recruit many late juvenile patients, but you know, and now it's closed. But I guess they will still think about how they're going to design it because the incidence of those are so much lower and I guess they need to follow them up for much longer because the natural history of late juvenile and adult onset will need follow-up for a long time. The ones who had BMT will need follow-up for such a long time and then with gene therapy. So I guess you know, but theoretically they tried to recruit into a trial because it is important to understand. So I think that may change the future.
[00:51:49] Dr Mireia Del Toro: I have a question from the audience for you: what other common conditions were initially considered before MLD was diagnosed in your patients?
[00:52:01] Dr Dipak Ram: Yeah, so in a previous talk I had done for one of these webinars, I had put out the differential diagnosis for a lot of these children. Sadly, many of them were diagnosed as being dysplexic, especially the juvenile patients. So either, just a bit of autistic spectrum disorder with dyspraxia or coordination difficulties, because in the juvenile patients the ataxia is one of the predominant features with some cognitive difficulties. So they're normally labelled as either learning difficulties or dyspraxia in some of the younger children. Sometimes, you know, the history wasn't taken well enough so it was thought to be just some problem with spasticity and an MRI scan was being planned, thinking about looking at cerebral palsy although there was no birth history. But when you see that lower limbs spasticity presenting between the ages of two to three, you know that is normally a warning sign. But many times people organise a scan rather than thinking about doing rapid enzyme levels so that may have delayed things even more as they then waited for scans. Because in children doing an MRI scan may need some planning, sedation or general anaesthetic, so that tends to delay things. But yeah, so lots of other differentials to think about. But our learning point is really, if you're seeing someone with a normal birth history who's presenting with any tone difficulties with a previously normal birth history and development, you should really be thinking about MLD.
[00:53:28] Dr Mireia Del Toro: Yeah, I think it should be included in all the in the first line of differential diagnosis of paraparesis in small children, because they will maybe not be candidates if they are already with paraparesis, but their siblings will be. And the other thing I wanted to point out is be careful with the MRI interpretations in children under two, because what they think is normal it's maybe not so normal as we saw in our case. Yeah, there's another question saying: is there any potential of combining gene therapy with other treatments or supportive care approaches? Absolutely, how will the durability of the treatment effect be assessed over time?
[00:54:23] Dr Dipak Ram: Yeah, that's interesting. That was, interestingly, that was the question I was going to ask you as well, but yeah, so we'll both take turns answering that. So one of the things which is interesting is that you know we really need a bridge between diagnosing someone to getting a gene, to getting gene therapy, and I think a lot of research is going into different options. You know there have been trials going into enzyme replacement and other things, but really what would be ideal would be having a bridge to gene therapy so that when someone has got symptoms of MLD, which are early juvenile or pre- symptomatic children, that you don't have to worry as much if you can give them a bridge, something temporary, and then do the gene therapy I mean. The other question is: Cumulative treatment, which you know in rare diseases doesn't seem to be anything that you know would happen in clinical trials, very interestingly compared to other conditions. So if you think about childhood cancer, you know treatment is always cumulative. You know you start regimen, this regimen and then when they don't respond, you add something else. And you add something else and you add something else, and that's well known and you know when you have clinical trials showing that something can be added on as added therapy that is beneficial in rare diseases it seems to be harder to do. That's one of the realities. Is that you know, because it's rare disease, funding and research and things and patient eligibility, sometimes a patient having had some other treatment precludes them from a particular clinical trial because that may modify the result, whereas if you look at childhood cancer that doesn't happen. So it is interesting how we may need to think, change our thinking with rare diseases. But for example, in Niemann–Pick C disease the rule will be to combine different treatments because there are different aspects of the disease that can be treated by different drugs. So I don't know what our government will think about it, but from a clinical point of view we have to try to combine different treatments. So, yeah, if for the moment that the myelination polyneuropathy of MLD is not quite totally corrected by gene therapy, we will maybe have to find another approach.
[00:56:37] Dr Mireia Del Toro: Yeah, to help the patients, and the durability is something we talked about earlier. The cases- this one is for me, yeah, the cases just presented in the twins monochorionic . yeah, that's true, the question is about the monochorionic twins, but the problem is when the first twin was. The problem is that there was a retardation in diagnosing the first twin. When the first twin was diagnosed, the second twin was diagnosed in two weeks, so it was really one after the other. The problem is that if the first twin would be that was more affected, should have been diagnosed earlier, then the second one would be asymptomatic and, yeah, and it's true, he could have undergone in that moment. It was for the trial, not approved yet, but for the trial of gene therapy. But it was in another center. It was we were. They came to our clinic after the diagnosis. But yeah, that's again that we have to be careful with MRIs, with that- when the child were a bit unstable with the gait and the MRI was normal, but it was not. Yeah, if in this case they were diagnosed at the same time, but it's true that if the first twin should have been diagnosed earlier, then the second one would have had the option to go for that for the trial.
[00:58:23] Dr Dipak Ram: Excellent, thank you.
[00:58:24] Dr Mireia Del Toro: Please can you tell us what is the best metabolic investigation to request if we are worried about MLD?
[00:58:33] Dr Mireia Del Toro: Yeah, so I think it really depends on where you are and what access to things you can get rapidly. So, for example, here the fastest thing that we can process in our laboratory is the ARSA enzyme so we can get those levels back in some metabolic laboratories within 24-48 hours. When it's flagged as a suspected MLD patient. That may not be the case everywhere. A lot of people use sulfatides, so sulfatides might be a very helpful thing when you see the raised sulfatides as well, and now in the era of rapid genomic sequencing as well, sometimes, if you are thinking about you know, if you know that this is a diagnosis and you are suspecting it and you're targeting your treatment, then you could get a diagnosis very quickly. So it really depends on where you work. What is the most rapid thing? I would urge you to speak to your metabolic colleagues and your geneticists in the area you work and find out what is the most accessible and fastest test that you can get, and it's interesting depending on. In the UK certainly the fastest thing we can get is enzyme testing, because that is faster than genetic testing and we get a result and we can act on it very quickly. But I know that in some areas the processing time of enzyme studies can be longer than rapid genomics. So it really depends where in the world you are and you know what.
[00:59:48] Dr Mireia Del Toro: In Spain we don't have sulfatides and we don't do them in all the countries, so we go directly. And again, remember the MRI. The MRI is quite not specific, but it's quite helpful for MLD and, yeah, and in Spain we go more. Yeah, in our hospital we will do our enzyme activity also, but in other hospitals they go directly to genomics.
[01:00:15] Dr Dipak Ram: Genomics, yeah, yeah, brilliant. I think we have gone slightly over. Yeah, yeah, but no. Thank you everyone for joining the webinar. I think we really enjoyed presenting together and, you know, hopefully managed to answer your questions and give you some food for thought. So thanks everyone for joining.
[01:00:38] Dr Mireia Del Toro: Thank you very much.
[01:00:39] Dr Dipak Ram: Bye.