Uroosa Ibrahim, MD provides a comprehensive review of sickle cell disease, including pathophysiology and clinical features, and the latest updates on transplant and gene therapy treatment modalities. Interspersed throughout are case studies that reveal the complexities of the disease and treatment challenges.
Morning, everyone. Morning, morning. Um, thank you for joining this morning for a grand rounds. My name is Fiona. I'm one of the medicine chiefs, and I'm very happy to introduce our speaker today. Doctor Urusa Ibrahim graduated from medical school in Karachi, Pakistan, following which she did her hematology oncology fellowship at Northwell Health and her BMT cellular therapy fellowship here at Mount Sinai. Doctor Ibrahim is currently an assistant professor of medicine in the division of Hematology and Medical Oncology, the associate director of the cellular therapy program at Tish Cancer Institute, as well as the gene therapy lead for sickle cell disease and beta thalassemia here at Mount Sinai. Doctor Ibrahim's clinical focus is on stem cell transplant for ALL and benign conditions including MS, sickle cell disease, and thalassemia. Uh, she also performs CAR T cell therapy for leukemia and lymphoma patients. Doctor Ibrahim's research focus is on complications and outcomes of CAR T cell therapy and outcomes of curated modalities for benign hematological diseases, um, so. Thank you for joining us today and I'll bring up Doctor Ebrahim. Thank you for the introduction and thank you for having me. Uh, no disclosures. This is the outline of my talk, uh, background pathophysiology, clinical features, um, of sickle cell disease, and we'll discuss some data and procedures in transplant and gene therapy for sickle cell disease, and we'll go over the treatment journey for individual patients, um, with some case-based vignettes, starting with the first one, A 26-year-old black female with a diagnosis of sickle cell anemia, SS genotype, and a history of migraine headaches, vasocclusive crises since childhood, avascular necrosis of right ankle and recurrent pulmonary embolism treated with apexaban is referred for curative therapy. She has been taking hydroxyurea since age 7 and underwent monthly red cell exchanges until adolescence. The patient has had weekly ED visits which he tries to avoid now and manages crises at home. For pain management, the patient takes gabapentin, duloxetine, oxycodone, methadone, and tizanidine. Several of these multiple times a day and is still not pain free. So sickle cell anemia affects millions of patients worldwide. In the United States, the prevalence is about 100,000 individuals at any given time, and in the EU, about 52,000 individuals. The global incidence is about over 300 to 400,000 infants being born annually. The history of the discovery of sickle cell disease goes back to 1910, where elongated sickle sept erythrocytes were first discovered in a dental student at the University of Chicago who had pulmonary symptoms. This student had immigrated from Africa at the time. It took another 20 years to figure out that these sickle cells were clogging up blood vessels and causing pain symptoms. In 1949, the hemoglobin that causes the sickle-shaped erythrocytes was discovered, and then in 1957, the single amino acid substitution that causes hemoglobin S was discovered and in 1970s, the single nucleotide mutation that causes hemoglobin S was found. The disease remained neglected neglected for many years thereafter until the civil rights movement where they called attention to racial inequality in health care, and it was the Black Panther Party that set up screening clinics in particularly in this black community, and the goal was to diagnose patients earlier, refer them for establishing care and counseling of families. In a lot of these clinics, it was pre-med students who had volunteered. Structural racism and interpersonal racism is very well described in sickle cell disease. A study in 2013 showed that black patients with sickle cell disease wait 25% longer in the ER than patients, other, other patients of other ethnicities before receiving care. Another study in 2020 showed that black patients are 22% less likely than white patients to receive the pain medication they need. So sickle cell disease is a genetic disorder associated with episodes of acute illness and progressive organ damage, essentially leading to accelerated aging. The normal hemoglobin structure comprises of hemoglobin A, 2 alpha 2 beta chains. These are polypeptide chains. They comprise 96% of normal adult hemoglobin. Then there's a small percentage of A2, which comprises of 2 alpha and 2 delta chains, 2 to 3%, and then there's F with 2 alpha 2 gamma chains, which predominates in the first year of life. And then along with the heme and iron, they form the hemoglobin molecule. The HBB gene on chromosome 11 encodes the hemoglobin beta chain, which forms the hemoglobin A along with alpha chains. In sickle cell disease, um, for hemoglobin S, the beta chain has a single nucleotide mutation between adenine and thiamine, which results in a single amino acid substitution from glutamine to valle, and this forms the hemoglobin S, which when undergoes deoxygenation, it forms polymers, and these polymers damage the cytoskeleton and they damage the plasma or cell membrane which leads to the sickle shape of the RBCs. And also they expose the cell surface glycoproteins and glycolipids, which when interact with the endothelium, they increase adherence to the endothelium and when they interact with leukocytes, and they attract leukocytes and cause adherence of those to the endothelium as well, leading to inflammation. These rigid herbicides obstruct the microvasculature, causing tissue hypoxia, which precipitates further sicking. These sickle cells hence have a shorter lifespan of 20 to 20 days as opposed to the 90 days of normal RBCs. So there are several types of sickle cell disease. Uh, the most common and severest form is sickle cell anemia, SCA, which is the homozygous form where both beta chains have the S mutation. Then there's trait where one beta chain is S, the other is the normal A, and there are no symptoms unless the cells are under low oxygen tension. Then there's sickle beta thalassemia, which is heterozygous, where one beta chain is S, the other may have the beta deletion or which is beta 0 or beta mutation or beta plus. This is a mild form. Then there's SC disease, which is a heterozygous form also. um, there's one beta chain that is S, and the other one is C, which is a similar mutation to S, but the amino acid substitution is glu uh from glutamine to lysine instead of ale. And this um usually is a mild presentation, but when we see patients for curative therapy, they usually have severe form of the disease. The cycling in um strate and C disease do not have cycling. SC has less sicking than SS. OK. So the inherit inheritance pattern as we could tell, is autosomal recessive. So parents with the trait have a 25% probability of having a child with sickle cell anemia and then 50% probability of having children with trait. Same with C and S, 25% probability of having a child with a C, and same inherent pattern for sickle beta thalassemia. This is important when we talk about donors, potential donors for patients. Clinical features are a result of vascular inclusion or chronic hemolysis. So when we look at organ systems, head to toe strokes, these can be ischemic strokes or conversion to hemorrhagic strokes, retinopathy, blindness, acute chest syndrome, which most of us are aware of, or a splenectomy, leading to susceptibility to infections, especially in encapsulated infections, renal fins, papillary necrosis, aseptic bone necrosis. Priapism, osteomyelitis, especially in patients who have undergone autosplenectomy, leg ulcers, and dactylitis. Effects of chronic hemolysis are mainly because of iron overload, um, congestive heart failure, jaundice, chronic hemolytic anemia, and pigmented gallstones. The primary reason for hospitalization is crises, which include vasocclusive crises, aplastic crisis, and hemolytic crises. So over time, um, as we can tell, these patients develop chronic organ damage and in about 50% of adults. Um, this is related to cardiac failure, um, pulmonary failure, or renal complications. So about 26% of deaths in adults are related to cardiovascular causes, 32% of, uh, cause of death is from pulmonary causes, and then 19% from, um, renal causes. And as a result, adults with sickle cells have a shortened lifespan of our median survival of 48 years, and there has been no change in the last 25 years. On the left is a graph from 1994 with the life expectancy, and then on the right is one from 2019, and there has been no change in the life expectancy despite approval of certain therapies. And this survival is poorer in individuals who have multi-organ impairment, so patients with one single organ impairment, the difference is about 7 years when patients have more than 1 organ impairment. OK. So since its discovery in 1910 initially, there have been 4 drug approvals. Um, the first one was hydroxyurea in 1998, and then in the past seven years there have been three drug approvals L glutamine, risenlizumab, which is a P-selectin inhibitor, and it had shown to decrease uh frequency of pain crises in adults, and it was approved for um adults over 16 years of age. Voelator, um, decreases hemoglobin Spolymerization. This was approved for, um. Patients 4 years of age or older with sickle cell disease. Voelator was linked to VOCs and death and was actually withdrawn from the market last year. The HopeEIDS 2 study showed of 36 children treated, eight patients died versus 21 placebo. In the results study, 8 of 88 participants died, so patients have been subsequently tapered off this medication, and so we're actually one less drug and then risenlizumab. The phase 3 trial failed to confirm clinical benefits, so it's market authorization, it was revoked in the EU and UK and it's also fallen out of favor in the US. So basically the two medications you had were are not there anymore. So there's more of a dire need for curative therapies because of that and then the median life expectancy which remains unchanged. And an ideal curative therapy has to have high efficacy rate, acceptable toxicity profile, and needs to be accessible for all patients. Moving to our second case, a 32-year-old male accounted by profession has SCASS genotype, complicated by recurrent BTE, acute chest syndrome, an MRA head, found to have cerebellar artery stenosis. He has been hospitalized with pain crises 8 times over the past year, has declined hydroxyurea because of possible side effects, takes Dilaudid 4 mg orally every 4 hours as needed for pain, and the patient requested a referral for gene therapy. The patient has 4 full siblings and 2 paternal half sisters. When we saw the patient, we did HLA typing. One sister is a full match and one brother is haploid identical. So what do we do? Continue supportive care, start red cell exchanges to prevent crises, um, HLA identical bone marrow transplant, or at all of this gene therapy. So the two curative approaches are allogenic transplant, where donor cells are used to replace the patient's hematopoietic and lymphoid system, and then autologous gene therapy, where the patient's stem cells are genetically modified either by adding a gene or editing a gene to correct the defect, and we'll go into that more. So allergenic transplant involves finding a suitably matched HLA donor, um, which can be a sibling or who's a half match or a full match, and we'll discuss data for both. The donor undergoes clearance and collection of stem cells which can be from peripheral blood or bone marrow. The stem cells are processed and undergo cryopreservation or can be used afresh. The patient is admitted to the hospital, undergoes high dose chemotherapy, usually with a combination of radiation, which we call the conditioning regimen. And then the stem cells from the donor and infused. It takes about 2 to 3 weeks for the donor, for the patient, the recipient, to form a new blood and lymphoid system. Um and lymphoid recovery takes a little longer. And it basically replaces the patient's stem cells with donor stem cells. Historically, the indications for transplant, um, as, as established by the American Society of Transplant and Cellular Therapy are for mass sibling donors. If you look at it, it pretty much includes every patient that we probably see for sickle cell disease. So recurrent acute chest syndrome, recurrent pain, vasocclusive crises, strokes, impaired cognition, neuropsychological dysfunction, elevated transcranial doppler velocity. Resumunization, pulmonary hypertension, osteonecrosis. Pretty much every any patient we see would fit some of these criteria, usually more than one. Alternative donor, um, the list is short, but, um, clinically we do treat patients now based on the data I'll show you next, um, with the same indications as for mass sibling donor transplant. So mass related donor transplant has been there for decades now. Donors are siblings with the same parents. The conditioning historically has been myeloablative. It's the most common form of transplant for children with sickle cell disease. Overall survival in several studies has shown to be about 95%, disease-free survival of 92%, and complications 1 in 10 children or 10% have graft versus host disease. This is data from the CIBMTR 91% survival for sibling donors. Um, this is, um, looking at 3 year overall survival, and then the European blood and marrow transplant, 95% survival for sibling donors. So excellent results. However, um, a very tiny fraction of, uh, patients actually undergo transplant with sickle cell disease in the US, and this is data from the CIBMTR where about a little over 200 patients underwent transplant in 2023, 2022. Um, as I mentioned earlier, there are about 100,000 individuals living with sickle cell disease, so that makes about 0.2% of patients actually undergoing transplant. The barriers include primarily lack of awareness of benefits of transplants, so physicians and patients are not aware of the option of having being available. Lack of donors because if you go for mass sibling donors, only about 18% of individuals have a matched sibling donor and even then, you know, whether or not they would be cleared for transplant, not always patients are eligible to undergo donation. Infertility risk because most patients, most of these patients are young and want are childbearing age. And then chronic complications such as graft versus host disease are a deterrent for many patients. And in adults, additionally, since this data is all with myeloablative conditioning, it's deemed very toxic for most adults because they've lived several decades of their lives, 3 or 4 decades, having sickle cell disease which causes chronic organ damage. So we have 60% have at least 1 organ damage if not more. So what we need is less toxicity and more donors. So in terms of less toxicity, the NIH developed this approach of conditioning which is chemo-free. Um, it uses the uh CD52 antibody, anti CD52 antibody tizumab with total body radiation, a small dose of 300 °C. This showed overall survival of 79% and event-free survival of 68.6% at two years, uh, which is not bad, but there's better data for Halo now. And the problem with this was increased risk of graft failure about 1811 to 14%, and then in the real world we see now that it's as high as 25%. Mixed primerism, which is the percentage donor cells versus percentage recipient cells, was 48%. And which increases risk of malignancy just because of the the hostile bone marrow environment that it creates by having multiple cell populations. This protocol was since discontinued and it's only, it's not used in children at all. In adults, in patients who are late 40s, 50s, who cannot have any other conditioning regimen, we are sometimes using this. Then how do we increase the donor pool? So historically identical sibling was the standard of care, but if we include half mashed or haploid identical siblings, that really increases our our probability of finding a donor. So if we include uh half-mast siblings, that increases the chance of having a donor by 75%, and we can also include parents, typically patients who are in their 20s, um, they have young parents who are in their 40s and. This really increases the chance of having finding a donor for patients. So the first study that was done with half mass transplant was at Hopkins with this conditioning platform that had ATG, fluidarabine, cyclophosphamide, small dose of TBI. This had a high graft failure rate of 43%, which is even higher than the fully matched 1, 14% mixed crimeism, but there was no cure or chronic GVHD and no mortality. So this meant that the conditioning could be improved upon. And there were 3 approaches that were taken to build up upon this conditioning platform. The first one was the Vanderbilt Consortium that added thiotepa 10 mg per kilogram just to increase the intensity, to improve, to improve upon graft failure. Hopkins revised its own approach by increasing the TBI dose to 400 and the BMTCTN study added hydroxyurea preconditioning for 2 months and then also added yotepa, similar to the Vanderbilt Consortium. And I'll discuss the results of the Vanderbilt Consortium because this is the one we've been using at Sinai. So this was a study over 10 years 2013 to 2023. Included 70 patients, included adults and pediatrics. The two year survival was 94.8%. With no difference between pediatric and adult, 97% of patients were off immunosuppression at one year. There were 5 deaths on trial. All 5 were infections, 2 were, um, COVID because this included COVID time, and then 2 were disseminated adenovirus infection, and the 5th 1 is also a form of pneumonia. The two year event free survival was 82% for both pediatric and adults, but for adults it was 94%. Pediatric 68.4%. So there is some difference in the pediatric and adult cohort, which means that the pediatric cohort further needs to be improved upon. The graft versus host disease rate was 7 total in each group, so 10%. This is similar to matched sibling data. And the 4 cases of primary graft failure and 4 of secondary graft failure were all in pediatrics, so no graft failure in adults. So in pediatrics, as I mentioned, we need to improve upon, um, so there's really data that is showing. Preconditioning with Hydria and hypertranfusion is actually improving, um, overall survival and disease-free survival in pediatrics. These data show that there is actually organ reversal after transplant. And this study is one example of that where cerebral hemodynamic changes after transplant, the changes that happen pre-transplant can be reversed post-transplant. So if you just look at the CBF, which is cerebral blood flow, what happens in transplant sickle patients with sickle cell disease is that there's low oxygenation, oxygen carrying capacity by sickle cells. So what happens is cerebral blood flow increases to compensate for the low oxygen. So prehaplo BMT, the cerebral blood for 67, that's mL per 100 g per minute. In healthy control it's about 47. After transplant, this goes down to the level of healthy controls. So that's a significant improvement. The oxygen extraction fraction, um, no, no significant change, but that's expected because the blood flow is increasing to improve oxygenation. So basically the, the cerebral blood vessels compensate to increase oxygen extraction fraction. Everything else, uh, if you know, uh, hemoglobin significantly higher, um, and hemoglobin S significantly lower. And this is just uh the imaging of the sea. The red, orange, yellow is the angry looking uh cerebral blood flow, which is high flow over 50, and then post transplant it decreases to less than 50, which is the blue, purple. Similarly, in patients who have pulmonary hypertension, this was a report where it was possible to reverse it post transplant. So the pulmonary artery pressure went down from high levels to normal levels one year post transplant. So the same thing with pulmonary artery wedge pressure, right atrial pressure. Um, hemoglobin pro BNP. One thing here to note is that the left ventricle ejection fraction was slightly lower before versus after transplant, which sometimes we see in patients post transplant with the toxicities related to the conditioning. Which is this list, um, so you know, whenever we see patients, we discuss the possible toxicities. Not every patient gets all of them, but every single organ can potentially be affected by the chemo conditioning or graft versus host disease and other possible complications. Going back to the case. So this is the patient who came in to us asking for gene therapy. We typed the siblings, one of them was a full match. Um, we had several discussions. We discussed data in match sibling transplant and haplo transplant and gene therapy. The patient was convinced that he went for a second opinion and he talked to friends and family and whatnot, and we decided that since there's so much long term data with matched sibling transplant, this is what we would proceed with. He was not on Hydria before because he was concerned about side effects, but we started Hydria just in order to improve to engraftment to prevent graft failure. Which he agreed to doing and patient underwent monthly red cell exchanges to prevent crises going into transplant. He received the conditioning, uh, which is the Vanderbilt, uh, Consortium one fluypa TGTBI with post-transplant cytoxin. The most significant complication he had was great for mucositis, requiring hydromorphone YPCA pump. By the 90, actually early on too, but it's day 30s cameism, which is the percentage donor cells was 100% and it has remained so now. This was his um hemoglobin electrophoresis, so pre-transplant A was 9.1%, post-transplant 97.6%, and S was 80, and post transplant zero. This also tells us that the patient sister did not have trait. This is the 3rd and final case. 40 year old male with sickle cell anemia, um, hemoglobin SS disease diagnosed at age 2, treated with monthly red cell exchanges, complicated by a vascular necrosis of the right hip and pain crises ranging from 2 to 5 per year. The patient has a haploidentical sister who has autoimmune disease. The patient is interested in gene therapy. He says, I will take any risks, but I do not want to live with this anymore. So for gene therapy, there are two FDA approved strategies. One is gene addition, which uses a lentiviral vector to package a normal hemoglobin gene and insert it into a blood stem cell that integrates into the nucleus and forms normal hemoglobin. The other approach is, CRISPR Cas9 mediator disruption of BCL-11A enhancer. This basically increases in endogenous hemoglobin F production. So the two FDA approved products are logo teabag Glugine Auto Temel, Logocell for short, Lifgenia is the brand name, and Exagam Glugine Auto Temel, Exae, and Cas Javi is the brand name. So gene addition, which uses the vector system which is lower cell, what happens is stem cells are collected from the patient. A normal hemoglobin A gene, which is manufactured also, is inserted into a lentiviral vector. This vector is introduced into the stem cell. It translocates to the nucleus, and this gene integrates into the DNA of the recipients stem cells. This leads to transcription, translation, and formation of the normal beta globin gene, which forms the normal hemoglobin then and a functional RBC. This hemoglobin A is called P87Q. It's very similar to normal hemoglobin A, but it has a single nucleotide substitution at amino acid threonine to glutamine, so it's named as such. Um, it could not be used with, uh, in patients who have a 2 gene alpha thalassemia. That's because you need functional alpha genes to form a normal hemoglobin molecule. And of course antiretrovirals cannot be used because um you need the viral integration into the DNA. So the study that looked at Lobocell had several groups of patients. It, it was a phase 12 clinical trial. The initial cohorts were A, B1, B2. So every cohort had um different protocols, mobilization collection protocols, drug manufacturing processes, and busulfan AOC goes busulfan was the conditioning chemo that was used. Um, so it basically was a refinement of the process which with each subsequent cohort. Group C was the final one, which was the commercially approved procedures, um, for the drug. It used plreho mobilization, which was not used in the previous cohorts. Flarephor is a CXCR4 inhibitor which improves the release of stem cells from the bone marrow, and Group C had apheresis, which is peripheral blood collection rather than bone marrow collection, which was done in the previous groups. It used an increased cell dose and it's also increased used an increased um chemo dose because there were a lot of failures in the previous cohorts. So the patients treated were between 12 and 50 years of age with a diagnosis of Genotype SS S beta 0 and S beta plus. So this shows the the the red triangles are uh BOEs, and the red circles are also BOEs, and this zero is the time of infusion of the drug product, and these are BOEs prior to infusion. And everything else is after infusion of the drug product, and you can see the difference in terms of patients not having VOEs. So 47 patients were infused as of February 2023. 34 were valuable for VOE endpoints. 94% of patients experienced complete resolution of severe BOEs in the 6 to 18 months post infusion, and 88% has resolution of all VOEs, severe and non-severe. And all patients who had VOE resolution had maintenance maintenance of that resolution. This was an update that was presented at Ash last year, 84 months of follow up, and this showed sustenance of VOE remission, including all VOEs, 86.8%, and severe VOEs, so CR was 94.7%. 100% of pediatric patients had VOECR. So This shows the green here is the patient's uh hemoglobin, which could be SS, beta 0 or S beta plus, and the red is the one that um the transduced gene is forming, the AT87Q. So two things to note here are one, the total hemoglobin goes from baseline to about 10 to 12, even a little higher than 12 in some cases. And the second thing to note, of course, is that the A forms to about 40 to 50%. Some, you know, when we see patients, the expectation is, oh, you know, we're going to have all the new hemoglobin A, but that doesn't happen because the viral vector is is transduced not in the 100% of cells. There's a percentage. The, the criteria, there are criteria for commercial release, which is 60%, but it could be less or higher than that. So patients will be expected to have a trait like picture, uh, which is sufficient to prevent crises and long-term complications. So that was Lovocell, the viral vector manufacturing that is used. The, the, the other one is gene editing, which is, which uses the CRISPR Cas9 system, which is a genome editing system derived from certain bacteria and in combination with an enzyme system they are able to edit genes. So what happens here is the same thing stem cells are collected from the patient using a technique of electroporation. Um, Cas9 single guide RNA is introduced into the stem cell. Now, for um the the the the idea is to increase endogenous hemoglobin F production. Now what happens normally is that you have BCL 11A, which is high in amount, and it suppresses hemoglobin F production by suppressing gamma chain production. So what this does, the Cas9 single uh guide RNA does is. It shuts off the BCL-11A erythroid enhancer. When it shuts off that, it decreases production of BCL-11A, which in turn enhances gamma chain production. Therefore, it enhances, increases hemoglobin F production. So less 11 less of the enhancer, reduced BCL-11A, high gamma chains, increase in hemoglobin F. The trial that looked at this was the climb trial. The primary outcome was looking at VOCs again, with inclusive crises, for absence of VOCs for 12 months in the 24 months of follow-up period. 97% of patients treated were free from VOCs in the in the initial results. 30 out of 30 patients free from hospitalizations for 12 months. Um, this one, the blue diamonds are the crises, severe crises, pre-treatment, and then post-treatment, again, significant improvement. And this was an update of this trial. This is 48 months of follow-up, and this one is 60 months of follow-up. This 5-year update was presented recently at TCT. It showed durable VOC free benefit in 93% of patients, 39 out of 42. Uh, the mean duration of EOC free beer was 9, 30.9 months. And I'd like to mention, you know, we've had patients who come and say, you know, we don't want to be in the 3, so we don't want this. So, so every, every number matters. The three participants who did not have VOEs and then we of course mentioned these things still had some form of benefit, you know, if they had some pain, they had, they had no reduced hospitalizations. They didn't have, they didn't have any significant severe complications such as acute chest syndrome. And then the patients who still had pain had identifiable triggers. Which were infections, uh, procedures or steroids or other triggers. And durable hospital free benefit also at 5 years. So 98% of patients achieved hospital-free um time of 12 months. So here we're increasing hemoglobin F and um what you note here is that the total hemoglobin goes up significantly and there's the difference between this and lobo cell, the prior product, is that here probably the hemoglobin goes up total hemoglobin goes up a little higher. There it was between 10 to 12, average of about 11 here, a lot of most patients had over 12, which sometimes is also a patient preference. And the percentage is also about half of the total hemoglobin, which is again sufficient to prevent crises. So adverse events, the list of complications is long. It's similar to what is expected of myeloablative conditioning which we use for transplant patients. They can be divided into four major categories cytopenias requiring transfusions, infections, GI toxicities, and pain. Similarly, with Lovo cell, the conditioning is the same and with both products abuse self fan, so same list of complications with one exception, a major exception where there are two cases of acute myeloid leukemia, um. In patients who received Lobocell, the lentiviral-based product, and we'll talk about those two cases. So comparison of these two products in the trial, the age range for low cell was 12 to 50, and the exo cell was 12 to 35, but both products are approved for over 12 years of age. The mechanism, as we saw, is different. There's a black box warning with low cell of hematologic malignancy. The cost is slightly different, $1 million. The, um, there are more treatment centers for Lovo cell, um, that are treating right now and there's more, um, uh, the length of available follow-up is longer for Lovo cell. So the two cases of AML, um, it's, it's amazing how patients when they come in, I think about 50% are aware of that, and they've read about the cases and, and they just know and they want to talk about it. I've had patients ask like randomly nurses and whatnot, so it's important for everybody to know about these. Um the both both cases were in Group A of the cohort, which means that the, the procedures were significantly refined thereafter. So it was in the early cohort of patients in the study. The first patient was 42 years of age at initial consent, developed MDS, AML 3 years post treatment, so 45 years of age. Now, in between that, the patient actually was not cured of sickle cell disease, still had anemia, had to be started on hydroxyurea, was an erythro potent stimulating agents, um, so still continued to have sickle cell disease. So when and then then the antiviral vector cell percentage was 22%, the the number that is good for release, commercial release is 60%, which means if there is less less percentage of vector, that means more replication cycles are needed to form the normal hemoglobin. Um, so that's, that's also um suboptimal, and there was very, very little hemoglobin derived from um the infused stem cells. The busulfan was under target, which means there may have been residual unablated cells, stem cells. The blasts did not have viral integration, which means these were residual cells which were which had persisted post chemo, and the blasts were monosomy 7 positive, which is known to be associated with alkyelating agents. Um, the second case was 25 years of age at treatment, developed AML 5.5 years after gene therapy. Same thing was not cured between that time period. Um, very little hemoglobin derived from the infused cells. Multiple, um, mutations also had Monsomy 7, the blasts, had drugs 1 PTP and 11 mutation. This patient had vector integration into the blasts, which means the leukemia was derived from the modified stem cells, but this integration was in a VAM4 gene which is associated, it's not an oncogene, it's associated with the Golgi apparatus and it was a noncoding region of the VAMP4 gene. So in both cases it was concluded that it wasn't the gene induction that was directly associated with the cancer. Uh, I mean, if you're curious, patient, the first patient, um, both patients underwent transplant. The first patient, um, had relapse post 6 months post transplant and was started on HMA when they took lax. The second patient had transplant, relapsed, and then unfortunately died. So I mean this is an important discussion when we see patients for transplant or gene therapy, but what what patients kind of sometimes don't really realize is that just having sickle cell disease increases risk of cancers by sometimes, you know, 7 to 11% in some studies, and those risk factors inherent to the disease are host factors such as chronic hypoxia, endothelial damage, chronic inflammation, erythropoietic stress, and CHIP mutations. Some patients are known to have. And then there are transplant-related factors which are similar to transplanting gene therapy when it comes to chemo radiation, um, when patients have graft failure after bone after stem cell transplant, then that increases risk of um secondary cancers. So having risk of just having sickle cell disease, risk of cancers, and then additionally any form of treatment would increase the risk of cancer. And this was a study that a comparison of HLMS sibling transplant, haplo, and gene therapy where they looked at hematologic malignancies for 100 years, and it showed what I just said that they all have risk of secondary malignancies. This is a little higher with HLMS just because this conditioning that is not no longer used is just associated with graft failure, mixed crierism, and more cancers. So patient's treatment journey um is long. When we first see the patient, um, and we discuss all treatment options, the average time prior to decision making is about 2 to 4 visits over 2 to 3 months. Um, we do workup for all patients, and insurance authorizations needed for transplant or gene therapy that takes up to 4 to 6 months. There's this basic, basic workup we do for all patients. They all have some form of chronic organ damage, and I feel like even when we don't see them for curative therapy, they should all be undergoing this workup. And this is the bare minimum. Most patients have some abnormality on all of those, um, more than one of those, and then they require further referrals, for example, neurology, pulmonary cardiology, and whatnot, hepatology. Um, once we decide that, say this is for gene therapy that we have to do the gene therapy, what we do is the patient undergoes this pre-mobilization transfusion regimen, which is red cell exchanges once a month um for at least 2 to 3 months. Um, this is just to prime the bone marrow to accept one firstly to for us to be able to collect stem cells and then to give chemo and give stem cells. Back, um, then, um, we admit the patient to the hospital for mobilization and collection of stem cells. That is typically a 4 day, um, hospitalization. The first day patient undergoes a red cell exchange, and then day 1 and day 2 are collection for the product manufacturing. Day 3 is collection for backup cells. Um, we send the cells for manufacturing that takes about 3 to 5 months. And then once the cells are ready, the patient continues red cell exchanges monthly during this time period. We admit the patient to the hospital for busul and myeloulative conditioning. Uh, the product is infused post-conditioning, and then, uh, the engraftment reconstitution time is up to 36 days, and it can be up to 2 months. We followed the patients mostly indefinitely. In the study, 13 years of follow-up was required. What we've seen is that patients usually require more than one mobilization cycle. So when you're collecting stem cells that have been failures for collection and manufacturing. So most patients require more than one collection cycle, and thankfully we haven't had that experience so much, but in the real world data we have consortiums where we discuss experiences across institutions where the recollection rate is up to 70%. So, um, How do we decide what treatment to do? Um, every patient is different. The, you know, situation is different, their preferences are different. Patients are very particular about, you know, they say we don't want cells from anybody or. So there have been patients like that. So basically what we do is we present all the data we discuss, and it's mutual decision making. I mean this is a table that Um, I discussed with all patients. This is just a summary of that, but they have like 3 such tables, and, and we discussed this. So upfront, there's, there are certain things that tell us that patients cannot do. For example, we see patients who are older, 40s, and they cannot undergo myeloablative conditioning, so that's out then. Um, if patients can undergo gene therapy, then they sometimes have preference in terms of, you know, when patients hear about the two cases of AML, they don't want it at all, and they want to wait. We don't have the CRISPR. We will be in the process of obtaining it at Sinai, but they want to wait for it and then do that. Some patients want to get over this as soon as possible, so they prefer transplant versus gene therapy, and this timeline is trial. This, this all this is from the trials, so 1 to 2 months is not realistic in the real world. Age wise, um, gene therapy is approved over 12 years of age, but patients treated have been in their 30s. So when we see patients in their 40s, we have to be clear that, you know, this has not been studied in patients who are older. So, so that's a decision that we have to make together. And then after transplant patients have to be on long term immunosuppression, um, so some patients prefer not to be on it versus some are OK with it. Hemoglobin is something that I've learned that patients are particular, you know, I want my hemoglobin to be 13 or 14. They're not happy with 9, 10, so, or 11. Event free survival or survival wise, they're very similar. Um, cost is different, of course. Coming back to her case, 40 year old, um, who had AVN of the hip, uh, excellent performance status, haploid identical sister, um, the patient did not prefer to have transplant also, and the sister had autoimmune disease, so, um, it was not also cleared for transplant. The patient stated he won, he would do anything, you know, he would take any risk cause he's 40, which increases the risk of complications. So we decided to do gene therapy. He underwent monthly res exchanges. We collected cells which were good with the first collection. He underwent conditioning with busulfan 16 mg per kilogram, received cells 6.3 million. The minimum is 2.5 million, so this was a good amount. 82% with the lentivirral vector positive cells, which is excellent. He had neutropenic fever, rash, no major, major complications such as ICU. Uh, this was his electrophoresis pre gene therapy. This is without exchanges, so S of 80%, A of 9.1. Um, post gene therapy at 1 month, 93% AS 3.5%, at 3 months, 24.3 S. He's very unhappy about this going up. Um, but this is expected, as I showed you, um, it will, it is expected to go up to 40, 45%, um, by 6 months or so. So we're still at about 4 months. So, but this is expected no crises. Um, the patient states, I'm tired. When we saw him in clinic after the hospitalization, I'm tired, but I no longer wake up with sickle cell pain. This is a final thought I would leave you with. Um, so each year 300,000 to 400,000 patients are born with sickle cell disease annually in the world. We're fortunate to be able to offer these expensive therapies to our patients here, which in the US, it comprises 5% of the total population in the world living with sickle cell disease, and even with those 5%, we're not able to provide them with this option, um, because of lack of access and obviously financially. Um, there are, um, consortiums, there are initiatives that are taking place to improve access, but there's still a very long way to go, um, if we continue to move forwards and not backwards. And as they say it takes a village, um, if I were to name everybody, um, it'll take another hour, but, um. Yeah, thank you to everyone. Thank you for that incredible talk. I'd like to open up um the form for any questions. While you're thinking of your questions, um, I'd like to ask, um, um, Doctor Ibrahim a question. So, given the very differential expense between aloe transplantation and gene therapy, have you, um, in your experience, have you, how have you navigated the insurance obstacles given the the multiple difference in expense if you have an option of offering both therapies to a particular patient. So you know, when we first started doing this, um, we had a list of insurances which were no, so we wouldn't even see those patients, which is still the case. Unfortunately, it shouldn't be. If you ask me as a physician, I would say, you know, I would see the patient, decide which one is best for them, and then start with the insurance process for that and not look at the insurance first in, in, in, in the, in the best case scenario. Um, I personally don't look at that first. But if patients we can't see, we don't see them, unfortunately. That done. thanks for the great talk. You see a lot of these patients on the inpatient side connection with complications. I personally, I think as a team, we don't normally engage them in discussions about curative intent, concentrating on their acute illness. Is that a moment when we can start engaging people and finding out what they've learned in the past? I would definitely, yeah. Any, any interaction. I mean, if you think it's the right, especially when they're acutely ill, I think they really want to. Get rid of that uh. Acute illness and for good. That's the goal of this talk. Thank you. Oh, Doctor Chen? Oh, I so I didn't. the many uh big advances in additional advances in stem cell therapy and IPS cells or other things in uh potential trials in the near horizon. Through the pos Existing Yeah, so the main one is, um, in terms of gene therapy, there's, there are trials looking at, um, so, so the main hindrance here for, especially for adults is um the chemo, busulfan, uh, myeloblative. So, so regimens that were radioactive or otherwise antibody mediated conditioning regimens that could get rid of the busulfan, there are ongoing trials with that to, to improve and yeah, that would make more patients eligible for treatment. Are we gonna We're working on it, yes. Financial hurdles. Excellent. If there are no further questions, thank you.
