Gene Therapy Clinical Trials Research Articles

Multi-year enzyme expression in patients with mucopolysaccharidosis type VI after liver-directed gene therapy.

Mucopolysaccharidosis type VI (MPS VI) is due to a deficiency of the lysosomal enzyme arylsulfatase B (ARSB) that results in multi-organ accumulation of glycosaminoglycans (GAGs). Limitations of current treatments prompted the development of a liver-directed gene therapy clinical trial for MPS VI. We report the long-term follow-up of patients with MPS VI who discontinued enzyme replacement therapy (ERT) and received a single intravenous infusion of high-dose (6×1012 genome copies/kg) recombinant adeno-associated virus serotype 8 (AAV8) vector expressing ARSB under the control of a liver-specific promoter (ClinicalTrials.gov: NCT03173521). Primary outcomes were safety and urinary GAG excretion. Secondary outcomes were endurance and respiratory function. Median follow-up time was 45months (n= 4, three females and one male; age range: 5-10 years). No late-emergent safety events were observed. Patients showed sustained serum ARSB activity (38%-67% of mean healthy reference values), a modest increase in urinary GAG concentrations, and no relevant changes in endurance, cardiac, or pulmonary function. In one of the four patients, ERT was restarted because of elevated urinary GAGs without decreased serum ARSB activity up to about 2.5 years after gene transfer. Liver and spleen size remained within the reference ranges. A single intravenous administration of AAV8.TBG.hARSB was safe and resulted in sustained ARSB expression and a modest increase in urinary GAGs in most patients, thus supporting liver-directed gene therapy for MPS VI. This study was sponsored by the Telethon Foundation ETS, the European Union, the Isaac Foundation, and the Italian Ministry of University and Research.

Gene Therapy in Cardiovascular Disease: Recent Advances and Future Directions in Science: A Science Advisory From the American Heart Association.

Cardiovascular disease remains the foremost cause of morbidity and mortality globally, affecting millions of individuals. Recent discoveries illuminate the substantial role of genetics in cardiovascular disease pathogenesis, encompassing both monogenic and polygenic mechanisms and identifying tangible targets for gene therapies. Innovative strategies have emerged to rectify pathogenic variants that cause monogenic disorders such as hypertrophic, dilated, and arrhythmogenic cardiomyopathies and hypercholesterolemia. These include delivery of exogenous genes to supplement insufficient protein levels caused by pathogenic variants or genome editing to correct, delete, or modify mutant sequences to restore protein function. However, effective delivery of gene therapy to specified cells presents formidable challenges. Viral vectors, notably adeno-associated viruses and nonviral vectors such as lipid and engineered nanoparticles, offer distinct advantages and limitations. Additional risks and obstacles remain, including treatment durability, tissue-specific targeting, vector-associated adverse events, and off-target effects. Addressing these challenges is an ongoing imperative; several clinical gene therapy trials are underway, and many more first-in-human studies are anticipated. This science advisory reviews core concepts of gene therapy, key obstacles, patient risks, and ongoing research endeavors to enable clinicians to understand the complex landscape of this emerging therapy and its remarkable therapeutic potential to benefit cardiovascular disease.

Expression and distribution of rAAV9 intrathecally administered in juvenile to adolescent mice.

Intrathecal (IT) lumbar puncture delivery of recombinant adeno-associated virus serotype 9 (rAAV9) is a gene therapy approach being explored in preclinical studies and ongoing gene therapy clinical trials for neurological diseases. Few studies address IT rAAV9 vector distribution, tropism, and expression with respect to age of administration. Therefore, we IT delivered a rAAV9/GFP vector in mice at ages ranging from early postnatal development through adulthood (P10-P90). Tissues were assessed for transgene expression, cell tropism, and vector distribution. In the CNS, transduction was highest when delivered at post-natal day 10 (P10) and there was an age-dependent decline in transduction. We found higher transduction of astrocytes relative to neurons when rAAV9 was administered at younger ages and a switch to higher neuronal transduction with delivery at older timepoints. Biodistribution analysis of peripheral tissues showed that when delivered at P10, rAAV9 has the greatest distribution to the heart. Conversely, at P90 rAAV9 liver distribution was highest. As rAAV9 IT-delivered gene therapies continue to emerge for neurological diseases, careful consideration of the age of delivery should be taken in relation to the expected distribution and cell expression in animal models, and how this may translate to human studies.

First, do no harm: the role of preclinical animal models in predicting adverse events in gene therapy clinical trials for Duchenne muscular dystrophy and X-Linked myotubular myopathy

The occurrence of severe adverse events (SAEs) in patients with Duchenne muscular dystrophy (DMD), X-linked myotubular myopathy (XLMTM), and other neuromuscular diseases treated with adeno-associated virus (AAV) constructs has prompted studies to improve the safety and efficacy of gene therapy. Physicians have weighed the medical tenet of “first, do no harm” against the perspective of patients with progressive life-threatening conditions who may accept greater risk. Regarding SAE pathogenesis, discussion has focused on total AAV exposure and patient mutations more likely to induce immunity, while stressing the limitations of animal models in predicting adverse events. Therapeutic strategies for reducing side effects have employed more myotropic AAV serotypes and efficient transgenes. Other recommendations include excluding certain DMD gene mutations associated with SAEs and substituting less immunogenic transgenes such as utrophin (DMD) and myotubularin-related protein (XLMTM). For the sake of preclinical studies, emphasis has been placed on outbred rodents and larger animals that better predict immunity. Here, the absence of side effects in canine DMD and XLMTM models might be explained partly by phenotypic differences between affected humans and dogs. Specifically, dystrophin- and myotubularin-deficient dogs exhibit milder lesions, including less muscle fat deposition and the absence of hepatopathy, respectively, which could lead to reduced immune responses to AAV constructs. To better predict future problems, thought should be given to tracking early subclinical markers of the innate immune response, especially complement activation. Regardless of steps taken to improve the predictive value of animal models for SAEs, some questions will only be answered through human clinical trials after carefully considering the risk-benefit ratio.

Challenges in Cardiomyopathy Gene Therapy Clinical Trial Design.

Gene therapy has emerged as a possible treatment for progressive, debilitating Mendelian cardiomyopathies with limited therapeutic options. This paper arises from discussions at the 2023 Cardiovascular Clinical Trialists Forum and highlights several challenges relevant to gene therapy clinical trials, including low prevalence and high phenotypic heterogeneity of Mendelian cardiomyopathies, outcome selection complexities and resulting regulatory uncertainty, and immune responses to the adeno-associated viral vectors that are being used in ongoing studies. Avenues to address these challenges such as natural history studies, external controls, novel regulatory pathways, and immunosuppression are discussed. Relevant cases of recent therapy approvals are highlighted. Ultimately, this work aims to broadly frame discussions on and provide potential future avenues for clinical trial design for rare cardiomyopathy gene therapies.

Preclinical ex vivo IL2RG gene therapy using autologous hematopoietic stem cells as an effective and safe treatment for X-linked severe combined immunodeficiency disease

X-linked severe combined immunodeficiency disease (X-SCID) is a rare inherited disease caused by mutations in the interleukin 2 receptor subunit gamma gene (IL2RG), which encodes the common γ chain protein, a subunit of the receptor for lymphocytes. X-SCID is characterized by profound defects in T-cell, B-cell, and natural killer cell function. Here, we report a Chinese cohort of nine X-SCID patients with six novel IL2RG mutations. Among those, the two adolescent patients carrying missense mutation with an atypical immunotype were confirmed by further analyzing IL-2-JAK-STAT5 signaling, T cell proliferation, and T cell receptor excision circles (Trecs). Interestingly, Bacillus Calmette-Guérin (BCG) disease occurred commonly in this cohort. Although allogeneic hematopoietic stem-cell transplantation is curative for the disease, it is not available to all patients due to the lack of suitable matched donors. Autologous gene therapy using a self-inactivating lentiviral vector (SIN-LV) technology, developed in recent decades has provided an alternative therapy for treating such mono-genetic diseases. Here, we performed the pre-clinical studies to assess our SIN-LV carrying IL2RG on human ED7R cells deficient in IL2RG and CD34+ stem cells derived from the bone marrow of a healthy donor and a patient with X-SCID. This work is done complied with the established "Good Manufacturing Practice" (GMP) used in the clinical trials. In addition, a safety study is performed using the transduced CD34+ cells implanted into the axilla of nude mice in vivo. Overall, our studies have demonstrated the efficiency and safety of SIN-IL2RG-LV, which paves the way for conducting X-SCID gene therapy clinical trials in China in the near future.

Phase I gene therapy clinical trial design of RP-A601 in adult patients with PKP2-arrhythmogenic cardiomyopathy (PKP2-ACM)

Abstract Background Arrhythmogenic cardiomyopathy (ACM) is a rare, progressive, autosomal dominant disorder characterized by increased risk of ventricular arrhythmias and sudden cardiac death. Up to 45% of all ACM cases are caused by pathogenic variants in the PKP2 gene, which encodes for the desmosomal protein Plakophilin-2. This genetic cardiomyopathy is referred to as PKP2-ACM. AAVrh.74-PKP2a is a recombinant adeno-associated viral (AAV) vector containing the coding sequence of human PKP2 isoform A (PKP2a) and delivers the functional PKP2 gene to cardiomyocytes. Preclinical testing conducted in a clinically relevant mouse model of PKP2-ACM (with survival ≤50 days post disease onset) demonstrated that administration of a single AAVrh.74-PKP2a dose after disease onset extended survival through 5 months with improved right ventricular (RV) function, and decreased cardiac dilation, myocardial fibrosis, and arrhythmias. Additional studies in rodents and nonhuman primates demonstrated AAVrh.74-PKP2a safety. These preclinical findings support clinical initiation. Purpose We describe the design of a phase I trial to assess safety and preliminary efficacy of AAVrh.74-PKP2a (RP-A601) in high-risk adult patients with PKP2-ACM. Methods This study (NCT05885412) is a multi-center, open-label, dose escalation trial evaluating the safety and preliminary efficacy of a single intravenous infusion of RP-A601 in adult patients (age ≥18 yrs) with clinical and genetic PKP2-ACM diagnosis and an implanted ICD. Patients with severe right ventricular dysfunction, LV ejection fraction ≤50% (echocardiogram or cardiac MRI) and/or NYHA Class IV heart failure are excluded. Preliminary efficacy will be assessed at 12 months after RP-A601 infusion and includes evaluation of change in PKP2 myocardial tissue expression and clinical markers of arrhythmia burden. Conclusions PKP2-ACM is a devastating disease associated with high morbidity and mortality. This Phase I trial will evaluate the safety and preliminary efficacy of RP-A601 and was initiated based on robust preclinical efficacy and safety data.

Infantile Nystagmus Syndrome—Associated Inherited Retinal Diseases: Perspectives from Gene Therapy Clinical Trials

Inherited retinal diseases (IRDs) are a clinically and genetically diverse group of progressive degenerative disorders that can result in severe visual impairment or complete blindness. Despite their predominantly monogenic inheritance patterns, the genetic complexity of over 300 identified disease-causing genes presents a significant challenge in correlating clinical phenotypes with genotypes. Achieving a molecular diagnosis is crucial for providing patients with definitive diagnostic clarity and facilitating access to emerging gene-based therapies and ongoing clinical trials. Recent advances in next-generation sequencing technologies have markedly enhanced our ability to identify genes and genetic defects leading to IRDs, thereby propelling the development of gene-based therapies. The clinical success of voretigene neparvovec (Luxturna), the first approved retinal gene therapy for RPE65-associated Leber congenital amaurosis (LCA), has spurred considerable research and development in gene-based therapies, highlighting the importance of reviewing the current status of gene therapy for IRDs, particularly those utilizing adeno-associated virus (AAV)-based therapies. As novel disease-causing mutations continue to be discovered and more targeted gene therapies are developed, integrating these treatment opportunities into the standard care for IRD patients becomes increasingly critical. This review provides an update on the diverse phenotypic–genotypic landscape of IRDs, with a specific focus on recent advances in the understanding of IRDs in children with infantile nystagmus syndrome (INS). We highlight the complexities of the genotypic–phenotypic landscape of INS-associated IRDs, including conditions such as achromatopsia, LCA, congenital stationary night blindness, and subtypes of retinitis pigmentosa. Additionally, we provide an updated overview of AAV-based gene therapies for these diseases and discuss the potential of gene-based therapies for underlying IRDs that lead to INS, offering a valuable resource for pediatric patients potentially eligible for ongoing clinical trials.

6765 Surveillance For Side Effects Of Glycemic Control: Von Gierke Disease And Recurrent Diarrhea With Hospitalized Approach

Abstract Disclosure: J. Gone: None. E. Fegahli: None. T. Thompson: None. Background: Von Gierke disease is an autosomal recessive disorder leading to the inability to break down glycogen. Clinical features manifest at 3-6 months including symptoms of hypoglycemia, short stature, thin legs, round face, protruding abdomen, muscular hypotonia, and psychomotor retardation. Workup shows hypoglycemia, lactic acidosis, hyperuricemia, hyperlipidemia, anemia, hepatomegaly, and renomegaly. Patients may develop inflammatory bowel disease, osteopenia, renal failure, hepatic tumors, and pulmonary hypertension. Molecular sequencing confirms the diagnosis. Feeding glucose at regular intervals prevents hypoglycemia. One should avoid fructose, lactose, sucrose, and galactose. Oral citrate or bicarbonate is used to treat lactic acidosis. Gout, hyperlipidemia, anemia, IBD and osteoporosis are managed accordingly. Regular screening for osteoporosis, renal failure, hepatic tumors, and pulmonary hypertension is recommended. Liver transplantation results in optimal management. Gene therapy clinical trials are underway. Clinical Case: We present a case of von Gierke disease in a 20-year-old male presenting to the Emergency Department for recurrent nausea, emesis, poor oral intake, water diarrhea and subjective fever. Inpatient workup showed lactic acidosis, hyperuricemia, hypertriglyceridemia, transaminitis, and fibrofatty hepatomegaly. Intravenous fluids, antiemetics and cornstarch were given. Symptoms including nausea, emesis, and diarrhea improved, most notably after adjustments made to cornstarch dosage and frequency. The patient was discharged with an antiemetic and an antidiarrheal and with recommendations to continue scheduled cornstarch. Patient was educated about the importance of proper diet compliance and close outpatient follow up. Hence, management of von Gierke disease should include not only strict glycemic control but also close surveillance for possible side effects, such as diarrhea. Moreover, future studies are necessary to support empiric modifications in management despite a basis of a hypothetical rationale. Conclusion: An essential goal of managing GSD-1 is not only strict glycemic control but also close surveillance for possible side effects, such as diarrhea. Adjustments to maintaining normoglycemia may be mandatory by manipulating factors including dosage and frequency of oral carbohydrates, such as cornstarch, to reduce the recurrence of side effects as much as possible. Treatment regimens should be individualized to each case because the initial presentation and response to treatment in every patient can be different, whether it is minor or major. Future studies about the mechanisms regarding possible side effects of treatment, such as diarrhea, are warranted to corroborate empiric changes in management, like adjusting dosage and frequency or medications, despite having a hypothetical rationale. Presentation: 6/1/2024

Establishment and Characterization of a Stable Producer Cell Line Generation Platform for the Manufacturing of Clinical-Grade Lentiviral Vectors.

Background/Objectives: To date, nearly 300 lentiviral-based gene therapy clinical trials have been conducted, with eight therapies receiving regulatory approval for commercialization. These advances, along with the increased number of advanced-phase clinical trials, have prompted contract development and manufacturing organizations (CDMOs) to develop innovative strategies to address the growing demand for large-scale batches of lentiviral vectors (LVVs). Consequently, manufacturers have focused on optimizing processes under good manufacturing practices (GMPs) to improve cost-efficiency, increase process robustness, and ensure regulatory compliance. Nowadays, the LVV production process mainly relies on the transient transfection of four plasmids encoding for the lentiviral helper genes and the transgene. While this method is efficient at small scales and has also proven to be scalable, the industry is exploring alternative processes due to the high cost of GMP reagents, and the batch-to-batch variability predominantly attributed to the transfection step. Methods: Here, we report the development and implementation of a reliable and clinical-grade envisioned platform based on the generation of stable producer cell lines (SCLs) from an initial well-characterized lentiviral packaging cell line (PCL). Results: This platform enables the production of VSV-G-pseudotyped LVVs through a fully transfection-free manufacturing process. Our data demonstrate that the developed platform will facilitate successful technological transfer to large-scale LVV production for clinical application. Conclusions: With this simple and robust stable cell line generation strategy, we address key concerns associated with the costs and reproducibility of current manufacturing processes.

Genetic testing for pediatric sensorineural hearing loss in the era of gene therapy.

To summarize indications, methods, and diagnostic yields for genetic testing for pediatric hearing loss. Genetic testing has become a cornerstone of clinical care for children with sensorineural hearing loss. Recent studies have shown the efficacy of gene panels and exome sequencing for any child with sensorineural hearing loss. Recent findings have underscored the importance of a diagnosis in clinical care. Clinical trials for gene therapy for hearing loss have begun. Genetic testing has become critical for personalized care for children with hearing loss. Recent studies have shown a 43% overall diagnostic yield for genetic testing for pediatric hearing loss, though the diagnostic yield may range from 10 to 60% depending on clinical features. Syndromic diagnoses comprise 25% of positive genetic tests for pediatric sensorineural hearing loss. While diagnostic yield is lower for children with unilateral or asymmetric sensorineural hearing loss, the likelihood of syndromic hearing loss finding is higher. An early and accurate genetic diagnosis is required for participating in clinical trials for gene therapy for hearing loss.

Reviewing The Latest Treatments for Haemophilia

Abstract: Advancements in haemophilia treatment have been significant in the first 20 years of the 21st century. However, the progress started with the fractionation of plasma in 1946. The first concentrates were developed after discovering FVIII in frozen plasma cryoprecipitate and FIX in the supernatant in the early 1960s, leading to initial attempts at replacement therapy. Unfortunately, due to the lack of screening methods for viral pathogens, people with haemophilia (PWH) received contaminated concentrates, leading to infections with the hepatitis A virus, hepatitis C virus, and human immunodeficiency virus. Thankfully, by 1985, viral screening methods and virucidal techniques were developed, making concentrates safe. The introduction of chromatography steps with monoclonal antibodies in the production process led to increasingly pure products. However, the problem of immunogenicity of administered concentrates persists. The development of alloantibodies against FVIII in a significant percentage of PWH is a serious adverse effect of replacement therapy. The next major advancement came with cloning the F8 and F9 genes, which allowed the production of factor concentrates using recombinant DNA technology. The injected FVIII and FIX molecules have a relatively short circulating half-life in the plasma of people with haemophilia A and B, approximately 12 and 18 hours, respectively. Methods such as conjugating the factor molecule with fragment crystallizable of IgG1, albumin, or adding polyethylene glycol have been applied to prolong the plasma half-life and extend the interval between injections, especially for risk. The next frontier in haemophilia therapy is the development of durable and potentially curative treatments, such as gene addition therapy. Experiments in haemophilia B have shown promising long-lasting responses. However, the results of gene therapy for haemophilia A have not been as remarkable, and the durability of the treatment is yet to be demonstrated. The long-term safety, predictability, durability, and efficacy of gene therapy for haemophilia A and B remain open questions. Currently, only healthy adult PWH has been enrolled in gene therapy clinical trials, and further studies are needed before gene therapy can be widely applied to children and those with pre-existing antibodies against the delivery vector.

Interim safety and efficacy of gene therapy for RLBP1-associated retinal dystrophy: a phase 1/2 trial

Gene therapy holds promise for treatment of inherited retinal dystrophies, a group of rare genetic disorders characterized by severe loss of vision. Here, we report up to 3-year pre-specified interim safety and efficacy results of an open-label first-in-human dose-escalation phase 1/2 gene therapy clinical trial in 12 patients with retinal dystrophy caused by biallelic mutations in the retinaldehyde-binding protein 1 (RLBP1) gene of the visual cycle. The primary endpoints were systemic and ocular safety and recovery of dark adaptation. Secondary endpoints included microperimetry, visual field sensitivity, dominant eye test and patient-reported outcomes. Subretinal delivery of an adeno-associated viral vector (AAV8-RLBP1) was well tolerated with dose-dependent intraocular inflammation which responded to corticosteroid treatment, and focal atrophy of the retinal pigment epithelium as the dose limiting toxicity. Dark adaptation kinetics, the primary efficacy endpoint, improved significantly in all dose-cohorts. Treatment with AAV8-RLBP1 resulted in the resolution of disease-related retinal deposits, suggestive of successful restoration of the visual cycle. In conclusion, to date, AAV8-RLBP1 has shown preliminary safety and efficacy in patients with RLBP1-associated retinal dystrophy. Trial number: NCT03374657.

Gene Therapy for Achromatopsia.

Achromatopsia is the most common cone dysfunction syndrome, affecting 1 in 30,000 people. It is an autosomal recessive disorder with a heterogeneous genetic background with variants reported in CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6. Up to 90% of achromatopsia patients harbour mutations in CNGA3 or CNB3, which encode for the alpha and beta subunits of the cone cyclic nucleotide-gated (CNG) channel in cone-specific phototransduction. The condition presents at birth or early infancy with poor visual acuity, nystagmus, photophobia, and colour vision loss in all axes. Multimodal retinal imaging has provided insightful information to characterise achromatopsia patients based on their genotype. There is no FDA-approved treatment for achromatopsia; however, studies have reported several preclinical gene therapies with anatomical and functional improvements reported in vivo. There are currently five gene therapy clinical trials registered for human patients at the phase I/II stage and for CNGA3 or CNGB3 causing achromatopsia. This review aims to discuss the genetics of achromatopsia, genotypic and phenotypic correlations in multimodal retinal imaging, and the developments and challenges in gene therapy clinical trials.

Gene therapy clinical trials worldwide to 2023-an update.

To date, 3,900 gene therapy clinical trials have been completed, are ongoing or have been approved worldwide. Our database brings together global information on gene therapy clinical activity from trial databases, official agency sources, published literature, conference presentations and posters kindly provided to us by individual investigators or trial sponsors. This review presents our analysis of clinical trials that, to the best of our knowledge, have been or are being performed worldwide. As of our March 2023 update, we have entries on 3,900 trials undertaken in 46 countries. We have analyzed the geographical distribution of trials, the disease indications (or other reasons) for trials, the proportions to which different vector types are used, and which genes have been transferred. Details of the analyses presented, and our searchable database are on The Journal of Gene Medicine Gene Therapy Clinical Trials Worldwide website at https://a873679.fmphost.com/fmi/webd/GTCT. We also provide an overview of the progress being made around the world, and discuss key trends since the previous review, namely the unprecedented increase in gene therapy clinical trial activity, including the implementation of genome editing technology with the potential to transform the field moving forward.

Hemophilia Healing with AAV: Navigating the Frontier of Gene Therapy.

Gene therapy for hemophilia has advanced tremendously after thirty years of continual study and development. Advancements in medical science have facilitated attaining normal levels of Factor VIII (FVIII) or Factor IX (FIX) in individuals with haemophilia, thereby offering the potential for their complete recovery. Despite the notable advancements in various countries, there is significant scope for further enhancement in haemophilia gene therapy. Adeno-associated virus (AAV) currently serves as the primary vehicle for gene therapy in clinical trials targeting haemophilia. Subsequent investigations will prioritize enhancing viral capsid structures, transgene compositions, and promoters to achieve heightened transduction efficacy, diminished immunogenicity, and more predictable therapeutic results. The present study indicates that whereas animal models have transduction efficiency that is over 100% high, human hepatocytes are unable to express clotting factors and transduction efficiency to comparable levels. According to the current study, achieving high transduction efficiency and high levels of clotting factor expression in human hepatocytes is still insufficient. It is also crucial to reduce the risk of cellular stress caused by protein overload. Despite encountering various hurdles, the field of haemophilia gene therapy holds promise for the future. As technology continues to advance and mature, it is anticipated that a personalized therapeutic approach will be developed to cure haemophilia effectively.

Adrenoleukodystrophy an Overview

Adrenoleukodystrophy (ALD) is a rare X-linked peroxisomal oxidation disease caused by mutations in ABCD1. It presents with various clinical manifestations, including cerebral ALD, myelopathy, and primary adrenal insufficiency. About 80% of ALD patients suffer from adrenal insufficiency, and cerebral ALD affects one-third of boys under twelve, progressing to total impairment and death without treatment. Hematopoietic stem cell transplantation (HSCT) is the only disease-modifying treatment for early-stage cerebral ALD, but it does not halt adrenal insufficiency progression and carries significant morbidity and mortality risks. A recent gene therapy clinical trial showed short-term MRI and neurological outcomes equivalent to past HSCT treatments without the adverse side effects. Additionally, over a dozen states have initiated newborn screening (NBS) for ALD, with the number expected to triple by 2020. Genetic testing of NBS-positive newborns has identified novel variations of unknown significance, raising questions about monitoring and treating preclinical or moderate adrenal insufficiency or cerebral involvement. This presents further opportunities for genetic characterization. The availability of matching donors, transplant centers, and specialists will impact prompt treatment for those diagnosed with ALD at birth. As NBS and gene therapy trials improve ALD's clinical management and prognosis, endocrine management of presymptomatic and subclinical adrenal insufficiency will become increasingly important.

Longitudinal biomarker evaluation in Fabry disease patients receiving lentivirus-mediated gene therapy

Aim: In 2016, a team of Canadian researchers initiated the world’s first gene therapy clinical trial for Fabry disease. The study, aiming to determine the safety and toxicity of lentivirus α-galactosidase A transduced autologous CD34+ cells in adult males with Fabry disease (n = 5), was conducted at three Canadian centers. The objective of the present work was to evaluate a profile of Fabry disease-related biomarkers in five participants during a 5-year surveillance period, as part of the evaluation of this novel therapy. Methods: Sixteen globotriaosylceramide (Gb3) isoforms and eight globotriaosylsphingosine (lyso-Gb3) analogues were measured by LC-MS/MS in plasma and urine at numerous time points before and after gene therapy. Plasma and peripheral blood leukocyte α-galactosidase A activity were also measured. Results: Levels of urine and plasma lyso-Gb3 and analogues, and urine Gb3 were lower after gene therapy and while treated with enzyme replacement therapy (ERT) compared to baseline (before gene therapy) in participants treated with ERT only. Three participants chose to cease ERT treatment at some point after gene therapy. Two of these patients had lower levels of urine and plasma lyso-Gb3 and analogues compared to baseline, whereas one participant had higher levels of these biomarkers compared to baseline. An increase in urine Gb3 was observed when ERT treatment ceased after gene therapy (P < 0.05) in all three participants. Conclusion: The evaluation of this complete glycosphingolipid biomarker profile was useful in monitoring the biochemical response to gene therapy in this cohort of five patients with Fabry disease.

Perimacular Atrophy Following Voretigene Neparvovec-Rzyl Treatment in the Setting of Previous Contralateral Eye Treatment With a Different Viral Vector.

To report on cases of unilateral perimacular atrophy after treatment with voretigene neparvovec-rzyl, in the setting of previous contralateral eye treatment with a different viral vector. Single-center, retrospective chart review. In this case series, four patients between the ages of six and 11years old with RPE65-related retinopathy were treated unilaterally with rAAV2-CB-hRPE65 as part of a gene augmentation clinical trial (NCT00749957). Six to 10 years later the contralateral eyes were treated with the Food and Drug Administration-approved drug, voretigene neparvovec-rzyl. Best-corrected visual acuity (BCVA), fundus photos, ocular coherence tomography, two-color dark-adapted perimetry, full field stimulus threshold testing (FST), and location of subretinal bleb and chorioretinal atrophy were evaluated. Three out of four patients showed unilateral perimacular atrophy after treatment with voretigene, ranging from five to 22months after treatment. Areas of robust visual field improvement were followed by areas of chorioretinal atrophy. Despite perimacular changes, BCVA, FST, and subjective improvements in vision and nyctalopia were maintained. Perimacular atrophy was not observed in the first eye treated with the previous viral vector. We observed areas of robust visual field improvement followed by perimacular atrophy in voretigene treated eyes, as compared to the initially treated contralateral eyes. Caution is advised when using two different viral vectors between eyes in gene therapy. This may become an important issue in the future with increasing gene therapy clinical trials for inherited retinal dystrophies.

Multicentric Longitudinal Prospective Study in a European Cohort of MYO7A Patients: Disease Course and Implications for Gene Therapy.

We investigated the natural history of retinal dystrophy owing to variants in the MYO7A gene. Fifty-three patients (mean age, 33.6 ± 16.7years) with Usher syndrome owing to biallelic, mostly pathogenic, variants in MYO7A underwent baseline and two annual follow-up visits. Best-corrected visual acuity (BCVA), semiautomatic kinetic visual field, full-field electroretinogram, color fundus imaging, microperimetry, spectral-domain optical coherence tomography, and fundus autofluorescence were assessed. At baseline, all patients presented with decreased BCVA (66.4 ± 17.9 Early Treatment Diabetic Retinopathy score and 59.5 ± 21.7 Early Treatment Diabetic Retinopathy score, in the better- and worse-seeing eyes, respectively), restricted semiautomatic kinetic visual field (III4e area, 3365.8 ± 4142.1°2; 4176.4 ± 4400.3°2) and decreased macular sensitivity (9.7 ± 9.9dB; 9.0 ± 10.2dB). Spectral-domain optical coherence tomography revealed reduced central macular thickness (259.6 ± 63.0µm; 250.7 ± 63.3µm) and narrowed ellipsoid zone band width (2807.5 ± 2374.6µm; 2615.5 ± 2370.4µm). Longitudinal analyses (50 patients) showed a significant decrease of BCVA in better-seeing eyes, whereas no changes were observed in worse-seeing eyes for any parameter. BCVA, semiautomatic kinetic visual field (III4e and V4e) and macular sensitivity were related significantly to age at baseline. Hyperautofluorescent foveal patch (16 eyes [31.4%]) and abnormal central hypoautofluorescence (9 eyes [17.6%]) were significantly associated with worse morphological and functional read-outs compared with the hyperautofluorescent ring pattern (22 eyes [43.1%]). Our European multicentric study offers the first prospective longitudinal analysis in one of the largest cohorts of MYO7A patients described to date, confirming the slow disease progression. More important, this study emphasizes the key role of fundus autofluorescence patterns in retinal impairment staging and advocates its adoption as an objective biomarker in patient selection for future gene therapy clinical trials.