The past, present, and future of enzyme-based therapies.

Enzyme-based therapeutics (EBTs) have the potential to tap into an almost unmeasurable amount of enzyme biodiversity and treat myriad conditions. Although EBTs were some of the first biologics used clinically, the rate of development of newer EBTs has lagged behind that of other biologics. Here, we review the history of EBTs, and discuss the state of each class of EBT, their potential clinical advantages, and the unique challenges to their development. Additionally, we discuss key remaining technical barriers that, if addressed, could increase the diversity and rate of the development of EBTs.

Update of treatment for mucopolysaccharidosis type III (sanfilippo syndrome).

Mucopolysaccharidosis III (Sanfilippo syndrome, MPS III) is caused by lysosomal enzyme deficiency, which is a rare autosomal recessive hereditary disease. For now, there is no approved treatment for MPS III despite lots of efforts providing new vision of its molecular basis, as well as governments providing regulatory and economic incentives to stimulate the development of specific therapies. Those efforts and incentives attract academic institutions and industry to provide potential therapies for MPS III, including enzyme replacement therapies, substrate reduction therapies, gene and cell therapies, and so on, which were discussed in this paper.

Enzyme therapy: a forerunner in catalyzing a healthy society?

INTRODUCTION: The use of enzymes in various industries has been prevalent for centuries. However, their potency as therapeutics remained latent until the late 1950 s, when scientists finally realized the gold mine they were sitting on. Enzyme therapy has seen rapid development over the past few decades and has been widely used for the therapy of myriad diseases, including lysosomal storage disorders, cancer, Alzheimer's disease, irritable bowel syndrome, exocrine pancreatic insufficiency, and hyperuricemia. Enzymes are also used for wound healing, the treatment of microbial infections, and gene therapy. AREAS COVERED: This is a comprehensive review of the therapeutic use of enzymes that can act as a guidepost for researchers and academicians and presents a general overview of the developments in enzyme therapy over the years, along with updates on recent advancements in enzyme therapy research. EXPERT OPINION: Although enzyme therapy is immensely beneficial and induces little auxiliary damage, it has several drawbacks, ranging from high cost, low stability, low production, and hyperimmune responses to the failure to cure a variety of the problems associated with a disease. Further fine-tuning and additional clinical efficacy studies are required to establish enzyme therapy as a forerunner to catalyzing a healthy society.

Comparison of recent pivotal recommendations for the diagnosis and treatment of late-onset Pompe disease using diagnostic nodes-the Pompe disease burden scale.

Pompe disease is a rare autosomal-recessive disorder characterised by limb-girdle myopathy and respiratory weakness in the late-onset form (LOPD). Various mutations in the acid alpha-glucosidase gene lead to toxic lysosomal and extra-lysosomal glycogen accumulation in all organs due to ineffective glycogen clearance by the encoded enzyme. Only one randomized trial demonstrated beneficial effects of respiratory function and meters walked in the 6-min walking test with enzyme replacement therapy (ERT). These results were confirmed in several retrospective and prospective observations and in meta-analyses. Due to a potential lifelong therapy, moderate efficacy and high treatment costs time of ERT initiation and cessation is an ongoing matter of debate. So far, several national and international recommendations have been published with different criteria concerning diagnosis, initiation and cessation of ERT in LOPD. We therefore formally analysed recent published recommendations and consensus statements of LOPD using diagnostic nodes (DODES) as a special software tool. With DODES, an objective analysis becomes possible if the content of the recommendations is represented as algorithms using cross-compatible elements. This analysis formally disclosed both, areas of great heterogeneity and concordance for the diagnosis and management of LOPD and paved the way for a Pompe disease burden scale focussing on ERT initiation. According to this investigation further clinical research should concentrate on ERT in pre-symptomatic and severely affected LOPD patients and on cessation criteria for ERT as these issues are areas of international uncertainty and discordance.

[Current status and future prospect of enzyme replacement therapy for Fabry disease].

Fabry disease is characterized by deficient activity of α-galactosidase A, which results in accumulation of glycolipids, such as globotriaosylceremide, in various tissue. Clinical symptoms are varied. In childhood, pain in extremities, hypohidrosis, and angiokeratoma are main symptoms, In adulthood, renal, cardiac and cerebrovascular symptoms are occurred In past, only symptomatic treatments were available. In early 2000th, enzyme replacement therapy was developed after positive results of clinical trials. Ten years after approval, the data of long term safety and efficacy of enzyme replacement.

Hot topics in Fabry disease.

Fabry disease is a rare inborn error of the enzyme α-galactosidase (α-Gal) and results in lysosomal substrate accumulation in tissues with a wide range of clinical presentations. The disease has attracted a lot of interest over the last years, in particular since enzyme replacement therapy (ERT) has become widely available in 2001. With rising awareness and rising numbers of (diagnosed) patients, physicians encounter new challenges. Over 900 α-Gal gene mutations are currently known, some with doubtful clinical significance, posing diagnostic and prognostic difficulties for the clinician and a lot of uncertainty for patients. Another challenge are patients who develop neutralising antibodies to ERT, which possibly leads to reduced therapy effectiveness. In this article, we summarise the latest developments in the science community regarding diagnostics and management of this rare lysosomal storage disorder and offer an outlook to future treatments.

Cardiac outcome in classic infantile Pompe disease after 13 years of treatment with recombinant human acid alpha-glucosidase.

BACKGROUND: Cardiac failure is the main cause of death in untreated classic infantile Pompe disease, an inheritable metabolic myopathy characterized by progressive hypertrophic cardiomyopathy. Since the introduction of enzyme replacement therapy (ERT), survival has increased significantly due to reduced cardiac hypertrophy and improved cardiac function. However, little is known about ERT's long-term effects on the heart. METHODS: Fourteen patients were included in this prospective study. Cardiac dimensions, function, conduction and rhythm disturbances were evaluated at baseline and at regular intervals thereafter. RESULTS: Treatment duration ranged from 1.1 to 13.9 years (median 4.8 years). At baseline, all patients had increased left ventricular mass index (LVMI) (median LVMI 226 g/m2, range 98 to 599 g/m2, Z-score median 7, range 2.4-12.4). During the first four weeks, LVMI continued to increase in six patients. Normalization of LVMI was observed in 13 patients (median 30 weeks; range 3 to 660 weeks). After clinical deterioration, LVMI increased again slightly in one patient. At baseline, PR interval was shortened in all patients; it normalized in only three. A delta-wave pattern on ECG was seen in six patients and resulted in documented periods of supraventricular tachycardias (SVTs) in three patients, two of whom required medication and/or ablation. One patient had severe bradycardia (35 beats/min). CONCLUSION: This study shows that ERT significantly reduced LVMI, and sustained this effect over a period of 13.9 years. The risk for rhythm disturbances remains. Regular cardiac evaluations should be continued, also after initially good response to ERT.

Emerging therapies for neuropathic lysosomal storage disorders.

Approximately 1 in 5000-8000 children are born annually with a lysosomal storage disease (LSD), which affects their cells' ability to break down naturally occurring substrates. Accumulation, or "storage," of undegraded substrates leads to a wide variety of clinical symptoms, and early mortality. Currently, for LSDs with central nervous system (CNS) involvement, there is no available treatment. Four methods of treatment are being explored in clinical trials and preclinical settings: enzyme replacement therapy, ex vivo gene therapy, in vivo gene therapy, and nanoparticle-based therapy. In general, each therapeutic approach has been hindered by an inability to cross the blood-brain barrier (BBB) without invasive intracranial surgeries. Also, once the treatment has entered the brain, it is difficult to ensure therapeutic levels of enzyme distributed evenly throughout the entire parenchyma. Enzyme replacement therapy (ERT) is the current standard of care for lysosomal diseases without CNS involvement. However, with the recent advent of nanoparticle-based therapy, direct targeting of either gene therapy or ERT to the brain has become plausible. Ex vivo gene therapy, in vivo gene therapy, ERT and nanoparticle-based therapies are explained, while synthesizing and analyzing their potential as clinical treatments targeted to the CNS. While difficulties in treating the entire brain remain, preclinical studies demonstrate profound therapeutic benefit in animal models and generate hope for successful translation to humans.

Treatment of Neurogenetic Developmental Conditions: From 2016 into the Future.

BACKGROUND: Neurogenetic developmental conditions represent a heterogeneous group of rare inherited disorders with neurological manifestation during development. Treatments for these conditions have largely been supportive; however, a number of treatments are emerging which target the underlying physiology and offer great potential. Our aim was to present a state-of-the-art overview of the current and potential causal treatments available or under development for neurogenetic developmental conditions. METHODS: In this review, we focus on the following neurogenetic developmental conditions: (1) inborn errors of metabolism causing neurogenetic developmental conditions, (2) fragile X syndrome, (3) Rett syndrome, (4) tuberous sclerosis complex, 5) Down syndrome and other neurogenetic developmental conditions. RESULTS: A large group of inborn errors of metabolism leads to neurodevelopmental disability, affecting the central nervous system during infancy or childhood and can present with comorbidities such as intellectual developmental disability, epilepsy, atypical cerebral palsy, autism spectrum disorder, behavioral and psychiatric disturbances, for which causal treatments are discussed. CONCLUSIONS: The advent of these new disease-modifying therapies has the potential to reverse the underlying neural mechanisms of these debilitating conditions, which may provide prospect to affected individuals.

Effectiveness of agalsidase alfa enzyme replacement in Fabry disease: cardiac outcomes after 10 years' treatment.

BACKGROUND: To explore long-term effects of agalsidase alfa on Fabry disease cardiomyopathy in adults. METHODS: Retrospective analysis of prospectively collected data at a single center in Mainz, Germany, revealed that 45 adult patients (21 men, 24 women) had received agalsidase alfa for approximately 10 years. Data were extracted for cardiac and heart failure status, echocardiographic evaluations of cardiac structure and function, and renal function at treatment start and during agalsidase alfa treatment. RESULTS: After 10 years of agalsidase alfa treatment, heart failure classification had improved by at least 1 class in 22/42 patients, and angina scores were stable or improved in 41/42 patients. During treatment, no patients without left ventricular hypertrophy (LVH) at treatment initiation developed LVH, and no patients with LVH at treatment initiation showed a decline in left ventricular mass. CONCLUSIONS: Approximately 10 years of agalsidase alfa treatment appeared to have beneficial effects for controlling progression and improving some symptoms of Fabry-associated cardiomyopathy.

Pancreatic enzyme replacement therapy for pancreatic exocrine insufficiency in the 21(st) century.

Restitution of normal fat absorption in exocrine pancreatic insufficiency remains an elusive goal. Although many patients achieve satisfactory clinical results with enzyme therapy, few experience normalization of fat absorption, and many, if not most, will require individualized therapy. Increasing the quantity of lipase administered rarely eliminates steatorrhea but increases the cost of therapy. Enteric coated enzyme microbead formulations tend to separate from nutrients in the stomach precluding coordinated emptying of enzymes and nutrients. Unprotected enzymes mix well and empty with nutrients but are inactivated at pH 4 or below. We describe approaches for improving the results of enzyme therapy including changing to, or adding, a different product, adding non-enteric coated enzymes, (e.g., giving unprotected enzymes at the start of the meal and acid-protected formulations later), use of antisecretory drugs and/or antacids, and changing the timing of enzyme administration. Because considerable lipid is emptied in the first postprandial hour, it is prudent to start therapy with enteric coated microbead prior to the meal so that some enzymes are available during that first hour. Patients with hyperacidity may benefit from adjuvant antisecretory therapy to reduce the duodenal acid load and possibly also sodium bicarbonate to prevent duodenal acidity. Comparative studies of clinical effectiveness of different formulations as well as the characteristics of dispersion, emptying, and dissolution of enteric-coated microspheres of different diameter and density are needed; many such studies have been completed but not yet made public. We discuss the history of pancreatic enzyme therapy and describe current use of modern preparations, approaches to overcoming unsatisfactory clinical responses, as well as studies needed to be able to provide reliably effective therapy.

Mitochondrial respiratory chain disorders in childhood: insights into diagnosis and management in the new era of genomic medicine.

BACKGROUND: Mitochondrial respiratory chain disorders (MRCDs) are some of the most common metabolic disorders presenting in childhood, however because of it clinical heterogeneity, diagnosis is often challenging. Being a multisystemic disorder with variable and non-specific presentations, definitive diagnosis requires a combination of investigative approaches, and is often a laborious process. SCOPE OF REVIEW: In this review we provide a broad overview of the clinical presentations of MRCDs in childhood, evaluating the different diagnostic approaches and treatment options, and highlighting the recent research advances in this area. MAJOR CONCLUSIONS: Extensive research over the years has significantly increased the frequency with which accurate diagnosis is being made, including the identification of new biomarkers and next generation sequencing (NGS) technologies. NGS has provided a breakthrough in unravelling the genetic basis of MRCDs, especially considering the complexity of mitochondrial genetics with its dual genetic contributions. GENERAL SIGNIFICANCE: With an increased understanding of the pathophysiology of this group of disorders, clinical trials are now being established using a number of different therapeutic approaches, with the hope of changing the focus of treatment from being largely supportive to potentially having a positive effect on the natural history of the disorder. This article is part of a Special Issue entitled: Special Issue: Frontiers of Mitochondria IG000218.

Treatment of lysosomal storage diseases: recent patents and future strategies.

Lysosomal storage diseases (LSDs) are a group of rare genetic multisystemic disorders, resulting in deficient lysosomal activity. These pathologies are characterized by progressive accumulation of storage material within the lysosomes, ultimately leading to organ dysfunctions. LSDs patient's clinical outcomes have significantly improved, since the advent of enzyme replacement therapy (ERT). ERT is approved worldwide for 6 LSDs: Gaucher disease, Fabry disease, Mucopolysaccharidosis types I, II, and VI, and Pompe disease. The efficacy and safety of ERT for LSDs has been confirmed by extensive clinical trials, however therapy with infused protein is life-long and disease progression is still observed in treated patients. Obstacles to successful ERT, such as immune reactions against the infused enzyme, miss-targeting of recombinant enzymes, and difficult delivery to crucial tissues (i.e. brain and bone), determine the need for further research, in order to ameliorate therapeutic strategies. Viral gene therapy, stem cell based therapy, pharmacological chaperones and could be considered essential tools for future improvement of recombinant enzyme trafficking and targeting. This review will discuss recent patents and new strategic approaches for enzyme delivery to highlight the most relevant aspects, concerning next generation LSDs treatment.

Familial LCAT deficiency: from renal replacement to enzyme replacement.

Familial LCAT deficiency (FLD) is a recessive lipid disorder ultimately leading to end-stage renal disease (ESRD). We present two brothers with considerable variation in the age at which they developed ESRD. Kidney biopsies revealed both tubular and glomerular pathology. To date, no causal therapy is available, yet enzyme replacement therapy is in development.

Clinical studies in lysosomal storage diseases: past, present and future.

Lysosomal storage disorders (LSDs) are made of over 40 diseases. Costly treatments have been developed. In this review, we consider the regulatory context in which LSDs studies are performed, and highlight design specificities and operational aspects. Orphan drug legislations in Europe and US were effective to stimulate LSDs drug development. However the flexibility of regulators to facilitate approval is inconsistent leading to worldwide differences in access to LSD treatments. Study designs are impacted because only few patients can be studied. This implies LSDs treatments need to demonstrate a large efficacy effect. Otherwise the level of evidence is difficult to demonstrate. While biomarkers could accelerate approvals, in LSDs none have been accepted as primary outcome of efficacy. Enrichment of study population can increase the chance of success, especially with clinical outcome. Adaptive designs are challenging. Innovative methods of analysis can be used, notably using a patient as his/her own control and responder analysis. Other characteristics include extension phases and patient registries to further data collection. Few patients are available per centers and more centers need to be initiated in multiple countries. This impacts time-lines and budget. For LSDs, development program should be individualized. Regulators flexibility will be essential to provide patients access to innovative treatments.

Challenges in diagnosis and treatment of late-onset Pompe disease.

PURPOSE OF REVIEW: The first reports published in 2010 on enzyme replacement therapy in late-onset Pompe disease (LOPD) allow us now to stand back and adapt the strategies. In the meantime, substantial progress has been made in basic and applied research on animal models to enhance the efficacy of treatments. This brief review highlights the new concepts in a contemporary approach. RECENT FINDINGS: Interest in LOPD rose since its acknowledgement as a treatable myopathy. New insights from extensive analysis of injurious mechanisms resulted, over the past years, in the development of enzyme replacement therapy and a better understanding of its limits. SUMMARY: It seems reasonable to consider Pompe disease as a large spectrum of a single ubiquitous lysosomal disease resulting from an enzyme defect, more severe in newborns because of rapid cardiopulmonary and hepatic failures, with a much better prognosis when symptomatic after 12 months. This late-onset form demands therapy to avoid progressive motor disability and pulmonary insufficiency. Diagnosis is easy to confirm through rapid and reliable biochemical tests with sampling of blood dots on filter paper. When started early, treatment would avoid serious irrevocable damage to cells. Increasing precocity of diagnosis and efficacy of treatments are the core challenges for the next few years.