Current and potential therapeutic strategies for mucopolysaccharidoses

Abstract

Summary What is known and objective Mucopolysaccharidoses (MPSs) are a group of rare inherited metabolic diseases caused by genetic defects in the production of lysosomal enzymes. MPSs are clinically heterogeneous and are characterized by progressive deterioration in visceral, skeletal and neurological functions. This article aims to review the classification and pathophysiology of MPSs and discuss current therapies and new targeted agents under development. Methods A Medline search through PubMed was performed for relevant articles and treatment guidelines on MPSs published in English for years 1970 to September of 2013 inclusive. The references listed in the identified articles, prescribing information of the drugs approved for the treatment of MPSs, as well as recent clinical trial information posted on Clinicaltrials.gov website, were reviewed. Results and discussion Until recently, supportive care was the only option available for the management of MPSs. In the early 2000s, enzyme replacement therapy (ERT) was approved by the United States Food and Drug Administration (FDA) for the treatment of MPS I, II and VI. Clinical trials of ERT showed substantial improvements in patients' somatic symptoms; however, no benefit was found in the neurological symptoms because the enzymes do not readily cross the blood–brain barrier (BBB). Haematopoietic stem cell transplantation (HSCT), another potentially curative treatment, is not routinely advocated in clinical practice due to its high risk profile and lack of evidence for efficacy, except in preserving cognition and prolonging survival in young patients with severe MPS I. In recent years, substrate reduction therapy (SRT) and gene therapy have been rapidly gaining greater recognition as potential therapeutic avenues. What is new and conclusion Enzyme replacement therapy (ERT) is effective for the treatment of many somatic symptoms, particularly walking ability and respiratory function, and remains the mainstay of MPS treatment. The usefulness of HSCT has not been established adequately for most MPSs. Although still under investigation, SRT and gene therapy are promising MPS treatments that may prevent the neurodegeneration not affected by ERT.

Survival in idursulfase‐treated and untreated patients with mucopolysaccharidosis type II: data from the Hunter Outcome Survey (HOS)

“…The multisystemic and progressive nature of MPS II means that a single cause of death is unlikely to reflect the full clinical picture in each patient. Nonetheless, the contribution of somatic aspects of disease to mortality is consistent with the positive impact of intravenous idursulfase on survival; approaches that aim to deliver therapeutic enzyme to the central nervous system are in development (Noh and Lee 2014;Muenzer et al 2016).…”

Social/economic costs and health-related quality of life of mucopolysaccharidosis patients and their caregivers in Europe

“…Since 2001, enzyme replacement therapies have been approved by the EMA for the treatment of MPS I (laronidase), II (idursulfase), IV (recombinant human n-acetylgalactosamine-6-sulfatase) and VI (galsulfase), resulting in substantial improvements in patients' somatic symptoms [10]. However, patients' access to costly new drugs varies geographically due to differences between national reimbursement schemes for orphan drugs [11][12][13].…”

Assessment and diagnosis of suspected glaucoma in patients with mucopolysaccharidosis

“…Clinical manifestations include dysmorphic facial features, cardiovascular and respiratory problems, musculoskeletal and neurological problems and intellectual impairment (Muenzer 2011;Fahnehjelm et al 2012a). Treatment such as enzyme replacement therapy (ERT), which is currently available for MPSI (Hurler), II (Hunter), IVa (Morquio) and VI (Maroteaux-Lamy), and haematopoietic stem cell transplantation (HSCT) for MPSI (Hurler) have been shown to improve some systemic parameters and increase the life span of patients with MPS (Noh & Lee 2014).…”