Impact on bone microarchitecture and failure load in a patient with type I Gaucher disease who switched from Imiglucerase to Eliglustat

Long-term eliglustat treatment of Gaucher patients over up to 10 years in Vienna

Gaucher disease has been the first lysosomal storage disorder for which an enzyme replacement therapy has been approved in the 1990s and was the first to receive approval for a first-line substrate reduction therapy in 2015. Eliglustat treatment has been started in Austria in patients recruited to a clinical trial, followed by its long-term extension and prescription treatment overall covering up to 10 years. In this case series the experience of treating Gaucher patients with eliglustat in Vienna is summarized. Patients were either switched from enzyme replacement therapy or were therapy naïve. Significant improvements were shown in hematological (thrombocytes, hemoglobin) and visceral (spleen volume) manifestations as well as in biomarkers (chitotriosidase, glucosylsphingosine [lyso-GL1], angiotensin converting enzyme) in a routine setting in a therapy-naïve patient. Stability was found in switch patients with slight improvement in bone density. Eliglustat was generally very well tolerated. Patient selection and regular monitoring is required to ensure effective and safe use.

Advancing the Research and Development of Enzyme Replacement Therapies for Lysosomal Storage Diseases

With the increasing interest in developing gene therapies for rare diseases, it is easy to overlook that there are numerous rare lysosomal storage diseases (LSD) with treatments that have been approved by regulatory agencies in the United States and Europe. These primarily consist of enzyme replacement therapies (ERT), which are recombinant human proteins that are delivered for the life of the patient via different routes and may have distinct safety and distribution advantages over gene therapies. The research and development of ERT is a lengthy and expensive process, which is usually performed in academic laboratories before transfer to pharmaceutical companies and is hence a process ripe for disruption. There may still be considerable scientific and investment potential for ERT, however we need to develop a pipeline of proteins analogous to what has been created in some open science efforts as well as apply technologies to decrease manufacturing costs. In this Perspective, we illustrate the opportunity to fill the rare LSD treatment gap with ERTs while gene therapies are in development for these life-shortening diseases.

The clinical application of high-resolution peripheral computed tomography (HR-pQCT) in adults: state of the art and future directions

High-resolution peripheral computed tomography (HR-pQCT) was developed to image bone microarchitecture in vivo at peripheral skeletal sites. Since the introduction of HR-pQCT in 2005, clinical research to gain insight into pathophysiology of skeletal fragility and to improve prediction of fractures has grown. Meanwhile, the second-generation HR-pQCT device has been introduced, allowing novel applications such as hand joint imaging, assessment of subchondral bone and cartilage thickness in the knee, and distal radius fracture healing. This article provides an overview of the current clinical applications and guidance on interpretation of results, as well as future directions. Specifically, we provide an overview of (1) the differences and reference data for HR-pQCT variables by age, sex, and race/ethnicity; (2) fracture risk prediction using HR-pQCT; (3) the ability to monitor response of anti-osteoporosis therapy with HR-pQCT; (4) the use of HR-pQCT in patients with metabolic bone disorders and diseases leading to secondary osteoporosis; and (5) novel applications of HR-pQCT imaging. Finally, we summarize the status of the application of HR-pQCT in clinical practice and discuss future directions. From the clinical perspective, there are both challenges and opportunities for more widespread use of HR-pQCT. Assessment of bone microarchitecture by HR-pQCT improves fracture prediction in mostly normal or osteopenic elderly subjects beyond DXA of the hip, but the added value is marginal. The prospects of HR-pQCT in clinical practice need further study with respect to medication effects, metabolic bone disorders, rare bone diseases, and other applications such as hand joint imaging and fracture healing. The mostly unexplored potential may be the differentiation of patients with only moderately low BMD but severe microstructural deterioration, which would have important implications for the decision on therapeutical interventions.