Bone density in Type 1 Gaucher disease

Imiglucerase, cholecalciferol, and bone-diet in skeletal health management of type I Gaucher disease patients: a pilot study and systematic review

Skeletal anomalies represent a characteristic feature of type 1 Gaucher disease (GD1). Here we evaluated the impact of an integrated therapy comprising enzyme-replacement therapy (ERT), cholecalciferol, and a normocalcemic-normocaloric-hyposodic diet (bone diet) on bone health in GD1 patients. We also performed a systematic review to compare our results with available data. From January 1, 2015 to February 28, 2019, all GD1 patients referred to Federico II University were enrolled and treated with the integrated therapy. Bone turnover markers and bone mineral density (BMD) were evaluated at baseline (T0) and after 24 months (T24). We enrolled 25 GD1 patients, all showing 25-hydroxy vitamin D (25OHD) levels < 50 nmol/l (hypovitaminosis D) at T0. Response to cholecalciferol treatment was effective, showing a direct relationship between 25OHD levels before and after treatment. At T0, 2 GD1 patients showed fragility fractures, 5 the Erlenmeyer flask deformity, 3 osteonecrosis, and 7 a BMD Z-score ≤ -2. Overall, GD1 patients with bone anomalies showed higher C-terminal telopeptide levels compared with those without bone anomalies. No new bone anomalies occurred during 2 years of follow-up. At T24, BMD remained stable across the entire study cohort, including in patients with bone anomalies. The systematic review showed that our study is the first that evaluated all bone health parameters. Hypovitaminosis D is prevalent in GD1 patients. The response to cholecalciferol treatment was effective but different to healthy subjects and in patients with metabolic bone disorders. Integrated therapy including ERT, cholecalciferol, and bone diet guarantees bone health.

Adult type I Gaucher disease with splenectomy caused by a compound heterozygous GBA1 mutation in a Chinese patient: a case report

Gaucher disease (GD) is an autosomal recessive ailment resulting from glucocerebrosidase deficiency caused by a mutation in the GBA1 gene, leading to multi-organ problems in the liver, spleen, and bone marrow. In China, GD is extremely uncommon and has a lower incidence rate than worldwide. In this study, we report the case of an adult male with an enlarged spleen for 13 years who presented with abdominal distension, severe loss of appetite and weight, reduction of the three-line due to hypersplenism, frequent nosebleeds, and bloody stools. Regrettably, the unexpected discovery of splenic pathology suggestive of splenic Gaucher disease was only made after a splenectomy due to a lack of knowledge about rare disorders. Our patient's delayed diagnosis may have been due to the department where he was originally treated, but it highlights the need for multidisciplinary consultation in splenomegaly of unknown etiology. We then investigated the patient's clinical phenotypes and gene mutation features using genetically phenotypical analysis. The analysis of the GBA1 gene sequence indicated that the patient carried a compound heterozygous mutation consisting of two potentially disease-causing mutations: c.907C > A (p. Leu303Ile) and c.1448 T > C (p. Leu483Pro). While previous research has linked the p. Leu483Pro mutation site to neurologic GD phenotypes (GD2 and GD3), the patients in this investigation were identified as having non-neuronopathic GD1. The other mutation, p. Leu303Ile, is a new GD-related mutation not indexed in PubMed that enriches the GBA1 gene mutation spectrum. Biosignature analysis has shown that both mutations alter the protein's three-dimensional structure, which may be a pathogenic mechanism for GD1 in this patient.

In-depth phenotyping for clinical stratification of Gaucher disease

BACKGROUND

The Gaucher Investigative Therapy Evaluation is a national clinical cohort of 250 patients aged 5-87 years with Gaucher disease in the United Kingdom-an ultra-rare genetic disorder. To inform clinical decision-making and improve pathophysiological understanding, we characterized the course of Gaucher disease and explored the influence of costly innovative medication and other interventions. Retrospective and prospective clinical, laboratory and radiological information including molecular analysis of the GBA1 gene and comprising > 2500 variables were collected systematically into a relational database with banking of collated biological samples in a central bioresource. Data for deep phenotyping and life-quality evaluation, including skeletal, visceral, haematological and neurological manifestations were recorded for a median of 17.3 years; the skeletal and neurological manifestations are the main focus of this study.

RESULTS

At baseline, 223 of the 250 patients were classified as type 1 Gaucher disease. Skeletal manifestations occurred in most patients in the cohort (131 of 201 specifically reported bone pain). Symptomatic osteonecrosis and fragility fractures occurred respectively in 76 and 37 of all 250 patients and the first osseous events occurred significantly earlier in those with neuronopathic disease. Intensive phenotyping in a subgroup of 40 patients originally considered to have only systemic features, revealed neurological involvement in 18: two had Parkinson disease and 16 had clinical signs compatible with neuronopathic Gaucher disease-indicating a greater than expected prevalence of neurological features. Analysis of longitudinal real-world data enabled Gaucher disease to be stratified with respect to advanced therapies and splenectomy. Splenectomy was associated with an increased hazard of fragility fractures, in addition to osteonecrosis and orthopaedic surgery; there were marked gender differences in fracture risk over time since splenectomy. Skeletal disease was a heavy burden of illness, especially where access to specific therapy was delayed and in patients requiring orthopaedic surgery.

CONCLUSION

Gaucher disease has been explored using real-world data obtained in an era of therapeutic transformation. Introduction of advanced therapies and repeated longitudinal measures enabled this heterogeneous condition to be stratified into obvious clinical endotypes. The study reveals diverse and changing phenotypic manifestations with systemic, skeletal and neurological disease as inter-related sources of disability.

Correction of pathology in mice displaying Gaucher disease type 1 by a clinically-applicable lentiviral vector

Gaucher disease type 1 (GD1) is an inherited lysosomal disorder with multisystemic effects in patients. Hallmark symptoms include hepatosplenomegaly, cytopenias, and bone disease with varying degrees of severity. Mutations in a single gene, glucosidase beta acid 1 (GBA1), are the underlying cause for the disorder, resulting in insufficient activity of the enzyme glucocerebrosidase, which in turn leads to a progressive accumulation of the lipid component glucocerebroside. In this study, we treat mice with signs consistent with GD1, with hematopoietic stem/progenitor cells transduced with a lentiviral vector containing an RNA transcript that, after reverse transcription, results in codon-optimized cDNA that, upon its integration into the genome encodes for functional human glucocerebrosidase. Five months after gene transfer, a highly significant reduction in glucocerebroside accumulation with subsequent reversal of hepatosplenomegaly, restoration of blood parameters, and a tendency of increased bone mass and density was evident in vector-treated mice compared to non-treated controls. Furthermore, histopathology revealed a prominent reduction of Gaucher cell infiltration after gene therapy. The vector displayed an oligoclonal distribution pattern but with no sign of vector-induced clonal dominance and a typical lentiviral vector integration profile. Cumulatively, our findings support the initiation of the first clinical trial for GD1 using the lentiviral vector described here.

The International Collaborative Gaucher Group GRAF (Gaucher Risk Assessment for Fracture) score: a composite risk score for assessing adult fracture risk in imiglucerase-treated Gaucher disease type 1 patients

Background

Fractures in Gaucher disease type 1 (GD1) patients cause significant morbidity. Fracture risk may be decreased by enzyme replacement therapy (ERT) but not eliminated. When considering initiation of treatment, it is useful to know to what extent fixed patient-specific factors determine risk for future fractures beyond standard risk factors that change with time and treatment, such as decreased bone mineral density. We developed a tool called the GRAF score (Gaucher Risk Assessment for Fracture) that applies 5 widely available characteristics (sex, age at treatment initiation [ATI], time interval between diagnosis and treatment initiation, splenectomy status, history of pre-treatment bone crisis) and provides a practical method to assess future fracture risk when imiglucerase ERT is initiated.

Methods

Inclusion criteria: GD1 patients in the International Collaborative Gaucher Group Gaucher Registry as of September 2019 initially treated with alglucerase/imiglucerase; known splenectomy status; at least one skeletal assessment on treatment (3216 of 6422 patients). Data were analyzed by ATI group (< 18, ≥ 18 to < 50, or ≥ 50 years of age) using Cox proportional hazards regression with all 5 risk factors included in the multivariable model. A composite risk score was calculated by summing the contribution of each parameter weighted by the strength of its association (regression coefficient) with fracture risk.

Results

Patients were followed from the date of treatment initiation (or age 18 years for patients if treatment started earlier) to the date of first adult fracture (n = 288 first fracture endpoints), death, or end of follow-up. The GRAF score for each ATI group was associated with a 2.7-fold increased risk of adult fracture for each one-point increase (p < 0.02 for < 18 ATI, p < 0.0001 for ≥ 18 to < 50 ATI and ≥ 50 ATI).

Conclusions

The GRAF score is a tool to be used with bone density and other modifiable, non-GD-specific risk factors (e.g. smoking, alcohol intake, frailty) to inform physicians and previously untreated GD1 patients about risk for a future fracture after starting imiglucerase regardless of whether there is an eventual switch to an alternative ERT or to substrate reduction therapy. GRAF can also help predict the extent that fracture risk increases if initiation of treatment is further delayed.

Imaging of non-neuronopathic Gaucher disease: recent advances in quantitative imaging and comprehensive assessment of disease involvement

Gaucher disease is an inherited metabolic disorder resulting in deficiency of lysosomal enzyme β-glucocerebrosidase causing the accumulation of abnormal macrophages (“Gaucher cells”) within multiple organs, most conspicuously affecting the liver, spleen, and bone marrow. As the most common glycolipid metabolism disorder, it is important for radiologists encountering these patients to be familiar with advances in imaging of organ and bone marrow involvement and understand the role of imaging in clinical decision-making. The recent advent of commercially available, reliable, and reproducible quantitative MRI acquisitions to measure fat fractions prompts revisiting the role of quantitative assessment of bone marrow involvement. This manuscript reviews the diverse imaging manifestations of Gaucher disease and discusses more optimal quantitative approaches to ascertain solid organ and bone marrow involvement with an emphasis on future applications of other quantitative methods including elastography.

Gaucher Disease in Bone: From Pathophysiology to Practice

Gaucher disease (GD) is a rare, genetic lysosomal disorder leading to lipid accumulation and dysfunction in multiple organs. Involvement of the skeleton is one of the most prevalent aspects of GD and a major cause of pain, disability, and reduced quality of life. Uniform recommendations for contemporary evaluation and management are needed. To develop practical clinical recommendations, an international group of experienced physicians conducted a comprehensive review of 20 years' of the literature, defining terms according to pathophysiological understanding and pointing out best practice and unmet needs related to the skeletal features of this disorder. Abnormalities of bone modeling, reduced bone density, bone infarction, and plasma cell dyscrasias accompany the displacement of healthy adipocytes in adult marrow. Exposure to excess bioactive glycosphingolipids appears to affect hematopoiesis and the balance of osteoblast and osteoclast numbers and activity. Imbalance between bone formation and breakdown induces disordered trabecular and cortical bone modeling, cortical bone thinning, fragility fractures, and osteolytic lesions. Regular assessment of bone mineral density, marrow infiltration, the axial skeleton and searching for potential malignancy are recommended. MRI is valuable for monitoring skeletal involvement: It provides semiquantitative assessment of marrow infiltration and the degree of bone infarction. When MRI is not available, monitoring of painful acute bone crises and osteonecrosis by plain X-ray has limited value. In adult patients, we recommend DXA of the lumbar spine and left and right hips, with careful protocols designed to exclude focal disease; serial follow-up should be done using the same standardized instrument. Skeletal health may be improved by common measures, including adequate calcium and vitamin D and management of pain and orthopedic complications. Prompt initiation of specific therapy for GD is crucial to optimizing outcomes and preventing irreversible skeletal complications. Investing in safe, clinically useful, and better predictive methods for determining bone integrity and fracture risk remains a need. © 2019 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Bone manifestations in neuronopathic Gaucher disease while receiving high-dose enzyme replacement therapy

Avascular necrosis (AVN), one type of bone infarction, is a major irreversible complication of Gaucher disease (GD). In this report, two pediatric patients with GD type 3, homozygous for the L483P pathogenic variant (formerly L444P), developed AVN despite treatment on long-term, high-dose enzyme replacement therapy (ERT). ERT was initiated in both patients, who had intact spleens, shortly after diagnosis with an initial dramatic response. However, both patients exhibited AVN after 5.5 and 11 years on high-dose ERT, respectively, despite good compliance and normalized hematological findings and visceral symptoms. This report demonstrates the importance of careful, regular surveillance of the musculoskeletal system in addition to monitoring the neurological symptoms associated with neuronopathic GD. Additionally, it highlights the limitations of ERT in terms of targeting certain sanctuary sites such as bone marrow and suggests the need for new treatment modalities other than ERT monotherapy to address these limitations.

Assessment of Bone Health in Patients With Type 1 Gaucher Disease Using Impact Microindentation

Gaucher disease (GD), one of the most common lysosomal disorders (a global population incidence of 1:50,000), is characterized by beta-glucocerebrosidase deficiency. Some studies have demonstrated bone infiltration in up to 80% of patients, even if asymptomatic. Bone disorder remains the main cause of morbidity in these patients, along with osteoporosis, avascular necrosis, and bone infarcts. Enzyme replacement therapy (ERT) has been shown to improve these symptoms. This cross-sectional study included patients with type 1 Gaucher disease (GD1) selected from the Catalan Study Group on GD. Clinical data were collected and a general laboratory workup was performed. Bone mineral density (BMD) was measured at the lumbar spine and hip using dual-energy X-ray absorptiometry (DXA). Patients with bone infarcts or any other focal lesion in the area of indentation visible on imaging were excluded. Bone Material Strength index (BMSi) was measured by bone impact microindentation using an Osteoprobe instrument. Analysis of covariance (ANCOVA) models were fitted to adjust for age, sex, weight, and height. Sixteen patients with GD1 and 29 age- and sex-matched controls were included. GD1 was associated with significantly lower BMSi (adjusted beta -9.30; 95% CI, -15.18 to -3.42; p = 0.004) and reduced lumbar BMD (adjusted beta -0.14; 95% CI, -0.22 to -0.06; p = 0.002) and total hip BMD (adjusted beta -0.09; 95% CI, -0.15 to -0.03; p = 0.006), compared to GD1-free controls. Chitotriosidase levels were negatively correlated with BMSi (linear R²  = 51.6%, p = 0.004). Bone tissue mechanical characteristics were deteriorated in patients with GD1. BMSi was correlated with chitotriosidase, the marker of GD activity. Bone disorder requires special consideration in this group of patients, and microindentation could be an appropriate tool for assessing and managing their bone health. © 2017 American Society for Bone and Mineral Research.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

Clinical manifestations and management of Gaucher disease

Gaucher disease is a rare multi-systemic metabolic disorder caused by the inherited deficiency of the lysosomal enzyme β-glucocerebrosidase, which leads to the accumulation of its normal substrate, glucocerebroside, in tissue macrophages with damage to haematological, visceral and bone systems. Anaemia, thrombocytopenia, enlargement of liver and/or spleen, skeletal abnormalities (osteopenia, lytic lesions, pathological fractures, chronic bone pain, bone crisis, bone infarcts, osteonecrosis and skeletal deformities) are typical manifestations of the most prevalent form of the disease, the so-called non-neuronopathic type 1. However, severity and coexistence of different symptoms are highly variable. The determination of deficient β-glucocerebrosidase activity in leukocytes or fibroblasts by enzymatic assay is the gold standard for the diagnosis of Gaucher disease. Comprehensive and reproducible evaluation and monitoring of all clinically relevant aspects are fundamental for the effective management of Gaucher disease patients. Enzyme replacement therapy has been shown to be effective in reducing glucocerebroside storage burden and diminishing the deleterious effects caused by its accumulation. Tailored treatment plan for each patient should be directed to symptom relief, general improvement of quality of life, and prevention of irreversible damage.

Gaucher disease: the role of the specialist on metabolic bone diseases

According to European legislation, a disease can be considered rare or "orphan" when it affects less than 1 subject of 2000 (1). Often these diseases affecting the pediatric age, are complex diseases and chronically debilitating and for this motive need the intervention of multidisciplinary skills specific. Among the rare disease as affecting the skeleton more than 400 are characterized by dysplastic changes of the skeleton (2). Alongside the disorders affecting the skeleton primitively, many systemic diseases can have a bone involvement. Among these, the Gaucher disease (GD), an heterogeneous lysosomal storage determined by hereditary enzyme deficiency of β-glucosidase. Patients with this disease have skeletal disorders of varying severity (Erlenmeyer flask deformity, lytic lesions and osteonecrosis, pathological fractures) that affects both the bone marrow, both mineralized bone with progressive damage of the tissue. The bone disease is the most debilitating of GD and can have a significant impact on the quality of life of patients. Thorough evaluations by monitoring biochemical markers of bone turnover and instrumental, with a quantitative and qualitative evaluation of the bone, are of fundamental importance to intervene early so they can prevent complications irreversible.

Gaucher disease and bone manifestations

Gaucher disease is a relatively rare metabolic disease caused by the inherited deficiency of the lysosomal enzyme glucocerebrosidase. Gaucher disease affects multiple organs, among which is the skeleton. Bone involvement occurs frequently in Gaucher disease, and is one of its most debilitating features, reducing the quality of life of patients. Bone status is an important consideration for treatment to ameliorate symptoms and reduce the risk of irreversible complications. We have conducted a systematic review of all the various aspects of Gaucher disease, focusing on different skeletal manifestations, pathophysiology of bone alterations, clinical symptoms, and current diagnostic and therapeutic approaches.

Enhanced differentiation of osteoclasts from mononuclear precursors in patients with Gaucher disease

Gaucher disease (GD) is an autosomal recessive disorder caused by deficiency of β-glucocerebrosidase. Storage of glucosylceramide in reticuloendothelial cells results in multiorgan pathology including bone disease. Established skeletal disease may remain problematic despite Gaucher-specific treatment. Both osteopenia and osteonecrosis have been described but the underlying pathophysiology, in particular the role of monocyte-derived osteoclasts is not well defined. The objective of this study was to explore the effect of glucocerebrosidase deficiency, inhibition and replacement on osteoclast development and function. In cultures derived from GD patients, or where GBA was chemically inhibited multinucleate giant cells expressing markers of osteoclast differentiation occurred earlier and in greater numbers compared to normal controls and the functional capacity of osteoclasts for bone resorption was enhanced. Increases in osteoclast number and activity correlated with radiological markers of active bone disease. Abnormalities were reversed by addition of specific therapies and were attenuated by co-culture with cells derived from healthy controls (HCs). Numbers of osteoblast lineage cells in the peripheral blood were mismatched to osteoclast precursors indicating uncoupling of osteoblast-osteoclast regulation which may further impact on bone remodelling. Elucidation of the underlying mechanisms of these changes will suggest rational therapies for the most disabling aspect of this condition.

Morbidity and mortality in type B Niemann-Pick disease

PURPOSE

The purpose of this study was to perform a systematic evaluation of morbidity and mortality in type B Niemann-Pick disease.

METHODS

A total of 103 patients with Niemann-Pick disease (49 males, 54 females, age range: 1-72 years) participated in natural history studies through Mount Sinai's International Center for Types A and B Niemann-Pick Disease between 1992 and 2012.

RESULTS

Serious morbidities included significant neurological, hepatic, and cardiac disease. Thirteen patients had some degree of neurological impairment. Nine patients had cirrhosis or liver failure requiring transplantation. Coronary artery and valvular heart disease were present in nine patients. Of note, only four patients were oxygen dependent, although progressive pulmonary disease is a well-described feature of Niemann-Pick disease. During the follow-up period, 18 deaths occurred. The median age of death was 15.5 years (range 1-72). Causes of death included pneumonia, liver failure, and hemorrhage. The majority of deaths (12 of 18) occurred in patients <21 years, yielding a mortality rate of 19% in the pediatric population.

CONCLUSION

This study demonstrates that Niemann-Pick disease is a life-threatening disorder with significant morbidity and mortality, especially in the pediatric population. The information collected in this series highlights the need for safe, effective therapy for Niemann-Pick disease.

Long-term bone mineral density response to enzyme replacement therapy in a retrospective pediatric cohort of Gaucher patients

Osteopenia is described as a relevant sign of bone involvement in Gaucher disease (GD) both in pediatric and adult patients. Furthermore, abnormal bone metabolism is considered to play a role in growth and pubertal delay. To analyze the long-term effect of enzyme replacement therapy (ERT) on bone mineral density (BMD), a retrospective observational study was conducted in a cohort of 18 GD pediatric patients (13 males, 5 females; median age 9.2 years). They received biweekly infusions of 20-60 IU/kg of alglucerase/imiglucerase. Clinical, laboratory and imaging parameters were evaluated every 2 years. According to the International Society of Clinical Densitometry guidelines, a Z-score ≤ -2.0 was considered pathological. Nine patients (group P0) began ERT during infancy and nine (group P1) during puberty. At baseline, in three patients (16.6 %; 1P0, 2P1) Z-score was ≤ -2.0 (range -2.47 to -2.25). In patient P0 it normalized after 2 years, while in the 2P1 patients (splenectomized siblings) it persisted abnormal. The remaining 15 patients (83.4 %) always presented a normal value. In group P0, Z-score improved in infancy but showed a significant decrease during puberty, on the contrary it constantly improved in group P1. Furthermore, at baseline group P0 showed a higher median Z-score than group P1: 0.79 (0.38; 1.50) and -1.61 (-2.25; -1.56) respectively. The use of correct BMD standards to interpret bone loss during pediatric age suggests a limited significance of bone loss in these patients. Moreover, the persistence of residual disease activity may affect normal bone growth during puberty in GD populations.

Minimal disease activity in Gaucher disease: criteria for definition

Gaucher disease type I is a metabolic disorder caused by a genetic deficiency of lysosomal β-glucocerebrosidase that leads to accumulation of glucocerebroside in macrophages, thus causing damage in different organ systems. Enzyme replacement therapy with imiglucerase improves organ impairment and clinical manifestations, but patients differ in response to treatment. While clinical remission is the most desirable therapeutic outcome, a more realistic goal in patients with high disease burden is reasonably good clinical status despite persistence of residual biochemical or imaging abnormalities. Therefore, the concept of minimal disease activity--used in certain haematological or rheumatologic conditions--needs to be introduced in Gaucher disease, with a level of disease activity that patients and physicians consider a useful treatment target. In this paper, we propose specific parameters and criteria for defining minimal disease activity in Gaucher disease and its stability over time, based on three major systemic domains typically involved: haematological, visceral, and skeletal. Biomarker parameters were not included as criteria, because currently they do not adequately reflect disease evolution in individual patients. Neurological and respiratory domains were also excluded, as their involvement per se indicates severe disease unlikely to respond to enzyme replacement therapy and achieve minimal disease status. Our goal in defining minimal disease activity and stability is to identify a tool to facilitate treatment decisions in clinical practice.

Risk factors for fractures and avascular osteonecrosis in type 1 Gaucher disease: a study from the International Collaborative Gaucher Group (ICGG) Gaucher Registry

We hypothesized that overall disease activity or the severity of involvement of individual disease compartments, as measured by clinical and surrogate markers, predict the risk of avascular osteonecrosis (AVN) or fractures in type 1 Gaucher disease (GD1). We applied our risk-set matched case-control method to identify four patient groups within the International Collaborative Gaucher Group (ICGG) Gaucher Registry based on the presence and absence of AVN and fractures. Characteristics of GD1 were examined by comparing the distributions of each risk factor in cases versus matched controls using conditional logistic regression to calculate adjusted odds ratios (OR). Potential risk factors included hematological and visceral parameters, GD1 biomarkers, white blood cells, GBA1 genotype, and spine and femur dual-energy X-ray absorptiometry (DXA) Z-scores. In the total population of 5894 ICGG Gaucher Registry patients, 544 experienced at least one episode of AVN; 2008 reported no history of AVN. Clinical and surrogate markers of disease activity were similar in patients with and without AVN; patients with AVN were 1.6 times more likely to be anemic compared to matched controls (OR = 1.59; 95% confidence interval [CI], 1.06-2.38, p < 0.05). For fractures, 319 patients suffered fractures and 1233 had no prior history of fractures. Clinical and surrogate markers of disease in patients with and without fractures were similar, except for mean lumbar spine DXA Z-scores. Among patients with fractures, 49.3% had DXA Z-scores ≤ -1 compared to 31.0% in the control group. Compared to controls with Z-scores > -1.0, GD1 patients exhibiting Z-scores ≤ -1 had an OR of 5.55 (95% CI, 1.81-17.02, p < 0.01) for fracture. In GD1, after controlling for gender, year of birth, treatment status, and splenectomy status, we identified new risk factors for AVN and fractures. Concurrent anemia was associated with an increased risk for AVN. Low bone mineral density of the lumbar spine was a strong risk factor for fractures of the spine and femur in GD1.

Miscellaneous non-inflammatory musculoskeletal conditions. Gaucher disease and bone

Gaucher disease (GD) is an inherited lysosomal storage disorder affecting multiple organs. Non-neuronopathic GD, the most common form, can present with hepatosplenomegaly, anaemia, bleeding tendencies, thrombocytopenia, skeletal pathologies, growth retardation and, in severe cases, with pulmonary disease. The bone manifestations include bone infarcts, avascular bone necrosis, lytic lesions, osteosclerosis, fractures due to osteoporosis and, rarely, acute osteomyelitis. Bone pain of varying intensity, fractures and joint collapses increase the patients' morbidity and impair their mobility and quality of life. Currently available therapies - enzyme replacement therapy and substrate reduction therapy - have shown to improve blood count and the visceral manifestations within a short time. Beneficial effects have also been documented on bone pain, bone crises and the extent of osteoporosis. The article focusses on the bone pathologies of GD including its pathophysiology, current diagnostics, clinical management and therapeutic effects of enzyme replacement therapy, substrate reduction therapy and bone-specific therapies.

Therapeutic approaches to bone pathology in Gaucher disease: past, present and future

Enzyme replacement therapy (ERT) is effective for the treatment of the systemic manifestations of Gaucher disease (GD) and can have a significant impact on skeletal manifestations. Bone involvement is broad and can occur in otherwise clinically asymptomatic individuals. The heterogeneity in GD-related bone disease may implicate multiple pathological processes such as disruption of coordinated bone cell activity, in addition to the physical impact of Gaucher cells causing vascular occlusion. Accumulated data suggests that earlier treatment initiation decreases skeletal complications and that bone disease may require a longer duration of treatment and higher dose than is necessary for organ involvement and hematopoietic manifestations. However, in some patients, bone manifestations persist and even worsen despite ERT, regardless of dose or duration of treatment. Treating skeletal disease should be considered of equal importance as treating visceral and hematologic manifestations. When treatment decisions involve multiple enzyme preparations and other therapeutic modalities such small molecules, the choice should be tailored on an individual basis with continuing evaluation.

Radiological aspects of Gaucher disease

Advances in imaging and the development of commercially available enzyme therapy have significantly altered the traditional radiology of Gaucher disease. The cost of treatment and need for monitoring response to therapy have magnified the importance of imaging. There are no recent comprehensive reviews of the radiology of this relatively common lysosomal storage disease. This article describes the modern imaging, techniques and radiological manifestations of Gaucher disease.

Osseous manifestations of adult Gaucher disease in the era of enzyme replacement therapy

Enzyme replacement therapy (ERT) for Gaucher disease with mannose-terminated glucocerebrosidase has proved its therapeutic position with salutary effects on hematologic abnormalities, visceral infiltration, and quality of life. The frequency of new bone complications is reduced but not eliminated. Established osteonecrosis is beyond salvage. A systematic description of the burden of bone manifestations, persisting despite ERT, should inform future remedial strategies. Thus, we conducted this study to quantify the burden of residual skeletal disease and to explore putative relationships between clinical, radiologic, and biochemical factors and bone sequelae associated with disability.Consecutive adult patients attending 3 referral centers in the United Kingdom were invited to participate. A representative group of 100 patients agreed to a structured interview, clinical examination, radiologic review, and completion of questionnaires. Osteonecrosis was evident in 43%, Erlenmeyer flask deformity in 59%, fragility fracture in 28%, osteomyelitis in 6%, and lytic lesions in 4%. Mobility was impaired in 32% of patients, while 15% experienced significant pain. The EuroQol 5D (EQ5D) quality of life summary measure was reduced and was associated with osteonecrosis and fragility fracture. Eight patients experienced new osteonecrosis after the start of ERT, though the presentation and evolution were often atypical. Nine patients had been treated from childhood and had an excellent outcome. Osteonecrosis was associated with age of presentation and with splenectomy-indeed, we observed a strong temporal association between splenectomy and incidence of osteonecrosis.The biomarkers PARC/CCL18 and chitotriosidase were associated with prevalent osteonecrosis, and, in particular, with osteonecrosis occurring despite treatment. This study documents significant residual skeletal pathology and disability in patients in the mature phase of their treatment in a developed region. The temporal association between splenectomy and osteonecrosis implies causation. The relationship between clinical and biochemical markers and existing bone complications sets the scene for future prospective studies that will focus on management strategies informed by credible assessment of risk.

Osteopenia in Gaucher disease develops early in life: response to imiglucerase enzyme therapy in children, adolescents and adults

BACKGROUND

In Gaucher disease (GD), acid-β-glucosidase (GBA1) gene mutations result in defective glucocerebrosidase and variable combinations of hematological, visceral, and diverse bone disease. Osteopenia is highly prevalent, but its age of onset during the natural course of GD is not known. It is also unclear if the degree of improvement in osteopenia, secondary to imiglucerase enzyme therapy, differs by the age of the patient.

OBJECTIVE

We hypothesized that osteopenia develops early in life, during the natural course of type 1 Gaucher disease (GD1), and that its response to treatment is maximal during this period.

METHODS

We examined data from the International Collaborative Gaucher Group (ICGG) Gaucher Registry of patients treated with imiglucerase between the ages of 5 and 50 years. Lumbar spine bone mineral density (BMD) (determined by dual-energy X-ray absorptiometry (DXA) and expressed as Z-scores) at baseline and for up to 10 years on imiglucerase were analyzed in children (ages ≥ 5 to <12 years), adolescents (≥ 12 to <20 years), young adults (≥ 20 to < 30 years), and older adults (≥ 30 to < 50 years). BMD was correlated with other disease characteristics. Pre-treatment, descriptive statistics were applied to 5-year age categories. Non-linear mixed effects regression models were used to analyze DXA Z-scores over time after treatment with imiglucerase.

RESULTS

Pre-treatment, low BMD was prevalent in all age groups, most strikingly in adolescents. DXA Z-scores were at or below -1 in 44% of children (n=43), 76% of adolescents (n=41), 54% of young adults (n=56) and 52% of older adults (n=171). The most common GBA1 genotype was N370S heteroallelic. Baseline hematological and visceral manifestations in the 4 age groups were similar. In children with DXA Z-scores ≤-1 at baseline, imiglucerase therapy for 6 years resulted in improvement of mean DXA Z-scores from -1.38 (95% CI -1.73 to -1.03) to -0.73 (95% CI -1.25 to -0.21); in young adults DXA Z-scores improved from -1.95 (95% CI -2.26 to -1.64) to -0.67 (95% CI -1.09 to -0.26). BMD also improved in older adults, but the magnitude of the improvement was lower compared to younger patients.

CONCLUSIONS

Low bone density is common in GD1 with the highest prevalence rate in adolescence, a developmental period critical to attainment of peak bone mass. Imiglucerase results in amelioration of osteopenia in all age groups, with the greatest improvements in younger patients.

Therapeutic approaches for lysosomal storage diseases

The lysosomal storage disorders (LSDs) comprise a heterogeneous group of inborn errors of metabolism characterized by tissue substrate deposits, most often caused by a deficiency of the enzyme normally responsible for catabolism of various byproducts of cellular turnover. Individual entities are typified by involvement of multiple body organs, in a pattern reflecting the sites of substrate storage. It is increasingly recognized that one or more processes, such as aberrant inflammation, dysregulation of apoptosis and/or defects of autophagy, may mediate organ dysfunction or failure. Several therapeutic options for various LSDs have been introduced, including hematopoietic stem cell transplantation, enzyme replacement therapy and substrate reduction therapy. Additional strategies are being explored, including the use of pharmacological chaperones and gene therapy. Most LSDs include a variant characterized by primary central nervous system (CNS) involvement. At present, therapy of the CNS manifestations remains a major challenge because of the inability to deliver therapeutic agents across the intact blood-brain barrier. With improved understanding of underlying disease mechanisms, additional therapeutic options may be developed, complemented by various strategies to deliver the therapeutic agent(s) to recalcitrant sites of pathology such as brain, bones and lungs.

Bone and joint involvement in Fabry disease

Fabry disease (FD) is an X-linked lysosomal storage disease caused by deficient activity of the enzyme alpha-galactosidase A. Although the disease has progressive effects on most organ systems in the body, data is limited regarding skeletal involvement in this rare disorder. We describe four family-related patients, three men and one premenopausal female, sharing a classic phenotype of FD. Dual-energy X-ray was performed in all cases and osteoporosis or osteopenia were found in all patients and osteoporotic fractures in one. One patient also showed both neuropathic joint disease and osteonecrosis. Several mechanisms that may explain osteoporosis and osteoarthropathy in the setting of FD are emphasized.

Goal-oriented therapy with miglustat in Gaucher disease

BACKGROUND

Gaucher disease (GD) is a highly heterogeneous disorder with multisystem involvement. Specific therapeutic goals for each manifestation of type 1 GD (GD1) were established in 2004 by an international panel of experts, to facilitate better management of GD1 patients. The goals were defined based on experience with enzyme replacement therapy (ERT) using imiglucerase. Miglustat, a small iminosugar, is the only commercially available substrate reduction therapy (SRT) for patients with GD1. Several clinical studies have demonstrated the beneficial effects of miglustat on cardinal disease manifestations of GD1.

OBJECTIVE

To review the currently available data on miglustat, and provide guidance on the attainment of the GD therapeutic goals with miglustat therapy.

METHODS

A literature search identified publications on miglustat using MEDLINE, HighWire Press, and Google Scholar databases. Articles were identified using the terms 'miglustat' and 'Gaucher disease type 1'.

FINDINGS

Improvements in hematological manifestations and organomegaly can be expected with miglustat therapy, with disease stabilization achievable over the long term. Recent data suggest that miglustat can maintain stability in patients with mild to moderate GD1 who have been previously treated with ERT. Miglustat may be beneficial with regards to bone manifestations, with reduction in the incidence of patients reporting bone pain and improvements in bone mineral density seen within the first 24 months of therapy.

CONCLUSIONS

Several of the therapeutic goals for patients with GD1 can be achieved with miglustat therapy. In select cases, miglustat can be considered an alternative to ERT for the treatment of patients with GD1. Long-term experience with the use of miglustat will help define its overall safety and efficacy; this information will be useful in determining the role of SRT using miglustat in the management of the general adult GD1 patient population.

Management of non-neuronopathic Gaucher disease with special reference to pregnancy, splenectomy, bisphosphonate therapy, use of biomarkers and bone disease monitoring

Enzyme replacement was introduced as treatment for non-neuronopathic Gaucher disease more than 15 years ago. To ensure the best use of this costly ultra-orphan agent, a systematic disease management approach has been proposed by an international panel; this includes the development, by consensus, of achievable treatment goals. Here we critically review these goals and monitoring guidelines and incorporate emerging experience of the disease in the therapeutic era, as well as contemporary clinical research. This review makes recommendations related specifically to the management of pregnancy; the appropriate use of splenectomy and bisphosphonate treatment; the relevance of biochemical markers to disease monitoring; and the use of semi-quantitative methods for assessing bone marrow infiltration. In addition, we identify key areas for development, including the requirement for a validated index of disease severity; the need to correlate widely used biomarkers with long-term disease outcomes, and the desirability of establishing agreed standards for monitoring of bone disease particularly in infants and children with Gaucher disease.

Osteopenia: a common aspect of Fabry disease. Predictors of bone mineral density

PURPOSE

We investigated the bone mineral status in patients with untreated Fabry disease (FD).

METHODS

Descriptive, cross-sectional study in 53 patients with FD investigating bone mineral density (BMD)/content (dual energy x-ray absorptiometry scan), bone metabolism (parathyroid hormone, osteocalcin, and insulin-like growth factor I), and renal function (ethylene diamine tetraacetic acid clearance).

RESULTS

Mean BMD z score at the lumbar spine and femoral neck were -0.05 +/- 1.46 SD and -0.37 +/- 1.02 SD, respectively. Approximately 50% had osteopenia in the hip or lumbar spine and additionally four had osteoporosis. Multivariate analysis including body weight, impaired renal function, and genotype overall explained 48% of the variance in lumbar spine BMD (P < 0.001), whereas body weight, impaired renal function, and menopausal status in the female population accounted for more than 50% of the variation in BMD of both the lumbar spine and femoral neck (both P < 0.001). Twenty percent of patients had hyperparathyroidism. Although the level of parathyroid hormone was significantly associated with impaired renal function, osteocalcin levels were significantly higher in patients with lumbar spine osteopenia or osteoporosis than in those with normal BMD.

CONCLUSIONS

Osteopenia was present in approximately 50% of patients with untreated FD. Whether BMD and bone metabolism will improve after enzyme replacement therapy remains to be established.

Molecular aspects of osteopathy in type 1 Gaucher disease: correlation between genetics and bone density

Bone-related complications in Gaucher disease are considered to be poorly responsive to specific enzyme replacement therapy. Polymorphisms of candidate genes associated with low bone density were investigated to see whether they are correlated with bone mineral density (BMD) and bone involvement in Gaucher disease. Genotyping for polymorphisms in candidate genes (interleukins 1alpha and 1beta, interleukin-1 receptor antagonist; cytochrome P450; collagen 1A1; low-density Lipoprotein Receptor; bone morphogenic protein 4; vitamin D receptor; and estrogen receptor 2beta) were performed using standard methodologies. BMD was measured by dual energy X-ray absorptiometry (DXA). One hundred and ninety-four patients and 100 controls were genotyped for the above polymorphisms. Thirteen haplotypes were obtained, with several correlations with BMD in patients; also, a haplotype (T889-T3954-C511-240VNTR of IL1) was significantly correlated with T-scores and Z-score for femur neck and lumbar spine (p = 0.01) in patients. Haplotypes of bone-specific candidate genes associated with BMD may predict severity of these features in Gaucher disease.

Improvement of bone disease by imiglucerase (Cerezyme) therapy in patients with skeletal manifestations of type 1 Gaucher disease: results of a 48-month longitudinal cohort study

Sims KB, Pastores GM, Weinreb NJ, Barranger J, Rosenbloom BE, Packman S, Kaplan P, Mankin H, Xavier R, Angell J, Fitzpatrick MA, Rosenthal D. Improvement of bone disease by imiglucerase (Cerezyme) therapy in patients with skeletal manifestations of type 1 Gaucher disease: results of a 48-month longitudinal cohort study. Clin Genet 2008: 73: 430–440. © Blackwell Munksgaard, 2008

Progressive skeletal disease accounts for some of the most debilitating complications of type 1 Gaucher disease. In this 48-month, prospective, non-randomized, open-label study of the effect of enzyme replacement therapy on bone response, 33 imiglucerase-naïve patients (median age 43 years with one or more skeletal manifestations such as osteopenia, history of bone crisis, or other documented bone pathology) received imiglucerase 60 U/kg/2 weeks. Substantial improvements were observed in bone pain (BP), bone crises (BC), and bone mineral density (BMD). Improvements in BP were observed at 3 months (p < 0.001 vs baseline) and continued progressively throughout the study, with 39% of patients reporting pain at 48 months vs 73% at baseline. Eleven of the 13 patients with a pre-treatment history of BC had no recurrences. Biochemical markers for bone formation increased; markers for bone resorption decreased. Steady improvement of spine and femoral neck BMD, measured using dual-energy X-ray absorptiometry was noted. Mean Z score for spine increased from −0.72 ± 1.302 at baseline to near-normal levels (−0.09 ± 1.503) by month 48 (p = 0.042) and for femoral neck from −0.59 ± 1.352 to −0.17 ± 1.206 (p = 0.035) at month 36. This increase was sustained at 48 months. With imiglucerase treatment, patients should anticipate resolution of BC, rapid improvement in BP, increases in BMD, and decreased skeletal complications.

Effect of miglustat on bone disease in adults with type 1 Gaucher disease: a pooled analysis of three multinational, open-label studies

BACKGROUND

Bone manifestations are a source of disability among patients with Gaucher disease (GD) and a focus of disease management. The effect of enzyme replacement therapy (ERT) on GD bone disease can be limited and may take up to 8 years to become manifest. Miglustat, a glucosylceramide synthase inhibitor, may have a positive influence on GD bone disease.

OBJECTIVES

The aim of this analysis was to evaluate the effects of miglustat on bone manifestations and bone mineral density (BMD) in patients with type 1 GD.

METHODS

This was a pooled analysis of data collected prospectively over an observation period of 2 years from patients who participated in 3 multinational, open-label clinical trials evaluating the efficacy and tolerability of miglustat 100 mg TID (the currently approved therapeutic dose). Bone manifestations were assessed qualitatively and in relation to treatment and spleen status. The effects of miglustat on BMD were assessed by dual-energy x-ray absorptiometry at the lumbar spine and/or femoral neck. Bone response was defined as a positive change in BMD, based on the change in BMD Z-score from baseline to months 6, 12, and 24. Changes in BMD were also analyzed according to spleen status and baseline severity of osteopenia.

RESULTS

The analysis involved 72 patients, including 41 (57%) who had received previous ERT and 20 (28%) who had undergone splenectomy. Patients' mean (SD) age was 41.2 (13.1) years. The most frequent bone-related manifestations at study entry were osteoporosis (43/63 [68%] patients) and bone pain (41/65 [63%] patients). At 2 years, 54/65 (83%) patients reported no bone pain. The reductions in bone pain were comparable among all subgroups, including high-risk patients (ie, splenectomized). No new cases of bone crisis, avascular necrosis, or pathologic fractures were reported. BMD Z-scores were improved from baseline at both the lumbar spine and femoral neck at each time point (months 6, 12, and 24) (P < 0.001). As early as 6 months after the initiation of miglustat monotherapy, significant increases from baseline in the BMD Z-score were observed at both the lumbar spine (mean, 0.15; P = 0.022) and femoral neck (0.23; P < 0.001); the increases remained significant at 12 months (0.19 [P = 0.012] and 0.21 [P = 0.017], respectively) and 24 months (0.21 [P = 0.015] and 0.18 [P = 0.039]). Significant increases in BMD Z-scores were observed at the femoral neck in splenectomized patients (P < 0.001) and at both sites in osteoporotic patients (lumbar spine: P < 0.001; femoral neck: P = 0.006).

CONCLUSION

This pooled analysis of 3 open-label studies of miglustat 100 mg TID suggests that miglustat monotherapy may reduce the incidence of bone pain and improve BMD in patients with type 1 GD, including those with a history of splenectomy and/or osteoporosis.

Atteintes ostéoarticulaires de la maladie de Gaucher chez l'adulte: de la physiopathologie au traitement

Gaucher disease frequently has severe osteoarticular manifestations that may be disabling. Ischemic phenomena cause the most serious complications and lead to irreversible lesions. Aseptic osteonecrosis of the hip is the most disabling complication; it causes intense early bone pain and often joint collapse and secondary osteoarthritis in young adults. Localized or systemic bone fragility explains osteopenia, osteoporosis, and fractures (vertebral collapse with irreversible kyphosis causing chronic morbidity). Although no double-blind randomized studies have assessed the bone effects of enzyme replacement therapy, it has been shown effective in reducing bone pain in about half of all treatment-naive patients within 1 to 2 years and in improving bone mineral density after 3 years. In open-label trials, substrate reduction therapy (miglustat) reduced both bone pain and bone marrow infiltration. Specific treatment for bone fragility, with bisphosphonates for example, should be considered after rigorous individualized evaluation and assessment of other risk factors.

Effect of enzyme replacement therapy with imiglucerase on BMD in type 1 Gaucher disease

The effect of ERT with imiglucerase on BMD in type 1 GD was studied using BMD data from the International Collaborative Gaucher Group Gaucher Registry. Data were analyzed for 160 untreated patients and 342 ERT-treated patients. Imiglucerase significantly improves BMD in patients with GD, with 8 years of ERT leading to normal BMD.

INTRODUCTION

The objective was to determine the effect of enzyme replacement therapy (ERT; Cerezyme, imiglucerase) on BMD in type 1 Gaucher disease (GD).

MATERIALS AND METHODS

The study population included all adults (men, 18-70 years; women, 18-50 years) enrolled in the International Collaborative Gaucher Group (ICGG) Gaucher Registry for whom lumbar spine BMD measurements were available. BMD data with up to 8 years of follow-up were analyzed for 160 patients who received no ERT and 342 patients treated with ERT alone. BMD was assessed by DXA of the lumbar spine. Z scores for patients with GD were compared with a reference population. From the model's estimate, percent of patients by age and sex with osteoporosis (T score < or = -2.5) were calculated.

RESULTS

DXA Z scores for patients with GD in the no ERT (untreated) group were significantly below normal (y intercept = -0.80 Z score units, p < 0.001) and remained approximately 1 SD below the reference population over time (slope = -0.010 Z score units per year, p = 0.68). The DXA Z scores for patients with GD who received ERT at a dose of 60 U/kg/2 weeks were significantly lower than the reference population at baseline (y-intercept = -1.17 Z score units, p < 0.001), but improved significantly over time (slope = +0.132 Z score units per year, p < 0.001). A significant dose-response relationship was noted for the ERT group, with the slopes for the three main dosing groups of 15, 30, and 60 U/kg/2 weeks of +0.064, +0.086, and +0.132 Z score units per year, respectively. The BMD of patients with GD treated with ERT increased to -0.12 (60 U/kg/2 weeks), -0.48 (30 U/kg/2 weeks), and -0.66 (15 U/kg/2 weeks) SD of the mean of the reference population after 8 years of ERT, approaching the reference population. Estimated risk of osteoporosis of this GD population, if left untreated, ranged from approximately 10 to 30% in women and 10% to 25% in men.

CONCLUSIONS

ERT with imiglucerase (Cerezyme) may increase BMD in patients with GD. Response to treatment with imiglucerase is slower for BMD than for hematologic and visceral aspects of GD. A normal (age- and sex-adjusted) BMD should be a therapeutic goal for patients with type 1 GD.

S-MRI score: A simple method for assessing bone marrow involvement in Gaucher disease

Semi quantitative MRI is a very useful procedure for evaluating the bone marrow burden (BMB) in Gaucher disease (GD). Score systems have been applied to obtain a parameter for evaluating the severity of bone disease. Our purpose was to test a simple, reproducible and accurate score to evaluate bone marrow involvement in GD patients. MRI was performed in spine, pelvis and femora at diagnosis in 54 adult GD1 patients, 61.1% of whom were female. Three MRI patterns and punctuation in each location were defined: normal, 0; non-homogeneous infiltration subtypes reticular, 1; mottled, 2; diffuse, 3; and homogeneous infiltration, 4. This score was called Spanish-MRI (S-MRI). Two independent observers applied the S-MRI and bone marrow burden score and compared the differences using the non-parametric Mann-Whitney test. Correlation rank test was calculated. In 46 patients (85.2%), bone involvement was observed. Thirty-nine (72.3%) had their spine affected, 35 (64.8%) pelvis and 33 (61.2%) femora. Fourteen patients had bone infarcts, 14 avascular necrosis, 2 vertebral fractures and 2 bone crises. Correlation analysis between S-MRI and BMB was (r(2)=.675; p=.0001). No evidence of correlation was observed between CT activity and S-MRI nor between CT activity and BMB. We have found a relationship between genotype and bone infiltration according to S-MRI site and complications. S-MRI is a simple method that provides useful information to evaluate bone infiltration and detect silent complications. Our results correlated with the BMB score but offer higher sensitivity, specificity and accuracy for classifying the extent of bone disease.

An open-label, noncomparative study of miglustat in type I Gaucher disease: efficacy and tolerability over 24 months of treatment

BACKGROUND

The substrate synthesis inhibitor miglustat (N-butyldeoxynojirimycin) is the first oral agent to receive regulatory approval for the treatment of type I Gaucher disease (GD).

OBJECTIVES

The aims of this study were to further assess previous observations of the effects of miglustat in adult patients with mild to moderate type I GD and to evaluate the tolerability and safety profile of this drug.

METHODS

This was a noncomparative, open-label study in adult patients with type I GD (confirmed by genotyping and glucocerebrosidase assay) who were unwilling or unable to receive enzyme replacement therapy (ERT) or who had discontinued ERT for at least 3 months. Patients received miglustat 100 mg TID for 12 months, with the option of continuing treatment for a further 12 months. The primary end point was the percentage change in liver volume. Secondary end points included the percentage change in spleen volume and changes in hematologic parameters (hemoglobin, platelets), chitotriosidase activity (a surrogate marker of disease burden), and bone assessments (dual-energy X-ray absorptiometry, magnetic resonance imaging, and radiography). Clinical safety was monitored, including assessment of neurologic status at baseline and throughout the study using a comprehensive battery of standardized neurologic tests (eg, Purdue Pegboard Test, Mini-Mental State Examination, nerve conduction studies) and neuropsychological tests.

RESULTS

Of the 10 patients (7 men, 3 women) who received at least 1 dose of miglustat, 7 completed 24 months of treatment. Patients were aged between 32 and 62 years (mean, 46.3 years) and weighed between 55 and 88 kg (mean, 72.4 kg). All patients had at least 1 manifestation of GD, including 10 with splenomegaly (mean size, 8.1 times normal; range, 3.9-15.9 times normal), 9 with thrombocytopenia, and 8 with hepatomegaly (mean size, 1.5 times normal; range, 1.0-2.0 times normal). At baseline, hemoglobin concentrations ranged from 11.5 to 15.1 g/dL (mean, 13.2 g/dL), platelet counts from 55 to 161 x 10(9)/L (mean, 83.8 x 10(9)/L), and chitotriosidase activity from 526 to 29636 nmol/mL . h (mean, 8143.7 nmol/mL . h). In the 8 patients comprising the efficacy set, significant mean percentage changes from baseline in liver volume were seen at 6 months (-8.4%; P = 0.036; 95% CI, -16.1 to -0.7) and 18 months (-15.1%; P = 0.022; 95% CI, -27.1 to -3.0). Although not statistically significant, the 95% CIs for the percentage changes in liver volume at 12 months (-9.4%; 95% CI, -19.5 to 0.6) and 24 months (-5.6%; 95% CI, -12.1 to 1.0) were similar to those at 6 and 18 months, supporting a consistent clinical effect. Significant mean percentage reductions in spleen volume were observed at 6 months (-19.0%; P = 0.006; 95% CI, -30.4 to -7.6) and 18 months (-24.3%; P = 0.001; 95% CI, -33.6 to -15.1). Mean hemoglobin concentrations, which were normal at baseline, remained stable over the course of the study. There were no significant changes in bone status. There was a significant mean increase in absolute platelet count at 12 months (by 13.9 x 10(9)/L; P = 0.030; 95% CI, 1.8 to 26.0); at 24 months, the mean percentage increase from baseline (23.0%) was not statistically significant. The mean percentage reduction from baseline in chitotriosidase activity at 24 months was 25.3%. Treatment was well tolerated, and the incidence of most adverse events decreased with time. Gastrointestinal and central nervous system adverse events reported during 3-month periods at the beginning (0-3 months) and end (>21-24 months) of the study were flatulence (10 and 2 patients, respectively), diarrhea (9 and 0), abdominal pain (7 and 1), tremor (4 and 1), paresthesia (3 and 0), headache (2 and 3), and abdominal distention (2 and 0). No evidence of clinically significant adverse effects on neurologic or neuropsychological function was found during the study.

CONCLUSIONS

In this small study in symptomatic adult patients with type I GD, miglustat treatment resulted in a significant decrease in liver and spleen volume at 6 and 18 months, with clinical improvement noted over 24 months. Bone involvement and platelet and hemoglobin values remained stable, with no significant changes noted during the observation period. The effects of treatment were consistent with those of earlier studies of miglustat in type I GD.

Evidence-based recommendations for monitoring bone disease and the response to enzyme replacement therapy in Gaucher patients

BACKGROUND

Bone disease is a serious complication of Gaucher disease. Untreated, it can result in pain, permanent bone damage and disability. Enzyme replacement therapy reverses many of the clinical signs of Gaucher bone disease but early assessment and treatment, and regular monitoring, are essential in optimising outcomes.

SCOPE

In September 2005, a group of European experts met to review current knowledge and identify best practice and unmet needs in the monitoring of Gaucher bone disease and the response to enzyme replacement therapy.

METHODS

Medline searches of peer-reviewed literature (no date restrictions) were conducted and supplemented by additional information considered relevant by panellists to furthering discussions.

FINDINGS AND CONCLUSIONS

The group's recommendations included: currently used biochemical bone markers are not clinically practical or reliable; plain X-rays should not be the sole method of assessing bone disease; MRI is the most sensitive method for monitoring bone marrow infiltration by Gaucher cells; semi-quantitative methods for assessing bone marrow infiltration in routine clinical practice should use readily available technology, include an assessment of Gaucher cell infiltration in the lumbar spine and femur, and be validated for inter-rater reliability and in comparison to other methods; a multidisciplinary approach is required for the treatment of Gaucher patients; all Gaucher patients should receive a comprehensive initial radiologic evaluation for bone disease and ongoing radiological monitoring at least once every 2 years.

Anesthesia for obstetric patients with Gaucher disease: survey and review

Pregnancy and delivery in patients with non-neuronopathic Gaucher disease, whether treated with enzyme replacement or untreated, are usually uncomplicated. Various factors may influence mode of delivery, vaginal or cesarean section, as well as type of anesthesia, general or regional, used during delivery. This retrospective review was intended to highlight some of the practical issues relating to obstetric anesthetic management, based on a review of the literature and experiences from a large referral clinic for Gaucher disease. In the past decade, there were 16 deliveries in 11 women in our institution. There were five normal vaginal deliveries, two vacuum extractions, one placental extraction, and eight cesarean sections. Platelet counts were 27-215 x 10(9)/L. Two spontaneous deliveries and one vacuum extraction were performed under epidural anesthesia; two other women having vaginal deliveries and one vacuum extraction were given i.v. analgesia; the fifth was given i.v. patient-controlled analgesia. The placental extraction was performed under general anesthesia. Seven of the women having cesarean deliveries received spinal anesthesia; the breech presentation required general anesthesia. There were no anesthesia-related side effects or complications, although there were some instances of post-partum bleeding irrespective of enzyme therapy. Gaucher disease affects multiple organs and can be a challenge to the anesthesiologist. Based on this survey we suggest that anesthetic management requires particular attention to hematological parameters before delivery. A multidisciplinary approach and extensive communication among obstetrician, hematologist and anesthesiologist is required to anticipate the possibility of post-partum hemorrhage, and preclude skeletal damage.

Gaucher disease and bone: laboratory and skeletal mineral density variations during a long period of enzyme replacement therapy

The usefulness of bone turnover markers in Gaucher disease is still unclear and their utility in monitoring the effects of enzyme replacement therapy (ERT) on bone metabolism has not yet been investigated exhaustively. Skeletal involvement seems to improve slowly during ERT, but only a few studies evaluating bone mineral density (BMD) changes during a long follow-up period have been reported. The aim of this study was to assess the efficacy of ERT on bone involvement in a group of 12 type I Gaucher disease (GD I) patients by monitoring biochemical indices of bone resorption/formation and BMD measured by dual energy x-ray absorptiometry (DEXA). Serum (calcium, phosphorus, bone alkaline phosphatase isoenzyme, carboxyterminal propeptide of type I procollagen (PICP), carboxyterminal telopeptide of type I collagen (ICTP), osteocalcin, intact parathyroid hormone) and urinary (calcium, phosphorus, hydroxyproline and free deoxypyridinoline) markers of bone metabolism and lumbar BMD were measured at baseline, after 6 and 12 months, and then every year for a mean ERT follow-up period of 4.5 years (range 4.4-6 years). Twelve healthy adult subjects matched for age and sex were tested as negative controls. A significant decrease of PICP was detected in the patient group at baseline (mean value 100.52 ng/ml vs 142.45 ng/ml, p = 0.017), while ICTP was remarkably higher: mean value 3.93 ng/ml vs 2.72 ng/ml, p = 0.004 (two-sided Student's t-test). No changes in bone formation indices were observed during the follow-up period, while urinary calcium excretion increased significantly from 0.065 to 0.191 mg/mg creatinine (p = 0.0014) (repeated measures ANOVA). A significant BMD improvement was also detected after an average ERT period of 4.5 years: Z-score increased from -0.81 to -0.56 (p = 0.005) (two-sided Student's t-test). These data evidenced the ineffectiveness of the biochemical markers used in monitoring ERT efficacy in GD I skeletal involvement, whereas DEXA was demonstrated to be a reliable method with which to follow up BMD improvement.