A benchmark analysis of the achievement of therapeutic goals for type 1 Gaucher disease patients treated with imiglucerase

The international cooperative Gaucher group (ICCG) Gaucher registry

Gaucher disease GD), is a rare lysosomal storage disorder caused by deficient acid β-glucosylceramidase activity and accumulation of glucosylceramide in tissue macrophages. With the 1991 advent of alglucerase enzyme replenishment therapy (ERT), the manufacturer (Genzyme Corporation) created the ICGG Gaucher Registry to collect longitudinal observational "real word" information about GD world-wide in heterogeneous patient populations, to annotate phenotypes and genotypes that define the natural history of GD in untreated patients, and to document and analyze treatment outcomes for alglucerase and any other future treatments. For 32 years, the ICGG Gaucher Registry has functioned as an educational tool for patients, clinicians, and other stakeholders to increase scientific knowledge of GD, to provide practical management guidance, and to positively impact patient care. This paper illustrates how an industry sponsored registry guided by a company independent scientific advisory board has successfully addressed its mission and evolved in step with technologic and scientific advances.

An observational study to investigate the relationship between plasma glucosylsphingosine (lyso-Gb1) concentration and treatment outcomes of patients with Gaucher disease in Japan

BACKGROUND

Gaucher disease (GD) is an autosomal recessive disease caused by GBA1 mutations resulting in glucosylceramide accumulation in macrophages. GD is characterized by hepatosplenomegaly, anemia, thrombocytopenia, bone complications, and neurological complications. Glucosylsphingosine (lyso-Gb1), a deacylated form of glucosylceramide, has been identified as a promising biomarker for the diagnosis and treatment response in GD. The aim of this study was to examine the relationship between plasma lyso-Gb1 and therapeutic goals for GD (improvements in hepatomegaly, splenomegaly, anemia, thrombocytopenia, bone pain, and bone crisis), as well as disease type and GBA1 mutation type, in Japanese patients with GD receiving velaglucerase alfa, an enzyme replacement therapy (ERT). Furthermore, this study compared the plasma lyso-Gb1 concentration observed in Japanese patients included in this study with that observed in a previous non-Japanese clinical study.

RESULTS

This non-interventional, open-label, multicenter observational cohort study (October 2020 to March 2021) included a total of 20 patients (of any age) with GD (type 1: n = 8; type 2: n = 9; type 3: n = 3) treated with velaglucerase alfa for ≥ 3 months. Median (minimum-maximum) duration of velaglucerase alfa treatment was 49.5 (3-107) months. A total of 14 (70.0%) patients achieved all therapeutic goals (i.e., 100% achievement; improvements in hepatomegaly, splenomegaly, anemia, thrombocytopenia, bone pain, and bone crisis). Overall, median (minimum-maximum) lyso-Gb1 concentration was 24.3 (2.1-150) ng/mL. Although not statistically significant, numerically lower plasma lyso-Gb1 concentrations were observed in patients with 100% achievement compared with those without; no statistically significant difference in plasma lyso-Gb1 concentration was observed between patients with different disease type or mutation type. Furthermore, lyso-Gb1 concentrations observed in Japanese patients were numerically lower than that observed in a previous study of non-Japanese patients with GD receiving ERT.

CONCLUSIONS

In this study, high achievement rates of therapeutic goals with low lyso-Gb1 concentration were observed, demonstrating a correlation between therapeutic goals and lower plasma lyso-Gb1 concentration in Japanese patients with GD treated with velaglucerase alfa. This study further suggests that plasma lyso-Gb1 concentration may be a useful biomarker for treatment response in patients with GD.

Upregulation of Cytotoxic T-cells in pediatric patients with Gaucher disease

Cytotoxic (CD8) T-cells and natural killer (NK) cells have a significant immune function role. The ongoing stimulation of immunity and the excessive release of proinflammatory cytokines observed in pediatric patients with Gaucher disease (GD) can affect immune cells. Few studies have looked at the proportion of cytotoxic CD8 T-cells and their subsets in children with GD. A prospective case-control study was performed involving twenty pediatric patients with type 1 GD and twenty healthy age-matched controls. All patients received regular enzyme replacement therapy (ERT) for at least 6 months before the study. Complete blood count and flow cytometric analyses of CD8 T, Tc1, Tc2, NK, and NK T-cells were performed. GD patients showed significantly increased of CD8 T, Tc1 and significantly decreased NK cells frequencies when compared to healthy controls. However, no significant difference in Tc2 and NK T-cells was found between the studied groups. GD patients on regular ERT have increased CD8+ T-cell frequencies, predominantly Tc1, together with a reduction in NK cells than in healthy controls. These crucial immunological changes may contribute to some extent to the pathogenesis and the progression of GD.

Gaucher disease type 1 patients from the ICGG Gaucher Registry sustain initial clinical improvements during twenty years of imiglucerase treatment

BACKGROUND

Alglucerase enzyme replacement therapy was approved for Gaucher disease (GD) in the United States in 1991; imiglucerase in 1994. We report hematologic, visceral, bone pain, bone crisis, height, weight, and Body Mass Index (BMI) outcomes in patients treated for 20 (±3) years with subset analyses based on pre-treatment severity, genotype, and age at treatment initiation.

METHODS

GD type 1 (GD1) patients in the ICGG Gaucher Registry with complete sets of baseline, 10-year, and 20-year data are included (N = 475). Ten-year and 20-year data are compared to pre-treatment baseline, stratified by splenectomy status.

RESULTS

Non-splenectomized patients: Improvements observed at 10 years were maintained at 20 years for most outcomes. Mean changes from baseline at 10 and 20 years, respectively, were: spleen volume: 18.2 multiples of normal (MN) to 5.1 MN and 4.2 MN; liver volume: 1.8 MN to 1.0 MN and 1.0 MN; hemoglobin: 11.4 g/dL to 13.7 g/dL and 13.8 g/dL; platelet count: 91.6 × 10⁹/L to 168.0 × 10⁹/L and 169.1 × 10⁹/L; without bone crisis: 85.0% to 98.2% and 96.5%; without bone pain: 52.5% to 72.0% at 10 years, no significant change at 20 years (58.5%). Splenectomized patients: significant changes were observed in liver volume: 2.3 MN to 1.1 MN and 1.0 MN; hemoglobin: 11.7 g/dL to 13.3 g/dL and 13.4 g/dL; platelet count: 229.1 × 10⁹/L to 288.1 × 10⁹/L and 257.0 × 10⁹/L; without bone crisis: 52.2% to 91.3% and 100%; without bone pain: 16.3% to 30.6% (not significant) and 46.9%. Similar results were found in each of the subset analyses. Patients who start treatment during childhood have normal weight and height in young adulthood. Many treated adult patients are overweight or obese; however, this is consistent with BMI trends observed in the general population. After 1-2 years, the average biweekly imiglucerase dose is ~40 units/kg body weight.

CONCLUSION

Imiglucerase is an effective, long-term treatment for GD1. In a long-term observational setting, improvements seen during early treatment years are sustained by continuing treatment for 20 years, except for bone pain in non-splenectomized patients. These results are consistent when analyzed by different patient subsets, including by disease severity.

A Quantitative Systems Pharmacology Model of Gaucher Disease Type 1 Provides Mechanistic Insight Into the Response to Substrate Reduction Therapy With Eliglustat

Gaucher’s disease type 1 (GD1) leads to significant morbidity and mortality through clinical manifestations, such as splenomegaly, hematological complications, and bone disease. Two types of therapies are currently approved for GD1: enzyme replacement therapy (ERT), and substrate reduction therapy (SRT). In this study, we have developed a quantitative systems pharmacology (QSP) model, which recapitulates the effects of eliglustat, the only first‐line SRT approved for GD1, on treatment‐naïve or patients with ERT‐stabilized adult GD1. This multiscale model represents the mechanism of action of eliglustat that leads toward reduction of spleen volume. Model capabilities were illustrated through the application of the model to predict ERT and eliglustat responses in virtual populations of adult patients with GD1, representing patients across a spectrum of disease severity as defined by genotype‐phenotype relationships. In summary, the QSP model provides a mechanistic computational platform for predicting treatment response via different modalities within the heterogeneous GD1 patient population.

Effect of Substrate Reduction Therapy in Comparison to Enzyme Replacement Therapy on Immune Aspects and Bone Involvement in Gaucher Disease

Gaucher disease (GD) is caused by mutations in the GBA gene, leading to deficient activity of the lysosomal enzyme glucocerebrosidase. Among all the symptoms across various organ systems, bone disease is a major concern as it causes high morbidity and reduces quality of life. Enzyme replacement therapy (ERT) is the most accepted treatment; however, there are still unmet needs. As an alternative, substrate reduction therapy (SRT) was developed using glucosylceramide synthase inhibitors. In the current study, the effects of ERT vs. SRT were compared, particularly the immunological and bone remodeling aspects. GD subjects were divided into three cohorts based on their treatment at initial visit: ERT, SRT, and untreated (UT). Immunophenotyping showed no significant immune cell alterations between the cohorts. Expression of RANK/RANKL/Osteoprotegerin pathway components on immune cells and the secreted markers of bone turnover were analyzed. In the ERT cohort, no significant changes were observed in RANK, RANKL or serum biomarkers. RANKL on T lymphocytes, Osteopontin and MIP-1β decreased with SRT treatment indicating probable reduction in osteoclast activity. Other secreted factors, Osteocalcin and RANKL/Osteoprotegerin did not change with the treatment status. Insights from the study highlight personalized differences between subjects and possible use of RANK pathway components as markers for bone disease progression.

Pharmacological treatment of pediatric Gaucher disease

INTRODUCTION

Gaucher disease (GD) is an autosomal recessive disorder resulting from the deficiency of the lysosomal enzyme glucocerebrosidase (b-glucosidase), associated with varying degrees of visceral, bone and central nervous system pathology, leading to wide phenotypic diversity. Response to therapy and clinical outcomes are very different between the three clinical subtypes - non-neuronopathic, acute neuronopathic, and chronic neuronopathic forms; hence a definitive clinical diagnosis is essential. The availability of two therapeutic options, i.e. enzyme replacement and substrate reduction, has transformed the natural course of the disease. As pre-treatment disease severity clearly impacts results of therapy, early diagnosis and initiation of treatment especially in the pediatric population are keys to achieving an optimal outcome. Areas covered: We reviewed the literature concerning the treatment of GD focusing on pediatric presentations, various pharmacological treatment options and recommendations for management goals. A PubMed literature search was performed for relevant publications between 1991 and September 2018. Expert commentary: The approval of enzyme replacement therapy (ERT) for GD in the pediatric age group has significantly altered the course of the disease, especially for non-neuronopathic and chronic neuronopathic forms, as ERT does not cross the blood-brain barrier. Early diagnosis, regular follow-up and early initiation of treatment can thus prevent some irreversible complications and improve patient quality of life.

Diagnosis and Management of Gaucher Disease in India – Consensus Guidelines of the Gaucher Disease Task Force of the Society for Indian Academy of Medical Genetics and the Indian Academy of Pediatrics

Justification

Gaucher disease (GD) is amongst the most frequently occurring lysosomal storage disorder in all ethnicities. The clinical manifestations and natural history of GD is highly heterogeneous with extreme geographic and ethnic variations. The literature on GD has paucity of information and optimal management guidelines for Indian patients.

Process

Gaucher Disease Task Force was formed under the auspices of the Society for Indian Academy of Medical Genetics. Invited experts from various specialties formulated guidelines for the management of patients with GD. A writing committee was formed and the draft guidelines were circulated by email to all members for comments and inputs. The guidelines were finalized in December 2016 at the annual meeting of the Indian Academy of Medical Genetics.

Objectives

These guidelines are intended to serve as a standard framework for treating physicians and the health care systems for optimal management of Gaucher disease in India and to define unique needs of this patient population.

Recommendations

Manifestations of GD are protean and a high index of suspicion is essential for timely diagnosis. Patients frequently experience diagnostic delays during which severe irreversible complications occur. Leucocyte acid β-glucosidase activity is mandatory for establishing the diagnosis of Gaucher disease; molecular testing can help identify patients at risk of neuronopathic disease. Enzyme replacement therapy for type 1 and type 3 Gaucher disease is the standard of care. Best outcomes are achieved by early initiation of therapy before onset of irreversible complications. However, in setting of progressive neurological symptoms such as seizures and or/neuroregression, ERT is not recommended, as it cannot cross the blood brain barrier. The recommendations herein are for diagnosis, for initiation of therapy, therapeutic goals, monitoring and follow up of patients. We highlight that prevention of recurrence of the disease through genetic counseling and prenatal diagnosis is essential in India, due to uniformly severe phenotypes encountered in our population.

A new framework for evaluating the health impacts of treatment for Gaucher disease type 1

Background

The Disease Severity Scoring System (DS3) is a validated measure for evaluating Gaucher disease type 1 (GD1) severity. We developed a new framework, consisting of health states, transition probabilities between those states, and preferences for those states (utilities) based on the DS3 to predict long-term outcomes of patients starting treatment. We defined nine mutually exclusive (alive) health states based on three DS3 categories: mild (0 ≤ DS3 ≤ 3.5) without symptoms of bone disease; mild with bone pain, mild with severe skeletal complications (SSC) defined as lytic lesions, avascular necrosis, or fracture; moderate (3.5 < DS3 ≤ 6.5) without SSC; moderate with SSC; marked (6.5 < DS3 ≤ 9.5) without SSC; marked with SSC; severe (9.5 < DS3 ≤ 19) without SSC; and severe with SSC. Health-state transition probabilities and utilities were estimated from a longitudinal sample of patients with GD1 who started enzyme replacement therapy (the DS3 Score Study). Age dependent GD1-specific mortality was derived from published data. We used a Markov state-transition model to illustrate how to estimate time spent in each health state.

Results

The average predicted utilities for each health state ranged from 0.76 for mild disease with no clinical symptoms of bone disease to 0.52 with severe disease with SSC. Transition probabilities depended on disease severity (DS3 score) at treatment initiation and whether patients had undergone a total splenectomy or had an intact spleen/partial splenectomy prior to starting treatment. Patients who started treatment with intact or residual spleens spent more time in better health states than those who started treatment with total splenectomy.

Conclusions

This new framework, which is based on the DS3, can be used to project the long-term outcomes of GD1 patients starting treatment. The framework could also be used to compare the long-term outcomes of different GD1 treatment options.

Trial registration

NCT01136304. Registered: May 31, 2010 (retrospectively registered).

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0592-6) contains supplementary material, which is available to authorized users.

Eliglustat maintains long-term clinical stability in patients with Gaucher disease type 1 stabilized on enzyme therapy

In the phase 3 Study of Eliglustat Tartrate (Genz-112638) in Patients With Gaucher Disease Who Have Reached Therapeutic Goals With Enzyme Replacement Therapy (ENCORE), at 1 year, eliglustat was noninferior to imiglucerase enzyme therapy in maintaining stable platelet counts, hemoglobin concentrations, and spleen and liver volumes. After this primary analysis period, patients entered a long-term extension phase in which all received eliglustat. Duration on eliglustat ranged from 2 to 5 years, depending on timing of enrollment (which spanned 2 years), treatment group to which patients were randomized, and whether they lived in the United States when commercial eliglustat became available. Here we report long-term safety and efficacy of eliglustat for 157 patients who received eliglustat in the ENCORE trial; data are available for 46 patients who received eliglustat for 4 years. Mean hemoglobin concentration, platelet count, and spleen and liver volumes remained stable for up to 4 years. Year to year, all 4 measures remained collectively stable (composite end point relative to baseline values) in ≥85% of patients as well as individually in ≥92%. Mean bone mineral density z scores (lumbar spine and femur) remained stable and were maintained in the healthy reference range throughout. Eliglustat was well tolerated over 4 years; 4 (2.5%) patients withdrew because of adverse events that were considered related to the study drug. No new or long-term safety concerns were identified. Clinical stability assessed by composite and individual measures was maintained in adults with Gaucher disease type 1 treated with eliglustat who remained in the ENCORE trial for up to 4 years. This trial was registered at www.clinicaltrials.gov as #NCT00943111.

Time of Initiating Enzyme Replacement Therapy Affects Immune Abnormalities and Disease Severity in Patients with Gaucher Disease

Gaucher disease (GD) patients often present with abnormalities in immune response that may be the result of alterations in cellular and/or humoral immunity. However, how the treatment and clinical features of patients impact the perturbation of their immunological status remains unclear. To address this, we assessed the immune profile of 26 GD patients who were part of an enzyme replacement therapy (ERT) study. Patients were evaluated clinically for onset of GD symptoms, duration of therapy and validated outcome measures for ERT. According to DS3 disease severity scoring system criteria, they were assigned to have mild, moderate or severe GD. Flow cytometry based immunophenotyping was performed to analyze subsets of T, B, NK, NKT and dendritic cells. GD patients showed multiple types of immune abnormalities associated to T and B lymphocytes with respect to their subpopulations as well as memory and activation markers. Skewing of CD4 and CD8 T cell numbers resulting in lower CD4/CD8 ratio and an increase in overall T cell activation were observed. A decrease in the overall B cells and an increase in NK and NKT cells were noted in the GD patients compared to controls. These immune alterations do not correlate with GD clinical type or level of biomarkers. However, subjects with persistent immune alterations, especially in B cells and DCs correlate with longer delay in initiation of ERT (ΔTX). Thus, while ERT may reverse some of these immune abnormalities, the immune cell alterations become persistent if therapy is further delayed. These findings have important implications in understanding the immune disruptions before and after treatment of GD patients.

Treatment-naïve Gaucher disease patients achieve therapeutic goals and normalization with velaglucerase alfa by 4years in phase 3 trials

Gaucher disease is an inherited metabolic disease characterized by β-glucocerebrosidase deficiency and commonly treated with enzyme replacement therapy (ERT). The efficacy of ERT with velaglucerase alfa was assessed based on the achievement of published therapeutic goals and the normalization of disease parameters in 39 treatment-naïve patients with type 1 Gaucher disease, 6 to 62years of age, enrolled in phase 3 clinical trials. After 4years of ERT, therapeutic goals for thrombocytopenia and splenomegaly had been achieved in 100% of patients; goals for anemia and hepatomegaly had been achieved in 95% and 94% of patients, respectively. Consistent with the goal for bone mineral density, lumbar spine bone density improved in 87% of patients ≥18years of age. At year 4, compared with clinical ranges for healthy individuals, 86% of patients with a low baseline hemoglobin concentration had normalized, 60% with a low baseline platelet count had normalized, 67% with baseline splenomegaly had normalized, 58% with hepatomegaly had normalized, and lumbar spine bone density had normalized in 53% of adults. The decade-old therapeutic goals do not reflect the potential for normalization of clinical parameters in ERT-treated patients. Goals consistent with normalization or near-normalization should be considered. ClinicalTrials.gov identifiers: NCT00430625, NCT00553631, NCT00635427.

Gaucher disease epidemiology and natural history: a comprehensive review of the literature

OBJECTIVES

The objectives of this research were: (1) to heighten awareness of Gaucher disease (GD), a rare lysosomal storage disorder with highly heterogeneous patterns of organ involvement and disease severity, to clinicians most likely to encounter these patients, and; (2) to summarize the published evidence on GD epidemiology which is essential to accurately depict the total societal burden of this rare worldwide disorder.

METHODS

A comprehensive literature review was undertaken to summarize the published evidence on the epidemiology of GD. MEDLINE, EMBASE, CENTRAL, and 'grey' literature sources published in English between January 1990 and March 2015 were searched to identify relevant publications.

RESULTS

In total, 188 full-text articles were reviewed and findings from 49 studies are summarized herein. The standardized birth incidence of GD in the general population varied from 0.39 to 5.80 per 100 000, and prevalence ranged from 0.70 to 1.75 per 100 000, respectively. Time from onset of GD symptoms to clinical diagnosis was highly variable, with median delays of up to 7 years reported.

DISCUSSION

The incidence and prevalence of GD is substantially higher among the Ashkenazi Jewish population than the general population. Limited epidemiologic information was available from Latin America, Africa, Asia, and developed nations such as the United States, Germany, and the United Kingdom.

CONCLUSIONS

Signs and symptoms of GD frequently mimic more common hematologic conditions resulting in missed or delayed diagnosis. Early diagnosis and prompt initiation of treatment when indicated is crucial to prevent or minimize life-altering or life-threatening liver and skeletal complications.

Imiglucerase in the management of Gaucher disease type 1: an evidence-based review of its place in therapy

Introduction

Gaucher disease is the first lysosomal disease to benefit from enzyme replacement therapy, thus serving as model for numerous other lysosomal diseases. Alglucerase was the first glucocerebrosidase purified from placental extracts, and this was then replaced by imiglucerase – a Chinese hamster ovary cell-derived glucocerebrosidase.

Aim

The aim was to review the evidence underlying the use of imiglucerase in Gaucher disease type 1

Evidence review

Data from clinical trials and Gaucher Registries were analyzed.

Conclusion

Imiglucerase has been prescribed and found to have an excellent efficacy and safety profile. We report herein the evidence-based data published for 26 years justifying the use of imiglucerase.

Skeletal involvement in Gaucher disease: An observational multicenter study of prognostic factors in the Argentine Gaucher disease patients

Patients with Gaucher type 1 (GD1) throughout Argentina were enrolled in the Argentine bone project to evaluate bone disease and its determinants. We focused on presence and predictors of bone lesions (BL) and their relationship to therapeutic goals (TG) with timing and dose of enzyme replacement therapy (ERT). A total of 124 patients on ERT were enrolled in a multi-center study. All six TG were achieved by 82% of patients: 70.1% for bone pain and 91.1% for bone crisis. However, despite the fact that bone TGs were achieved, residual bone disease was present in 108 patients on ERT (87%) at time 0. 16% of patients showed new irreversible BL (bone infarcts and avascular osteonecrosis) despite ERT, suggesting that they appeared during ERT or were not detected at the moment of diagnosis. We observed 5 prognostic factors that predicted a higher probability of being free of bone disease: optimal ERT compliance; early diagnosis; timely initiation of therapy; ERT initiation dose ≥45 UI/kg/EOW; and the absence of history of splenectomy. Skeletal involvement was classified into 4 major phenotypic groups according to BL: group 1 (12.9%) without BL; group 2 (28.2%) with reversible BL; group 3 (41.9%) with reversible BL and irreversible chronic BL; and group 4 (16.9%) with acute irreversible BL. Our study identifies prognostic factors for achieving best therapeutic outcomes, introduces new risk stratification for patients and suggests the need for a redefinition of bone TG. Am. J. Hematol. 91:E448-E453, 2016. © 2016 Wiley Periodicals, Inc.

A Novel Nonsense Mutation of the AGL Gene in a Romanian Patient with Glycogen Storage Disease Type IIIa

Background. Glycogen storage disease type III (GSDIII) is a rare metabolic disorder with autosomal recessive inheritance, caused by deficiency of the glycogen debranching enzyme. There is a high phenotypic variability due to different mutations in the AGL gene. Methods and Results. We describe a 2.3-year-old boy from a nonconsanguineous Romanian family, who presented with severe hepatomegaly with fibrosis, mild muscle weakness, cardiomyopathy, ketotic fasting hypoglycemia, increased transaminases, creatine phosphokinase, and combined hyperlipoproteinemia. GSD type IIIa was suspected. Accordingly, genomic DNA of the index patient was analyzed by next generation sequencing of the AGL gene. For confirmation of the two mutations found, genetic analysis of the parents and grandparents was also performed. The patient was compound heterozygous for the novel mutation c.3235C>T, p.Gln1079(⁎) (exon 24) and the known mutation c.1589C>G, p.Ser530(⁎) (exon 12). c.3235 >T, p.Gln1079(⁎) was inherited from the father, who inherited it from his mother. c.1589C>G, p.Ser530(⁎) was inherited from the mother, who inherited it from her father. Conclusion. We report the first genetically confirmed case of a Romanian patient with GSDIIIa. We detected a compound heterozygous genotype with a novel mutation, in the context of a severe hepatopathy and an early onset of cardiomyopathy.

Long-term treatment outcomes in Gaucher disease

Following the treatment of the first Gaucher disease patient with enzyme replacement therapy (ERT), it was clear that ERT had the potential to be transformative with dramatic improvements in systemic manifestations of the disease within 2 years. Following over 20 years existence of the International Collaborative Gaucher Group Gaucher Registry and evidence from ∼6000 patients, the long-term effects of therapy have been documented. It has been shown that ERT can result in improvements in all clinical and laboratory parameters of nonneuronopathic disease. However, different aspects of the disease, such as hematologic parameters, organ volumes and bone disease do not necessarily respond to therapy at the same rate or to the same extent, and this has had major implications for disease monitoring and for the establishment of therapeutic goals for ERT. Response may be affected by factors such as the timing of therapy initiation, the presence of irreversible complications such as osteonecrosis, and by enzyme dose. It is also apparent that ERT has no impact on neurological aspects of disease and highlights the need for additional or alternative treatment strategies able to meet the needs of patients with neuronopathic disease.

Evaluation of disease burden and response to treatment in adults with type 1 Gaucher disease using a validated disease severity scoring system (DS3)

BACKGROUND

GD1-DS3 is an integrated assessment of type 1 Gaucher disease (GD1) burden based on bone, hematologic and visceral domains. We investigated this disease severity scoring system (DS3) methodology for initial assessment, long-term follow-up and evaluation of treatment responses.

METHODS

We enrolled 133 treated adult GD1 patients. Baseline DS3 scores were calculated near the initial treatment date and patients stratified by severity as marked (DS3 6.00-19.00), moderate (DS3 3.00-5.99), mild (DS3 < 3.00). Follow-up scores were calculated annually. Minimal clinically important improvement (MCII), is defined as ΔDS3 of -3.1.

RESULTS

PATIENT CHARACTERISTICS

N370S was the most common allele (118 patients had at least one), 52 were N370S/N370S (48/52 were Ashkenazi Jews), N370S/L444P was the most common genotype among non-Jews. Median age of treatment: 45 years; median follow-up: 14 years. Baseline DS3 scores: Patients with marked disease (N = 58; median 7.84) were least likely to be N370S homozygous (19 %) and most likely to have had splenectomy (53 %), early age at diagnosis (median 18 years) and major pre-treatment bone pathology (76 %). Among patients with moderate disease (N = 53; median 4.33), 49 % were N370S/N370S, 15.1 % had splenectomy and 17 % had major bone disease. Median age at diagnosis: 32 years. No patient with mild disease (N = 22; median 2.4) had splenectomy or major skeletal disease. Median age at diagnosis: 40 years. 68 % were N370S homozygous. Response to treatment: Health-state transitions occurred primarily during the early treatment years. At Year 5, among 48 evaluable patients with marked baseline disease, eight were unchanged in severity status whereas 40 had MCII of varying degrees with 11 scored as mild. Among 42 evaluable moderate patients, none worsened, 16 remained moderate and 26 improved to mild. Among 16 evaluable mild patients, 14 remained so and 2 had DS3 scores in the low moderate range.

CONCLUSIONS

DS3 is effective for assessing disease burden in GD1 and for monitoring response. ERT was associated with MCII in DS3 scores in patients with high severity. Nevertheless, despite better DS3 scores with treatment, GD1 patients especially those with splenectomy and pre-treatment bone pathology, continued to have bone complications.

Impact of imiglucerase supply constraint on the therapeutic management and course of disease in French patients with Gaucher disease type 1

Background

In 2009, a worldwide supply constraint of imiglucerase led to treatment modifications or interruptions for patients with Gaucher disease (GD) type 1. In France, joint treatment recommendations were issued to protect the most vulnerable patients. This observational study evaluated the impact of imiglucerase treatment modifications on the clinical and biological course of GD.

Methods

Retrospective data on patients’ characteristics, treatment, clinical and biological parameters from 01 June 2009 to 31 October 2010 were collected during a single visit.

Results

Ninety-nine GD1 patients, aged 7–84 years, were included (median age 47 years); 10 were children. Patients experienced a median of 4 different treatment modifications. Median change from pre-supply constraint dose (92 U/kg/4-weeks) was −69, −51, −29 and −60 U/kg/4-weeks at 3, 6, 9 and 12 months after first modification, respectively, with imiglucerase discontinuation reported for 70%, 47%, 29% and 55% of patients at these timepoints. Replacement with another ERT was reported for 35 patients. Results show a statistically significant decrease in hemoglobin (−0.8 g/L/month) and platelets (−5905.10³/mm³/month) and an increase in chitotriosidase (+537 nmol/mL/h/month) and angiotensin-converting enzyme (+4 IU/L/month) in the subgroup of 61 patients who discontinued treatment for at least 3 months; this magnitude of change was not seen in the subgroup (32 patients) treated with reduced imiglucerase for at least 3 consecutive months. GD-related events were spontaneously reported by the study investigators for 39% of the whole study population, including asthenia/fatigue (8%), bone infarction and bone pain (4% each), and hepatomegaly (3%). A Kaplan-Meier estimate of the probability for a patient to present a bone, hematological or visceral event during the constraint was 37% for patients who discontinued the treatment and 10% for patients treated with a reduced imiglucerase dose.

Conclusion

The release of recommendations and individuals’ close follow-up allowed satisfactory management of patients during the imiglucerase supply constraint in France. This study suggests that during this period, lowering the dose of imiglucerase had less impact on the outcomes of patients than interrupting treatment. However, general effects (such as fatigue, bone pain) reported in some patients, emphasize the importance of maintaining appropriate individualized dosing.

Management of bone disease in Gaucher disease type 1: clinical practice

Gaucher disease is a rare autosomal recessive disorder of glycosphingolipid metabolism resulting from deficient activity of the lysosomal enzyme beta-glucocerebrosidase that causes accumulation of glucosylceramide in tissue macrophage with damage to hematological, visceral, and skeletal organ systems. Severity and progression may vary independently among these domains, necessitating individualized therapy. Skeletal involvement is highly prevalent and often associated with intense pain, impaired mobility, and reduced quality of life. Enzyme replacement therapy improves parameters in all affected domains, but skeletal involvement requires longer treatment and higher dosages to obtain significant results. Despite numerous papers on bone complications in patients with Gaucher disease, there are no specific indications on how to assess properly bone involvement in such condition, the frequency of assessment, the use of markers for osteoblast and osteoclast activity, or the administration of bisphosphonates or other symptomatic drugs in adult and pediatric patients. Starting from a re-evaluation of cases with bone involvement, we have identified some common errors in the diagnostic approach and management. The aim of this paper was to propose a methodological and critical approach to the diagnosis, follow-up and treatment of bone disease in patients with Gaucher disease type 1.

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.

Early diagnosis of Gaucher disease in pediatric patients: proposal for a diagnostic algorithm

Gaucher disease (GD) is caused by an enzyme deficiency that leads to the accumulation of glycolipids in various organs. Although the signs and symptoms of GD emerge in childhood in the majority of patients, the disease often remains unrecognized for many years with delay of benefits of therapy or development of irreversible complications. Based on published data and data from the International Collaborative Gaucher Group Registry, an algorithm has been drafted for early diagnosis of GD in pediatric patients. It will help hematologists in promoting a timely diagnosis and early access to therapy for pediatric patients with GD.

Study of enzyme replacement therapy for Gaucher Disease: comparative analysis of clinical and laboratory parameters at diagnosis and after two, five and ten years of treatment

Objective

To evaluate the impact of enzyme replacement therapy for Gaucher Disease on clinical and laboratory parameters after two, five and ten years of treatment.

Methods

Data were collected from patient records and analyzed using BioEstat software (version 5.0). Student's t-test, Analysis of Variance (ANOVA), Wilcoxon test and Kruskal–Wallis test were used for statistical analysis. Hepatomegaly and splenomegaly were analyzed using the Kappa test.

Results

There was a significant increase in hemoglobin levels (p-value <0.01) and platelet counts (p-value = 0.01) within two years of therapy. At the same time, the frequencies of splenomegaly (p-value <0.01) and hepatomegaly (p-value <0.05) reduced. These results were similar at five and ten years of enzyme replacement therapy.

Conclusions

There are substantial and quick (within two years) laboratory and clinical responses to enzyme replacement therapy. These improvements continue as long as enzyme replacement therapy is administered every two weeks, as recommended by the literature.

Patients with type 1 Gaucher disease in South Florida, USA: demographics, genotypes, disease severity and treatment outcomes

Background

Gaucher disease, an autosomal recessive condition due to deficiency of lysosomal glucocerebrosidase, is a multisystemic disease, with variable age of onset, severity and progression. It is classified into subtypes delineated by the absence (type 1) or presence (type 2 and 3) of primary nervous system involvement.

The ethnically diverse, largely immigrant population in South Florida has a spectrum of Gaucher disease phenotypes, creating a challenge for optimization of disease management and an opportunity to explore treatment patterns.

Methods

Ninety-three records from patients with Gaucher type I in South Florida were retrieved from the International Collaborative Gaucher Group (ICGG) Registry. Individual genotypes were correlated with severity scores and success at achieving published therapeutic goals for haemoglobin concentration, platelet count, spleen volume, liver volume and amelioration of bone pain and bone crises.

Results

The majority of patients were diagnosed during the fifth decade of life. Almost two-thirds were homozygous for the N370S mutation, reflecting the large Ashkenazi Jewish population in South Florida. The majority received imiglucerase (62.8%) at various intervals. 24.5% of patients underwent splenectomy before starting enzyme replacement therapy. After a median 12 treatment years, South Florida patients matched or exceeded the ICCG 4 year therapeutic goal achievement for platelet count (85.4% vs. 79.6% success), spleen volume (93.3% vs. 78.0% success), liver volume (93.4% vs. 90.6% success), and bone crises (100% vs. 99% success). Nevertheless, fewer patients with intact spleens had sustained achievement of all 6 therapeutic goals (30.4% versus 41.4%) and only 40% of the splenectomy patients sustained achievement of 5/5 possible goals. 54.7% of the intact spleen patients continued to have bone pain vs. 29.8% in ICCG. Significantly, only 37% of the ICGG patient cohort had bone pain prior to initiation of treatment compared to 73.4% of the South Florida patients (moderate or severe pain in 59.6%).

Conclusions

Demographic characteristics are a significant determinant of the differences in response to treatment observed in South Florida Gaucher patients compared to those described in the international population enrolled in the ICGG Gaucher Registry. Individual genotypes and ethnic background are important considerations for optimizing patient care for Gaucher disease.

Achievement of therapeutic goals with low-dose imiglucerase in Gaucher disease: a single-center experience

Gaucher disease, a lysosomal storage disorder, is a multisystem disorder with variable and unpredictable onset and severity. Disease-specific enzyme replacement therapy (ERT) has been shown to reverse or ameliorate disease-specific hepatosplenomegaly and anemia and thrombocytopenia. ERT also impacts bone manifestations, including bone crises, bone pain, and appearance of new osteonecrosis, and improves bone mineral density to varying degrees. The objective of this study was to assess achievement of predefined therapeutic goals based on international registry outcomes for Israeli patients with Gaucher disease receiving imiglucerase for four consecutive years on a low-dose regimen followed in a single center. All data were taken from patient files. The therapeutic goals were taken from standards published in the literature for disease-specific clinical parameters. Among 164 patients at baseline, values for spleen and liver volumes, hemoglobin and platelet counts, and Z-scores for lumbar spine and femoral were significantly different from the goal. After four years ERT, there was a significant improvement (P = 0.000) in each of the therapeutic goal parameters from baseline. 15.2% of these patients achieved all hematology-visceral goals. In children, there was achievement of linear growth and puberty. This survey highlights the good overall response in symptomatic patients receiving low-dose ERT with imiglucerase in Israel.

Long-term clinical outcomes in type 1 Gaucher disease following 10 years of imiglucerase treatment

OBJECTIVE

We studied the effect of long-term alglucerase/imiglucerase (Ceredase®/Cerezyme®, Genzyme, a Sanofi company, Cambridge, MA, USA) treatment on hematological, visceral, and bone manifestations of Gaucher disease type 1 (GD1).

METHODS

The International Collaborative Gaucher Group (ICGG) Gaucher Registry identified GD1 patients treated with alglucerase/imiglucerase who had dose and clinical data at first infusion and after 10 years of follow-up. Data for hemoglobin, platelet count, organ volumes, bone pain, and bone crisis were analyzed. Tests of the null hypothesis (no change from first infusion to 10 years) were performed using t tests for within-patient absolute change in continuous measurements and McNemar/chi-square tests for change in distributions using categorical values. An alpha level of 0.05 designated statistical significance.

RESULTS

As of October 2011, 557 nonsplenectomized and 200 splenectomized patients met the inclusion criteria. The majority of GD1 patients had at least one N370S allele. Compared with nonsplenectomized patients at first infusion, splenectomized patients had lower percentages of anemia (26.0 % vs. 42.8 %) and thrombocytopenia (14.2 % vs. 76.3 %), similar percentages of moderate or severe hepatomegaly (81.2 % vs. 80.0 %), and higher percentages of bone pain (88.9 % vs. 52.4 %) and bone crises (38.3 % vs. 16.0 %). After 10 years, both groups showed significant (p < 0.05) improvements in mean hemoglobin levels, platelet count, liver, and spleen (nonsplenectomized) volumes, and bone crises. Initial dosing in both groups ranged from <15 U/kg to ≤90 U/kg every 2 weeks. After 10 years, the majority was receiving 15 to ≤45 U/kg every 2 weeks.

CONCLUSION

Ten years of imiglucerase treatment results in sustainable improvements in all GD1 parameters.

Safety and efficacy of velaglucerase alfa in Gaucher disease type 1 patients previously treated with imiglucerase

Velaglucerase alfa is a glucocerebrosidase produced by gene activation technology in a human fibroblast cell line (HT-1080), and it is indicated as an enzyme replacement therapy (ERT) for the treatment of Gaucher disease type 1 (GD1). This multicenter, open-label, 12-month study examined the safety and efficacy of velaglucerase alfa in patients with GD1 previously receiving imiglucerase. Eligible patients, ≥2 years old and clinically stable on imiglucerase therapy, were switched to velaglucerase alfa at a dose equal to their prior imiglucerase dose. Infusion durations were 1 hr every other week. Forty patients received velaglucerase alfa (18 male, 22 female; four previously splenectomized; age range 9-71 years). Velaglucerase alfa was generally well tolerated with most adverse events (AEs) of mild or moderate severity. The three most frequently reported AEs were headache (12 of 40 patients), arthralgia (9 of 40 patients), and nasopharyngitis (8 of 40 patients). No patients developed antibodies to velaglucerase alfa. There was one serious AE considered treatment-related: a grade 2 anaphylactoid reaction within 30 min of the first infusion. The patient withdrew; this was the only AE-related withdrawal. Hemoglobin concentrations, platelet counts, and spleen and liver volumes remained stable through 12 months. In conclusion, adult and pediatric patients with GD1, previously treated with imiglucerase, successfully transitioned to velaglucerase alfa, which was generally well tolerated and demonstrated efficacy over 12 months' treatment consistent with that observed in the velaglucerase alfa phase 3 clinical trial program.

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.

The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients

Background

Clinical features, complications and treatments of Gaucher’s disease (GD), a rare autosomal–recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described.

Methods

All patients with known GD, living in France, with ≥1 consultations (1980–2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥1 follow-up visits, to investigate complications; recently followed (2009–2010) patients; and patients treated during 2009–2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables.

Results

Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal–lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0–77) and 22 (0–84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1–67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson’s disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009–2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%–26.5%) and 19.8% (13.5%–26.1%).

Conclusion

This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.

Imiglucerase in the treatment of Gaucher disease: a history and perspective

The scientific and therapeutic development of imiglucerase (Cerezyme(®)) by the Genzyme Corporation is a paradigm case for a critical examination of current trends in biotechnology. In this article the authors argue that contemporary interest in treatments for rare diseases by major pharmaceutical companies stems in large part from an exception among rarities: the astonishing commercial success of Cerezyme. The fortunes of the Genzyme Corporation, latterly acquired by global giant Sanofi SA, were founded on the evolution of a blockbuster therapy for a single but, as it turns out, propitious ultra-orphan disorder: Gaucher disease.

Genome-wide association study of N370S homozygous Gaucher disease reveals the candidacy of CLN8 gene as a genetic modifier contributing to extreme phenotypic variation

Mutations in GBA1 gene result in defective acid β-glucosidase and the complex phenotype of Gaucher disease (GD) related to the accumulation of glucosylceramide-laden macrophages. The phenotype is highly variable even among patients harboring identical GBA1 mutations. We hypothesize that modifier gene(s) underlie phenotypic diversity in GD and performed a GWAS study in Ashkenazi Jewish patients with type 1 GD (GD1), homozygous for N370S mutation. Patients were assigned to mild, moderate, or severe disease categories using composite disease severity scoring systems. Whole-genome genotyping for >500,000 SNPs was performed to search for association signals using OQLS algorithm in 139 eligible patients. Several SNPs in linkage disequilibrium within the CLN8 gene locus were associated with the GD1 severity: SNP rs11986414 was associated with GD1 severity at P value 1.26 × 10(-6) . Compared to mild disease, risk allele A at rs11986414 conferred an odds ratio of 3.72 for moderate/severe disease. Loss of function mutations in CLN8 causes neuronal ceroid-lipofuscinosis, but our results indicate that its increased expression may protect against severe GD1. In cultured skin fibroblasts, the relative expression of CLN8 was higher in mild GD compared to severely affected patients, in whom CLN8 risk alleles were overrepresented. In an in vitro cell model of GD, CLN8 expression was increased, which was further enhanced in the presence of bioactive substrate, glucosylsphingosine. Taken together, CLN8 is a candidate modifier gene for GD1 that may function as a protective sphingolipid sensor and/or in glycosphingolipid trafficking. Future studies should explore the role of CLN8 in pathophysiology of GD.

[Therapeutic targets in Gaucher's disease]

Gaucher's disease (GD) occurs because of deficiency of the enzyme beta-glucocerebrosidase that results in accumulation of this glycolipid compound in the cells of the macrophage-monocyte system. There are 3 types: type 1 is non-neuronopathic with primarily visceral signs and symptoms which range tremendously in severity; infantile-onset type 2 and later-onset type 3 involve the central nervous system. More than 300 mutations have been described in the gene, partially explaining phenotypic heterogeneity. Commercialization in 1991 of the first enzyme replacement therapy, alglucerase, resulted in a revolution in the management of patients with symptomatic GD (i.e., by improving the hematological and visceral signs and symptoms). Within the first 5 years of alglucerase, its safety and efficacy in improving hemoglobin levels and platelet counts, and in reducing splenic and hepatic enlargement were confirmed albeit recognizing its inability to impact neurological symptoms and signs because of its large molecular size. Recombinant imiglucerase soon replaced alglucerase as the standard of care for GD. The therapeutic targets recently defined as treatment goals were: normalization of cell counts; reduction of liver and spleen volume; elimination of the infiltration in the bone marrow to prevent the complications, and improvement in surrogate biomarkers.

Gaucher's disease: the changing paradigm of a lysosomal disorder

Gaucher's disease (GD) is the most common lysosomal storage disease with a frequency of approximately 1:50,000 people. It is the result of the deficiency of the lysosomal enzyme beta-glucocerebrosidase. The deficiency of the enzyme results in the accumulation of the substrate, glucosyl-ceramide, in the organs. Substitutive enzymatic treatment has been available since almost 20 years. This brief overview highlights some of the most important milestones and the treatments for this disease. The study of this rare disorder is beginning to provide information on the pathogenesis of common diseases such as Parkinson's disease or cancer. Individuals with GD are at greater risk of developing cancer in general, especially hepatobiliary and hematologic (multiple myeloma and B-cell neoplasms). This association has been attributed to the immunologic abnormalities associated with abnormal expression of cytokines such as interleukin-6. Alternative and complementary, some recently marketed and licensed, are providing options for patients throughout Europe and the world.

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.

Pivotal trial with plant cell–expressed recombinant glucocerebrosidase, taliglucerase alfa, a novel enzyme replacement therapy for Gaucher disease

Taliglucerase alfa (Protalix Biotherapeutics, Carmiel, Israel) is a novel plant cell–derived recombinant human β-glucocerebrosidase for Gaucher disease. A phase 3, double-blind, randomized, parallel-group, comparison-dose (30 vs 60 U/kg body weight/infusion) multinational clinical trial was undertaken. Institutional review board approvals were received. A 9-month, 20-infusion trial used inclusion/exclusion criteria in treatment-naive adult patients with splenomegaly and thrombocytopenia. Safety end points were drug-related adverse events: Ab formation and hypersensitivity reactions. Primary efficacy end point was reduction in splenic volume measured by magnetic resonance imaging. Secondary end points were: changes in hemoglobin, hepatic volume, and platelet counts. Exploratory parameters included biomarkers and bone imaging. Twenty-nine patients (11 centers) completed the protocol. There were no serious adverse events; drug-related adverse events were mild/moderate and transient. Two patients (6%) developed non-neutralizing IgG Abs; 2 other patients (6%) developed hypersensitivity reactions. Statistically significant spleen reduction was achieved at 9 months: 26.9% (95% confidence interval [CI]: −31.9, −21.8) in the 30-unit dose group and 38.0% (95% CI: −43.4, −32.8) in the 60-unit dose group (both P < .0001); and in all secondary efficacy end point measures, except platelet counts at the lower dose. These results support safety and efficacy of taliglucerase alfa for Gaucher disease. This study was registered at www.clinicaltrials.gov as NCT00376168.

Reducing selection bias in case-control studies from rare disease registries

BACKGROUND

In clinical research of rare diseases, where small patient numbers and disease heterogeneity limit study design options, registries are a valuable resource for demographic and outcome information. However, in contrast to prospective, randomized clinical trials, the observational design of registries is prone to introduce selection bias and negatively impact the validity of data analyses. The objective of the study was to demonstrate the utility of case-control matching and the risk-set method in order to control bias in data from a rare disease registry. Data from the International Collaborative Gaucher Group (ICGG) Gaucher Registry were used as an example.

METHODS

A case-control matching analysis using the risk-set method was conducted to identify two groups of patients with type 1 Gaucher disease in the ICGG Gaucher Registry: patients with avascular osteonecrosis (AVN) and those without AVN. The frequency distributions of gender, decade of birth, treatment status, and splenectomy status were presented for cases and controls before and after matching. Odds ratios (and 95% confidence intervals) were calculated for each variable before and after matching.

RESULTS

The application of case-control matching methodology results in cohorts of cases (i.e., patients with AVN) and controls (i.e., patients without AVN) who have comparable distributions for four common parameters used in subject selection: gender, year of birth (age), treatment status, and splenectomy status. Matching resulted in odds ratios of approximately 1.00, indicating no bias.

CONCLUSIONS

We demonstrated bias in case-control selection in subjects from a prototype rare disease registry and used case-control matching to minimize this bias. Therefore, this approach appears useful to study cohorts of heterogeneous patients in rare disease registries.

How I treat Gaucher disease

This review presents a cohesive approach to treating patients with Gaucher disease. The spectrum of the clinical presentation of the disease is broad, yet heretofore there was only one disease-specific treatment. In the past 2 years, a global shortage of this product has resulted in reassessment of the “one enzyme–one disease–one therapy” mantra. It has also showcased the multiple levels that engage the patient, the treating physician, and the third-party insurer in providing adequate treatment to all symptomatic patients. The key points summarizing the way I manage my patients include accurate enzymatic diagnosis with mutation analysis (for some prognostication and better carrier detection in the family), a detailed follow-up every 6-12 months (with an option to see consultants and attention to comorbidities), and initiation of enzyme replacement therapy according to symptoms or deterioration in clinically significant features or both. I do not treat patients with very mild disease, but I consider presymptomatic therapy for patients at risk, including young women with poor obstetric history. I prefer the minimal-effective dose rather than the maximally tolerated dose, and when the difference between high-dose and lower-dose regimens is (merely statistically significant but) clinically meaningless, minimizing the burden on society by advocating less-expensive treatments is ethically justified.

[Enzyme replacement therapy of lysosomal storage diseases]

Extraction and purification of an acid β-glucosidase from human placenta (alglucerase) for the treatment of Gaucher disease, replaced a few years later by a recombinant enzyme (imiglucérase, Cerezyme(®)), has paved the way to the development of enzyme replacement therapies (ERT) for the treatment of lysosomal storage diseases (LSD) among which Fabry disease for which the long-term efficacy of the two currently available preparations (agalsidase alfa, Replagal(®) and Fabrazyme(®)) is still being investigated. Mucopolysaccharidosis (MPS) type I (Hurler and Scheie diseases), II (Hunter syndrome) and VI (Maroteaux-Lamy disease) also benefit from ERT using laronidase (Aldurazyme(®)), idursulfase (Elaprase(®)) and galsulfase (Naglazyme(®)), respectively. ERT reduces the hepatosplenomegaly and improves the physical and respiratory capacities of MPS patients with a globally acceptable safety profile although the possibility of infusion-associated should always be kept in mind. Alglucosidase alpha (Myozyme(®)) improves the cardiomyopathy and life expectancy of infants suffering from Pompe disease and is under evaluation for the treatment of the juvenile and adult forms of the disease. CNS involvement remains a major challenge for many LSD and innovative research and approaches are needed to address the fact that recombinant enzymes do not cross the blood-brain barrier and therefore are not expected to lead to any improvement in CNS damages, except if alternative routes such as intrathecal administration would be developed. Molecular chaperones (e.g. migalastat for Fabry disease) and inhibitors of glucosylceramide synthesis (e.g. eliglustat tartrate for Gaucher disease) are currently under investigation in various clinical trials.

Evaluation of high density lipoprotein as a circulating biomarker of Gaucher disease activity

Circulating biomarkers are important surrogates for monitoring disease activity in type I Gaucher disease (GD1). We and others have reported low high-density lipoprotein (HDL) in GD1. We assessed HDL cholesterol as a biomarker of GD1, with respect to its correlation with indicators of disease severity and its response to imiglucerase enzyme replacement therapy (ERT). In 278 consecutively evaluated GD1 patients, we correlated HDL cholesterol, chitotriosidase, and angiotensin-converting enzyme (ACE) with indicators of disease severity. Additionally, we measured the response of these biomarkers to ERT. HDL cholesterol was negatively correlated with spleen volume, liver volume, and GD severity score index; the magnitude of this association of disease severity with HDL cholesterol was similar to that for ACE and for chitotriosidase. Within individual patients monitored over many years, there was a strikingly strong correlation of HDL with liver and spleen volumes; there was a similarly strong correlation of chitotriosidase and ACE with disease severity in individual patients monitored serially over many years (chitotriosidase r = 0.96 to 0.98, ACE r = 0.88 to 0.94, and HDL r = -0.84 to -0.94, p < 0.001). ERT for 3 years resulted in a striking increase of HDL while serum levels of chitotriosidase and ACE decreased. Our results reveal markedly low HDL cholesterol in untreated GD1, a correlation with indicators of disease severity in GD1, and a rise towards normal after ERT. These findings suggest HDL cholesterol merits inclusion within the "biomarker basket" for monitoring of patients with GD1.

Velaglucerase alfa in the treatment of Gaucher disease type 1

Gaucher disease is an autosomal recessively inherited lysosomal storage disease that results from the defective activity of the enzyme acid β-glucosidase (glucocerebrosidase). Velaglucerase alfa was recently developed and approved as an alternative form to imiglucerase enzyme therapy. Despite differences in primary structure and glycosylation patterns, recent preclinical and clinical trials of the preparation have shown similar efficacy and safety profiles to those of imiglucerase. The development of alternative therapies, such as velaglucerase alfa for Gaucher disease, is providing clinicians with a larger armamentarium of therapies, allowing for a more personalized approach to patient care.

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.

A reappraisal of Gaucher disease-diagnosis and disease management algorithms

Type 1 (non-neuronopathic) Gaucher disease was the first lysosomal storage disorder for which an effective enzyme replacement therapy was developed and it has become a prototype for treatments for related orphan diseases. There are currently four treatment options available to patients with Gaucher disease, nevertheless, almost 25% of Type 1 Gaucher patients do not gain timely access to therapy because of delays in diagnosis after the onset of symptoms. Diagnosis of Gaucher disease by enzyme testing is unequivocal, but the rarity of the disease and nonspecific and heterogeneous nature of Gaucher disease symptoms may impede consideration of this disease in the differential diagnosis. To help promote timely diagnosis and optimal management of the protean presentations of Gaucher disease, a consensus meeting was convened to develop algorithms for diagnosis and disease management for Gaucher disease.

Gaucher disease: clinical profile and therapeutic developments

Gaucher disease is a rare inborn error of glycosphingolipid metabolism due to deficiency of lysosomal acid β-glucocerebrosidase; the condition has totemic significance for the development of orphan drugs. A designer therapy, which harnesses the mannose receptor to complement the functional defect in macrophages, ameliorates the principal clinical manifestations in hematopoietic bone marrow and viscera. While several aspects of Gaucher disease (particularly those affecting the skeleton and brain) are refractory to treatment, enzyme (replacement) therapy has become a pharmaceutical blockbuster. Human β-glucocerebrosidase was originally obtained from placenta and the Genzyme Corporation (Allston, MA) subsequently developed a recombinant product. After purification, the enzyme is modified to reveal terminal mannose residues which facilitate selective uptake of the protein, imiglucerase (Cerezyme^®), in macrophage-rich tissues. The unprecedented success of Cerezyme has attracted fierce competition: two biosimilar agents, velaglucerase-alfa, VPRIV^® (Shire Human Genetic Therapies, Dublin, Ireland) and taliglucerase-alfa (Protalix, Carmiel, Israel), are now approved or in late-phase clinical development as potential ‘niche busters’. Oral treatments have advantages over biological agents for disorders requiring lifelong therapy and additional stratagems which utilize small, orally active molecules have been introduced; these include two chemically distinct compounds which inhibit uridine diphosphate glucose: N-acylsphingosine glucosyltransferase, the first step in the biosynthesis of glucosylceramide – a key molecular target in Gaucher disease and other glycosphingolipidoses. Academic and commercial enterprises in biotechnology have combined strategically to expand the therapeutic repertoire in Gaucher disease. The innovative potential of orphan drug legislation has been realized – with prodigious rewards for companies embracing its humanitarian precepts. In the era before enzyme therapy, bone marrow transplantation was shown to correct systemic disease in Gaucher patients by supplying a source of competent donor macrophages. As a radical advance on cell- or protein-replacement techniques, contemporary methods for transferring genes to autologous hematopoietic stem cells, and to the brain, merit further exploration. At present, the inflated pharmaceutical niche of Gaucher disease appears to be resilient, but if the remaining unmet needs of patients are to be convincingly addressed and commercial development sustained, courageous scientific investment and clinical experimentation will be needed.