Long-term effects of eliglustat on skeletal manifestations in clinical trials of patients with Gaucher disease type 1

Development of selective nanomolar cyclic peptide ligands as GBA1 enzyme stabilisers

The stabilisation of recombinant glycosidases by exogenous ligands, known as pharmacological chaperones or enzyme stabilisers, has recently garnered great clinical interest. This strategy can prevent enzyme degradation in the blood, reducing required dosages of recombinant enzyme and extending IV injection intervals, thereby reducing side effects, improving patient lifestyles and treatment costs. While this therapeutic approach has been successfully implemented for treating Pompe and Fabry diseases, clinical studies for Gaucher disease using chaperones alone or in combination with enzyme replacement therapy (ERT) have been limited, and no small molecule chaperones have yet been approved for this condition. Developing such therapies requires selective and effective reversible GBA1 ligands. Here, we describe the development of a new class of selective macrocyclic peptide GBA1 ligands using random nonstandard peptides integrated discovery (RaPID) technology, and demonstrate their ability to bind and stabilise rhGBA1 in plasma at nanomolar concentrations. These cyclic peptides do not inhibit endogenous GBA1 in cells due to poor cell permeability but can stabilise extracellular rhGBA1 in plasma, presenting significant potential as a combinatorial ERT-pharmacological chaperone therapy for Gaucher disease.

Eliglustat substrate reduction therapy in children with Gaucher disease type 1

Importance

Gaucher disease (GD) is a rare lysosomal storage disorder with limited treatment options for pediatric patients. Oral substrate reduction therapy (SRT) with eliglustat offers a potential alternative, particularly for those with barriers to enzyme replacement therapy (ERT).

Objective

Evaluate the safety and efficacy of eliglustat SRT in pediatric patients with type 1 Gaucher disease (GD1), both as initial therapy and as a switch from intravenous ERT.

Design

A prospective case series was conducted from 2017 to 2024.

Setting

Yale's National Gaucher Disease Treatment Center, New Haven, CT, United States.

Participants

Fourteen pediatric GD1 patients with significant barriers to receiving ERT.

Intervention

Eliglustat SRT was dosed pharmacogenomically based on CYP2D6 metabolizer status.

Primary outcomes and measures

Primary outcomes included safety and efficacy in reversing indicators of disease activity. Secondary outcomes involved changes in patient and parent-reported quality of life, assessed using PROMIS questionnaires.

Results

Eliglustat was initiated at a mean age of 12.5 years (range: 6-17 years) and administered for a mean duration of 3.6 years (range: 1-7 years). All patients remained on treatment and exhibited sustained reductions in glucosylsphingosine (GlcSph) levels compared to baseline (p = 0.005). Other disease indicators demonstrated corresponding improvements. Adverse effects were limited to transient gastroesophageal reflux in 3/14 patients (21%). Serial electrocardiograms (EKGs) were normal. Growth and developmental milestones were appropriate for age in all patients. Patients and their parents reported a global improvement in quality of life.

Conclusions

Eliglustat demonstrated significant clinical benefits in pediatric GD1 patients, as evidenced by reductions in GlcSph levels and other disease indicators. The therapy showed a favorable safety profile comparable to that observed in adults. These findings suggest eliglustat is a promising therapeutic option for pediatric GD1 patients, providing an effective alternative to ERT.

Current and Emerging Therapies for Lysosomal Storage Disorders

Lysosomal storage disorders (LSDs) are rare inherited metabolic disorders characterized by defects in the function of specific enzymes responsible for breaking down substrates within cellular organelles (lysosomes) essential for the processing of macromolecules. Undigested substrate accumulates within lysosomes, leading to cellular dysfunction, tissue damage, and clinical manifestations. Clinical features vary depending on the degree and type of enzyme deficiency, the type and extent of substrate accumulated, and the tissues affected. The heterogeneous nature of LSDs results in a variety of treatment approaches, which must be tailored to patient presentation and characteristics. The treatment landscape for LSDs is rapidly evolving. An up-to-date discussion of current evidence is required to provide clinicians with an appropriate overview of treatment options. Therefore, we aimed to review current and ongoing trials pertaining to the treatment of common LSDs.

Emerging biomarkers in Gaucher disease

Gaucher disease (GD) is a rare lysosomal disorder characterized by the accumulation of glycosphingolipids in macrophages resulting from glucocerebrosidase (GCase) deficiency. The accumulation of toxic substrates, which causes the hallmark symptoms of GD, is dependent on the extent of enzyme dysfunction. Accordingly, three distinct subtypes have been recognized, with type 1 GD (GD1) as the common and milder form, while types 2 (GD2) and 3 (GD3) are categorized as neuronopathic and severe. Manifestations variably include hepatosplenomegaly, anemia, thrombocytopenia, easy bruising, inflammation, bone pain and other skeletal pathologies, abnormal eye movements and neuropathy. Although the molecular basis of GD is relatively well understood, currently used biomarkers are nonspecific and inadequate for making finer distinctions between subtypes and in evaluating changes in disease status and guiding therapy. Thus, there is continued effort to investigate and identify potential biomarkers to improve GD diagnosis, monitoring and potential identification of novel therapeutic targets. Here, we provide a comprehensive review of emerging biomarkers in GD that can enhance current understanding and improve quality of life through better testing, disease management and treatment.

An Overview of Gaucher Disease

BACKGROUND

Gaucher disease (GD) is a rare autosomal recessive disorder caused by mutations in the GBA1 gene that lead to a deficiency in the glucocerebrosidase gene. This deficiency results in the accumulation of glucocerebrosides in macrophages, primarily affecting the liver, spleen, and bone marrow. Focusing on the Mexican population, this study aims to review GD's epidemiology, clinical manifestations, and treatment options to enhance early diagnosis and optimize treatment outcomes.

METHODS

This study is a comprehensive literature review analyzing epidemiological data, clinical presentations, and current therapeutic approaches for Gaucher disease, including enzyme replacement therapy (ERT) and substrate reduction therapy (SRT).

CONCLUSIONS

Early diagnosis and individualized treatment, primarily through enzyme replacement therapy, significantly improve the prognosis of patients with Gaucher disease, particularly type 1. Continued research is required to enhance therapeutic approaches for the neuropathic types and better understand the disease's epidemiology in Mexico. These efforts will contribute to improved clinical outcomes and quality of life for patients.

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.

The Liver and Lysosomal Storage Diseases: From Pathophysiology to Clinical Presentation, Diagnostics, and Treatment

The liver, given its role as the central metabolic organ, is involved in many inherited metabolic disorders, including lysosomal storage diseases (LSDs). The aim of this manuscript was to provide a comprehensive overview on liver involvement in LSDs, focusing on clinical manifestation and its pathomechanisms. Gaucher disease, acid sphingomyelinase deficiency, and lysosomal acid lipase deficiency were thoroughly reviewed, with hepatic manifestation being a dominant clinical phenotype. The natural history of liver disease in the above-mentioned lysosomal disorders was delineated. The importance of Niemann-Pick type C disease as a cause of cholestatic jaundice, preceding neurological manifestation, was also highlighted. Diagnostic methods and current therapeutic management of LSDs were also discussed in the context of liver involvement.

Osteonecrosis in Gaucher disease in the era of multiple therapies: Biomarker set for risk stratification from a tertiary referral center

Background

A salutary effect of treatments for Gaucher disease (GD) has been a reduction in the incidence of avascular osteonecrosis (AVN). However, there are reports of AVN in patients receiving enzyme replacement therapy (ERT) , and it is not known whether it is related to individual treatments, GBA genotypes, phenotypes, biomarkers of residual disease activity, or anti-drug antibodies. Prompted by development of AVN in several patients receiving ERT, we aimed to delineate the determinants of AVN in patients receiving ERT or eliglustat substrate reduction therapy (SRT) during 20 years in a tertiary referral center.

Methods

Longitudinal follow-ups of 155 GD patients between 2001 and 2021 were analyzed for episodes of AVN on therapy, type of therapy, GBA1 genotype, spleen status, biomarkers, and other disease indicators. We applied mixed-effects logistic model to delineate the independent correlates of AVN while receiving treatment.

Results

The patients received cumulative 1382 years of treatment. There were 16 episodes of AVN in 14 patients, with two episodes, each occurring in two patients. Heteroallelic p.Asn409Ser GD1 patients were 10 times (95% CI, 1.5-67.2) more likely than p.Asn409Ser homozygous patients to develop osteonecrosis during treatment. History of AVN prior to treatment initiation was associated with 4.8-fold increased risk of AVN on treatment (95% CI, 1.5-15.2). The risk of AVN among patients receiving velaglucerase ERT was 4.68 times higher compared to patients receiving imiglucerase ERT (95% CI, 1.67-13). No patient receiving eliglustat SRT suffered AVN. There was a significant correlation between GlcSph levels and AVN. Together, these biomarkers reliably predicted risk of AVN during therapy (ROC AUC 0.894, p<0.001).

Conclusions

There is a low, but significant risk of AVN in GD in the era of ERT/SRT. We found that increased risk of AVN was related to GBA genotype, history of AVN prior to treatment initiation, residual serum GlcSph level, and the type of ERT. No patient receiving SRT developed AVN. These findings exemplify a new approach to biomarker applications in a rare inborn error of metabolism to evaluate clinical outcomes in comprehensively followed patients and will aid identification of GD patients at higher risk of AVN who will benefit from closer monitoring and treatment optimization.

Funding

LSD Training Fellowship from Sanofi to MB.