Gaucher disease 2 (GD2) is a rare and rapidly progressive neuropathic lysosomal storage disorder with an average survival of 11-19 months. To date, no approved therapy is available, but the variant-dependent pharmacological chaperone ambroxol (ABX) has emerged as a promising off-label therapy. This long-term observational study encompasses 2 GD2 patients treated with high-dose ABX from the age of 4 and 1 months, respectively, in addition to enzyme replacement therapy (ERT). Previously published data of patient 1 demonstrated a significant increase in β-glucocerebrosidase activity in ABX-treated patient fibroblasts alongside nearly age-appropriate neurocognitive and motor development after 3 years of ABX therapy. Follow-up assessments at the present age of 6.5 years continued to show normal neurocognitive development. Glucosylsphingosine (Lyso-GL1) levels in cerebrospinal fluid (CSF) remained significantly decreased compared to pre-treatment levels. In patient 2, ABX-treated fibroblasts exhibited a slight increase in β-glucocerebrosidase activity. Nevertheless, Lyso-GL1 levels in CSF showed a notable decrease compared to baseline. Neurocognitive and motor function assessments at 40 months of age indicated a moderate to severe developmental delay, yet continuous developmental progress. These interim findings contribute to the mounting evidence supporting ABX as a variant-dependent treatment for GD2 patients.

The GM1 and GM2 gangliosidoses and type 2 Gaucher disease (GD2) are inherited lysosomal storage disorders with most cases having symptom onset in infancy and reduced life expectancy. The conditions are rare, and there is therefore a need for accurate and up to date information concerning the disease course and survival to assist in the design of clinical trials. RETRIEVE is a natural history study aiming to: (1) collect data on the survival of patients with early-onset (onset of first neurological manifestation before 24 months of age) GM1, GM2, or GD2; (2) collect data that could constitute a historical control group for future clinical trials; and (3) evaluate whether the conditions can be assessed together in a single interventional clinical trial. Group A included patients who were deceased or with unknown survival status at enrollment and was thus limited to retrospective data. Group B included patients who were alive at enrollment, who were followed prospectively with additional retrospective data collection. Group A included 185 patients (60 with GM1, 78 with GM2, and 47 with GD2), and Group B included 40 patients (18 with GM1, 16 with GM2, and 6 with GD2). Mean and median age at diagnosis and age at onset of first neurological manifestation were youngest in patients with GD2 and oldest in patients with GM2 in both groups. In Group A, median (95% CI) survival was 19.0 (18.0, 22.0), 44.0 (37.0, 51.9) and 14.0 (10.0, 16.0) months in patients with GM1, GM2 and GD2, respectively. In Group B, hypotonia was experienced by most patients with GM1 (17/18, 94.4%), and was less common in patients with GM2 (12/16, 75.0%) and GD2 (4/6, 66.7%). Strabismus and splenomegaly were reported in all six patients with GD2. RETRIEVE is one of the largest natural history studies of GM1, GM2, and GD2. Results were generally consistent with the published literature, with differences potentially due to variation in inclusion criteria. The difference in median survival between patients with early-onset GM1, GM2, and GD2 reported in this study suggests that the three diseases should not be pooled for study in clinical trials.

Neuropathic lysosomal storage diseases (NLSDs), including ceroid lipofuscinosis neuronal 3 (CLN3) disease and Gaucher disease type 2 (GD2), are typically present in adolescents; however, there are no approved therapies. CLN3 disease is the most common of the 13 types of neuronal ceroid lipofuscinosis, and Gaucher disease is the most common type of lysosomal storage disease. These NLSDs share oxidative stress and lysosomal dysfunction with Parkinson's disease. In this study, we used patient-derived cells (PDCs) and resorcinol to develop a therapeutic agent based on peroxisome proliferator-activated receptor γ (PPARγ) activation. PPARγ is a major regulator of autophagy and reactive oxygen species (ROS). Resorcinol, a polyphenolic compound, has been reported to exhibit PPARγ agonistic potential. Protein levels were analyzed by immunoblotting and immunofluorescence microscopy. Changes in cellular metabolism, including ROS levels, lipid droplet content, and lysosomal activity, were measured by flow cytometry. Resorcinol reduced ROS levels by suppressing hypoxia-inducible factor 1α levels in CLN3-PDCs. Resorcinol upregulated autophagy and reduced lipid accumulation in CLN3-PDCs; however, these effects were abolished by autophagy inhibitors. Resorcinol increased nuclear PPARγ levels in CLN3-PDCs, and PPARγ antagonists abolished the therapeutic effects of resorcinol. Moreover, Resorcinol upregulated nuclear PPARγ levels and lysosomal activity in GD2-PDCs, and reduced lipid accumulation and ROS levels. In summary, resorcinol alleviated the shared pathogenesis of CLN3 disease and GD2 through PPARγ upregulation. These findings suggest that resorcinol is a potential therapeutic candidate for alleviating NLSD progression.

Gaucher disease (GD), an autosomal recessive lysosomal storage disease, results from GBA1 variants causing glucocerebrosidase (GCase) deficiency. While enzyme replacement therapy (ERT) helps with systemic symptoms, neurological complications in GD2 and GD3 persist due to the blood-brain-barrier (BBB) limiting ERT efficacy. Ambroxol, a BBB-permeable chaperone, enhances GCase activity. Our review explores high-dose ambroxol's therapeutic potential, both preclinical and clinical, in GD2 and GD3. PubMed was searched for studies published before March 2023, including clinical, animal, and in vitro studies focusing on the effect of high-dose ambroxol in GD2 and GD3. A narrative synthesis was performed. Nine in vitro, three animal, and eight clinical studies were included, demonstrating varied responses to ambroxol across diverse outcome measures. In vitro and animal studies demonstrated reduced endoplasmatic reticulum stress due to the relocation of GCase from the ER to the lysosomes. In vitro cell lines exhibited varying degrees of increased GCase activity. Clinical trials observed reduced lyso-GL1 levels in plasma (41-89%) and cerebrospinal fluid (CSF) (26-97%), alongside increased GCase activity in GD3 patients. Ambroxol exhibited varying effects on neurological outcomes and development. No severe adverse events were reported. High-dose ambroxol shows promise in managing neurological manifestations in GD3, albeit with uncertainties resulting from genetic heterogeneity and variable response. Further clinical trials, are essential for elucidating dosage-response relationships and refining treatment outcomes and strategies for neuronopathic GD.

Our aim was to compare the costs and efficacy of ambroxol in combination with imiglucerase with the costs and efficacy of imiglucerase only in the treatment of Gaucher disease type 2 (GD2) in the socio-economic settings of the Republic of Serbia, an upper-middle-income European economy. The perspective of the Serbian Republic Health Insurance Fund was chosen for this study, and the time horizon was 6 years. The main outcomes of the study were quality-adjusted life years gained with ambroxol + imiglucerase and comparator, and direct costs of treatment. The study was conducted through the generation and simulation of the Markov chain model. The model results were obtained after Monte Carlo microsimulation of a sample with 1,000 virtual patients. Treatment with ambroxol in combination with imiglucerase was cost-effective when compared with imiglucerase only and was associated with positive values of net monetary benefit regardless of the onset of the disease. Such beneficial result for ambroxol and imiglucerase combination is primarily driven by the low cost of ambroxol and its considerable clinical effectiveness in slowing the progression of neural complications of GD2. If ambroxol and imiglucerase are used in combination for the treatment of GD2, it is more cost-effective than using imiglucerase alone.