The efficacy of enzyme replacement therapy in patients with chronic neuronopathic Gaucher's disease.

OBJECTIVE: To assess the long-term systemic and neurologic responses to enzyme replacement therapy (ERT) with macrophage-targeted glucocerebrosidase in patients with type 3 Gaucher's disease. STUDY DESIGN: Patients with type 3 Gaucher's disease (n = 21), aged 8 months to 35 years, were enrolled in a prospective study. Enzyme dose was adjusted to control systemic manifestations. Clinical and laboratory evaluations were performed at baseline and every 6 to 12 months thereafter. Patients were followed up for 2 to 8 years. RESULTS: Significant improvement in hemoglobin levels, platelet count, and acid phosphatase values occurred. Liver and spleen volume markedly decreased, and bone structure improved. Nineteen patients had asymptomatic interstitial lung disease unresponsive to ERT. Supranuclear gaze palsy remained stable in 19 patients, worsened in one patient, and improved in one. Cognitive function remained unchanged or improved over time in 13 patients but decreased in 8 patients, 3 of whom developed progressive myoclonic encephalopathy accompanied by cranial magnetic resonance imaging and electroencephalographic deterioration. CONCLUSIONS: At relatively high doses, ERT reverses almost all the systemic manifestations in patients with type 3 Gaucher's disease. Most treated patients do not deteriorate neurologically. Novel therapeutic strategies are required to reverse the pulmonary and neuronopathic aspects of the disease.

Comparative efficacy of dose regimens in enzyme replacement therapy of type I Gaucher disease.

Gaucher disease is caused by a deficiency of beta-glucocerebrosidase activity. The optimum dose and frequency of enzyme replacement therapy for Gaucher patients have not been determined. We set to compare the therapeutic effects of initiating treatment with macrophage-targeted glucocerebrosidase at a high dose followed by progressive dose reductions with that produced by initial treatment at a low dose in patients with type I Gaucher disease. The study included two parts: (i) Twelve patients received every 2 weeks enzyme replacement therapy at 60 IU/kg body wt for 24 months followed by sequential dose reduction every 6 months to 30 and then to 15 IU/kg body wt. (ii) Thirty-two patients received enzyme replacement therapy at 10 IU/kg every 2 weeks for 12 months. Hematologic parameters and liver and spleen volume were monitored in all patients. All patients had intact spleens. In patients who were started on high-dose enzyme replacement therapy, hemoglobin, acid phosphatase, and organ volume improved or remained unchanged at the end of each dose reduction. Platelet count decreased significantly when the dose of enzyme was reduced from 30 to 15 IU/kg body wt. Initiation of therapy at a low dose led to a significant improvement in all measured parameters at the end of 1 year. We conclude that the minimal effective dose for the nonskeletal manifestations of Gaucher disease can be achieved either by initiating enzyme replacement therapy with a high dose followed by a stepwise dose reduction or by starting treatment at the minimal dose. High dose provides a faster clinical response and should be considered for patients with more aggressive disease. The therapeutic threshold for macrophage-targeted glucocerebrosidase appears to be 10-15 IU/kg body wt every 2 weeks.

Infusion of alpha-galactosidase A reduces tissue globotriaosylceramide storage in patients with Fabry disease.

Fabry disease is a lysosomal storage disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). This enzymatic defect results in the accumulation of the glycosphingolipid globotriaosylceramide (Gb(3); also referred to as ceramidetrihexoside) throughout the body. To investigate the effects of purified alpha-gal A, 10 patients with Fabry disease received a single i.v. infusion of one of five escalating dose levels of the enzyme. The objectives of this study were: (i) to evaluate the safety of administered alpha-gal A, (ii) to assess the pharmacokinetics of i.v.-administered alpha-gal A in plasma and liver, and (iii) to determine the effect of this replacement enzyme on hepatic, urine sediment and plasma concentrations of Gb(3). alpha-Gal A infusions were well tolerated in all patients. Immunohistochemical staining of liver tissue approximately 2 days after enzyme infusion identified alpha-gal A in several cell types, including sinusoidal endothelial cells, Kupffer cells, and hepatocytes, suggesting diffuse uptake via the mannose 6-phosphate receptor. The tissue half-life in the liver was greater than 24 hr. After the single dose of alpha-gal A, nine of the 10 patients had significantly reduced Gb(3) levels both in the liver and shed renal tubular epithelial cells in the urine sediment. These data demonstrate that single infusions of alpha-gal A prepared from transfected human fibroblasts are both safe and biochemically active in patients with Fabry disease. The degree of substrate reduction seen in the study is potentially clinically significant in view of the fact that Gb(3) burden in Fabry patients increases gradually over decades. Taken together, these results suggest that enzyme replacement is likely to be an effective therapy for patients with this metabolic disorder.

Radiographic findings in type 3b Gaucher disease.

The purpose of this paper is to describe the radiographic findings in type 3 b Gaucher disease, a chronic neuronopathic form of the illness with severe systemic manifestations. Between 1980 and 1985 17 consecutive patients were evaluated with radiography of the chest, long bones and spine, CT of the head and chest, abdominal sonography, and MRI of the head, abdomen and spine. Clinical manifestations were severe, and led to death from hepatic, pulmonary or cardiac failure in nine patients. Type 3 b Gaucher disease shares the same spectrum of radiographic findings observed in type 1 disease, but the systemic manifestations are more severe. Pulmonary infiltrates, thoracic lymph node enlargement, vertebral compression fractures and osteonecrosis of the long bones occur much more frequently in patients with type 3 b disease.