Atherogenic lipid profile in patients with Niemann-Pick disease type B: What treatment strategies?

Niemann-Pick disease (NPD) type A and type B are part of the spectrum disease of the acid sphingomyelinase deficiency (ASMD). Plasma lipid abnormalities are frequently associated with both NPD-A and NPD-B, and include decreased high-density lipoprotein cholesterol (HDL-C), increased low-density lipoprotein cholesterol (LDL-C), and hypertriglyceridemia. The atherogenic lipid profile has been associated to early atherosclerotic vascular disease and coronary artery disease in NPD-B patients. Thus, early treatment of dyslipidemia in these patients is advisable. We present here a pediatric case of NPD-B with an atherogenic lipid profile not responding to lifestyle changes, low fat diet, and daily supplementation with plant sterols. We reviewed the existing literature about the treatment strategies for dyslipidemia in ASMD patients, with a special focus on the pediatric age. Finally, we speculated on the mechanisms underlying dyslipidemia in this disorder. The clinical experiences in lipid-lowering strategies in NPD-B patients are limited, in particular in the pediatric age. Olipudase alfa appears as the most promising candidate for improving lipid profile. Since olipudase alfa is not yet approved and, due to its costs, it will probably not be available for all patients worldwide, further research is needed to broaden our knowledge on this clinical need and to evaluate the efficacy and the long-term effects of lipid-lowering agents in ASMD patients. A deep understanding of the pathophysiology of dyslipidemia in ASMD may promote the identification of new targets and support the identification of new therapeutic strategies.

Niemann-Pick disease type-B: a unique case report with compound heterozygosity and complicated lipid management.

BACKGROUND: Niemann-Pick disease (NPD) is a rare autosomal recessive hereditary disease characterized by deficient activity of acid sphingomyelinase. CASE PRESENTATION: We present a case of NPD type B with a unique compound heterozygosity for SMPD1 (NM_000543.4:c.[84delC];[96G > A]) in which both mutations that induce an early stop codon are located before the second in-frame initiation codon. The clinical presentation of the patient is compatible with NPD type B. She was initially diagnosed of Gaucher Disease, but her altered lipid profile led to a clinical suspicion of NPD. Combined high doses of atorvastatin and ezetimibe were given to treat the severe hypercholesterolemia. CONCLUSIONS: The pharmacological management of the lipid profile in these patients is important. A unique compound mutation in SMPD1 gene is described.

Clearance of Hepatic Sphingomyelin by Olipudase Alfa Is Associated With Improvement in Lipid Profiles in Acid Sphingomyelinase Deficiency.

Acid sphingomyelinase deficiency (ASMD; Niemann-Pick disease type A and B) is a lysosomal storage disorder characterized by abnormal intracellular sphingomyelin (SM) accumulation. Prominent liver involvement results in hepatomegaly, fibrosis/cirrhosis, abnormal liver chemistries, and a proatherogenic lipid profile. Olipudase alfa (recombinant human ASM) is in clinical development as an investigational enzyme replacement therapy for the non-neurological manifestations of ASMD. In a phase 1b study conducted to evaluate the safety and tolerability of within-patient dose escalation with olipudase alfa, measurement of SM levels in liver biopsies was used as a pharmacodynamic biomarker of substrate burden. Five adult patients with non neuronopathic ASMD received escalating doses of olipudase alfa every 2 weeks for 26 weeks. Liver biopsies obtained at baseline and 26 weeks after treatment were evaluated for SM storage by histomorphometric analysis, biochemistry, and electron microscopy. Biopsies were also assessed for inflammation and fibrosis, and for the association of SM levels with liver volume, liver function tests, and lipid profiles. At baseline, SM storage present in Kupffer cells and hepatocytes ranged from 9.8% to 53.8% of the microscopic field. After 26 weeks of treatment, statistically significant reductions in SM (P<0.0001) measured by morphometry were seen in 4 patients with evaluable liver biopsies. The 26-week biopsy of the fifth patient was insufficient for morphometric quantitation. Posttreatment SM levels ranged from 1.2% to 9.5% of the microscopic field, corresponding to an 84% to 92% relative reduction from baseline. Improvements in liver volume, liver function tests, and lipid profiles were also observed. This study illustrates the utility of SM assessment by liver biopsy as a pharmacodynamic biomarker of disease burden in these patients.

Novel first-dose adverse drug reactions during a phase I trial of olipudase alfa (recombinant human acid sphingomyelinase) in adults with Niemann-Pick disease type B (acid sphingomyelinase deficiency).

PURPOSE: Enzyme replacement therapy with olipudase alfa (recombinant human acid sphingomyelinase) is being developed for Niemann-Pick disease type B (NPD B). METHODS: A single-center, open-label, nonrandomized, single-ascending-dose trial evaluated the safety of intravenous olipudase alfa (0.03-1.0 mg/kg) in 11 adults with NPD B. Patients were monitored in the hospital for 72 h after infusion and had follow-up visits on days 14 and 28. RESULTS: Plasma ceramide, a product of sphingomyelin catabolism by olipudase alfa, showed dose-dependent elevations by 6 h postdose, or postinfusion. No serious adverse drug reactions (ADRs) occurred during the study. Acute phase reaction-type ADRs, as evidenced by elevated inflammatory biomarkers (high-sensitivity C-reactive protein, interleukin-8, and calcitonin) and constitutional symptoms (fever, pain, nausea, and/or vomiting) emerged 12-24 h following doses ≥0.3 mg/kg olipudase alfa. Three patients experienced hyperbilirubinemia. The study was terminated after a patient dosed at 1 mg/kg exhibited severe hyperbilirubinemia; he was subsequently diagnosed with Gilbert syndrome. CONCLUSION: The maximum tolerated dose of olipudase alfa in adults with NPD B was 0.6 mg/kg. First-dose ADRs were likely induced by elevated concentrations of ceramide (or its downstream derivatives) generated by the catabolism of accumulated sphingomyelin. Within-patient dose escalation to slowly catabolize sphingomyelin stores may be a strategy to mitigate first-dose ADRs in patients with NPD B.Genet Med 18 1, 34-40.

Evaluation of Aminoglycoside and Non-Aminoglycoside Compounds for Stop-Codon Readthrough Therapy in Four Lysosomal Storage Diseases.

Nonsense mutations are quite prevalent in inherited diseases. Readthrough drugs could provide a therapeutic option for any disease caused by this type of mutation. Geneticin (G418) and gentamicin were among the first to be described. Novel compounds have been generated, but only a few have shown improved results. PTC124 is the only compound to have reached clinical trials. Here we first investigated the readthrough effects of gentamicin on fibroblasts from one patient with Sanfilippo B, one with Sanfilippo C, and one with Maroteaux-Lamy. We found that ARSB activity (Maroteaux-Lamy case) resulted in an increase of 2-3 folds and that the amount of this enzyme within the lysosomes was also increased, after treatment. Since the other two cases (Sanfilippo B and Sanfilippo C) did not respond to gentamicin, the treatments were extended with the use of geneticin and five non-aminoglycoside (PTC124, RTC13, RTC14, BZ6 and BZ16) readthrough compounds (RTCs). No recovery was observed at the enzyme activity level. However, mRNA recovery was observed in both cases, nearly a two-fold increase for Sanfilippo B fibroblasts with G418 and around 1.5 fold increase for Sanfilippo C cells with RTC14 and PTC124. Afterwards, some of the products were assessed through in vitro analyses for seven mutations in genes responsible for those diseases and, also, for Niemann-Pick A/B. Using the coupled transcription/translation system (TNT), the best results were obtained for SMPD1 mutations with G418, reaching a 35% recovery at 0.25 µg/ml, for the p.W168X mutation. The use of COS cells transfected with mutant cDNAs gave positive results for most of the mutations with some of the drugs, although to a different extent. The higher enzyme activity recovery, of around two-fold increase, was found for gentamicin on the ARSB p.W146X mutation. Our results are promising and consistent with those of other groups. Further studies of novel compounds are necessary to find those with more consistent efficacy and fewer toxic effects.

Liver and skin histopathology in adults with acid sphingomyelinase deficiency (Niemann-Pick disease type B).

Acid sphingomyelinase deficiency (ASMD) is a lysosomal storage disorder characterized by the pathologic accumulation of sphingomyelin (SM) in multiple cell types, and occurs most prominently within the liver, spleen, and lungs, leading to significant clinical disease. Seventeen ASMD patients underwent a liver biopsy during baseline screening for a phase 1 trial of recombinant human acid sphingomyelinase (rhASM) in adults with Niemann-Pick disease type B. Eleven of the 17 were enrolled in the trial and each received a single dose of rhASM and underwent a repeat liver biopsy on day 14. Biopsies were evaluated for fibrosis, SM accumulation, and macrophage infiltration by light and electron microscopy. When present, fibrosis was periportal and pericellular, predominantly surrounding affected Kupffer cells. Two baseline biopsies exhibited frank cirrhosis. SM was localized to isolated Kupffer cells in mildly affected biopsies and was present in both Kupffer cells and hepatocytes in more severely affected cases. Morphometric quantification of SM storage in liver biopsies ranged from 4% to 44% of the microscopic field. Skin biopsies were also performed at baseline and day 14 to compare the SM distribution in a peripheral tissue with that of liver. SM storage was present at lower levels in multiple cell types of the skin, including dermal fibroblasts, macrophages, vascular endothelial cells, vascular smooth muscle cells, and Schwann cells. This phase 1 trial of rhASM in adults with ASMD provided a unique opportunity for a prospective assessment of hepatic and skin pathology in this rare disease and their potential usage as pharmacodynamic biomarkers.