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Background: Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by deficiency in acid beta-glucosidase. GD exhibits a wide clinical spectrum of disease severity with an unpredictable natural course. Plasma chitotriosidase activity and CC chemokine ligand 18 (CCL18) have been exchangeably used for monitoring GD activity and response to enzyme replacement therapy in conjunction with clinical assessment. Yet, a large-scale head-to-head comparison of these two biomarkers is currently lacking. We propose a collaborative systematic review with meta-analysis of individual participant data (IPD) to compare the accuracy of plasma chitotriosidase activity and CCL18 in assessing type I (i.e., non-neuropathic) GD severity. Methods: Eligible studies include cross-sectional, cohort, and randomized controlled studies recording both plasma chitotriosidase activity and CCL18 level at baseline and/or at follow-up in consecutive children or adult patients with type I GD. Pre-specified surrogate outcomes reflecting GD activity include liver and spleen volume, hemoglobin concentration, platelet count, and symptomatic bone events with imaging confirmation. Primary studies will be identified by searching Medline (1995 onwards), EMBASE (1995 onwards), and Cochrane Central Register of Controlled Trials (CENTRAL). Electronic search will be complemented by contacting research groups in order to identify unpublished relevant studies. Where possible, IPD will be extracted from published articles. Corresponding authors will be invited to collaborate by supplying IPD. The methodological quality of retrieved studies will be appraised for each study outcome, using a checklist adapted from the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome will be a composite of liver volume >1.25 multiple of normal (MN), spleen volume >5 MN, hemoglobin concentration <11 g/dL, or platelet count <100 x 10 9/L. Effect size estimates for biomarker comparative accuracy in predicting outcomes will be reported as differences in areas under receiver operating characteristic curves along with 95% confidence intervals. Effect size estimates will be reported as (weighted) mean differences along with 95% confidence intervals for each biomarker according to outcomes. IPD meta-analysis will be conducted with both one- and two-stage approaches. Discussion: Valid and precise accuracy estimates will be derived for CCL18 relative to plasma chitotriosidase activity in discriminating patients according to GD severity. Systematic review registration: PROSPERO 2015 CRD42015027243 [ABSTRACT FROM AUTHOR]

The characteristics of Gaucher disease ( GD) associated with persistent thrombocytopenia despite imiglucerase enzyme therapy in type 1 GD ( GD1) were investigated by retrospective analysis of International Collaborative Gaucher Group ( ICGG) Registry data. The study involved 1016 GD1 patients with an intact spleen for whom date of diagnosis, therapy initiation, and platelet counts were known, and who received continuous imiglucerase therapy for 4 to 5 years. These patients were stratified by last platelet count: ≥120 × 109/l ( n = 772); ≥100 to <120 × 109/l ( n = 94); ≥80 to <100 × 109/l ( n = 80); and <80 × 109/l ( n = 70; 20 with <60 × 109/l) and characterized by initial and cumulative average imiglucerase dose, body mass index, platelet count, anaemia, hepatomegaly, splenomegaly, and skeletal assessments at baseline and after 4-5 years of therapy. Statistically significant associations were found between persistent thrombocytopenia and baseline platelet count (<80 × 109/l), splenomegaly, and anaemia (all P < 0·0001). After 4-5 years, statistically significant associations were found with splenomegaly ( P < 0·0001), anaemia ( P < 0·0001), white blood cell count ( P = 0·049), hepatomegaly ( P = 0·004) and bone pain ( P = 0·035). Exponential platelet decay in relation to splenomegaly suggests that platelets increase only when spleen volume decreases substantially. [ABSTRACT FROM AUTHOR]

Abstract: Background: To investigate the relationship between chemokines and cytokines and osteonecrosis in Gaucher disease, we conducted multiplex assays in a cohort of 100 adult patients. Methods: Mean age was 45years (18–86); 92 Gaucher patients received imiglucerase (median duration 8years (2–18)). Forty-three had experienced osteonecrosis (ON), and eight had ON despite enzyme therapy. Serum cytokines/chemokines were determined by fluorimetric bead arrays in samples from Gaucher patients and healthy volunteers (10 males and 10 females). Intra-assay and inter-assay coefficients of variation were 2%–9.8% and 5.6%–15%, respectively. Results: VEGF and CCL5/RANTES did not differ between Gaucher and control samples. Concentrations of CCL3/MIP-1α, CCL4/MIP-1β, CCL2/MCP-1, CXCL8/IL-8, IL-1ra and CCL18/PARC were elevated in Gaucher patients (p <0.05 for each). Median CCL4/MIP-1β, CXCL8/IL-8, CCL5/RANTES and CCL18/PARC concentrations were greater in the 43 osteonecrosis patients (88.6pg/mL, 30.5pg/mL, 89.6ng/mL and 434ng/mL, respectively) compared with the 57 patients who had no evidence of osteonecrosis (medians of 59.4, 13.3, 62.7 and 283, respectively, p <0.05). Moreover, the eight patients with ON despite imiglucerase had median concentrations of CCL3/MIP-1α, CCL4/MIP-1β, CXCL8/IL-8, CCL5/RANTES and CCL18/PARC (73.2, 120.9, 36.3pg/mL, 105 and 767ng/mL, respectively), which significantly exceeded the values in 84 patients now free of ON (52.3, 71.2, 16.5pg/mL, 69.5 and 315ng/mL, respectively, p <0.05). Treatment exposures were similar. Conclusion: Numerous serum cytokines are elevated in Gaucher disease. CCL18/PARC, CCL3/MIP-1α, CCL4/MIP-1β, CCL5/RANTES and CXCL8/IL-8 are potential biomarkers of osteonecrosis and may allow prediction of this disabling complication. [ABSTRACT FROM AUTHOR]

Taliglucerase alfa is a β-glucosidase enzyme replacement therapy (ERT) approved in the US and other countries for the treatment of Gaucher disease (GD) in adults and is approved in pediatric and adult patients in Australia and Canada. It is the first approved plant cell-expressed recombinant human protein. A Phase 3, multicenter, open-label, 9-month study assessed safety and efficacy of switching to taliglucerase alfa in adult and pediatric patients with GD treated with imiglucerase for at least the previous 2 years. Patients with stable disease were offered taliglucerase alfa treatment using the same dose (9–60 U/kg body weight) and regimen of administration (every 2 weeks) as imiglucerase. This report summarizes results from 26 adult and 5 pediatric patients who participated in the trial. Disease parameters (spleen and liver volumes, hemoglobin concentration, platelet count, and biomarker levels) remained stable through 9 months of treatment in adults and children following the switch from imiglucerase. All treatment-related adverse events were mild or moderate in severity and transient in nature. Exploratory parameters of linear growth and development showed positive outcomes in pediatric patients. These findings provide evidence of the efficacy and safety profile of taliglucerase alfa as an ERT for GD in patients previously treated with imiglucerase. This trial was registered at www.clinicaltrials.gov as # NCT00712348 . [ABSTRACT FROM AUTHOR]