Plasma Globotriaosylsphingosine Research Articles

Clinical outcomes in patients switching from agalsidase beta to migalastat: A Fabry Registry analysis.

Fabry Registry data were analyzed among 83 agalsidase beta-treated patients with Fabry disease who switched to migalastat. Outcomes (estimated glomerular filtration rate [eGFR], urine protein-creatinine ratio [UPCR], plasma globotriaosylceramide [GL-3], plasma globotriaosylsphingosine [lyso-GL-3], interventricular septal wall thickness [IVST], left posterior wall thickness [LPWT], left ventricular mass index [LVMI]) were assessed using linear mixed models to estimate annual change over time in the pre- and postswitch periods. eGFR decreased throughout both periods (preswitch: -0.85 mL/min/1.73 m2/year; postswitch: -1.96 mL/min/1.73 m2/year; both p < 0.0001), with steeper decline postswitch (ppre/post = 0.01) in both classic and late-onset patients. UPCR increased significantly postswitch (ppre/post = 0.003) among classic patients and was stable in both periods among late-onset patients. GL-3 trajectories worsened postswitch across phenotypes (ppre/post = 0.0005 classic, 0.02 late-onset). LPWT was stable preswitch (0.07 mm/year, p = 0.25) and decreased postswitch (-0.51 mm/year, p = 0.0005; ppre/post = 0.0009), primarily among late-onset patients. IVST and LVMI slopes varied significantly by phenotype. Among classic patients, IVST and LVMI were stable and decreasing, respectively preswitch and increasing postswitch (ppre/post = 0.02 IVST, 0.01 LVMI). Among late-onset patients, IVST significantly decreased postswitch (ppre/post = 0.0003); LVMI was stable over time (ppre/post = 0.89). Ultimately, eGFR and GL-3 trajectories worsened postswitch across phenotypes, while UPCR and cardiac measures worsened among classic and stabilized/improved among late-onset patients. These findings indicate variability in long-term outcomes after switching from ERT to migalastat, underscoring the importance of careful monitoring.

#636 A phase 4, open label, multicenter prospective study of the safety and efficacy of agalsidase beta in Chinese patients with Fabry disease

Abstract Background and Aims Fabry disease (FD) is a rare inherited lysosomal storage disease caused by pathogenic GLA gene variants which result in a deficiency of the enzymatic activity of α-galactosidase A. Enzyme replacement therapy (ERT) is the mainstay of FD-specific treatment, but there are currently no reported clinical trials of ERT for FD in the Chinese population. This is the first phase 4 study to evaluate the safety and efficacy of ERT for FD in China since the approval of agalsidase beta in China in 2019. Method A 54-week, phase 4, open label, single arm, prospective, post-marketing surveillance (PMS) study of agalsidase beta (NCT05054387) was performed at 6 sites in China. Twenty-two Chinese ERT-naïve FD participants (≥8 years) with estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2 were enrolled and received infusions of agalsidase beta (Fabrazyme®, Sanofi) at a dose of 1.0 mg/kg every 2 weeks for up to 48 weeks. The primary endpoint was safety and tolerability of agalsidase beta. The endpoints of clinical efficacy included the changes of plasma globotriaosylceramide (GL-3), globotriaosylsphingosine (Lyso-GL-3), FD symptoms (including angiokeratoma, hypohidrosis, anhidrosis, abdominal pain, headache, tinnitus, heat tolerance, and activity tolerance), and eGFR from baseline to week 48. A post-hoc subgroup analysis was conducted to explore the differences in ERT efficacy between two subgroups of different ages (&amp;lt;30 years and ≥30 years). Results All 22 patients completed the study intervention. There were 18 males (81.8%) and the mean age of ERT initiation was 29.0 ± 13.5 years. Treatment-related adverse events (AEs) and infusion-associated reactions (IARs) were reported in 8 participants (36.4%), which was less than ∼60% as previously reported for IARs. Most AEs were mild or moderate and no AE caused permanent treatment discontinuation or death. The mean plasma GL-3 and Lyso-GL-3 levels decreased remarkably at week 6 and remained stable throughout the trial, with the mean percentage reduction from baseline to week 6 through week 48 ranged from −34.6% ± 27.4% to ­41.9% ± 14.9% and −58.8% ± 20.2% to ­64.9% ± 12.7%, respectively (Fig. 1a and b). The reduction was more remarkable for the classic male patients (n = 18; GL-3: 7.99 ± 2.19 ug/mL at baseline and 4.31 ± 1.71 ug/mL at week 48, −46.0% ± 18.4%; Lyso-GL-3: 83.11 ± 25.69 ng/mL at baseline and 25.89 ± 13.43 ng/mL at week 48, −67.8% ± 17.6%). Thirteen (59.1%) participants experienced improved FD symptoms at week 48, with no cases of worsening symptoms. The mean eGFR was 115.6 ± 37.3 mL/min/1.73 m2 at baseline and 118.4 ± 42.9 mL/min/1.73 m2 at week 48, with a change of 0.0 ± 12.4 mL/min/1.73 m2 from baseline to week 48 (Fig. 1c). In the subgroup analysis, participants were divided into the younger group with age &amp;lt;30 years (n = 11) and the older group with age ≥30 years (n = 11) according to their age of ERT initiation. At week 48, the reduction of mean plasma GL-3 (−47.1% ± 23.6% vs −22.0% ± 26.0%) and Lyso-GL-3 levels (−72.4 ± 17.3% vs −48.2% ± 19.8%), the stabilization of renal function (the mean change of eGFR from baseline to week 48: 5.2 ± 7.9 mL/min/1.73 m2 vs −5.2 ± 14.1 mL/min/1.73 m2) and the percentage of symptom improvement (81.8% vs. 36.4%) were generally more remarkable in the younger group than in the older group (Table 1). Conclusion This first phase 4 study of ERT for Fabry disease in China demonstrates that agalsidase beta is safe and well tolerated with a relatively low IAR rate, and effective in reducing plasma GL-3 and Lyso-GL-3, improving symptoms, and stabilizing renal function in Chinese patients with FD. Furthermore, the present study implies that patients who initiate ERT at a younger age benefit more from the therapy. Funding: Commercial support - Sanofi Pharmaceuticals.

Potential Usefulness of Lifetime Globotriaosylsphingosine Exposure at Diagnosis and Baseline Modified Disease Severity Score in Early-Diagnosed Patients With Fabry Disease.

Fabry disease (FD) is a lysosomal storage disease caused by a deficit of α-galactosidase A (GAL). Recently, plasma globotriaosylsphingosine (lyso-Gb3), a pathogenic analog of a substrate of GAL, has been suggested as a potential biomarker for FD, and disease severity scores, such as the Mainz Severity Score Index (MSSI), the Disease Severity Scoring System (DS3), and FASTEX (FAbry STabilization indEX), are useful tools for evaluating the severity of signs and symptoms in symptomatic FD patients. However, a more useful method of evaluating disease severity in early-diagnosed FD patients such as children, adult females, and asymptomatic patients is needed. Here, we proposed modified MSSI and DS3 scores to which we added phenotype, urinary mulberry bodies, and history of past pain attacksand examined the clinical usefulness of lyso-Gb3 and modified scores for early-diagnosed FD patients. In 13 early-diagnosed FD patients, we developed modified MSSI and DS3 scores and examined the correlation of lifetime lyso-Gb3 exposure at diagnosis with the conventional or modified scores.Lifetime lyso-Gb3 exposure was positively correlated only with the modified DS3 score. Additionally, we examined the long-term changes in plasma lyso-Gb3 concentration and in conventional MSSI, DS3, and FASTEX. In males, plasma lyso-Gb3 concentration decreased more rapidly than in females. In all patients, the severity scores were mild and remained nearly stable throughout the follow-up period. Our data suggest that lifetime lyso-Gb3 exposure and the modified DS3 score are useful in early-diagnosed patients.

Biomarkers in anderson-Fabry disease: what should we use in the clinical practice?

Major organ involvement in Anderson-Fabry disease (FD) is clinically silent for a long period and clinically heterogeneous; thus, it is difficult to identify the patients at increasing risk of a progressive disorder. Moreover, accumulating evidence suggests that early disease-specific treatment (DST) is safe and effective in preventing the progression of heart and kidney damage, with poorer results in patients with extensive myocardial fibrosis, advanced glomerulosclerosis, and/or heavy proteinuria. Therefore, biomarkers defining preclinical involvement, with a prognostic value and a correlation with response to treatment, are an urgent need in FD. Several types of biomarkers are recognized in FD, pertaining to total disease burden and specific organ involvement (central nervous system, heart, and kidney). Currently, plasma globotriaosylsphingosine (lyso-Gb3), cardiac and brain imaging, and albuminuria are recognized as the “gold standard” biomarkers of total disease burden or specific organ involvement in FD. However, severe globotriaosylceramide (Gb3) storage and organ damage may occur within the affected organs with minimal changes in these standard tests. Given the heterogeneity and rarity of the disease, the identification of new biomarkers is challenging. Several ways may be used to identify new biomarkers in FD, namely “omic” medicine, biomarkers identified in other pathological models similar to FD, and biomarkers linked to the pathophysiological pathways involved in FD. This article aims to review the clinical value of the available biomarkers in FD and give an overview of the research on new biomarkers.

Frequency of Fabry disease in chronic kidney disease patients including patients on renal replacement therapy in Korea.

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by the deficient activity of α-galactosidase (α-Gal A), affecting multiple organs including kidney. In this study, we aimed to determine the prevalence of FD in patients with chronic kidney disease (CKD) including those on renal replacement therapy in Korea. This is a national, multicenter, observational study performed between August 24, 2017 and February 28, 2020. Patients with the presence of proteinuria or treated on dialysis were screened by measuring the α-Gal A enzyme activity using either dried blood spot or whole blood, and plasma globotriaosylsphingosine (lyso-GL3) concentration. A GLA gene analysis was performed in patients with low α-Gal A enzyme activity or increased plasma lyso-GL3 concentration. Of 897 screened patients, 405 (45.2%) were male and 279 (31.1%) were on dialysis. The α-Gal A enzyme activity was measured in 891 patients (99.3%), and plasma lyso-GL3 concentration was measured in all patients. Ten patients were eligible for a GLA gene analysis: eight with low α-Gal A enzyme activity and two with increased plasma lyso-GL3 concentration. The GLA mutations were analyzed in nine patients and one patient was found with a pathogenic mutation. Therefore, one patient was identified with FD, giving a prevalence of 0.1% (1 of 897) in this CKD population. Although the prevalence of FD in the CKD population was low (0.1%), screening tests are crucial to detect potential diseases in patients with relatives who can benefit from early treatment.

Clinical analysis of 10 patients with Fabry disease

We aimed to analyze the clinical data of 10 patients (6 male and 4 female) with Fabry disease (FD). The mean age of the patients was (28.80±9.27) years. Seven patients had classical FD and three had delayed onset FD. Among the 10 patients, six had skin involvement and cutaneous angiokeratoma; five had hypohidrosis or anhidrosis; nine had intermittent neuralgia; and three had supraorbital ridge protrusion, forehead bulge, and lip thickening. Five patients had proteinuria, including one with chronic kidney disease stage 3 and one with chronic kidney disease stage 5. Cardiac involvement occurred in three patients, two had myocardial hypertrophy and one had valvular insufficiency. The activity of galactosidase decreased in seven patients (2.80-1.55 μmol·L-1·h-1). Plasma deacetyl-GL-3 was elevated in all 10 patients(3.12-120.00 ng/ml). Three patients underwent renal biopsy, wherein two cases of focal segmental glomerulosclerosis and one of mesangial proliferative glomerulonephritis was found. A large number of myeloid and zebra bodies were found in the podocytes in three patients, including a small number of myeloid and zebra bodies in the renal tubular epithelial cells in one patient with occasional zebra bodies in the renal interstitium. Nine patients had GLA gene mutations. One patient was c.102T>A, a de novo mutation. Four patients were treated with agalsidase α injection (0.2 mg/kg, intravenous infusion every 2 weeks), and their prognosis was good. FD has various clinical manifestations and multi-system involvement, which requires multidisciplinary cooperation. Detection of galactosidase activity, plasma globotriaosylsphingosine, and GLA gene mutation can help for accurate diagnosis.

Early Risk Stratification for Natural Disease Course in Fabry Patients Using Plasma Globotriaosylsphingosine Levels.

Fabry disease is a very heterogeneous X-linked lysosomal storage disease. Disease manifestations in the kidneys, heart, and brain vary greatly, even between patients of the same sex and with the same disease classification (classical or nonclassical). A biomarker with a strong association with the development of disease manifestations is needed to determine the need for Fabry-specific treatment and appropriate frequency of follow-up because clinical manifestations of the disorder may take decennia to develop. We investigated the levels of plasma lysoGb3 levels over time and its association with disease manifestations and disease course in 237 untreated patients with Fabry disease (median age 42 years, 38% male) using linear mixed-effect models. LysoGb3 levels are stable over time in plasma of untreated patients with Fabry disease. Higher levels of lysoGb3 were associated with steeper decline in eGFR ( P = 0.05) and a faster increase in albuminuria (measured as the urinary albumin-to-creatinine ratio, P < 0.001), left ventricular mass (measured on echocardiography, P < 0.001), left atrial volume index ( P = 0.003), and Fazekas score ( P = 0.003). In addition, regardless of age, higher lysoGb3 levels were associated with higher relative wall thickness ( P < 0.001) and unfavorable functional markers on echocardiography, including septal mitral annular early diastolic velocity (e', P < 0.001) and the ratio of early transmitral velocity (E) to e' (E/e', P = 0.001). In an individual patient with Fabry disease, the plasma lysoGb3 level reached a specific level in early childhood which, in the absence of Fabry-specific treatment, remained stable throughout life. The level of lysoGb3 in untreated patients was associated with nearly all Fabry-specific disease manifestations, regardless of the sex of the patient.

Brain MRI correlations with disease burden and biomarkers in Fabry disease

ObjectiveTo quantitatively evaluate cerebral small vessel disease (CSVD) in brain magnetic resonance imaging (MRI) and its correlation with disease burden and markers in Fabry disease, a rare X-linked lysosomal storage disease.MethodsWe collected brain MRI data from seventy-one Chinese patients with Fabry disease. CSVD was evaluated using an age-related white matter change rating scale, Fazekas scale, enlarged perivascular spaces grading scale, lacunar infarction scale, Microbleed Anatomical Rating Scale, global cortical atrophy scale, and small-vessel disease score. Factors associated with MRI lesions, including sex, clinical subtype, disease severity, disease burden, genotype, and biomarkers, were also analyzed.ResultsOf 71 patients, 16 (22.5%) experienced ischemic stroke. The incidences of lacunar infarctions, white matter hyperintensities, and cerebral microbleeds were 55%, 62%, and 33%, respectively. The abnormal MRI group had later disease onset, longer disease duration, and a higher Mainz Severity Score Index (p < 0.05) than the normal MRI group. Patients with more severe clinical phenotypes also had higher CVSD-related scores. Sex and GLA mutational type were not closely associated with brain MRI lesions. Of the disease markers, the Mainz Severity Score Index and plasma globotriaosylsphingosine (Lyso-Gb3) were closely correlated with the majority of the MRI scores, whereas α-galactosidase A activity was not.ConclusionBrain MRI revealed progressive lacunar infarctions, white matter hyperintensities, and decreased brain volume in patients with Fabry disease. Brain MRI lesions were closely related to onset-age; disease duration, severity, burden; and plasma Lyso-Gb3. However, they were not associated with sex, α-galactosidase A activity, or GLA mutation type.

Can the use of urinary and plasma globotriaosylsphingosine and their analogues as diagnostic biomarkers be confirmed in male patients with Fabry disease?

Can the use of urinary and plasma globotriaosylsphingosine and their analogues as diagnostic biomarkers be confirmed in male patients with Fabry disease?

Fabry disease with atypical phenotype identified by massively parallel sequencing in early-onset kidney failure.

The cause of chronic kidney disease (CKD) remains unknown in ∼20% of patients with kidney failure. Massively parallel sequencing (MPS) can be a valuable diagnostic tool in patients with unexplained CKD, with a diagnostic yield of 12%-56%. Here, we report the use of MPS to establish a genetic diagnosis in a 24-year-old index patient who presented with hypertension, nephrotic-range proteinuria and kidney failure of unknown origin. Additionally, we describe a second family with the same mutation presenting with early-onset CKD. In Family 1, MPS identified a known pathogenic variant in GLA (p.Ile319Thr), and plasma globotriaosylsphingosine and α-galactosidase A activity were compatible with the diagnosis of Fabry disease (FD). Segregation analysis identified three other family members carrying the same pathogenic variant who had mild or absent kidney phenotypes. One family member was offered enzyme therapy. While FD could not be established with certainty as the cause of kidney failure in the index patient, no alternative explanation was found. In Family 2, the index patient had severe glomerulosclerosis and a kidney biopsy compatible with FD at the age of 30 years, along with cardiac involvement and a history of acroparesthesia since childhood, in keeping with a more classical Fabry phenotype. These findings highlight the large phenotypic heterogeneity associated with GLA mutations in FD and underline several important implications of MPS in the work-up of patients with unexplained kidney failure.

Assessment and impact of dose escalation on anti-drug antibodies in Fabry disease.

Enzyme replacement therapy (ERT) with recombinant α-galactosidase A (AGAL) can lead to the formation of neutralizing anti-drug antibodies (ADA), which significantly limit treatment efficacy in patients with Fabry disease (FD). The effects of dose escalation on ADA titer and plasma globotriaosylsphingosine (lyso-Gb3) level are unknown. We screened 250 FD patients (200 males, 50 females) under ERT for ADAs and assessed the impact of an approved dose escalation in affected patients, focusing on ADA titers and plasma lyso-Gb3. ADA-positive patients were identified by serum-mediated inhibition assays, followed by titration assays to determine the individual inhibitory capacities of ADAs against agalsidase-alfa and agalsidase-beta. 70 (35%) of the male patients were ADA-positive, with a mean inhibitory capacity of 83.5 ± 113.7mg AGAL. Although patients receiving agalsidase-beta showed higher inhibitory capacities (84.7 ± 34.7mg) than patients under agalsidase-alfa (60.3 ± 126.7mg, p<0.001), the "theoretical deficit" to the infused dose was lower in patients receiving agalsidase-beta. In seven patients receiving agalsidase-alfa (0.2 mg/kg) ADAs were saturable by switching patients to agalsidase-beta (1.0 mg/kg). The switch resulted in increasing ADA titers within the first months. In 2 out of 7 (28.6%) therapy switchers, dose escalation could lead to durable ADA saturation. Independent of an increase in ADA titers, lyso-Gb3 levels decrease and cardiac and renal parameters remained stable after dose escalation. Dose escalation results in a heterogeneous, unpredictable ADA response, with more than a quarter of all treatment switchers succeeding in ADA saturation. Longitudinal ADA measurements are required to assess the individual risk of affected patients.

Monitoring of anti-drug antibodies and disease-specific biomarkers in three patients from a Japanese Fabry family treated with enzyme replacement therapy

We monitored anti-drug antibodies and disease-specific biomarkers in three patients with a nonsense mutation from a Japanese Fabry family treated with enzyme replacement therapy (ERT). In two male patients from the family, neutralizing anti-drug antibodies were induced at an early stage of ERT, the antibody titer peak being found at an earlier stage of ERT in the patient treated with 1.0 mg/kg agalsidase beta than in that treated with 0.2 mg/kg agalsidase alfa. Then, the antibody titers decreased with continuation of ERT. The formation of neutralizing anti-drug antibodies adversely affected the plasma globotriaosylsphingosine (Lyso-Gb3) level and urinary globotriaosylceramide (Gb3) excretion in both patients, the impact being greater in the patient treated with 0.2 mg/kg agalsidase alfa than in that treated with 1.0 mg/kg agalsidase beta. The difference might be explained by the different doses of the infused enzymes based on supersaturation of the antibodies. In a heterozygous Fabry female from the family, no sign of antibody formation was found, and both the plasma Lyso-Gb3 level and urinary Gb3 excretion, which were moderately increased at the baseline, decreased gradually. No deterioration of the manifestations or laboratory findings was observed during ERT in either of the patients. Thus, monitoring of anti-drug antibodies and biomarkers in these Fabry patients provided us with important information on their pathological condition during ERT.

Plasma Globotriaosylsphingosine and α-Galactosidase A Activity as a Combined Screening Biomarker for Fabry Disease in a Large Japanese Cohort.

Fabry disease is an X-linked disorder of α-galactosidase A (GLA) deficiency. Our previous interim analysis (1 July 2014 to 31 December 2015) revealed plasma globotriaosylsphingosine as a promising primary screening biomarker for Fabry disease probands. Herein, we report the final results, including patients enrolled from 1 January to 31 December 2016 for evaluating the potential of plasma globotriaosylsphingosine and GLA activity as a combined screening marker. We screened 5691 patients (3439 males) referred from 237 Japanese specialty clinics based on clinical findings suggestive of Fabry disease using plasma globotriaosylsphingosine and GLA activity as primary screening markers, and GLA variant status as a secondary screening marker. Of the 14 males who tested positive in the globotriaosylsphingosine screen (≥2.0 ng/mL), 11 with low GLA activity (<4.0 nmol/h/mL) displayed GLA variants (four classic, seven late-onset) and one with normal GLA activity and no pathogenic variant displayed lamellar bodies in affected organs, indicating late-onset biopsy-proven Fabry disease. Of the 19 females who tested positive in the globotriaosylsphingosine screen, eight with low GLA activity displayed GLA variants (six classic, two late-onset) and five with normal GLA activity displayed a GLA variant (one classic) and no pathogenic variant (four late-onset biopsy-proven). The combination of plasma globotriaosylsphingosine and GLA activity can be a primary screening biomarker for classic, late-onset, and late-onset biopsy-proven Fabry disease probands.

Lentivirus-mediated gene therapy for Fabry disease

Enzyme and chaperone therapies are used to treat Fabry disease. Such treatments are expensive and require intrusive biweekly infusions; they are also not particularly efficacious. In this pilot, single-arm study (NCT02800070), five adult males with Type 1 (classical) phenotype Fabry disease were infused with autologous lentivirus-transduced, CD34+-selected, hematopoietic stem/progenitor cells engineered to express alpha-galactosidase A (α-gal A). Safety and toxicity are the primary endpoints. The non-myeloablative preparative regimen consisted of intravenous melphalan. No serious adverse events (AEs) are attributable to the investigational product. All patients produced α-gal A to near normal levels within one week. Vector is detected in peripheral blood and bone marrow cells, plasma and leukocytes demonstrate α-gal A activity within or above the reference range, and reductions in plasma and urine globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) are seen. While the study and evaluations are still ongoing, the first patient is nearly three years post-infusion. Three patients have elected to discontinue enzyme therapy.

Combined analysis of plasma or serum glucosylsphingosine and globotriaosylsphingosine by UPLC-MS/MS

PurposeTo develop a method for the combined analysis of plasma and serum glucosylsphingosine (lyso-Gb1) and globotriaosylsphingosine (lyso-Gb3), biomarkers of Gaucher disease (GD) and Fabry disease (FD), respectively. MethodsInternal standards were added to 100 µL of plasma/serum and glycosphingolipids: lyso-Gb1, lyso-Gb3, and galactosylsphingosine (GalSph) were extracted with dichloromethane/methanol and analyzed by UPLC-MS/MS. Samples from unaffected controls and patients with GD were first analyzed using a HILIC column to separate lyso-Gb1 from its isomer, GalSph. Samples from patients with FD or GD were analyzed using a C18 column to measure lyso-Gb3 and the hexosylsphingosine (HexSph: lyso-Gb1 + GalSph) fraction in a single combined method. ResultsExtraction efficiency was between 73% and 87% and day-to-day variability showed a relative standard error of <7.5%. GalSph was determined to have minimal to no contribution to the HexSph fraction in samples from unaffected controls and patients with GD. Lyso-Gb3 and HexSph measurements by the combined method were in good agreement with established methods, with no bias. ConclusionsHexSph and lyso-Gb3 analysis by reversed-phase chromatography UPLC-MS/MS is a cost-effective, time-efficient approach for evaluating these glycosphingolipid biomarkers in patients with a suspected or confirmed diagnosis of GD and FD.

Incidental finding of cornea verticillata or lamellar inclusions in kidney biopsy: measurement of lyso-Gb3 in plasma defines between Fabry disease and drug-induced phospholipidosis

IntroductionTherapy with cationic amphiphilic drugs (Amiodarone or hydroxychloroquine) may result in biochemically and ultrastructurally similar lipid inclusions in many cells also affected by Fabry disease (FD). In addition, it often results in similar clinical manifestations such as cornea verticillata. This may lead to a FD misdiagnosis, especially when a complete medical history is not available to the ophthalmologist confronted with cornea verticillata or to the pathologist examining a kidney biopsy. When enzymatic/genetic test or pathological studies are not conclusive, a specific biomarker may help clarify this dilemma. The plasma globotriaosylsphingosine (lyso-Gb3) assay has high sensitivity and specificity and is elevated above normal levels in FD. Materials and methodsWe measured plasma lyso-Gb3 levels in male patients receiving Amiodarone or hydroxychloroquine and compared it with male patients with classic and late onset variant of FD. ResultsIn all Fabry patients (classic and late onset variant) α-GalA activity was deficient in dried blood spot and plasma lyso-Gb3 was above normal levels. Patients on treatment with Amiodarone or hydroxychloroquine had normal values for α-GalA activity and lyso-Gb3 in plasma. ConclusionsEven when Amiodarone or hydroxychloroquine may decrease α-GalA activity in vitro or in cell culture, our results showed that in all patients lyso-Gb3 plasma levels remain normal with no evidence of reduction in α-GalA activity, confirming the specificity of this biomarker for the diagnosis of FD.

Anti-drug antibody formation in Japanese Fabry patients following enzyme replacement therapy

Enzyme replacement therapy (ERT) for Fabry disease (deficiency of α-galactosidase A, α-Gal) with recombinant α-Gals (agalsidase alfa and agalsidase beta) is widely available and improves some of the clinical manifestations and biochemical findings. However, recent reports suggest that recurrent administration of recombinant enzymes often induces the formation of anti-drug antibodies, which may have a negative impact on the outcome of the therapy. We examined the formation of anti-drug antibodies using blood samples from 97 Japanese Fabry patients following ERT and tried to characterize them by means of enzyme-linked immunosorbent assay (ELISA), serum-mediated α-Gal inhibition, and immunochromatographic (IC) assay, followed by GLA gene analysis and measurement of plasma globotriaosylsphingosine (lyso-Gb3). ELISA revealed that 20/35 (57%) classic Fabry males were antibody (Immunoglobulin G, IgG) -positive (Ab+) at 6 months after the initiation of ERT, although only two of the seventeen (12%) later-onset Fabry males and none of the 45 Fabry females were. The Ab+ state was maintained at least until 24 months after the initiation of ERT in most of the cases, the exceptions being two patients who acquired immune tolerance during ERT. As many Ab+ patients have nonsense mutations, attention should be paid to the formation of anti-drug antibodies in Fabry patients harboring such gene mutations, who hardly produce α-Gal protein. Serum-mediated α-Gal inhibition was seen in most of the Ab+ patients and the antibodies affected the reduction of the plasma lyso-Gb3 level following ERT, suggesting that the antibodies inhibit the enzyme activity. There was a correlation between the results of the IC test and those of the ELISA. As the former is easy and rapid, it should be useful as a bed-side test.

Pharmacokinetics and pharmacodynamics of JR-051, a biosimilar of agalsidase beta, in healthy adults and patients with Fabry disease: Phase I and II/III clinical studies

Fabry disease is a rare X-linked lysosomal disease, in which mutations in the gene encoding α-galactosidase A result in progressive cellular accumulation of globotriaosylceramide (GL-3) in various organs including the skin, kidney, and heart, often leading to life-threatening conditions. Enzyme replacement therapy is currently the standard therapy for the disease, to which two α-galactosidase A formulations have been approved: agalsidase α (Replagal®, Shire) and agalsidase β (Fabrazyme®, Sanofi). We have recently developed a biosimilar of agalsidase β, JR-051, and investigated its pharmacokinetics and pharmacodynamics to assess its bioequivalence to agalsidase β. In a randomized phase I study, healthy adult male volunteers were treated with JR-051 or agalsidase β and the pharmacokinetics of the drugs were compared. The ratio of geometric means (90% confidence interval [CI]) of the AUC0–24 and Cmax for JR-051 over agalsidase β were 0.91 (0.8294, 1.0082) and 0.90 (0.7992, 1.0125), respectively. In a 52-week, single-arm, phase II/III study, patients with Fabry disease switched therapy from agalsidase β to JR-051 to evaluate its pharmacodynamics. The mean (95% CI) plasma GL-3 concentrations at weeks 26 and 52 relative to pre-JR-051 administration were 1.03 (0.91, 1.15) and 0.96 (0.86, 1.06), respectively, which were within the pre-determined bioequivalence acceptance range (0.70, 1.43). The mean (95% CI) plasma globotriaosylsphingosine (lyso-GL-3) concentrations at weeks 26 and 52 relative to pre-JR-051 administration were 1.07 (0.92, 1.23) and 1.13 (1.03, 1.22), respectively. Estimated glomerular filtration rate and left ventricular mass index, as renal and cardiac function indicators, showed no notable changes from baseline throughout the study period, and no new safety concerns were identified. In conclusion, these studies demonstrated bioequivalence of JR-051 to agalsidase β in terms of its pharmacokinetics and pharmacodynamics. JR-051 offers a potential new treatment option for patients with Fabry disease.

Development of a new pharmacological chaperone therapeutic strategy for Fabry disease

Fabry disease is a rare X-linked lysosomal disease, in which mutations in the gene encoding α-galactosidase A result in progressive cellular accumulation of globotriaosylceramide (GL-3) in various organs including the skin, kidney, and heart, often leading to life-threatening conditions. Enzyme replacement therapy is currently the standard therapy for the disease, to which two α-galactosidase A formulations have been approved: agalsidase α (Replagal®, Shire) and agalsidase β (Fabrazyme®, Sanofi). We have recently developed a biosimilar of agalsidase β, JR-051, and investigated its pharmacokinetics and pharmacodynamics to assess its bioequivalence to agalsidase β. In a randomized phase I study, healthy adult male volunteers were treated with JR-051 or agalsidase β and the pharmacokinetics of the drugs were compared. The ratio of geometric means (90% confidence interval [CI]) of the AUC0–24 and Cmax for JR-051 over agalsidase β were 0.91 (0.8294, 1.0082) and 0.90 (0.7992, 1.0125), respectively. In a 52-week, single-arm, phase II/III study, patients with Fabry disease switched therapy from agalsidase β to JR-051 to evaluate its pharmacodynamics. The mean (95% CI) plasma GL-3 concentrations at weeks 26 and 52 relative to pre-JR-051 administration were 1.03 (0.91, 1.15) and 0.96 (0.86, 1.06), respectively, which were within the pre-determined bioequivalence acceptance range (0.70, 1.43). The mean (95% CI) plasma globotriaosylsphingosine (lyso-GL-3) concentrations at weeks 26 and 52 relative to pre-JR-051 administration were 1.07 (0.92, 1.23) and 1.13 (1.03, 1.22), respectively. Estimated glomerular filtration rate and left ventricular mass index, as renal and cardiac function indicators, showed no notable changes from baseline throughout the study period, and no new safety concerns were identified. In conclusion, these studies demonstrated bioequivalence of JR-051 to agalsidase β in terms of its pharmacokinetics and pharmacodynamics. JR-051 offers a potential new treatment option for patients with Fabry disease.

Selective screening for lysosomal disorders in a large cohort of minority groups shows higher incidence rates and novel variants

Fabry disease (FD) is a genetic disorder caused by defective α-galactosidase-A enzyme due to mutations in the GLA gene. A reliable diagnosis in classical FD males can be made by measuring the enzyme activity while diagnosing classical FD females and non-classical FD patients requires mutation analysis. Plasma globotriaosylsphingosine (Lyso-Gb3) has progressively gained more importance as a diagnostic biomarker for FD in recent years. Having another biomarker to complement plasma Lyso-Gb3 will increase the diagnostic accuracy in the era of mass screening, and also precision medicine. This study aims to highlight the clinical utility of the total concentration of urinary Lyso-Gb3 plus its analogues in diagnosing FD.Random urine samples collected from 42 FD patients and 48 healthy individuals. Lyso-Gb3 and its analogues were enriched by solid phase extraction and analysed by liquid chromatography tandem mass spectrometry.The total concentration of Lyso-Gb3 plus its analogues in classical FD male and female patients were 1124.4 ± 181.2 and 308.6 ± 78.6 pmol/mmol creat., respectively. The levels in non-classical FD male and female patients were 229.2 ± 169.4 and 314.4 ± 156.4 pmol/mmol creat., respectively. Urinary Lyso-Gb3 and its analogues were virtually undetectable in healthy volunteers making it 100% specific for FD diagnosis. For FD male and female patients, total concentration of urinary Lyso-Gb3 plus its analogue levels ≥0.25 pmol/mmol creat. yielded a diagnostic sensitivity and specificity of 100% (AUC = 1, p < 0.00001).Our study findings support that the total concentration of Lyso-Gb3 plus its analogues in urine is specific to FD and may provide extra diagnostic utility for both classical and non-classical FD patients.