Assessment of plasma lyso-Gb3 for clinical monitoring of treatment response in migalastat-treated patients with Fabry disease.

PURPOSE: To assess the utility of globotriaosylsphingosine (lyso-Gb3) for clinical monitoring of treatment response in patients with Fabry disease receiving migalastat. METHODS: A post hoc analysis evaluated data from 97 treatment-naive and enzyme replacement therapy (ERT)-experienced patients with migalastat-amenable GLA variants from FACETS (NCT00925301) and ATTRACT (NCT01218659) and subsequent open-label extension studies. The relationship between plasma lyso-Gb3 and measures of Fabry disease progression (left ventricular mass index [LVMi], estimated glomerular filtration rate [eGFR], and pain) and the relationship between lyso-Gb3 and incidence of Fabry-associated clinical events (FACEs) were assessed in both groups. The relationship between changes in lyso-Gb3 and kidney interstitial capillary (KIC) globotriaosylceramide (Gb3) inclusions was assessed in treatment-naive patients. RESULTS: No significant correlations were identified between changes in lyso-Gb3 and changes in LVMi, eGFR, or pain. Neither baseline lyso-Gb3 levels nor the rate of change in lyso-Gb3 levels during treatment predicted FACE occurrences in all patients or those receiving migalastat for ≥24 months. Changes in lyso-Gb3 correlated with changes in KIC Gb3 inclusions in treatment-naive patients. CONCLUSIONS: Although used as a pharmacodynamic biomarker in research and clinical studies, plasma lyso-Gb3 may not be a suitable biomarker for monitoring treatment response in migalastat-treated patients.

The utility of the FIPI score in predicting long-term clinical outcomes in patients with Fabry disease receiving enzyme replacement therapy with agalsidase alfa.

Fabry disease is a rare X-linked lysosomal storage disorder in which there is deficiency of alpha galactosidase A. Enzyme replacement therapy (ERT) is commercially available and has been demonstrated to improve cardiac and renal outcomes. Predictive scores, such as the Fabry International Prognostic Index (FIPI), have been developed to stratify disease severity; however, these have not been validated to predict outcomes in patients receiving ERT. We show that the FIPI score at baseline can predict outcomes in a group of patients on long-term ERT.

Impact of sphingolipids on osteoblast and osteoclast activity in Gaucher disease.

Gaucher disease (GD) is an inherited disorder in which mutations in the GBA1 gene lead to deficient ß-glucocerebrosidase activity and accumulation of its substrate glucosylceramide. Bone disease is present in around 84% of GD patients, ranging from bone loss including osteopenia and osteonecrosis to abnormal bone remodelling in the form of Erlenmeyer flask formation. The range of severity and variety of types of bone disease found in GD patients indicate the involvement of several mechanisms. Here we investigate the effects of exogenous sphingolipids on osteoclasts, osteoblasts, plasma cells and mesenchymal stem cells (MSC) and the interactions between these cell types. Osteoclasts were differentiated from the peripheral blood of Gaucher patients and control subjects. Osteoblasts were differentiated from mesenchymal stem cells isolated from bone marrow aspirates of Gaucher patients and control subjects. The human osteoblast cell line SaOS-2 was also investigated. Osteoclasts, osteoblasts and a human myeloma plasma cell line NCI-H929 were cultured with relevant exogenous sphingolipids to assess effects on cellular viability and function. Calcium deposition by osteoblasts differentiated from Gaucher patient MSC's was on average only 11.4% of that deposited by control subject osteoblasts. Culture with glucosylsphingosine reduced control subject MSC viability by 10.4%, SaOS-2 viability by 17.4% and plasma cell number by 40%. Culture with glucosylceramide decreased calcium deposition by control MSC-derived osteoblasts while increasing control subject osteoclast generation by 55.6%, Gaucher patient osteoclast generation by 37.6% and plasma cell numbers by up to 29.7%. Excessive osteoclast number and activity and reduced osteoblast activity may have the overall effect of an uncoupling between osteoclasts and osteoblasts in the GD bone microenvironment.

Functional analysis of variant lysosomal acid glycosidases of Anderson-Fabry and Pompe disease in a human embryonic kidney epithelial cell line (HEK 293 T).

The functional significance of missense mutations in genes encoding acid glycosidases of lysosomal storage disorders (LSDs) is not always clear. Here we describe a method of investigating functional properties of variant enzymes in vitro using a human embryonic kidney epithelial cell line. Site-directed mutagenesis was performed on the parental plasmids containing cDNA encoding for alpha-galactosidase A (α-Gal A) and acid maltase (α-Glu) to prepare plasmids encoding relevant point mutations. Mutant plasmids were transfected into HEK 293 T cells, and transient over-expression of variant enzymes was measured after 3 days. We have illustrated the method by examining enzymatic activities of four unknown α-Gal A and one α-Glu variants identified in our patients with Anderson-Fabry disease and Pompe diseases respectively. Comparison with control variants known to be either pathogenic or non-pathogenic together with over-expression of wild-type enzyme allowed determination of the pathogenicity of the mutation. One leader sequence novel variant of α-Gal A (p.A15T) was shown not to significantly reduce enzyme activity, whereas three other novel α-Gal A variants (p.D93Y, p.L372P and p.T410I) were shown to be pathogenic as they resulted in significant reduction of enzyme activity. A novel α-Glu variant (p.L72R) was shown to be pathogenic as this significantly reduced enzyme activity. Certain acid glycosidase variants that have been described in association with late-onset LSDs and which are known to have variable residual plasma and leukocyte enzyme activity in patients appear to show intermediate to low enzyme activity (p.N215S and p.Q279E α-Gal A respectively) in the over-expression system.

Twenty years of the Fabry Outcome Survey (FOS): insights, achievements, and lessons learned from a global patient registry.

BACKGROUND: Patient registries provide long-term, real-world evidence that aids the understanding of the natural history and progression of disease, and the effects of treatment on large patient populations with rare diseases. The year 2021 marks the 20th anniversary of the Fabry Outcome Survey (FOS), an international, multicenter, observational registry (NCT03289065). The primary aims of FOS are to broaden the understanding of Fabry disease (FD), an X-linked lysosomal storage disorder, and to improve the clinical management of affected patients. Here, we review the history of FOS and the analyses and publications disseminated from the registry, and we discuss the contributions FOS studies have made in understanding FD. RESULTS: FOS was initiated in April 2001 and, as of January 2021, 4484 patients with a confirmed diagnosis and patient informed consent have been enrolled from 144 centers across 26 countries. Data from FOS have been published in nearly 60 manuscripts on a wide variety of topics relevant to FD. Analyses of FOS data have investigated the long-term effectiveness and safety of enzyme replacement therapy (ERT) with agalsidase alfa and its effects on morbidity and mortality, as well as the benefits of prompt and early treatment with agalsidase alfa on the progression of cardiomyopathy and the decline in renal function associated with FD. Based on analyses of FOS data, ERT with agalsidase alfa has also been shown to improve additional signs and symptoms of FD experienced by patients. FOS data analyses have provided a better understanding of the natural history of FD and the specific populations of women, children, and the elderly, and have provided practical tools for the study of FD. FOS has also provided methodology and criteria for assessing disease severity which contributed to the continuous development of medical practice in FD and has largely improved our understanding of the challenges and needs of long-term data collection in rare diseases, aiding in future rare disease real-world evidence studies. CONCLUSION: FOS over the last 20 years has substantially increased the scientific knowledge around improved patient management of FD and continues to expand our understanding of this rare disease.

A validated disease severity scoring system for Fabry disease.

Fabry disease is a lysosomal storage disorder with onset of adverse signs and symptoms usually during childhood and progressive life-threatening decline in organ functions. A validated and feasible Fabry disease severity scoring system (DS3) is needed to reliably quantify the disease burden, monitor disease progression and treatment response, and compare disease status among patient cohorts in clinical studies. We developed a new Fabry DS3 and tested its reliability and validity using a combination of expert consensus formation and statistical techniques. Relevant Fabry disease domains and items were identified, inclusion of items was refined and scaling of scores for individual assessments was optimized to maximize the correlation between the instrument's total score and the assigned clinical global impression of severity (CGI-S scores). Furthermore, the minimum clinically important difference in each of the instrument's domains was estimated and the DS3's quantitative content validity was judged. The current Fabry DS3 working model has 5 domains; 4 clinical domains (Peripheral Nervous System, Renal, and Cardiac, each with 3 items, Central Nervous System with 2 items) and a patient-reported domain (Patient-Reported domain with one item). The domain score is obtained by averaging the scores for all domain items. The Content Validity Index and Feasibility Index were shown to be good; 0.96 and 0.97, respectively. There was no significant inter-rater difference and the level of concordance was high. Correlation with the CGI-S was R(2)=0.89 indicating excellent criterion and construct (convergent) validity. In summary, initial estimations of validity, reliability and feasibility for the new Fabry DS3 instrument suggest that it is a feasible and reliable means of assessing disease severity and progression over time and comparing inter-patient severity of Fabry disease. Our results demonstrate that the Fabry DS3 correlates highly with the clinical assessment by Fabry disease experts.

Generation of osteoclasts from type 1 Gaucher patients and correlation with clinical and genetic features of disease.

Gaucher disease (GD) is a rare autosomal recessive disorder caused by deficient activity of ß-glucocerebrosidase resulting in the accumulation of glucosylceramide. Bone disease is a common feature with radiological evidence in up to 93% of patients. Severity of bone involvement ranges from osteoporosis to pathological fractures. The progressive course of type 1 GD is largely mitigated by treatment with enzyme replacement therapy (ERT) or substrate reduction. A number of studies have shown some patients suffer bone events while receiving ERT. Studies of biochemical markers of bone turnover have generated varied results and as a consequence are not generally used to assess bone disease in GD. In vitro osteoclast generation from peripheral blood samples of 74 Gaucher patients followed over a period of up to 10 years was correlated with bone events, reports of bone pain, anaemia, spleen status, bone mineral density, chitotriosidase activity, treatment with Gaucher specific therapies, bisphosphonates, mutation status and severity. Osteoclast generation, enumerated when cultured on glass, was significantly higher when differentiated from the peripheral blood of Gaucher patients which reported bone pain (116.4 ±â€¯18.0 vs 69.0 ±â€¯8.6, p < 0.01), had anaemia (153.7 ±â€¯34.9 vs 78.5 ±â€¯8.8, p < 0.01), had a splenectomy (137.6 ±â€¯41.1 vs 60.8 ±â€¯13.0, p < 0.05), versus those who did not. Osteoclast generation was also indicative of in vivo Gaucher specific therapy response as those naïve to therapy generated significantly more osteoclasts than those on therapy (111.2 ±â€¯35.8 vs 45.1 ±â€¯10.3, p < 0.05), as did patients receiving therapy but still suffering bone events (125.1 ±â€¯31.37 vs 45.1 ±â€¯10.33, p < 0.05). These findings demonstrate that the in vitro osteoclast assay may be a useful method for following bone disease progression in Gaucher patients.

Selective apoptotic killing of malignant hemopoietic cells by antibody-targeted delivery of an amphipathic peptide.

The alpha-helical amphipathic peptide D-(KLAKLAK)2 is toxic to eukaryotic cells if internalized by a suitable targeting mechanism. We have targeted this peptide to malignant hemopoietic cells via conjugation to monoclonal antibodies, which recognize lineage-specific cell surface molecules. An anti-CD19/peptide conjugate efficiently killed 3/3 B lymphoid lines. However, an anti-CD33/peptide conjugate was cytotoxic to only one of three CD33-positive myeloid leukemia lines. The IC50 towards susceptible lines were in the low nanomolar range. Conjugates were highly selective and did not kill cells that did not express the appropriate cell surface cognate of the antibody moiety. Anti-CD19/peptide conjugates efficiently killed cells from patients with chronic lymphocytic leukemia but anti-CD33/peptide reagents were less effective against fresh acute myeloid leukemia cells. We therefore suggest that amphipathic peptides may be of value as targeted therapeutic agents for the treatment of a subset of hematologic malignancies.

Prevalence and clinical significance of cardiac arrhythmia in Anderson-Fabry disease.

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by a deficiency in the enzyme alpha-galactosidase A. More than 60% of patients with AFD have evidence for cardiac involvement; the prevalence and clinical significance of arrhythmia in AFD are unknown. Seventy-eight consecutive patients (mean age 43.5 +/- 15.0 years, range 13.0 to 83.0; 43 men) with AFD were studied for 1.9 years (range 0.25 to 10). All patients underwent clinical evaluation, 12-lead electrocardiography, and echocardiography. Sixty patients (76.9%) underwent 24-hour ambulatory electrocardiographic monitoring. Persistent atrial fibrillation (AF) was present in 3 of 78 patients (3.9%); 8 (13.3%) had paroxysmal AF, and 5 (8.3%) had nonsustained ventricular tachycardia (VT). Patients with nonsustained VT were all men, with a maximal left ventricular (LV) wall thickness >20 mm. Age (p <0.001), left atrial diameter (p = 0.001), maximal LV wall thickness (p = 0.003), LV mass index (p = 0.009), and angina (p = 0.02) were univariate predictors of AF or paroxysmal AF. Using these predictors in a stepwise logistic regression analysis model, age was the only independent predictor of AF or paroxysmal AF (odds ratio 1.2, 95% confidence interval 1.1 to 1.3, p = 0.001). During follow-up, there was 1 sudden cardiac death, 4 patients received pacemakers for bradyarrhythmia, and 1 received a biventricular pacemaker and an internal cardioverter defibrillator. In conclusion, arrhythmias are common in older patients with AFD. The high incidence of pacemaker implantation and sudden cardiac death suggests that arrhythmia has a significant impact on the natural history of AFD.

Rituximab in the treatment of refractory autoimmune cytopenias in adults.

We report the results of four cycles of rituximab therapy in eleven patients with chronic warm antibody type autoimmune hemolytic anemia (AIHA) and six patients with chronic idiopathic thrombocytopenia (ITP). The overall response rate was 64% in the AIHA group (3 complete responses and 4 partial responses) and 83% in the ITP group (4 complete responses, 1 partial response). Responses in AIHA patients with underlying lymphoproliferative disorders receiving rituximab with chemotherapy were generally better sustained, whereas responses in ITP were often transient.

V(H) gene usage differs in germline and mutated B-cell chronic lymphocytic leukemia.

BACKGROUND AND OBJECTIVES: Given the prognostic relevance that the identification of mutated and germline subgroups of chronic lymphocytic leukemia (CLL) has recently acquired we set out to analyze in depth individual VH gene usage rearrangements in patients with mutated and germline CLL. DESIGN AND METHODS: Using sequence analysis of FR1/JH polymerase chain reaction products, the VH immunoglobulin gene configuration was analyzed in 159 rearranged IgH alleles from 154 CLL patients. Having previously identified a spatial relationship between VH gene usage and JH proximity in patients with acute lymphocytic leukemia (ALL), we performed linear and Poisson regression analysis on patients with germline and mutated CLL against VH rearrangements from normal peripheral blood. RESULTS: Sequence analysis showed that 102 patients (64%) had mutated sequences (>2% DNA base pair changes) while 57 (36%) had germline sequences. The germline CLL group showed JH proximal overusage similar to that reported in ALL patients, while the mutated CLL group showed a pattern comparable to that of the control group (peripheral blood rearranged VH sequences). The CDR3 region was statistically longer in the patients with germline CLL than in those with mutated CLL. INTERPRETATION AND CONCLUSIONS: This study highlights differences in the VDJ profile in mutated and germline CLL, consistent with the suggestion that CLL comprises two subgroups. The interpretation of these differences is that the B-cell of CLL, particularly in the germline group, may derive from a pool that has been unable to follow or complete the normal pathway of B-cell differentiation.

Clinical effects and P-glycoprotein inhibition in patients with acute myeloid leukemia treated with zosuquidar trihydrochloride, daunorubicin and cytarabine.

BACKGROUND AND OBJECTIVES: P-glycoprotein (P-gp) is a major cause of multidrug resistance (MDR) in acute myelogenous leukemia (AML) and is thought to contribute to the failure of chemotherapy. Zosuquidar trihydochloride (Z.3HCL) is a potent and selective inhibitor of P-gp which rapidly and effectively inhibits drug efflux. DESIGN AND METHODS: The aim of this study was to evaluate the clinical effects of Z.3HCL and determine its influence on P-gp activity. Sixteen AML patients were entered into a phase 1 dose ranging clinical trial of Z.3HCL, co-administered intravenously with daunorubicin and cytosine arabinoside (ARA-C). Clinical outcomes, toxicity abd adverse events were assessed. P-gp function was analyzed by flow cytometry. In vitro cytotoxicity was studied using the MTT assay. RESULTS: Eleven patients achieved a complete remission and one a partial remission with a median survival of 559 (range 38-906) days. Non-hematologic grade 3 and 4 toxicities were seen in 4 patients. Z.3HCL infusion was associated with rapid inhibition of Rh123 efflux in CD56+ cells in 16/16 patients and in CD33+ cells from 6/10 patients. The median inhibition was 95% for CD56+ cells and 85.25% for CD33+ cells was significantly elevated in 6/16 patients. The median IC50, using a MTT assay for daunorubicin, decreased significantly between Z.3HCL modulated and unmodulated cells (n=11,153 and 247 ng/mL respectively, p=0.01). INTERPRETATION AND CONCLUSIONS: The modulator Z.3HCL is a specific inhibitor of P-gp efflux and can be given safely to patients with AML in combination with induction doses of conventional cytotoxic drugs.

Difficulties and barriers in diagnosing Fabry disease: what can be learnt from the literature?

INTRODUCTION: Fabry disease (FD) is an X-linked disorder of glycosphingolipid metabolism caused by deficiency of the lysosomal enzyme alpha galactosidase A. Clinical features include neuropathic pain, rash, proteinuria renal failure, stroke and cardiomyopathy accompanied by a reduced life expectancy. Patients report an average delay of > 10 years between symptom onset and diagnosis. Newborn screening studies suggest a much higher prevalence than that found on population studies supporting the notion that FD is under-diagnosed. AREAS COVERED: Four key challenges in the diagnosis of FD and strategies to overcome them are discussed. The clinical features of FD are highly heterogeneous resulting in patients presenting to many different specialists, often with non-specific symptoms with a wide differential diagnosis. The pathophysiological mechanisms underlying this are poorly understood and the prediction of pathogenicity on the basis of gene mutation analysis can be problematic. While the availability of treatment adds an impetus to make the correct diagnosis, our understanding of when and if treatment may be required in a specific individual is incomplete. EXPERT OPINION: Improving diagnostic rates of FD requires a greater awareness of the disorder among physicians to whom patients may present, new strategies to determine the pathogenicity of novel mutations and a greater understanding of the natural history of FD across the phenotypic spectrum. Collaborative clinical and laboratory research is vital in furthering knowledge of the underlying mechanisms of this disorder and how they may be impacted by current or future therapies.

Prevalence of Anderson-Fabry disease in patients with hypertrophic cardiomyopathy: the European Anderson-Fabry Disease survey.

OBJECTIVES: The prevalence of Anderson-Fabry disease (AFD) in patients presenting with unexplained left ventricular hypertrophy (LVH) is controversial. The aim of this study was to determine the prevalence of AFD in a large, consecutive cohort of patients with hypertrophic cardiomyopathy (HCM) using rapid mutation screening. DESIGN, SETTING AND PATIENTS: A European multicentre cross-sectional study involving 13 referral centres. Inclusion criteria for the study were: men aged at least 35 years and women aged at least 40 years with unexplained LVH (maximum left ventricular wall thickness ≥ 1.5 cm). All patients were screened using a denaturing high-performance liquid chromatography protocol for rapid mutation screening of the α-galactosidase A (α-Gal A) gene and, if a sequence variant was found, direct sequencing was performed. 1386 patients (63.9% men, mean age 57.9 ± 12.0 years) were enrolled in the study. RESULTS: Seven (0.5%) patients (age 57.4 ± 9.0 years (45-72); three (43%) men) had pathogenic α-galactosidase A mutations. Polymorphisms were identified in 283 patients (20.4%). Maximal left ventricular wall thickness in patients carrying a disease-causing mutation was 18 ± 2 mm (range 15-22); four patients had concentric LVH and the remainder had asymmetric septal hypertrophy. CONCLUSIONS: The prevalence of AFD gene mutations in a large, consecutive cohort of European patients with unexplained LVH is 0.5%.

Gaucher disease: outcome following total hip replacements and effect of enzyme replacement therapy in a cohort of UK patients.

Only a limited number of reports of total hip replacements (THRs) in patients with Gaucher disease (GD) have been published, with the majority showing high rates of early aseptic loosening as well as an increased number of peri-operative complications. We present a series of twelve THRs in nine affected patients, with a mean age of 39 years at the time of surgery (median 37 years; range 27-60 years). We examine the medium- to long-term results and present the outcome scores, survival, and assess the effect of enzyme replacement therapy (ERT). Four hips (33.3%) required revision for aseptic loosening at a mean time of 11.5 years. There was no significant difference in survival between the group on ERT at the time of surgery and group not on ERT. Those on ERT did, however, have fewer peri-operative complications and there was a trend to better outcome scores. Five of the 12 THRs were performed when the diagnosis of GD was unknown and all of these had early complications.?Our results show better survival of THRs in patients with GD than previously thought. The use of ERT pre-operatively did not have an effect on survival, nor outcome scores, but did reduce the peri-operative complication rate. Those not on ERT at the time of surgery were commenced on it at some point in their treatment (at an average of 8.6 years following THR) and we believe the use of ERT, at any time in the treatment, could have contributed to the improved survival seen in our series compared to historical results in the literature.

An unusual case of transient dermatological reaction to bortezomib in AL amyloidosis.

We report an unusual dermatological reaction to bortezomib in a 61-year-old man with AL amyloidosis. Systemic AL amyloidosis is a rare complication of monoclonal gammopathy or myeloma in which abnormally unstable free light chains cause fibrillary deposits in organs leading to multisystem disease. The treatment of AL amyloidosis is directed at the underlying plasma cell dyscrasia and most regimes have been adapted from myeloma, but drug toxicity is more common in AL amyloidosis because of the more extensive nature of the disease. We report a patient who developed asymptomatic purple discolouration of the veins of his left arm several days after receiving the infusion in his left hand, although the infusion itself had been uncomplicated with no extravasation. The discolouration resolved completely within 2 weeks; there was recurrence on a subsequent dose of bortezomib but this also subsided spontaneously. This reaction may have been transient phlebitis or a local vasogenic reaction; its transient nature and the lack of systemic features suggest it is a benign phenomenon. There appears to be no indication for discontinuation of bortezomib treatment or dose alteration in such cases.

Glucosylceramide synthase inhibitors sensitise CLL cells to cytotoxic agents without reversing P-gp functional activity.

Malignant B-cells from most chronic lymphocytic leukaemia (CLL) patients over-express MDR1 encoded P-glycoprotein (P-gp) multidrug efflux pump. Inhibition of glucosylceramide (GC) synthesis has been shown in cell lines to correlate with the expression and function of P-gp and sensitise cancer cells to cytotoxic agents. We investigated the hypothesis that reducing intracellular GC levels will reduce P-gp expression in malignant cells from CLL patients. We studied the ability of glucosylceramide synthase (GCS) inhibitors N-butyl-deoxygalactonojirimycin (OGB-1) and N-nonyl-deoxygalactonojirimycin (OGB-2) to sensitise CLL cells to conventional cytotoxic drug 2-chlorodeoxyadenosine (CdA) and the cytostatic drugs chlorambucil and fludarabine. The effect on P-gp activity was analysed using the calcein-AM accumulation assay where a multidrug activity factor (MAF) of >10 in the presence of a P-gp inhibitor denotes P-gp functional activity. The P-gp over-expressing cell line CEM-VLB showed a MAF value of 96.4 with the P-gp inhibitor Z.3HCL, which fell to 15.7 after co-incubation with OGB-1 and 45.9 with OGB-2. The IC(50) for vincristine fell from >10 microg/ml to 55.5 ng/ml in the presence of OGB-2. In P-gp(+ve) peripheral blood mononuclear cells from three normal volunteers, the mean MAF values for Z.3HCL, OGB-1 and OGB-2 were 23.86, 1.83 and 16.2 respectively. In 9/13 CLL samples the mean P-gp functional activity was 22.15 and P-gp was over-expressed in 12/13 samples. However, the MAF value with OGB-1 and OGB-2 was <10. Nevertheless, sensitisation in CLL cells was observed by a reduction in the IC(50) in the presence of OGB-1 and OGB-2 with the conventional drugs. We conclude that although GCS inhibitors sensitize CLL cells to cytotoxic and cytostatic drugs, they do not appear to have any effect on P-gp functional activity.

Haemorheology in Gaucher disease.

UNLABELLED: In Gaucher disease, a deficiency of glucocerebrosidase results in the accumulation of glucocerebroside within the lysosomes of the monocyte-macrophage system. Prior to the availability of enzyme replacement therapy (ERT), splenectomy was often indicated for hypersplenism. Haemorheological abnormalities could be expected in view of the anaemia and abnormal lipid metabolism in these patients and the role of the spleen in controlling erythrocyte quality. OBJECTIVES: To investigate the effect of Gaucher disease on blood and plasma viscosity, erythrocyte aggregation and erythrocyte deformability, and to determine whether observed rheological differences could be attributed to splenectomy. METHODS: Haematological and haemorheological measurements were made on blood collected from 26 spleen-intact patients with Gaucher disease, 16 splenectomised patients with Gaucher disease, 6 otherwise healthy asplenic non-Gaucher disease subjects and 15 healthy controls. RESULTS: No haemorheological differences could be demonstrated between spleen-intact patients with Gaucher disease and the control group. Compared to controls, both asplenic Gaucher disease and asplenic non-Gaucher disease study groups had a reduced MCHC (P = 0.003 and 0.005, respectively) and increased whole blood viscosity at 45% haematocrit (Hct), relative viscosity and red cell aggregation index - all measured at low shear (P < 0.05 for all). Additionally, asplenic patients with Gaucher disease alone showed an increased MCV (P = 0.006), an increased whole blood viscosity at 45% Hct measured at high shear (P = 0.019), and a reduced relative filtration rate (P = 0.0001), compared to controls. CONCLUSION: These observations demonstrate a direct and measurable haemorheological abnormality in Gaucher disease only revealed when there is no functioning spleen to control erythrocyte quality.

Infusional 5-fluorouracil in Cutaneous Leukaemia: a Novel Palliative Therapy in Haematological Malignancy; Malignancy.

We describe the management of a woman suffering from acute myelomonocytic leukaemia with cutaneous involvement. Following treatment with conventional chemotherapy she was in complete remission, but then suffered an isolated skin relapse. In order to limit side effects and myelotoxicity, an experimental therapy using a continuous infusion of 5-fluorouracil was employed. This was completely successful in eradicating the skin lesions, the patient suffered no side effects and blood counts remained within normal limits throughout. Infusional 5FU may have a role in palliative therapy in haematological malignancy.