The following three cases of Gaucher Disease (GD) illustrate situations encountered in clinical practice; several common pitfalls are highlighted.

Transcription

1 SUPPLEMENT Management of Bone Disease in Gaucher Disease Type 1: Clinical Practice ABSTRACT Gaucher disease (GD) is a rare autosomal recessive disorder of glycosphingolipid metabolism resulting from deficient activity of the lysosomal enzyme beta-glucocerebrosidase that causes accumulation of glucosylceramide in tissue macrophage, with damage to hematological, visceral, and skeletal organ systems. Severity and progression may vary independently among these domains, necessitating individualized therapy. Skeletal involvement is highly prevalent and often associated with intense pain, impaired mobility and reduced quality of life. Enzyme replacement therapy improves parameters in all affected domains, but skeletal involvement requires longer treatment and higher dosages to obtain significant results. Despite numerous papers on bone complications in patients with GD, there are no specific indications on how to properly assess bone involvement, the frequency of assessment, the use of markers for osteoblast and osteoclast activity, or the administration of bisphosphonates or other symptomatic drugs in adult and pediatric patients. With re-evaluation of cases with bone involvement we have identified some common errors in the diagnostic approach and management. The aim of this paper is to propose a methodological and critical approach to the diagnosis, follow up and treatment of bone disease in patients with Gaucher disease type 1. CASE REPORTS The following three cases of Gaucher Disease (GD) illustrate situations encountered in clinical practice; several common pitfalls are highlighted. Case 1 The patient was an asymptomatic woman diagnosed with GD at the age of 4 years. At the time of diagnosis glucocerebrosidase activity was 2.15 nmol/mg/h (normal value 11.5 ± 3.6 nmol/mg/h) and she had a genotype of L444P/N370S. Subsequent hematological examinations were normal. Dual energy X- ray absorptiometry (DXA) was not performed at diagnosis, but at the age of 49 years magnetic resonance imaging (MRI) revealed a Terk classification of 1a, with mild infiltration. The results from a DXA at this

2 time showed a spinal column T-score of -3.5 and a Z-score of She still had regular menses. Deviation of the spinal column was noted (Supplementary Fig. 1). Blood tests revealed ferritin levels of 623 ng/ml, hemoglobin (Hb) of 13.7 g/dl and platelet count of 102,000/mm 3 ; vitamin D levels were normal and she was not receiving supplements. Imiglucerase 30 U/kg/2 weeks was started at the age of 50 years. After 2 years, her platelet count had normalized. An MRI showed that the low level of marrow infiltration had been maintained, but the spinal column T-score and Z-score had not improved; imiglucerase had increased to 60 U/kg/2 weeks. After a further 2 years, DXA revealed a spinal column T-score of -3.1, and femoral T-score -2.6 (Supplementary Fig. 1). The patient refused further therapy. This patient had severely reduced bone mineral density (BMD) when premenopausal, with skeletal involvement affecting primarily the vertebrae in the absence of other signs. Her lack of response to enzyme replacement therapy (ERT) is likely due to late diagnosis, delayed treatment, severity of the BMD deficit and the short course of therapy administered (4 years of ERT, with high dosage for only 2 years). This case highlights the need for thorough assessment and monitoring of skeletal parameters even in asymptomatic patients. DXA at diagnosis may have revealed the BMD deficit and prompted early treatment with high-dosage ERT and anti-osteoporotic drugs. Case 2 This patient was male with a history of splenomegaly from the age of 3 year. He underwent a splenectomy when diagnosed with DG at the age of 5 years. In adult life, recurrent thrombosis prompted analysis for coagulopathy, which revealed homozygous Factor V Leiden mutation. GD genotyping revealed IVS2G>A/R170P. Low dosage ERT (30 U/kg/month) was started at age of 35 years, and was increased to 60 U/kg/month after 1 year due to the onset of pulmonary hypertension. He presented at a specialist center at the age of 38 years. DXA evaluation at the age of 38 years revealed a vertebral (L2- L4) BMD of g/cm 2 and T-score of -3.02, and a total body BMD of g/cm 2 and T-score of MRI of the vertebral column revealed hypointensity and partial collapse of L1 with a wedge-shaped deformation and hypointensity of both femoral heads. Imiglucerase dosage was increased to 60 U/kg/2 weeks; vitamin D and calcium supplements were administered. Zoledronic acid was administered over the next 2 years. Approximately 4 years later (aged 42 years), BMD values had normalized (Supplementary Table A).

3 Supplemental Table A. Changes in T-score, bone marrow burden score and chitotriosidase activity after increasing the ERT dosage from 60 U/kg/month to 60 U/kg/every 2 weeks. ERT treatment history can be summarized as follows: 30 U/kg/month in 1998, increased to 60 U/kg/month in 1999 due to the onset of pulmonary hypertension, and finally to 60 U/kg/every 2 weeks in T-Score BMB na na na 6 na 4 na na 1 Chitotriosidase (n.v nmol/h/ml) na 510 na 204 na 373 na 683 BMB, bone marrow burden score; na, not available. MRI also performed at age 42 revealed that the vertebral collapse was associated with marrow infiltration, although osteopenia could not be ruled out as a contributing factor. Splenectomy placed this patient at higher risk for complications including osteonecrosis and pulmonary hypertension [1, 2]. BMD improved significantly after the ERT dosage was increased to 60 U/kg/every 2 weeks, highlighting the doseresponse relationship already reported in the literature [3]. However, the improvement cannot be attributed completely to ERT as the patient received also bisphosphonate therapy. Case 3 The patient is a woman who had been diagnosed with spherocytosis at the age of 3 years, although her red blood cell (RBC) osmotic resistance was normal. At the age of 15 years, she had a non-traumatic (fragility) fracture of the medial distal humerus, but no further investigations were performed. At the age of 31 years she reported pain in the left shoulder; X-ray revealed bone cysts, but she refused computed tomography (CT). One year later, MRI for persistent pain revealed collapse of the left humeral head (Supplementary Fig. 2), but no action was taken. A CT scan at age of 35 years confirmed osteonecrosis of the left humeral head. Two years later, abdominal ultrasound showed marked hepatosplenomegaly; abdominal CT revealed fatty liver with splenomegaly. She had leukopenia, anemia and thrombocytopenia. The diagnosis of spherocytosis was reconsidered and eventually excluded. At the age of 37 years a liver biopsy revealed a lysosomal storage disease; the diagnosis of GD was confirmed at a Gaucher specialist centre (beta-glucosidase activity 2.8 nmol/mg/h, [normal range nmol/mg/h]; chitotriosidase activity 9,559 nmol/h/ml [normal range <200 nmol/h/ml]; genotype N370S/W184R). DXA showed a BMD at the lower limit of normal for femur and vertebrae (T-1.5 and -1.6; Z -1.3 and -1.5, respectively). MRI showed a bone marrow burden (BMB) score of 9. At the age of 38 years, imiglucerase therapy was started at 60 U/kg every 2 weeks.

4 This patient was initially misdiagnosed and the correct diagnosis was made after 35 years, despite the occurrence of osteonecrosis. The bone involvement was probably primarily due to marrow infiltration, resulting in osteonecrosis and subsequent collapse of the humeral head. This event may have been preventable with earlier diagnosis and administration of ERT and bisphosphonate therapy. Osteopenia was moderate, and could be considered consistent with age. ACKNOWLEDGMENTS All authors had full access to all of the data in this study and take complete responsibility for the integrity of the data and accuracy of the data analysis. All authors contributed equally to this work. No funding or sponsorship was received for this study or publication of this article. Conflict of Interest. Gaetano Giuffrida has received honoraria from Genzyme a Sanofi Company, Modena, Italy, Shire, Florence, Italy, Bayer, Milan, Italy and Novo Nordisk, Rome, Italy. Maria Domenica Cappellini has received consultancy fees from Novartis, Origgio, Italy, Genzyme a Sanofi Company, Modena, Italy and Celgene, Milan, Italy. Francesca Carubbi has received speaker honoraria from Genzyme a Sanofi Company, Modena, Italy and travel grants from Shire, Florence, Italy and Genzyme a Sanofi Company, Modena, Italy. Maja Di Rocco has received honoraria from Genzyme a Sanofi Company, Modena, Italy, Shire, Florence, Italy, Actelion, Imola, Italy and BioMarin Europe Limited, London, England. Giovanni Iolascon has received honoraria as a speaker from Amgen, Milan, Italy, Grunenthal Italia, Milan, Italy, Eli Lilly Italia, Sesto Fiorentino, Italy and MSD Italia, Rome, Italy. Compliance with Ethics Guidelines. Informed consent was obtained from all patients for being included in the study. Collaborators. Elena Cassinerio, Fondazione Ca Granda IRCCS,Policlinico Hospital, Milan, Italy; Rita Lombardo, Ernesto Di Francesco, University of Catania, Ospedale Ferrarotto, Catania, Italy; Annalisa Madeo, Gaslini Institute, Genoa, Italy; Chiara Masetti, University of Modena and Reggio Emilia, AUSL Modena, Italy; Antimo Moretti, Second University of Naples, Italy; Maria Ruberto, Second University of Naples, Italy; Maria Francesca Zenobii, University of Modena and Reggio Emilia, AUSL Modena, Italy.

5 REFERENCES 1. Deegan PB, Pavlova E, Tindall J, et al. Osseous manifestations of adult Gaucher disease in the era of enzyme replacement therapy. Medicine (Baltimore). 2011;90: Mistry PK, Deegan P, Vellodi A, Cole JA, Yeh M, Weinreb NJ. Timing of initiation of enzyme replacement therapy after diagnosis of type 1 Gaucher disease: effect on incidence of avascular necrosis. Br J Haematol. 2009;147: Wenstrup RJ, Kacena KA, Kaplan P, et al. Effect of enzyme replacement therapy with imiglucerase on BMD in type 1 Gaucher disease. J Bone Miner Res. 2007;22:

6 Supplementary Table 1 Summary of published skeletal response studies in adult patients with Gaucher disease treated with enzyme replacement therapy Therapeutic Treatment Citation Study design Sample Study duration goal (ERT)* size (N) (years) (Andersson et al 2005) [48] Lessen or Imiglucerase Weinreb et al 356 ( eliminate bone 2013 [61] with bone pain pain, 169 data with bone Prevent bone crises) crises Sims et al 2008 Multicenter, 33 4 [62] nonrandomized, open-label, single-cohort, prospective Charrow et al 463 ( [63] with bone data analysis pain; 219 with bone crises) Weinreb et al 229 (with [10] bone pain) long-term data 93 (with bone crises) Prevent Imiglucerase Deegan et al. Descriptive 100 N/A osteonecrosis 2011 [12] cross-sectional study

7 Mistry et al 2009 [14] descriptive incidence 2700 at risk 5 Sims et al 2008 [62] Multicenter, nonrandomized, open-label, single-cohort, prospective 33 4 Improve BMD Imiglucerase Mistry et al (56 10 [8] young study adults; 171 older adults) Sims et al 2008 [62] Multicenter, nonrandomized, open-label, single-cohort, prospective 33 4 Wenstrup et al [11] (342 treated study with ERT) Ciana et al 2005 [35] Observational prospective Velaglucerase Elstein et al 2011 [64] Prospective, nonrandomized, open-label, extension

8 Additional skeletal pathology addressed Reduce BMB Imiglucerase De Fost et al Median (range) [47] comparative in 2 7 (3 11) cohort cohorts: Germany 9 (1 12) (57) Holland (49) Velaglucerase Elstein et al 2014 [65] Post-hoc Elstein et al Improve QoL Imiglucerase Weinreb et al Multicenter, 32 4 for patients 2007 [66] prospective, with bone open-label, manifestations single-cohort, year study *only enzyme replacement therapies approved in Europe. BMB bone marrow burden, BMD bone mineral density, ERT enzyme replacement therapy, QoL quality of life, N/A not applicable

9 Supplementary Table 2 Summary of published skeletal response studies in pediatric patients with Gaucher disease treated with enzyme replacement therapy Therapeutic Treatment Citation Study design Sample Study goal (ERT)* size (N) duration (Andersson (years) et al 2005) [48] Prevent Imiglucerase Andersson bone crises et al 2008 [13] data Improve Imiglucerase Mistry et 84 (43 10 BMD al 2011 children; 41 [8] study adolescents) Andersson et al 2008 [13] data Normalize Imiglucerase Andersson growth in et al 2008 pediatric [13] patients data Ida et al [67] analysis *only enzyme replacement therapies approved in Europe. BMD bone mineral density, ERT enzyme replacement therapy

10 Supplementary Fig. 1 DXA A) lumbar spine, B) femoral head and hip, and C) whole body. Graphs show bone mineral density (left) and T-score (right) as a function of age. Green normal, yellow osteopenia, red osteoporosis, blue reference mean ± 1 (darker blue) or 2 (lighter blue) standard deviations. DXA dual energy X-ray absorptiometry A B C

11 Supplementary Fig 2 (A) coronal plane and (B) sagittal plane T2-weighted turbo spin-echo magnetic resonance sequence of the right shoulder/arm, without contrast. Severe structural alteration of the humeral head with loss of material is evident. Cancellous bone is diffusely hypointense, with areas of T2 hyperintensity likely corresponding to infarcted areas A B