Multicenter Extension Study of Velaglucerase Alfa in Japanese Patients With Gaucher Disease

A Multicenter, Open-label Extension Study of Velaglucerase Alfa Enzyme Replacement Therapy in Japanese Patients With Gaucher Disease

Gaucher disease is an inherited deficiency of the lysosomal enzyme glucocerebrosidase (GCB) that leads to progressive accumulation of glucocerebroside within macrophages and subsequent tissue and organ damage; typically of the liver, spleen, bone marrow, and brain. Type 1 Gaucher disease affects an estimated 30,000 persons worldwide and is the most common. Type 1 Gaucher disease does not involve the central nervous system. Patients with Type 2 Gaucher disease present with acute neurological deterioration, which leads to early death. Those with Type 3 disease typically display a more sub-acute neurological course, with later onset and slower progression. The primary objective of this study is to evaluate the long-term safety of every other week (EOW) dosing of velaglucerase alfa in Japanese patients with Gaucher disease who completed study HGT-GCB-087 and elected to continue treatment with velaglucerase alfa. Velaglucerase alfa has been developed and approved as an enzyme replacement therapy for Type 1 Gaucher disease.

Gaucher disease is an inherited deficiency of the lysosomal enzyme glucocerebrosidase (GCB) that leads to progressive accumulation of glucocerebroside within macrophages and subsequent tissue and organ damage; typically of the liver, spleen, bone marrow, and brain. Gaucher disease has been designated in the list of Specified Rare and Intractable Diseases by Specified Disease Treatment Research Program of Ministry of Health, Labor and Welfare (MHLW) as one of "lysosomal storage diseases" since 2001. Gaucher disease is also designated in the Medical Aid Program for Specified Categories of Chronic Pediatric Diseases. The prevalence of mutations and the phenotype of patients with Gaucher disease in Japan differs from that in non-Japanese populations. Some patients with type 1 Gaucher disease in Japan have more severe and progressive disease compared to non-Japanese patients and the disease is characterized by an earlier onset of symptoms. Velaglucerase alfa, a highly-purified form of the naturally occurring enzyme glucocerebrosidase, has been developed as an enzyme replacement therapy for Gaucher disease for the symptoms (anemia, thrombocytopenia, hepatomegaly, splenomegaly, and bone manifestation). The primary objective of this study is to evaluate the long-term safety of every other week (EOW) dosing of velaglucerase alfa in Japanese patients with Gaucher disease who completed study HGT-GCB-087 and elected to continue treatment with velaglucerase alfa.

Number of Participants With Drug-related Adverse Events (AEs), Infusion-related AEs, and Serious AEs (SAEs)

An AE was any noxious, pathologic, or unintended change in anatomical, physiologic, or metabolic function as indicated by physical signs, symptoms, or laboratory changes occurring in any phase of a clinical study, whether or not considered related to investigational product. A SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged in-patient hospitalization; life threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. An infusion-related AE was defined as an AE that started either during or within 12 hours after the start of the infusion and that was judged as possibly or probably related to investigational product.

Laboratory test results were considered abnormal and clinically significant at the discretion of the investigator.

Serum samples were collected for all participants for determination of anti-velaglucerase alfa antibodies every 12 weeks.

Baseline was the modified baseline hemoglobin concentration, the average of the values from screening, baseline, and Week 1 Day 1 from Study HGT-GCB-087 (NCT01614574).

Baseline was the modified baseline platelet count, the average of the values from screening, baseline, and Week 1 Day 1 from Study HGT-GCB-087 (NCT01614574).

Liver volume was measured using magnetic resonance imaging (MRI). Liver volume measurements were normalized to the percentage of body weight. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Spleen volume was measured using MRI. Spleen volume measurements were normalized to the percentage of body weight. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

BMD was measured by dual energy x-ray absorptiometry (DXA) for lumbar spine and femurs. To ensure standardization and allow for comparisons of BMD, results were converted to standardized Z-scores (matched for age and gender). Z-scores express the BMD as the number of standard deviations (SDs) above or below the average BMD of a healthy participant of the same age and gender. Statistical analysis plan only required summarization if greater than (>) 50 percent (%) of participants had evaluable data. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

BMD was measured by DXA for lumbar spine and femurs. To ensure standardization and allow for comparisons of BMD, results were converted to standardized T-scores; normal values were used from databases from Hologic based on standard criteria. T-scores are the number of SDs above or below the average for a young adult at peak BMD. Statistical analysis plan only required summarization if >50% of participants had evaluable data. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

BMB Score was measured using MRI, range from 0 (no abnormalities) to 8 points (severe disease) for the lumbar spine and from 0 (no abnormalities) to 8 points (severe disease) for the femurs. The total score was calculated as the sum of scores for femur and lumbar spine regions which ranged from 0-16 points. A higher BMB score signified more severe bone marrow involvement. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

The Z-score, or Standard Deviation Score, is a measure of number of SDs above or below the average BMD of a healthy participant of the same age and gender. World Health Organization 2007 growth reference data were used for Z-score calculation. Statistical analysis plan only required summarization if >50% of participants had evaluable data. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Skeletal age was measured via radiography (X-ray) of the left hand and wrist by the method of Greulich and Pyle. The Z-score, or Standard Deviation Score, is a measure of number of SDs above or below the average BMD of a healthy participant of the same age and gender. Statistical analysis plan only required summarization if >50% of participants had evaluable data. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Plasma chitotriosidase activity levels were measured using an enzymatic assay with 4-methylumbelliferyl-deoxychitobiose as a substrate. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Neurological status was considered normal or abnormal based on investigator's discretion. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Plasma CCL18 concentrations were measured using a time-resolved fluorescence assay. Week 51 of Study HGT-GCB-087 (NCT01614574) was considered as baseline for this endpoint.

Inclusion Criteria: The patient has completed treatment with EOW velaglucerase alfa through Week 51 of study HGT-GCB-087. Female patients of child bearing potential must agree to use a medically acceptable method of contraception at all times during the study. The patient, the patient's parent(s)or legal guardian(s) has provided written informed consent that has been approved by the Institutional Review Board/Independent Ethics Committee(IRB/IEC) The patient must be sufficiently cooperative to participate in this clinical study as judged by the Investigator. Exclusion Criteria: The patient has received treatment with any investigational drug, other than velaglucerase alfa, or investigational device within 30 days prior to study entry; such use during the study is not permitted. The patient, patient's parent(s), or patient's legal guardian(s) is/are unable to understand the nature, scope, and possible consequences of the study. The patient has a significant comorbidity, as determined by the Investigator that might affect study data or confound the study results. The patient is unable to comply with the protocol as determined by the Investigator.

Ida H, Tanaka A, Matsubayashi T, Murayama K, Hongo T, Lee HM, Mellgard B. A multicenter, open-label extension study of velaglucerase alfa in Japanese patients with Gaucher disease: Results after a cumulative treatment period of 24months. Blood Cells Mol Dis. 2016 Jul;59:140-7. doi: 10.1016/j.bcmd.2015.10.002. Epub 2015 Oct 16.