Position statement: National Gaucher Foundation Medical Advisory Board, January 7, 2014

Osteonecrosis in Gaucher disease in the era of multiple therapies: Biomarker set for risk stratification from a tertiary referral center

Background

A salutary effect of treatments for Gaucher disease (GD) has been a reduction in the incidence of avascular osteonecrosis (AVN). However, there are reports of AVN in patients receiving enzyme replacement therapy (ERT) , and it is not known whether it is related to individual treatments, GBA genotypes, phenotypes, biomarkers of residual disease activity, or anti-drug antibodies. Prompted by development of AVN in several patients receiving ERT, we aimed to delineate the determinants of AVN in patients receiving ERT or eliglustat substrate reduction therapy (SRT) during 20 years in a tertiary referral center.

Methods

Longitudinal follow-ups of 155 GD patients between 2001 and 2021 were analyzed for episodes of AVN on therapy, type of therapy, GBA1 genotype, spleen status, biomarkers, and other disease indicators. We applied mixed-effects logistic model to delineate the independent correlates of AVN while receiving treatment.

Results

The patients received cumulative 1382 years of treatment. There were 16 episodes of AVN in 14 patients, with two episodes, each occurring in two patients. Heteroallelic p.Asn409Ser GD1 patients were 10 times (95% CI, 1.5-67.2) more likely than p.Asn409Ser homozygous patients to develop osteonecrosis during treatment. History of AVN prior to treatment initiation was associated with 4.8-fold increased risk of AVN on treatment (95% CI, 1.5-15.2). The risk of AVN among patients receiving velaglucerase ERT was 4.68 times higher compared to patients receiving imiglucerase ERT (95% CI, 1.67-13). No patient receiving eliglustat SRT suffered AVN. There was a significant correlation between GlcSph levels and AVN. Together, these biomarkers reliably predicted risk of AVN during therapy (ROC AUC 0.894, p<0.001).

Conclusions

There is a low, but significant risk of AVN in GD in the era of ERT/SRT. We found that increased risk of AVN was related to GBA genotype, history of AVN prior to treatment initiation, residual serum GlcSph level, and the type of ERT. No patient receiving SRT developed AVN. These findings exemplify a new approach to biomarker applications in a rare inborn error of metabolism to evaluate clinical outcomes in comprehensively followed patients and will aid identification of GD patients at higher risk of AVN who will benefit from closer monitoring and treatment optimization.

Funding

LSD Training Fellowship from Sanofi to MB.

Healthcare resource utilization and cost of care for Gaucher patients in Iran

Introduction

Gaucher disease (GD) is an inherited recessive enzyme deficiency with a multisystem condition. The Iranian government covers the therapeutic expenditure of GD patients as it is not affordable for the patients. The aim of this study is to identify the main components of the cost of care in Gaucher patients (GPs) in Iran.

Methods

The Gaucher patients were identified from the Iran Food and Drug Administration (IFDA) national registry database. The direct medical costs, including medication, diagnostic services, and physician visits were considered. The prices of therapeutic and diagnostic services were extracted from Iranian medical tariff book 2014-15. Iran Food and Drug Administration determined the cost of medications.

Results

164 Gaucher patients have been registered in Iran. A valid and reliable diagnostic tests are not used to identify the type of GD. The average health care cost per annum was 20,758 USD per patient, which is higher than 4 GDP per capita in Iran. Medication cost constitutes 95.2% of the total cost. The average cost of each GP was $1,473,818 in his/her total life.

Conclusion

GD is amongst the high-cost diseases and should be managed effectively. The application of oral medication for eligible GPs could improve allocative efficiency in GD management significantly. A sound, valid and reliable national clinical guideline could improve the efficiency of healthcare resources effectively. Selecting appropriate strategies for reducing the birth of a child with Gaucher, could support allocative efficiency of the limited resources effectively.

The Clinical Efficacy of Imiglucerase versus Eliglustat in Patients with Gaucher's Disease Type 1: A Systematic Review

Gaucher's disease (GD) is one of the most common lysosomal diseases in humans. It results from β-glucosidase deficiency and leads to necrosis, especially in macrophages with the accumulation of glucosylceramidase in cells. Most of the deleterious effects of the disease are seen in the liver, spleen, and bone marrow. The aim of this study was to compare the efficacy of Imiglucerase with Eliglustat in treating patients with GD. PubMed/Medline, Cochrane Library, Scopus, Web of Science, Embase, and Google Scholar were searched from inception to August, 2018. Predefined inclusion criteria for included studies were based on search methodology and are as follows: All randomized, quasi-randomized controlled, and cohort studies about patients with GD Type 1 that Imiglucerase was compared with Eliglustat were included. Two authors independently choose the papers based on the inclusion criteria. From 2979 recognized studies, three studies including two randomized clinical trials and one cohort study were recognized to meet the inclusion criteria. The primary outcomes were hemoglobin level, platelets count, liver, and spleen size, and the secondary outcomes were the immunological side effects of the medicines and bone complications. The results showed that there is no meaningful difference between the two medicines in terms of increasing blood hemoglobin, platelets count, and reducing the liver and spleen size. The findings of this review showed that both medicines are effective in the treatment of GD Type 1 and there is no statistically significant difference between their efficacies.

Stability is maintained in adults with Gaucher disease type 1 switched from velaglucerase alfa to eliglustat or imiglucerase: A sub-analysis of the eliglustat ENCORE trial

Gaucher disease type 1 is an autosomal recessive disorder caused by deficient activity of the lysosomal enzyme acid β-glucosidase resulting in accumulation of glucosylceramide and clinical manifestations of anemia, thrombocytopenia, hepatosplenomegaly, and skeletal disease. The historic standard of care is intravenous recombinant enzyme therapy with imiglucerase. Eliglustat, an oral substrate reduction therapy, is a first-line treatment for adults with Gaucher disease type 1 who have a compatible CYP2D6-metabolizer phenotype (≈ 95% of patients). The 12-month ENCORE trial (NCT00943111) found eliglustat non-inferior to imiglucerase in maintaining stability in adult Gaucher patients previously stabilized after ≥ 3 years of enzyme therapy (imiglucerase or velaglucerase alfa). This post-hoc analysis examined safety and efficacy in the 30 ENCORE patients who were receiving velaglucerase alfa at study entry and were randomized to eliglustat (n = 22) or imiglucerase (n = 8). Efficacy and safety in velaglucerase alfa-transitioned patients were consistent with the full ENCORE trial population; 90% of patients switched to eliglustat and 88% of patients switched to imiglucerase met the composite endpoint (stable hemoglobin concentration, platelet count, spleen volume, and liver volume). Clinical stability was maintained for 12 months in Gaucher disease type 1 patients in the ENCORE trial who switched from velaglucerase alfa to either eliglustat or imiglucerase.

Evaluation of disease burden and response to treatment in adults with type 1 Gaucher disease using a validated disease severity scoring system (DS3)

BACKGROUND

GD1-DS3 is an integrated assessment of type 1 Gaucher disease (GD1) burden based on bone, hematologic and visceral domains. We investigated this disease severity scoring system (DS3) methodology for initial assessment, long-term follow-up and evaluation of treatment responses.

METHODS

We enrolled 133 treated adult GD1 patients. Baseline DS3 scores were calculated near the initial treatment date and patients stratified by severity as marked (DS3 6.00-19.00), moderate (DS3 3.00-5.99), mild (DS3 < 3.00). Follow-up scores were calculated annually. Minimal clinically important improvement (MCII), is defined as ΔDS3 of -3.1.

RESULTS

PATIENT CHARACTERISTICS

N370S was the most common allele (118 patients had at least one), 52 were N370S/N370S (48/52 were Ashkenazi Jews), N370S/L444P was the most common genotype among non-Jews. Median age of treatment: 45 years; median follow-up: 14 years. Baseline DS3 scores: Patients with marked disease (N = 58; median 7.84) were least likely to be N370S homozygous (19 %) and most likely to have had splenectomy (53 %), early age at diagnosis (median 18 years) and major pre-treatment bone pathology (76 %). Among patients with moderate disease (N = 53; median 4.33), 49 % were N370S/N370S, 15.1 % had splenectomy and 17 % had major bone disease. Median age at diagnosis: 32 years. No patient with mild disease (N = 22; median 2.4) had splenectomy or major skeletal disease. Median age at diagnosis: 40 years. 68 % were N370S homozygous. Response to treatment: Health-state transitions occurred primarily during the early treatment years. At Year 5, among 48 evaluable patients with marked baseline disease, eight were unchanged in severity status whereas 40 had MCII of varying degrees with 11 scored as mild. Among 42 evaluable moderate patients, none worsened, 16 remained moderate and 26 improved to mild. Among 16 evaluable mild patients, 14 remained so and 2 had DS3 scores in the low moderate range.

CONCLUSIONS

DS3 is effective for assessing disease burden in GD1 and for monitoring response. ERT was associated with MCII in DS3 scores in patients with high severity. Nevertheless, despite better DS3 scores with treatment, GD1 patients especially those with splenectomy and pre-treatment bone pathology, continued to have bone complications.