Alglucerase. A pharmacoeconomic appraisal of its use in the treatment of Gaucher's disease

Review of the safety and efficacy of imiglucerase treatment of Gaucher disease

Most patients who suffer from symptomatic Gaucher disease will benefit from enzyme replacement therapy (ERT) with imiglucerase. The safety profile is excellent, only a small percentage of those exposed developing antibodies; similarly, very few patients require pre-medication for allergic reactions. Within 3 to 5 years of imiglucerase therapy, best documented at doses of 30 to 60 units/kg/infusion, hepatosplenomegaly can be expected to be reduced so that the liver volume will be maintained at 1 to 1.5 times normal (30% to 40% reduction from advent of ERT) and spleen volume to </= 2 to 8 times normal (50% to 60% reduction from advent of ERT). For anemic and thrombocytopenic patients, with 2 to 5 years of imiglucerase, hemoglobin levels are expected to be >/= 11 g/dL for women and children and >/= 12 g/dL for men; and platelet counts in patients with an intact spleen, depending on the baseline value, should approximately be doubled. Bone crises and bone pain but not irreversible skeletal damage will improve in most patients. Nonetheless, some features and some symptomatic patients apparently do not respond equally well and/or perhaps inadequately. The benefit for patients with the neuronopathic forms is primarily in improved visceral and hematological signs and symptoms. There are still several unresolved issues, the high per-unit cost being an important one, which have spurred the development of biosimilar enzymes as well as chaperone therapies currently in clinical trials.

Review of the safety and efficacy of imiglucerase treatment of Gaucher disease

Most patients who suffer from symptomatic Gaucher disease will benefit from enzyme replacement therapy (ERT) with imiglucerase. The safety profile is excellent, only a small percentage of those exposed developing antibodies; similarly, very few patients require pre-medication for allergic reactions. Within 3 to 5 years of imiglucerase therapy, best documented at doses of 30 to 60 units/kg/infusion, hepatosplenomegaly can be expected to be reduced so that the liver volume will be maintained at 1 to 1.5 times normal (30% to 40% reduction from advent of ERT) and spleen volume to </= 2 to 8 times normal (50% to 60% reduction from advent of ERT). For anemic and thrombocytopenic patients, with 2 to 5 years of imiglucerase, hemoglobin levels are expected to be >/= 11 g/dL for women and children and >/= 12 g/dL for men; and platelet counts in patients with an intact spleen, depending on the baseline value, should approximately be doubled. Bone crises and bone pain but not irreversible skeletal damage will improve in most patients. Nonetheless, some features and some symptomatic patients apparently do not respond equally well and/or perhaps inadequately. The benefit for patients with the neuronopathic forms is primarily in improved visceral and hematological signs and symptoms. There are still several unresolved issues, the high per-unit cost being an important one, which have spurred the development of biosimilar enzymes as well as chaperone therapies currently in clinical trials.

Current and emerging therapies for the lysosomal storage disorders

Targeted treatments for the lysosomal storage disorders (LSDs), in the form of enzyme replacement and/or substrate depletion, have been shown to be relatively safe and effective in reversing core disease features in selected clinical subtypes (including Gaucher disease types I and III, Fabry disease and the Hurler-Scheie syndrome). These approaches have expanded the therapeutic options available to patients with rare genetic disorders, beyond palliative measures (such as liver or kidney transplantation for end-organ failure) and cellular replacement through bone marrow transplantation. Present efforts are focused on the development of novel strategies, including chaperone-mediated enzyme enhancement and genetically engineered stem cell therapy. In the coming decades, a broadening therapeutic horizon for patients with inborn errors of metabolism is anticipated, and the growing experience in the management of patients with LSDs will serve as an instructive model. Among the many challenges will be determination of the extent to which these therapies have modified the course of disease beyond merely extending the age of survival, but also enabling a meaningful patient quality of life, and the minimisation of current resource use. The projected lifetime acquisition costs of newly introduced therapeutic options also raises several issues, related to equitable access and the large opportunity costs for other therapeutic areas, that will need to be addressed by healthcare policy makers and third-party payers.

[Current framework of biotechnology products according to the available pharmacoeconomic studies]

BACKGROUND AND OBJECTIVE

Biotechnologic drugs have a high impact in health system because they contribute in new indications as well as in its high cost. The study's aim is to do a descriptive analysis from the pharmacoeconomic studies. The objective of the study was to establish the standards of efficiency and utility, as well as to know its therapeutic usefulness and rationale.

MATERIAL AND METHOD

The detection and selection of originals has been made through repeated searches in MEDLINE (PubMed) with every one of the different biotechnology products crossing the product name with life, year and saved. In function of the cost for year of life saved (YLS) were defined categories: saving of cost (< 0$/YLS), highly cost-effectiveness (0-20000$/YLS), cost-effectiveness (20001-40000$/YLS), doubtfully cost-effectiveness (40001-60000$/YLS), and no cost-effectiveness (> 60001$/YLS).

RESULTS

There are published figures only in 31% of the total of the searched biotechnological drugs. In 2 clinic conditions the drug reduces the cost, in 33 is highly cost-effectiveness, in 11 is cost-effectiveness, in 4 occasions is doubtfull cost-effectiveness and in 14 is no cost-effectiveness.

CONCLUSIONS

In spite of the high heterogeneity of methodology used in the pharmacoeconomic studies about biotechnological products, in the majority of the clinic situations evaluated we observed a good cost-effectiveness relation in the use of the biotechnological products.

The health-related quality of life of adults with Gaucher's disease receiving enzyme replacement therapy: results from a retrospective study

Few studies have reported on the effect of Gaucher's disease on patient-reported, health-related quality of life (HRQoL) and we do not know how the HRQoL burden of Gaucher's disease compares to that of other chronic conditions, what areas of HRQoL are most affected or how the course of change in HRQoL compares with that observed for other conditions or for the general adult population. The purpose of this study was to estimate (1) the HRQoL burden associated with Gaucher's disease managed by enzyme replacement therapy (ERT), (2) recalled changes in HRQoL since ERT initiation and (3) risk factors predictive of HRQoL outcomes. We sampled 212 patients with Gaucher's disease recruited from 146 physicians prescribing ERT in the US. The patients were at least 14 years of age and had been on ERT from 1 to 51 months. The mean (SD) age of the participants was 45 (17) years. Forty-nine percent had had a prior splenectomy and 26% had had a joint replacement. We administered the SF-36 Health Survey (SF-36) and three questions about changes in physical, mental and general HRQoL since starting ERT. The patients with Gaucher's disease scored significantly worse than the age- and gender-adjusted US norms on five of the eight SF-36 subscales (p < 0.05). Age (p < 0.0001) and joint replacement (p < 0.001) were negatively associated with physical health. The presence of an intact spleen (p < 0.01) and a longer duration of ERT (p < 0.01) were associated with better mental health. When asked about changes in HRQoL since starting ERT, at least half of the patients reported fewer limitations in physical activities (53%), better general health perceptions (77%) and less negative emotions (49%) at the time of the interview. Patients who had been receiving ERT for approximately 4 years recalled four and five times more improvement in general HRQoL in comparison with recalled changes over a 4 year period among adults in the general population (p < 0.001) and a congestive heart failure population (p < 0.01), respectively. Odds ratios (ORs) revealed that female patients were more likely to report improvements in general HRQoL than males (OR = 4.50 and 95% CI = 2.19-9.25) and 45 year old patients were less likely to report improvements than 35 year olds (OR = 0.76 and 95% CI = 0.62-0.94). Relative to patients who had been receiving ERT for 1 year, those who had been receiving ERT for 2 and 4 years were 1.40 (95% CI = 1.06-1.84) and 2.75 (95% CI = 1.20-6.27) times more likely to report improvements in general HRQoL, respectively. In summary, patients with Gaucher's disease on ERT reported an improvement in HRQoL that was greater than that reported by patients with other chronic diseases. However, Gaucher's patients treated for up to 51 months scored below equivalent adults in the general population. The risk factors, including age and history of splenectomy and joint replacement, warrant further study. Standardized HRQoL measures are likely to prove useful in understanding better the outcomes from the Gaucher's patient's perspective.