Hypersensitivity reaction during enzyme replacement therapy in lysosomal storage disorders. A systematic review of desensitization strategies

Lysosomal storage diseases (LSDs) are rare genetic metabolic disorders that cause the accumulation of glycosaminoglycans in lysosomes due to enzyme deficiency or reduced function. Enzyme replacement therapy (ERT) represents the gold standard treatment, but hypersensitivity reaction can occur resulting in treatment discontinuation. Thus, desensitization procedures for different culprit recombinant enzymes can be performed to restore ERT. We searched desensitization procedures performed in LSDs and focused on skin test results, protocols and premedication performed, and breakthrough reactions occurred during infusions. Fifty-two patients have been subjected to desensitization procedures successfully. Skin tests, with the culprit recombinant enzyme, deemed positive in 29 cases, doubtful in two cases, and not performed in four patients. Moreover, 29 of the 52 desensitization protocols used at the first infusion were breakthrough reaction free. Different desensitization strategies have proved safe and effective in restoring ERT in patients with previous hypersensitivity reactions. Most of these events seem to be Type I hypersensitivity reactions (IgE-mediated). Standardized in vivo and in vitro testing is necessary to better estimate the risk of the procedure and find the safest individualized desensitization protocol.

Management of hypersensitivity reactions to enzyme replacement therapy in children with lysosomal storage diseases

BACKGROUND

Intravenous recombinant enzyme replacement therapy (ERT) is currently available for 8 lysosomal diseases. Hypersensitivity reactions (HSRs) may be observed during this long-term treatment.

OBJECTIVE

To evaluate the frequency and clinical treatment features of ERT HSRs and the management of desensitizations in children.

METHODS

Medical records were reviewed retrospectively for patients who received ERT. Those who had experienced HSRs to ERT were included in the study. The demographic characteristics of the patients, culprit enzyme, signs and symptoms, diagnostic tests, management of the reaction, and the protocol employed for the maintenance of ERT were recorded.

RESULTS

During the study period, 54 patients received ERT in our institution. A total of 11 patients (20.4%) experienced HSR to ERT. All reactions were of immediate type. The most common symptoms were cutaneous manifestations. A total of 9 patients experienced urticaria, and 2 had anaphylaxis as initial reaction. Patients who had isolated cutaneous symptoms continued their treatments with antihistamines, corticosteroid premedication, slower infusion rate or both. Patients who had recurrent urticaria with these modalities or those who had anaphylaxis continued their ERT with desensitization (n = 8). A total of 3 patients required revisions in desensitization protocols because of recurrent anaphylaxis.

CONCLUSION

The reactions that develop during this long-term treatment may be treated by premedication-prolonged infusion, but in some patients, desensitization protocols are necessary for the continuation of therapy. Revisions in desensitization protocols may be required.

Therapeutic Options for Mucopolysaccharidoses: Current and Emerging Treatments

Mucopolysaccharidoses (MPS) are inborn errors of metabolism produced by a deficiency of one of the enzymes involved in the degradation of glycosaminoglycans (GAGs). Although taken separately, each type is rare. As a group, MPS are relatively frequent, with an overall estimated incidence of around 1 in 20,000-25,000 births. Development of therapeutic options for MPS, including hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT), has modified the natural history of many MPS types. In spite of the improvement in some tissues and organs, significant challenges remain unsolved, including blood-brain barrier (BBB) penetration and treatment of lesions in avascular cartilage, heart valves, and corneas. Newer approaches, such as intrathecal ERT, ERT with fusion proteins to cross the BBB, gene therapy, substrate reduction therapy (SRT), chaperone therapy, and some combination of these strategies may provide better outcomes for MPS patients in the near future. As early diagnosis and early treatment are imperative to improve therapeutic efficacy, the inclusion of MPS in newborn screening programs should enhance the potential impact of treatment in reducing the morbidity associated with MPS diseases. In this review, we evaluate available treatments, including ERT and HSCT, and future treatments, such as gene therapy, SRT, and chaperone therapy, and describe the advantages and disadvantages. We also assess the current clinical endpoints and biomarkers used in clinical trials.