Olipudase alfa enzyme replacement therapy for acid sphingomyelinase deficiency (ASMD): sustained improvements in clinical outcomes after 6.5 years of treatment in adults

Hepatomegaly and Splenomegaly: An Approach to the Diagnosis of Lysosomal Storage Diseases

Clinical findings of hepatomegaly and splenomegaly, the abnormal enlargement of the liver and spleen, respectively, should prompt a broad differential diagnosis that includes metabolic, congestive, neoplastic, infectious, toxic, and inflammatory conditions. Among the metabolic diseases, lysosomal storage diseases (LSDs) are a group of rare and ultrarare conditions with a collective incidence of 1 in 5000 live births. LSDs are caused by genetic variants affecting the lysosomal enzymes, transporters, or integral membrane proteins. As a result, abnormal metabolites accumulate in the organelle, leading to dysfunction. Therapeutic advances, including early diagnosis and disease-targeted management, have improved the life expectancy and quality of life of people affected by certain LSDs. To access these new interventions, LSDs must be considered in patients presenting with hepatomegaly and splenomegaly throughout the lifespan. This review article navigates the diagnostic approach for individuals with hepatosplenomegaly particularly focusing on LSDs. We provide hints in the history, physical exam, laboratories, and imaging that may identify LSDs. Additionally, we discuss molecular testing, arguably the preferred confirmatory test (over biopsy), accompanied by enzymatic testing when feasible.

The Long-term Lung and Respiratory Outcomes of Acid Sphingomyelinase Deficiency: A 10- and 20-year Follow-up Study

BACKGROUND/AIM

Acid sphingomyelinase deficiency (ASMD) is a rare lysosomal storage disorder characterized by sphingomyelin accumulation causing progressive lung disease, respiratory failure, and death.

PATIENTS AND METHODS

This retrospective observational study used the TriNetX database of electronic health records for 15,108 patients with ASMD from 2000-2020. After exclusions, 8,980 individuals were followed for 10 or 20 years. Outcomes included incidence and prevalence of respiratory disorders. Associations of age, sex and race were assessed.

RESULTS

Nearly all respiratory outcomes increased significantly over 20 versus 10 years. Other respiratory disorders, specified respiratory disorders and secondary pulmonary hypertension exhibited the greatest increases, reflecting progressive lung damage in ASMD. While outcomes were poor overall, older age, male sex, and racial minority status associated with greater risks, indicating differences in disease progression or care.

CONCLUSION

This study confirms the progressive nature of ASMD and need for close monitoring and treatment of pulmonary complications to reduce long-term morbidity and mortality. Genetic testing enabling diagnosis even for milder, adult-onset forms is critical to optimize outcomes.

Continued improvement in disease manifestations of acid sphingomyelinase deficiency for adults with up to 2 years of olipudase alfa treatment: open-label extension of the ASCEND trial

BACKGROUND

Olipudase alfa is a recombinant human acid sphingomyelinase enzyme replacement therapy for non-central-nervous-system manifestations of acid sphingomyelinase deficiency (ASMD). The ASCEND randomized placebo-controlled trial in adults with ASMD demonstrated reductions in sphingomyelin storage, organomegaly, interstitial lung disease and impaired diffusion capacity of the lung (DLCO), during the first year of olipudase alfa treatment. In an ongoing open-label extension of the ASCEND trial, individuals in the placebo group crossed over to olipudase alfa, and those in the olipudase alfa group continued treatment.

RESULTS

Thirty-five of 36 participants continued in the extension trial, and 33 completed year 2. Change-from-baseline results are presented as least-square mean percent change ± SEM. Improvements in the cross-over group after 1 year of treatment paralleled those of the olipudase alfa group from the primary analysis, while clinical improvement continued for those receiving olipudase alfa for 2 years. In the cross-over group, percent-predicted DLCO increased by 28.0 ± 6.2%, spleen volume decreased by 36.0 ± 3.0% and liver volume decreased by 30.7 ± 2.5%. For those with 2 years of olipudase alfa treatment, the percent predicted DLCO increased by 28.5 ± 6.2%, spleen volume decreased by 47.0 ± 2.7%, and liver volume decreased by 33.4 ± 2.2%. Lipid profiles and elevated liver transaminase levels improved or normalized by 1 year and remained stable through 2 years of treatment. Overall, 99% of treatment-emergent adverse events were mild or moderate, with one treatment-related serious adverse event (extrasystoles; previously documented cardiomyopathy). No individual discontinued due to an adverse event.

CONCLUSION

Treatment with olipudase alfa is well tolerated and reduces manifestations of chronic ASMD with sustained efficacy. Trial registration NCT02004691 registered 9 December 2013, https://clinicaltrials.gov/ct2/show/NCT02004691.

Olipudase Alfa in Non-CNS Manifestations of Acid Sphingomyelinase Deficiency: A Profile of Its Use

Olipudase alfa (Xenpozyme™) is an intravenously administered acid sphingomyelinase enzyme replacement therapy indicated to treat non-CNS manifestations of acid sphingomyelinase deficiency (ASMD) in adult and paediatric patients. It is the first and currently the only disease-modifying treatment for ASMD. Olipudase alfa treatment improves hepatosplenomegaly, lung function and platelet counts, along with multiple other pathological features of ASMD in adult and paediatric patients with ASMD. These benefits are sustained through at least 24 months of treatment. Olipudase alfa is generally well tolerated; infusion-associated reactions (mostly mild) were the most common treatment-related adverse events. Other warnings and precautions associated with its use include risks of hypersensitivity reactions (including anaphylaxis) and elevated transaminase levels seen in clinical trials, and foetal malformation based on animal studies. All these risks are generally manageable. A gradual dose escalation of olipudase alfa, followed by a maintenance phase, is required to reduce the risks of toxic sphingomyelin catabolites build up, infusion-associated reactions and transient transaminase elevations.