Clinical bottom line
Substrate reduction therapy (SRT) represents a promising adjunct or alternative to enzyme replacement therapy (ERT) in managing rare lysosomal storage disorders (LSDs) such as Gaucher, Fabry, Pompe, and mucopolysaccharidoses. By targeting the biosynthesis of accumulating substrates, SRT aims to restore lysosomal homeostasis and alleviate disease manifestations. While ERT remains the standard of care for many LSDs, SRT offers oral administration and potential CNS penetration advantages. However, clinical experience is limited, and long-term efficacy and safety require further validation. Multidisciplinary management remains essential given the multisystemic nature of these disorders.
What the evidence shows
LSDs are characterized by deficient lysosomal enzymes leading to substrate accumulation and progressive tissue damage (Zhou et al., 2020). ERT has transformed outcomes in several LSDs but is limited by intravenous administration, immunogenicity, and poor blood-brain barrier penetration (Grunwald et al., 2020). SRT, by contrast, reduces substrate synthesis upstream, potentially complementing or substituting ERT (Platt et al., 2007).
Miglustat, an iminosugar inhibitor of glucosylceramide synthase, is the first approved SRT for type 1 Gaucher disease and Niemann-Pick type C (Lachmann et al., 2006). It has demonstrated clinical benefit in reducing organomegaly and improving hematologic parameters, though gastrointestinal side effects are common. Torralba-Cabeza et al. (2018) emphasize that integrating SRT into a multidisciplinary care framework can optimize patient outcomes in Gaucher disease.
In Fabry disease, characterized by α-galactosidase A deficiency and globotriaosylceramide accumulation, SRT approaches targeting mutant enzyme stabilization and substrate reduction are under investigation (Modrego et al., 2021). These strategies may address limitations of ERT, including antibody formation and limited tissue penetration.
Pompe disease management has evolved with ERT targeting acid α-glucosidase deficiency; however, Estevez Barcia et al. (2026) highlight emerging SRT and gene-based therapies aiming to improve muscle and CNS manifestations by reducing glycogen accumulation. These novel approaches remain largely experimental but represent a future therapeutic frontier.
Genetic substrate reduction therapy, involving RNA interference or gene editing to downregulate substrate synthesis enzymes, is an emerging concept with preclinical promise (Coutinho et al., 2016). This approach may offer more precise and durable substrate control but requires extensive validation.
Caveats and uncertainty
Current evidence for SRT efficacy is strongest in type 1 Gaucher disease with miglustat, but even here, side effects and variable responses limit universal applicability (Lachmann et al., 2006). For other LSDs, SRT remains largely investigational or adjunctive. Long-term safety data are sparse, and CNS efficacy is uncertain given blood-brain barrier challenges.
ERT remains the backbone of treatment for many LSDs, and SRT is not yet established as a standalone therapy except in select cases. Patient heterogeneity, mutation type, and disease severity influence therapeutic response, necessitating individualized approaches (Torralba-Cabeza et al., 2018).
Multidisciplinary care involving geneticists, neurologists, metabolic specialists, and supportive services is critical to address the complex manifestations and optimize quality of life (Torralba-Cabeza et al., 2018; Zhou et al., 2020).
How this may change practice
Clinicians managing LSDs should consider SRT as a complementary option, particularly for patients who are poor candidates for ERT or have CNS involvement. Oral administration of SRT may improve adherence and quality of life. Emerging genetic SRT strategies warrant close attention as they progress through clinical development.
Integration of SRT into multidisciplinary care models can enhance monitoring and management of side effects and disease progression. Personalized treatment plans based on genotype, phenotype, and patient preference will become increasingly important.
Ongoing clinical trials and real-world registries will be essential to define the long-term role of SRT in rare LSDs and guide evidence-based practice.