Acid sphingomyelinase (ASM, encoded by SMPD1) inhibitors represent an emerging therapeutic approach within the ceramide/sphingolipid pathway for neurodegenerative diseases. ASM catalyzes the hydrolysis of sphingomyelin to [ceramide](/mechanisms/ceramide-signaling-neurodegeneration):
Elevated ASM activity contributes to excess ceramide generation in neurodegeneration, promoting apoptosis, neuroinflammation, and protein aggregation. ASM inhibitors reduce ceramide accumulation from the sphingomyelin catabolism pathway — complementary to ceramide synthase inhibitors (which block de novo ceramide synthesis) and glucosylceramide synthase inhibitors (which block downstream conversion).
Small Biotech Programs
1. Olapasertan (ASP1618) — Sanofi
Company: Sanofi (formerly in partnership with AeXceed)
Mechanism: Selective ASM inhibitor; reduces ceramide generation from sphingomyelin hydrolysis[@schuchman2016].
Development:
Originally developed for Niemann-Pick disease type A/B (lysosomal storage disorder)
Phase 1/2 trials completed in NP-A/B patients
Exploring repositioning for PD and other neurodegeneration
Clinical Data:
Demonstrated ASM inhibition and ceramide reduction in plasma
Good safety profile in NP-A/B patients
Plans for PD trials under evaluation
2. BBP-831 (ASM Inhibitor) — Biobo Pharma
Company: Biobo Pharma (Germany)
Mechanism: Novel ASM inhibitor with enhanced brain penetration.
Development:
Preclinical stage
In vivo proof-of-concept in MPTP mouse model of PD
Demonstrated neuroprotection and reduced neuroinflammation[@gomez2019]
3. Ceramiden Therapeutics (Preclinical)
Company: Ceramiden Therapeutics (Cambridge, MA) — a biotechnology startup focused on sphingolipid biology.
Pipeline:
CT-001: ASM inhibitor for PD, IND-enabling studies
CT-002: Dual ASM/CerS inhibitor for ALS and FTD
CT-003: Brain-penetrant ceramide analog for neuroprotection
Partnerships:
Collaboration with Johns Hopkins University for biomarker development
Partnership with WuXi AppTec for CMC
4. Lipimetix Development
Company: Lipimetix (Boston, MA)
Focus: Peptide-based sphingolipid modulators with novel mechanisms.
Assets:
Peptide-ceramide conjugates that cross the BBB
ASM-targeting constructs with reduced off-target effects
Drug Repurposing: ASM Inhibitors in Clinical Use
Amitriptyline — Off-Label Repurposing
Mechanism: Tricyclic antidepressant with off-target ASM inhibitory activity at therapeutic concentrations[@harzer2012].
Evidence:
Inhibits ASM with IC50 ~5 μM (achievable at 75-150 mg/day)
Reduces ceramide accumulation in cellular models
Retrospective clinical data suggest slower progression in PD patients on amitriptyline
Clinical Trials:Rationale: The established safety profile of amitriptyline (decades of clinical use) enables rapid evaluation in neurodegeneration.
Desipramine — Off-Label
Mechanism: Tricyclic antidepressant with ASM inhibitory properties similar to amitriptyline[@harzer2012].
Status:
Preclinical evidence in ALS and PD models
No active clinical trials in neurodegeneration targeting ASM
Mechanism Comparison: ASM vs Other Sphingolipid Targets
Therapeutic Rationale for ASM Inhibition in PD
Biological Basis
Ceramide accumulation: ASM generates ceramide from sphingomyelin; inhibition reduces this source
Neuroinflammation: Ceramide promotes microglial activation and pro-inflammatory cytokine release
Protein aggregation: Ceramide promotes α-synuclein misfolding and aggregation