SOD1-Targeting Therapies encompasses therapeutic approaches designed to modify the progression of SOD1-linked amyotrophic lateral sclerosis (ALS). Superoxide Dismutase 1 (SOD1) was the first gene linked to familial ALS, with over 250 pathogenic mutations identified that cause approximately 20% of familial ALS cases[1]. The development of SOD1-targeted therapies has become one of the most advanced pipelines in ALS drug development. [1:1]
SOD1 is a metalloenzyme that catalyzes the dismutation of superoxide radicals to hydrogen peroxide. In ALS, mutant SOD1 proteins acquire toxic gain-of-function properties that lead to: [2]
The most common SOD1 mutations include A4V (most common in North America), D90A, G93A, H46R, and I113T[2:1]. [3]
ASOs are single-stranded DNA molecules that bind to complementary mRNA sequences, promoting RNase H-mediated degradation of the target transcript. This reduces SOD1 protein production throughout the CNS. [4]
| ASO | Company | Target | Route | Development Status | [5]
|-----|---------|--------|-------|-------------------| [6]
| Tofersen (BIIB067) | Biogen/Ionis | SOD1 | Intrathecal | NDA filed (2024) | [7]
| WVE-004 | Wave Life Sciences | SOD1 (allele-selective) | Intrathecal | Phase I/II | [8]
| ALSAZ-LAO-01 | AIBSL | SOD1 | Intrathecal | Preclinical |
Tofersen is the most advanced SOD1-targeting therapy. The Phase 3 VALOR study demonstrated significant reduction in SOD1 protein in CSF and a trend toward slower functional decline in fast-progressing patients[3:1].
Using adeno-associated virus (AAV) vectors to deliver shRNA constructs that silence SOD1 expression.
| Approach | Vector | Target | Status |
|---|---|---|---|
| AAV-shRNA-SOD1 | AAV9 | Motor neurons | Preclinical |
| miRNA-based silencing | AAVrh.10 | CNS-wide | Preclinical |
CRISPR-Cas9 approaches to directly edit mutant SOD1 alleles.
| Approach | Delivery | Mechanism | Status |
|---|---|---|---|
| CRISPR-Cas9 | AAV | Allele-specific cutting | Preclinical |
| Base editing | AAV | Convert mutant to wild-type | Preclinical |
Since SOD1 requires copper for proper folding and function, copper modulation strategies have been explored.
| Compound | Mechanism | Company | Status |
|---|---|---|---|
| ATN-224 | Copper chelator | Avid Bioservices | Phase II |
| Copper ATS | Copper chaperone mimic | ALS Therapy Development Institute | Preclinical |
Drugs designed to prevent mutant SOD1 aggregation and promote clearance.
| Compound | Mechanism | Company | Status |
|---|---|---|---|
| Arimoclomol | HSP90 inducer | Orphazyme | Phase III (completed) |
| Cytosporone B | PGC-1α activator | Preclinical |
Delivery of wild-type SOD1 protein to motor neurons to compensate for mutant SOD1 dysfunction.
| Approach | Delivery Method | Status |
|---|---|---|
| Recombinant SOD1 | AAV-mediated | Preclinical |
| Trial | Therapy | Phase | Key Findings |
|---|---|---|---|
| VALOR | Tofersen | Phase 3 | 36% reduction in CSF SOD1; positive trend in functional decline |
| CENTAUR | Arimoclomol | Phase 2 | Significant slowdown in functional decline |
| HEALEY ALS | Zinbryta (CD52) | Phase 2 | Did not meet primary endpoint |
| Trial | Therapy | Phase | Status |
|---|---|---|---|
| Lighthouse | Tofersen | Open-label extension | Recruiting |
| FUSION | WVE-004 | Phase I/II | Recruiting |
Several biomarkers are used to track SOD1-ALS progression and treatment response:
| Biomarker | Matrix | Use |
|---|---|---|
| SOD1 in CSF | Cerebrospinal fluid | Pharmacodynamic marker of ASO activity |
| NfL | CSF/Plasma | Neurodegeneration marker |
| pNfH | CSF/Plasma | Axonal injury marker |
Rosen et al. Nature 1993 — SOD1 mutations in familial ALS. 1993. ↩︎ ↩︎
Miller et al. NEJM 2022 — Tofersen in SOD1-ALS. 2022. ↩︎ ↩︎
Couthouis et al. Nature 2014 — RNA targeting in ALS. 2014. ↩︎
Benatar et al. [Lancet Neurology 2023 — SOD1 biomarker studies](https://doi.org/10.1016/S1474-4422(23). 2023. ↩︎
Lo Russo et al. Nature 2020 — CRISPR therapy in SOD1 mice. 2020. ↩︎
Ay I. et al. Science Translational Medicine 2023 — AAV delivery to spinal cord. 2023. ↩︎