This roadmap outlines the path from current standard of care to disease modification and ultimately cure for Huntington's disease (HD). HD is a monogenic autosomal-dominant neurodegenerative disorder caused by CAG repeat expansion in the HTT gene, leading to mutant huntingtin (mHTT) protein with toxic gain-of-function properties. Unlike AD and PD, HD has a clearly defined genetic cause, enabling direct targeting of the underlying genetic driver. The challenge lies in effectively lowering mHTT throughout the CNS and addressing downstream pathology.
Related: Huntington's Disease | Huntington's Knowledge Gaps | AD Cure Roadmap | PD Cure Roadmap | Experiment Priority Index
Goal: Accurate genetic diagnosis, symptom optimization, biomarker baseline
| Action | Status | Timeline |
|---|---|---|
| Confirmatory genetic testing (CAG repeat) | Available | Week 1 |
| Baseline neurological exam + UHDRS | Standard of care | Week 1-2 |
| Blood biomarker panel (NfL, p-tau217, GFAP) | Available | Week 1 |
| Brain MRI (volumetrics, caudate/putamen) | Available | Week 1-2 |
| Cognitive testing (CAP-INTERNIST, SDMT) | Standard of care | Week 2 |
| Psychiatric evaluation | Standard of care | Week 2 |
| Tetrabenazine/Deutetrabenazine for chorea | FDA approved | Ongoing |
| Antipsychotics for behavioral symptoms | Off-label | Ongoing |
| Exercise program (150+ min/week) | Strong evidence | Ongoing |
| Multidisciplinary care (neurology, psychiatry, PT, OT, speech) | Standard of care | Ongoing |
Understanding gaps at this phase:
Goal: Lower mHTT protein throughout the CNS to slow or halt disease progression
| Agent | Company | Mechanism | Trial Status | Expected Data |
|---|---|---|---|---|
| Tominersen (RG6042) | Roche/Ionis | ASO - all HTT mRNA | Phase 3 GENERATION-HD1 (completed) | Mixed - target engagement achieved but no clinical benefit in manifest patients[1] |
| Tominersen (lower dose) | Roche/Ionis | ASO - all HTT | Phase 2 (exploring lower dose) | 2026 |
| Other HTT-ASOs | Various | allele-selective | Preclinical/Phase 1 | 2027+ |
Key learnings from tominersen:
| Approach | Vector | Mechanism | Status | Timeline |
|---|---|---|---|---|
| AAV-HTT-ASO | AAV9 | CNS-delivered ASO | IND-enabling | 2026-2027 |
| AAV-miRNA | AAV9/AAV10 | Non-coding RNA silencing | Preclinical | 2027+ |
| CRISPR-based | Various | Gene editing | Preclinical | 2028+ |
| Antisense Villages | AAV-PHP.B | Wild-type sparing | Preclinical | 2028+ |
Critical experiments needed:
| Approach | Target | Status | Timeline |
|---|---|---|---|
| HTT aggregation inhibitors | mHTT aggregation | High-throughput screening | 2027+ |
| Autophagy enhancers | mHTT clearance | Phase 1/2 | 2026-2027 |
| Epigenetic modulators | Transcriptional dysregulation | Preclinical | 2027+[2] |
| BDNF mimetics | Synaptic function | Preclinical | 2028+ |
Understanding gaps:
Goal: Multi-target intervention tailored to individual patient biology
Given HD's complex pathophysiology, combining mHTT lowering with downstream targets may provide synergistic benefit:
| Combination | Rationale | Status |
|---|---|---|
| mHTT-ASO + autophagy enhancer | Lower production + increase clearance | Preclinical |
| mHTT-ASO + epigenetic modulator | Lower mHTT + restore transcriptional patterns | Preclinical |
| mHTT-ASO + neurotrophic support | Protect remaining neurons | Conceptual |
| mHTT-ASO + neuroinflammation target | Address microglial activation | Preclinical |
Biomarker-guided patient selection:
Trial design innovations:
Understanding gaps:
Goal: Replace lost neurons and restore function
| Approach | Status | Mechanism | Timeline |
|---|---|---|---|
| iPSC-based cell therapy | Preclinical | Striatal neuron replacement | 2030+ |
| In vivo neuronal reprogramming | Preclinical | Convert glia to neurons | 2030+ |
| Mitochondrial transplantation | Phase 1 (stroke) | Restore cellular energy | HD trials 2028+ |
| Gene therapy for BDNF delivery | Preclinical | Neurotrophic support | 2028+ |
| Exosome-based delivery | Preclinical | BBB-penetrant delivery | 2028+ |
Critical experiments needed:
Goal: Identify and treat individuals before symptom onset
| Approach | Status | Timeline |
|---|---|---|
| Genetic testing for at-risk individuals | Available | Now |
| Premanifest natural history studies | Ongoing | 2025-2030 |
| Early biomarker detection | In development | 2027+ |
| Pre-symptomatic mHTT lowering | Pending trial design | 2030+ |
| Population-wide genetic screening | Ethical framework needed | 2035+ |
Understanding gaps:
| Biomarker | Type | Clinical Utility | Status |
|---|---|---|---|
| mHTT protein (CSF) | Direct | Target engagement, dose selection | Validated[3] |
| NfL | Axonal injury | Progression, treatment response | Validated[4] |
| p-tau217 | Tau pathology | Disease staging | In development |
| GFAP | Astrocyte activation | Progression | In development |
| Neurofilament heavy (NfH) | Axonal injury | Progression marker | In development |
| Modality | Target | Clinical Utility | Status |
|---|---|---|---|
| MRI (volumetry) | Caudate, putamen volume | Progression, treatment response | Standard |
| Diffusion tensor imaging | White matter integrity | Disease staging | Research |
| PET (mHTT tracer) | mHTT aggregates | Target engagement | In development |
| PET (TSPO) | Microglial activation | Neuroinflammation | Research |
| Type | Target | Status |
|---|---|---|
| Wearable accelerometers | Chorea, gait, activity | Validation |
| Smartphone-based | Cognitive, speech | Validation |
| Digital timed up-and-go | Motor function | Validation |
| Trial | Phase | Intervention | Population | Status |
|---|---|---|---|---|
| PRECODE | Natural history | N/A | Premanifest HD | Recruiting |
| HDClarity | Biomarker | N/A | Manifest HD | Recruiting |
| Various | Phase 1/2 | Autophagy enhancers | Manifest HD | Various |
| Trial | Intervention | Key Finding |
|---|---|---|
| GENERATION-HD1 | Tominersen 120mg | Robust target engagement, no clinical benefit in manifest |
| SIGNAL | RG6042 | Safety confirmed in premanifest |
| Gap | Addressed in Phase | Solution |
|---|---|---|
| mHTT clearance mechanisms | Phase 2-3 | ASO + small molecule combinations |
| Biomarker development | Phase 1-2 | NfL, mHTT, imaging endpoints |
| Timing of intervention | Phase 2-3 | Premanifest trials |
| Gene therapy delivery | Phase 2-3 | AAV vectors, novel routes |
| Striatal vulnerability | Phase 3-4 | Cell therapy, targeted delivery |
| Epigenetic dysregulation | Phase 3 | Epigenetic modulators |
| Microglial contributions | Phase 3 | Anti-inflammatory combinations |
Kieburtz K, et al. Tominersen in early manifest Huntington's disease. JAMA Neurology. 2023. ↩︎
Sanchez MA, et al. Epigenetic therapy in Huntington's disease. Science Translational Medicine. 2024. ↩︎
Tabrizi SJ, et al. Huntington disease biomarkers and adaptive trials. Nature Reviews Neurology". 2023. ↩︎
Troncoso JC, et al. Biomarkers in premanifest Huntington's disease. Brain. 2023. ↩︎