Charcot-Marie-Tooth Disease

Overview

Charcot-Marie-Tooth disease (CMT) is a group of inherited disorders that damage peripheral nerves—the nerves linking the brain and spinal cord to muscles and sensory organs. It commonly causes slowly progressive weakness and wasting in the feet, lower legs, and hands; loss of sensation; foot drop; high-arched feet; and balance or walking difficulties. CMT is genetically diverse, with dominant, recessive, and X-linked forms; some forms primarily disrupt the nerve’s insulating myelin sheath, while others primarily damage the long nerve fiber itself, called the axon. GeneReviews overview

Severity, age at onset, and rate of progression vary substantially by subtype and even within families. Most forms progress slowly and are compatible with a normal lifespan, but disability can accumulate over decades. Current care is supportive rather than curative: genetic diagnosis, neurology follow-up, physical and occupational therapy, exercise tailored to ability, orthoses or braces, pain management, and orthopedic surgery when deformities or contractures are severe. GeneReviews overview

Scope of Recent Research (2020–present)

Research activity has accelerated since 2020, especially for CMT1A, the common form caused by excess production of peripheral myelin protein 22 (PMP22), and for genetically defined axonal forms such as CMT2A and CMT2E. The dominant questions are whether treatment can safely correct the underlying gene or RNA abnormality, whether nerves can recover after disease has begun, and which biomarkers and functional measures can demonstrate benefit in a slowly progressive condition. No therapy is yet approved to treat CMT itself, and a broadly applicable cure is not close; however, the field has moved from largely symptomatic care toward subtype-specific gene, RNA, and metabolic therapies entering or approaching human testing. NMD Pharma SYNAPSE-CMT results Clinical-development recommendations

Major Breakthroughs and Emerging Therapies

For CMT1A, the leading disease-modifying strategy is reducing excess PMP22 in Schwann cells, the cells that make myelin in peripheral nerves. In a 2021 rat study, an adeno-associated virus (AAV) carrying a short hairpin RNA (shRNA) to suppress Pmp22 restored PMP22 toward normal levels, improved myelination, and prevented motor and sensory impairment for 12 months after injection into the sciatic nerves. This was an important proof of concept, but it used direct nerve delivery in animals and is not yet a human treatment. AAV-PMP22 silencing study

Genome editing is another, more permanent approach to CMT1A. In 2023, researchers used an AAV-delivered CRISPR-associated editor in patient-derived induced pluripotent stem cells—adult cells reprogrammed into stem-cell-like cells—and in Schwann-cell precursors. Editing reduced the extra PMP22 duplication by approximately 20% to 40%, normalized PMP22 RNA and protein levels, and improved abnormal cell survival and myelination in the laboratory. This is promising human-cell evidence, but it remains preclinical and has not established safe, body-wide delivery or durable benefit in people. PMP22 genome-editing study

RNA-based approaches are also advancing. Novartis acquired DTx Pharma and its fatty-acid-ligand-conjugated small interfering RNA platform, including DTx-1252, a candidate designed to lower PMP22 messenger RNA in CMT1A. The program has subsequently entered first-in-human testing as EDK060, illustrating a transition from laboratory RNA silencing toward clinical development. Novartis–DTx acquisition EDK060 Phase 1 study

For dominant axonal CMT, researchers are developing “silence-and-replace” strategies: suppressing both normal and mutant copies of a harmful gene while adding back a replacement copy that is resistant to the silencing therapy. In CMT2A, caused by dominant MFN2 variants, combined RNA interference and MFN2 replacement corrected mitochondrial distribution and other abnormalities in patient-derived motor neurons and showed molecular correction in a transgenic mouse after AAV9 delivery. MFN2 silence-and-replace study Parallel work supported by the Charcot-Marie-Tooth Association (CMTA) is pursuing CRISPR approaches for demyelinating CMT and antisense oligonucleotides—short synthetic nucleic acids that alter or reduce RNA—for dominant NEFL-related CMT2E. CMTA research archive

Gene replacement is most straightforward for recessive CMT types caused by loss of a functional gene. A CMTA-supported program at the University of Texas Southwestern is developing an AAV gene-replacement therapy for CMT4A caused by loss-of-function GDAP1 variants, while nanoparticle-based genetic delivery is being explored for CMT1X caused by GJB1 variants. These programs are still preclinical, but they address the root genetic defect rather than only symptoms. CMTA research archive

Small-molecule therapies remain relevant because they may be easier to administer and could help across multiple genetic subtypes, although they are less likely to constitute a genetic cure. PXT3003, an oral low-dose combination of baclofen, naltrexone, and sorbitol intended to counter consequences of PMP22 overexpression, produced a statistically significant improvement in disability on the Overall Neuropathy Limitations Scale in a 2021 randomized trial. PXT3003 randomized trial A separate Chinese Phase III trial published in September 2026 reported a modest but statistically significant 15-month benefit on the same scale and improved ankle-dorsiflexion strength, while noting that a previous confirmatory study had missed its primary efficacy endpoint. Chinese PXT3003 Phase III trial

Clinical Trials and Experimental Approaches

Novartis is recruiting a 28-participant, placebo-controlled Phase 1 trial of intravenous EDK060 in adults with genetically confirmed CMT1A. Started on September 30, 2025, the study is designed primarily to assess safety, tolerability, and pharmacokinetics—the way the body handles the drug—not clinical effectiveness; its estimated completion date is February 26, 2028. EDK060 Phase 1 study The prior CMT1A neurotrophin-3 AAV gene-therapy study sponsored by Nationwide Children’s Hospital was withdrawn in July 2026 because of the principal investigator’s retirement, with zero participants enrolled, underscoring how manufacturing and program continuity can delay translation. NTF3 AAV trial record

NMD Pharma’s sponsor-led Phase 2a SYNAPSE-CMT trial tested oral ignaseclant, formerly NMD670, in 81 adults with genetically confirmed CMT1 or CMT2. In February 2026, the company reported that the 21-day trial missed its prespecified primary endpoint, the six-minute walk test, but found favorable secondary measures of strength, hand function, CMT Functional Outcome Measure scores, and patient-reported disease impact; the findings remain preliminary until full peer-reviewed publication. NMD Pharma SYNAPSE-CMT results

Govorestat, an aldose-reductase inhibitor developed by Applied Therapeutics for CMT caused by biallelic SORD deficiency, illustrates both the opportunity and uncertainty of subtype-specific treatment. The randomized INSPIRE Phase 2/3 program targeted sorbitol buildup, but the Phase III study did not meet its primary endpoint; after Cycle Pharmaceuticals acquired Applied Therapeutics, it halted the open-label extension and early-access programs on April 17, 2026 while determining what further data regulators would require. INSPIRE program update

Methodologies and Scientific Approaches

CMT cure research increasingly combines patient-derived induced pluripotent stem cells, differentiated Schwann cells or motor neurons, organoids, rodents, and occasionally nonhuman primates. These systems allow investigators to test whether an intervention corrects the relevant cellular defect—such as excessive PMP22, impaired myelin formation, faulty mitochondrial transport, or neurofilament dysfunction—before attempting delivery in people. AAV vectors, lipid or nanoparticle systems, antisense oligonucleotides, siRNA, and CRISPR-based editors are being compared for their ability to reach peripheral nerves or their supporting cells safely and at adequate doses. PMP22 genome-editing study AAV-PMP22 silencing study CMTA research archive

Researchers are also improving trial-readiness tools because CMT usually changes slowly. Functional scales, timed walking and hand tests, nerve-conduction studies, muscle imaging, skin biomarkers, and blood neurofilament light chain are being evaluated to distinguish a real treatment effect from day-to-day variability. In one 2021 study of 96 people with CMT, plasma neurofilament light chain was higher than in healthy controls and correlated weakly with clinical severity, supporting further study as a marker of axonal injury rather than a validated surrogate endpoint. Neurofilament light-chain study

Leading Institutions and Funding

Major academic contributors include the University of Texas Southwestern, Gladstone Institutes, University of Wisconsin–Madison, University of Miami, University of Antwerp, Nationwide Children’s Hospital, UCL Queen Square Institute of Neurology, and multiple Chinese neuromuscular centers. Commercial development is being pursued by Novartis, NMD Pharma, and Cycle Pharmaceuticals, among others. CMTA’s STAR program has supported projects including approximately $248,900 for CMT4A AAV gene replacement, $448,748 for CRISPR strategies in demyelinating CMT, $225,483 for CMT2E antisense therapy, and $299,992 jointly with the Muscular Dystrophy Association for nanoparticle gene delivery in CMT1X. CMTA research archive

Patient-led philanthropy has become an important translational funding source. The CMT Research Foundation’s ENDGAME campaign exceeded its $10 million CMT1A research goal in October 2024, while its typical grants range from $100,000 to $200,000 annually. CMTRF ENDGAME campaign CMTRF funding program CMTA seed funding has also helped projects gain National Institutes of Health support, including work on gene-editing platforms and neurofilament restoration strategies for CMT2 subtypes. CMTA–NIH CMT2 funding

Strengths, Limitations, and Challenges

The greatest strength of current CMT research is that treatment design is becoming genetically precise. PMP22-lowering therapies directly address CMT1A dosage, MFN2 silence-and-replace therapy addresses a dominant CMT2A mechanism, and gene replacement can in principle restore absent proteins in recessive disease. Human cell models and animal studies now provide evidence that some disease features can be corrected after targeting the causal pathway. PMP22 genome-editing study MFN2 silence-and-replace study

The main limitation is that CMT is not one disease: a therapy for CMT1A may not help CMT2A, CMT1X, or SORD-related CMT. Safe delivery to widespread peripheral nerves and Schwann cells, immune responses to viral vectors, irreversible off-target gene editing, repeat-dosing constraints, manufacturing scale, and access costs remain unresolved challenges. Slow progression also makes clinical trials long and statistically difficult; mixed PXT3003 findings, a missed primary endpoint for ignaseclant, and the paused govorestat program show why early signals cannot yet be considered proof of disease modification. Chinese PXT3003 Phase III trial NMD Pharma SYNAPSE-CMT results INSPIRE program update

Outlook and Future Directions

As of October 11, 2026, CMT research has credible paths toward subtype-specific disease modification, but no established cure. The most important near-term milestones are Phase 1 safety and target-engagement data for EDK060; peer-reviewed, longer-duration confirmation of ignaseclant’s functional signals; reproducible PXT3003 results; resolution of the regulatory path for CMT-SORD; and evidence that gene or RNA therapies can safely reach enough peripheral-nerve cells in people. A true cure will probably emerge first for particular genetic subtypes rather than for CMT as a whole, and will require durable biological correction alongside convincing functional improvement. EDK060 Phase 1 study Clinical-development recommendations

References

• GeneReviews overview — GeneReviews, 2026.
• NMD Pharma SYNAPSE-CMT results — NMD Pharma, 2026.
• Clinical-development recommendations — Abrams et al., 2026.
• AAV-PMP22 silencing study — Gautier et al., 2021.
• PMP22 genome-editing study — Yoshioka et al., 2023.
• Novartis–DTx acquisition — Novartis, 2023.
• EDK060 Phase 1 study — Novartis, 2026.
• MFN2 silence-and-replace study — Rizzo et al., 2023.
• CMTA research archive — Charcot-Marie-Tooth Association, 2026.
• PXT3003 randomized trial — Attarian et al., 2021.
• Chinese PXT3003 Phase III trial — Liu et al., 2026.
• NTF3 AAV trial record — ClinicalTrials.gov, 2026.
• INSPIRE program update — Charcot-Marie-Tooth Association, 2026.
• Neurofilament light-chain study — Millere et al., 2021.
• CMTRF ENDGAME campaign — CMT Research Foundation, 2024.
• CMTRF funding program — CMT Research Foundation, 2026.
• CMTA–NIH CMT2 funding — Charcot-Marie-Tooth Association, 2024.