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Amyotrophic Lateral Sclerosis

Recent research efforts aimed at curing Amyotrophic Lateral Sclerosis.

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Amyotrophic Lateral Sclerosis

Overview

Amyotrophic lateral sclerosis (ALS) is a progressive disease in which motor neurons—the nerve cells that control voluntary movement—degenerate, causing worsening weakness, loss of speech and swallowing ability, paralysis, and eventually respiratory failure. In the United States, ALS is most often diagnosed between ages 55 and 75, affects men somewhat more often than women, and is familial in roughly 5–10% of cases; average survival is about 2–5 years after symptoms begin, although progression varies substantially among individuals. CDC ALS Registry

There is currently no cure. Standard care combines an experienced multidisciplinary ALS clinic with symptom management, nutritional support, communication technology, and non-invasive ventilation when needed; riluzole is routinely offered, while edaravone may help selected patients. Canadian ALS best-practice recommendations In the United States, tofersen (Qalsody) is additionally available for adults with ALS caused by a mutation in the SOD1 gene, but it is not a treatment for most ALS cases. FDA Qalsody approval

Scope of Recent Research (2020–present)

ALS research since 2020 has become more precise and more clinically organized, with major emphasis on silencing disease-causing genes, treating people before symptoms begin, improving delivery of treatments into the brain and spinal cord, and using biomarkers such as neurofilament light chain (NfL) to measure nerve injury more quickly. FDA Qalsody approval The field has produced an important proof of principle—targeted reduction of a causal ALS protein in people—but no intervention has restored lost motor neurons or cured ALS, and progress remains most advanced for rare inherited subtypes rather than the broader population with sporadic disease. Tofersen phase 3 trial

Major Breakthroughs and Emerging Therapies

The clearest advance is RNA therapeutics for SOD1-ALS. Tofersen is an antisense oligonucleotide (ASO), a short synthetic strand of nucleic acid designed to bind SOD1 messenger RNA and reduce production of the toxic SOD1 protein. Tofersen phase 3 trial In the randomized 28-week VALOR phase 3 trial, tofersen substantially reduced SOD1 in cerebrospinal fluid and reduced plasma NfL, but did not significantly improve the trial’s primary functional endpoint; an open-label comparison at 52 weeks numerically favored earlier treatment over delayed treatment. Tofersen phase 3 trial The FDA nevertheless granted accelerated approval on April 25, 2023, based on NfL reduction as a surrogate marker reasonably likely to predict benefit, making tofersen the first U.S.-approved genetically targeted ALS therapy. FDA Qalsody approval

A related strategy targets FUS-ALS, an uncommon but often aggressive inherited form. Jacifusen (ulefnersen/ION363) is an ASO intended to lower FUS RNA; a multicenter expanded-access case series reported experience in individual patients, while its effectiveness is being tested in the pivotal phase 3 FUSION trial. Jacifusen case series FUSION trial This is a rational “root-cause” approach, but it remains investigational and cannot yet be described as disease-stopping or curative. FUSION trial

Not all gene-silencing programs have succeeded, which has been scientifically informative. In C9orf72-associated ALS, the ASO BIIB078 was designed to destroy toxic repeat-containing RNA, but its phase 1 trial found concerning NfL increases and numerical clinical worsening at higher doses; development was discontinued. BIIB078 phase 1 trial This result shows that lowering a genetically implicated RNA is not automatically beneficial: researchers must identify which disease products to suppress, preserve normal gene function where necessary, and intervene early enough to prevent irreversible neuronal loss. BIIB078 phase 1 trial

Gene therapy and gene editing aim for longer-lasting suppression than repeated ASO injections. In a landmark report, two people with SOD1-ALS received a single intrathecal infusion of an adeno-associated virus (AAV) carrying a microRNA that targets SOD1; investigators detected reduced SOD1 in spinal-cord tissue from one participant, but clinical effects were uncertain and one participant developed meningoradiculitis, an inflammatory complication affecting the membranes and nerve roots around the spinal cord. AAV microRNA SOD1 study UniQure’s AMT-162, an intrathecal AAV therapy encoding an artificial SOD1-targeting microRNA, is now in an early phase 1/2 dose-escalation study, with safety and exploratory efficacy—not cure—its central objectives. AMT-162 trial Separately, CRISPR/Cas9 editing prevented ALS-like disease in two SOD1 mouse models, but large unintended DNA deletions occurred, underscoring why permanent genome editing remains preclinical for ALS. CRISPR SOD1 mouse study

For the much larger group with non-SOD1, non-FUS, or apparently sporadic ALS, investigators are testing approaches aimed at inflammation, cell stress, metabolism, protein handling, and motor-neuron support. The HEALEY ALS Platform Trial has been particularly important because it tests multiple medicines under one adaptive master protocol and can share placebo data across regimens. CNM-Au8 HEALEY trial However, recent results have been mostly negative: zilucoplan, a complement-C5 inhibitor, was stopped early for futility, and CNM-Au8 showed no benefit on disease progression at 24 weeks. Zilucoplan HEALEY trial CNM-Au8 HEALEY trial

Cell therapy remains experimental rather than restorative. NurOwn, an autologous bone-marrow-derived mesenchymal stem-cell product engineered to secrete neurotrophic factors, did not meet its primary or secondary endpoints in a randomized phase 3 trial, and the FDA concluded that the data did not support the proposed clinical benefit. FDA update on NurOwn The result does not rule out all cell-based approaches, but it demonstrates that supplying supportive cells has not yet reliably protected or replaced motor neurons in people with ALS. FDA update on NurOwn

Clinical Trials and Experimental Approaches

The most consequential ongoing prevention study is ATLAS, Biogen’s phase 3 trial of tofersen in clinically presymptomatic adults who carry a high-risk SOD1 mutation and have elevated NfL. ATLAS trial ATLAS tests whether beginning gene-lowering therapy before weakness develops can delay the emergence of clinically manifest ALS; as of September 9, 2026, it is active but not recruiting, has enrolled 158 participants, and has estimated primary completion in August 2027. ATLAS trial In parallel, the FUSION phase 3 trial is evaluating jacifusen for FUS-ALS, and the AMT-162 phase 1/2 study is evaluating one-time SOD1 microRNA gene therapy in a small number of participants. FUSION trial AMT-162 trial

The HEALEY Platform Trial has also generated valuable negative evidence efficiently. Zilucoplan did not alter ALS progression in its randomized regimen, and CNM-Au8 did not meet its primary or secondary efficacy endpoints, despite plausible anti-inflammatory and metabolic rationales. Zilucoplan HEALEY trial CNM-Au8 HEALEY trial Likewise, the larger PHOENIX phase 3 trial of sodium phenylbutyrate–taurursodiol (AMX0035; Relyvrio) failed its prespecified primary and secondary endpoints, prompting the manufacturer to voluntarily remove the product from the U.S. and Canadian markets in 2024. Amylyx 2024 filing

Methodologies and Scientific Approaches

Researchers use genetically engineered mice, patient-derived induced pluripotent stem cells (iPSCs), and increasingly detailed human natural-history data to determine which molecular defects actually drive motor-neuron death. CRISPR-edited iPSC-derived motor neurons can create genetically matched diseased and non-diseased cells, allowing researchers to examine protein aggregation, damaged axons, impaired synapses, and abnormal nerve signaling in a human-cell system. CRISPR-edited iPSC motor-neuron model The U.S. National ALS Registry also supplies epidemiologic data, participant surveys, biospecimens, and linked research resources that help identify risk factors and improve trial planning. CDC National ALS Registry dashboard

Clinical development increasingly combines direct measures of function and survival with biological measures of whether a therapy reaches its intended target. ASO trials measure target proteins in cerebrospinal fluid, while blood NfL is used as a marker of axonal injury; the FDA’s accelerated approval of tofersen made this biomarker central to ALS drug development while also requiring confirmatory clinical evidence. FDA Qalsody approval For gene therapies, key methodological challenges are selecting AAV vectors that reach enough motor neurons, controlling immune reactions, and achieving durable gene suppression without unsafe off-target effects. AAV microRNA SOD1 study CRISPR SOD1 mouse study

Leading Institutions and Funding

Massachusetts General Hospital’s Sean M. Healey & AMG Center for ALS, working with the Northeast ALS Consortium (NEALS), has led the HEALEY Platform Trial, while University of Massachusetts investigators, Massachusetts General Hospital, and collaborating gene-therapy centers pioneered early SOD1 AAV-microRNA treatment. CNM-Au8 HEALEY trial AAV microRNA SOD1 study Major industry participants include Biogen for tofersen, Ionis for jacifusen, and UniQure for AMT-162. ATLAS trial FUSION trial AMT-162 trial

The ALS Association, NIH, FDA, patient advocates, and philanthropic organizations are also shaping the field through grants, shared data, and trial infrastructure. The ALS Association reports commitments of more than $162 million to nearly 600 research projects since 2014, a $58 million Hoffman ALS Impact Fund, and nearly $4 million in clinical-trial support in its 2024 progress report. ALS Association awards and programs ALS Association 2024 progress report The same report describes the Accelerating Medicines Partnership in ALS, a public-private effort involving NIH, FDA, and private partners to build an open ALS data platform for diagnostics, biomarkers, and treatment development. ALS Association 2024 progress report

Strengths, Limitations, and Challenges

The field’s greatest strength is the transition from treating ALS as one uniform disorder to targeting defined biological causes. Tofersen proves that an RNA drug can lower a causal disease protein in the central nervous system, and ATLAS tests the especially promising hypothesis that treatment before symptoms may preserve motor neurons that would otherwise be lost. Tofersen phase 3 trial ATLAS trial Adaptive trials such as HEALEY can also reject ineffective therapies faster and with less duplicated infrastructure than separate conventional trials. Zilucoplan HEALEY trial

The central limitation is that target engagement is not the same as clinical recovery. Tofersen’s controlled trial did not meet its primary functional endpoint, and its use entails repeated lumbar punctures and risks including myelitis, aseptic meningitis, radiculopathy, increased intracranial pressure, and papilledema. Tofersen phase 3 trial Failed C9orf72, complement-inhibition, metabolic, stem-cell, and AMX0035 programs further show that promising mechanisms and early signals often do not translate into durable functional benefit in heterogeneous human ALS. BIIB078 phase 1 trial Zilucoplan HEALEY trial FDA update on NurOwn Amylyx 2024 filing

Outlook and Future Directions

As of September 9, 2026, a broad cure for ALS is not close enough to forecast responsibly, but the most credible near-term milestones are whether presymptomatic SOD1 treatment in ATLAS can delay clinical onset, whether FUS lowering in FUSION produces clear functional benefit, and whether early AAV or RNA-interference programs can safely achieve durable gene suppression. ATLAS trial FUSION trial AMT-162 trial A genuine cure will likely require early diagnosis, biologically matched treatment or combinations of treatments, reliable delivery throughout the motor system, and ultimately strategies that both halt ongoing degeneration and restore lost neural function. FDA Qalsody approval CRISPR SOD1 mouse study

References

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