Integrative ALS therapy: gene targeted therapy by base editing and potential exercise rehabilitation as synergistic strategies for functional recovery

Abstract

[Purpose]

A key pathological hallmark of amyotrophic lateral sclerosis (ALS) is transactive response DNA-binding protein 43 (TDP-43, encoded by TARDBP) proteinopathy. Mutations in TARDBP and cellular stress can drive nuclear clearance and cytoplasmic aggregation of TDP-43. TDP-43 is an essential nuclear RNA-binding protein that regulates RNA metabolism, and cytoplasmic TDP-43 aggregation leads to aberrant splicing of essential neuronal transcripts including stathmin-2 (STMN2) and unc-13 homolog A (UNC13A). Dysregulated RNA splicing causes cryptic exon (CE) inclusion in STMN2 and UNC13A mRNA, resulting in non-functional proteins and disruption of axonal regeneration and synaptic integrity. Splice-switching antisense oligonucleotides and gene-editing platforms can correct STMN2 and UNC13A mis-splicing defects. However, restoring STMN2 and UNC13A expression alone is not sufficient to regenerate neuromuscular junctions or reverse skeletal muscle atrophy, both of which are crucial for functional recovery in patients with ALS.

[Methods]

We reviewed gene-targeted treatment strategies and rehabilitative mechanisms that inhibit ALS progression and reverse neuromuscular degeneration by analyzing databases, including Google Scholar, PubMed, and ScienceDirect. We proposed a dual-modality therapeutic approach integrating base-editing-mediated gene therapy with exercise-based rehabilitation.

[Results]

Antisense oligonucleotides and genome editing can restore transcript fidelity by preventing cryptic exons inclusion in STMN2 and UNC13A, thereby stabilizing neuronal function. Gene-targeted therapies halt ALS progression; however, these treatments alone are insufficient to reverse neuromuscular degeneration or achieve functional recovery needed for patients with ALS to return to daily life.

[Conclusion]

Integrated rehabilitation is a crucial step in gene-targeted therapy for ALS. This strategy halts disease progression and restores neuromuscular function, thereby improving the lifespan and quality of life of patients with ALS.

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is an irreversible neurodegenerative disorder characterized by the loss of upper and lower motor neurons, leading to progressive muscle wasting, ultimately resulting in death due to respiratory failure [1]. The clinical diagnosis of ALS is often delayed owing to the heterogeneous and subtle onset of early symptoms, with an average age of approximately 55 years at diagnosis [2,3]. Early diagnosis of ALS is critical, as the median survival is typically less than 5 years following symptom onset [4]. This reflects the rapid degeneration of motor neurons after disease onset and the absence of effective treatment strategies. Oxidative stress and excitotoxicity are key cellular hallmarks of ALS pathogenesis and contribute to progressive motor neuron degeneration and synaptic dysfunction. The overproduction of reactive oxygen species (ROS) and failure of endogenous antioxidant defense systems create an oxidative cellular environment [5]. Furthermore, impaired glutamate clearance leads to excitotoxicity, disrupting synaptic transmission and further exacerbating motor neuron vulnerability in patients with ALS [6]. Current food and drug administration (FDA)-approved ALS treatments modestly extend survival by mitigating excitotoxicity and oxidative damage; however, none of these can reverse disease pathogenesis [7-9]. Thus, there is an urgent need for transformative therapeutic approaches capable of reversing ALS progression.

An emerging treatment strategy for ALS focuses on transactive response DNA-binding protein 43 (TDP-43) proteinopathy, a pathological condition observed in approximately 97% of patients [10,11]. Cytoplasmic mis-localization and aggregation of TDP-43 is a key hallmark of TDP-43 proteinopathy, which disrupts normal RNA metabolism and splicing. STMN2 and UNC13A are the most frequently alternatively spliced genes in patients with ALS who exhibit nuclear TDP-43 depletion [12]. Cytoplasmic TDP-43 aggregation drives cryptic exons (CE) inclusion in STMN2 and UNC13A mRNA, resulting in the production of truncated, non-functional proteins. This molecular pathology impairs both axonal repair and synaptic function, consequently accelerating ALS progression. Preventing CE inclusion by directly targeting the splice motifs of STMN2 and UNC13A using Antisense Oligonucleotides (ASOs) or genome editing represents a transformative strategy to reverse the functional consequences of TDP-43 proteinopathy. ASO treatment targeting STMN2 and UNC13A CEs restores transcript integrity in vitro and in preclinical animal models. However, the effects of ASO treatment are transient; thus, repeated administration is required for clinical applications [13]. In contrast, genome editing offers permanent correction of mis-splicing by disrupting CE splice sites or excising entire CEs [14,15]. Although genome editing successfully corrects STMN2 splicing defects in vitro, restoration of the Stathmin 2 (STMN2) protein in mouse models failed to consistently induce behavioral or functional recovery. Thus, there is a critical need for novel complementary therapeutic strategies to reverse existing neuromuscular degeneration [14]. Emerging evidence from neurorehabilitation and oncology rehabilitation suggests that exercise-based interventions enhance functional recovery by improving muscle strength, neural plasticity, and motor coordination [16-18]. The therapeutic application of exercise rehabilitation in ALS remains controversial because of inconsistent results due to variations in exercise timing, type, and intensity across different stages of ALS [19-21]. However, exercise training activates multiple downstream signaling pathways that mitigate neuromuscular degeneration and promote functional restoration in patients with ALS. Exercise training upregulates the expression of genes involved in mitochondrial biogenesis and antioxidant defense, providing neuroprotective effects similar to those of pharmacological antioxidants [22,23]. Furthermore, exercise training upregulates the expression of neurotrophic factors and promotes neuromuscular junction (NMJ) stability and skeletal muscle hypertrophy, thereby supporting the recovery of neuromuscular function [24,25]. Correction of these key pathogenic splicing defects effectively prevents further progression of neuromuscular vulnerability characteristic of ALS. In this stabilized state, exercise rehabilitation becomes uniquely effective in restoring or preserving neuromuscular function. We expanded our previous study on ALS gene targets by focusing on base editing-mediated correction of STMN2 mis-splicing. Furthermore, we propose that post-treatment exercise rehabilitation is essential to translate this genetic correction into measurable functional recovery in patients with ALS. This review advocates a synergistic therapeutic framework in which gene-targeted therapies halt ALS progression while post-exercise rehabilitation potentiates both molecular and functional neuromuscular restoration, ultimately improving physical strength and mobility of patients with ALS.

METHODS

To ensure academic rigor and methodological transparency, we conducted a literature review in accordance with the Scale for the Assessment of Narrative Review Articles guidelines. A comprehensive literature search was performed across electronic databases, including PubMed, ScienceDirect, and Google Scholar, which identified 1,411 articles. The search strategy employed key terms including ALS, Genome Editing, ASOs, TDP-43 Proteinopathy, and Exercise Rehabilitation, which were used individually or in combination using Boolean operators (AND, OR). Duplicate records identified across the databases were removed before screening. The selection process was executed in three stages: an initial screening based on titles and abstracts, retrieval and review of the full texts of potentially eligible articles, and a detailed full-text review to determine the final eligibility. Studies were excluded if they were deemed out of scope (irrelevant to specific research objectives) or if the full text was unavailable, thereby ensuring the quality and focus of the narrative review. Finally, 1,367 articles were excluded, and 44 studies were included in the final narrative review. All the studies included in the final bibliography were published in English, with publication years ranging from 1996 to 2025. The detailed study identification and selection processes are summarized in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart (Figure 1).

Figure 1. Preferred reporting items for systematic reviews and meta-analyses (PRISMA) flowchart of included studies.

RESULTS

Etiology

ALS has an estimated annual incidence of approximately 3 cases per 100,000 individuals, with about 5,000 new diagnoses every year in the United States [26,27]. The age at ALS onset is mostly between 45 and 75 years, with age-specific incidence rates peaking at approximately 8 per 100,000 individuals annually [28]. The increased incidence of ALS in middle-aged individuals is attributed to two primary factors. Cumulative exposure to environmental toxins and the increased vulnerability of aging motor neurons to oxidative stress due to mitochondrial dysfunction and accumulation of misfolded proteins. ALS develops due to a complex interplay between toxic environmental exposure, lifestyle factors, age-related neurophysiological decline, and genetic variations [29-31]. While the etiology of most cases remains unknown, approximately 90-95% are classified as sporadic ALS (sALS), typically exhibiting an age of onset between 58 and 63 years. Age-related neurodegeneration is a critical driver of ALS [32]. In contrast, familial ALS (fALS) accounts for only 5-10% of cases and presents at an earlier age, which is attributed to inherited pathogenic mutations that alter the cellular environment during early development [33,34]. More than 30 genes have been implicated in the development of fALS, with mutations in superoxide dismutase 1 (SOD1), TARDBP, RNA-binding protein fused in sarcoma (FUS), and GGGGCC hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9orf72) recognized as major contributors (Table 1) [35-37]. Mutations in fALS-associated genes exacerbate motor neuron degeneration through diverse pathogenic mechanisms, including oxidative stress, protein misfolding, aberrant RNA splicing, and formation of toxic RNA foci [38-40]. TDP-43 is a nuclear RNA-binding protein that regulates pre-mRNA splicing, stability, and transport [41]. Most ALS-associated TDP-43 mutations are located in the low-complexity domain (LCD) of the C-terminal region. LCD is a prion-like structure that mediates protein-protein interactions and governs subcellular localization. Furthermore, it regulates TDP-43 liquid-liquid phase separation and facilitates its incorporation into stress granules in response to cellular stress [42,43]. Aberrant phosphorylation of residues within LCD drives a liquid-to-solid phase transition in TDP-43, leading to the accumulation of insoluble pathological aggregates [44]. The aggregation of TDP-43 sequesters essential functional proteins and RNAs within insoluble inclusion bodies, thereby inducing potent cellular toxicity [45]. The cytoplasmic aggregation of TDP-43 leads to widespread splicing defects characterized by abnormal CE inclusion and subsequent destabilization of transcripts essential for neuronal survival in ALS [14]. STMN2 is a neuron-specific protein that regulates microtubule dynamics, a process essential for axonal outgrowth and regeneration. The inclusion of CE within the STMN2 transcript leads to premature polyadenylation, producing a truncated, non-functional mRNA in ALS. Depletion of functional STMN2 impairs neuronal regeneration capacity following axonal injury and contributes to neurodegeneration [14]. UNC13A regulates synaptic vesicle priming and neurotransmitter release at presynaptic nerve terminals. TDP-43 proteinopathy-associated splicing dysregulation results in the inclusion of a CE between exons 20 and 21 of UNC13A. This aberrant splicing defect triggers the nonsense-mediated decay of the transcript, leading to reduced gene expression and compromised synaptic integrity. Genome-wide association studies have identified single nucleotide variations (SNVs) in UNC13A as major risk factors for ALS. Specifically, SNVs located proximal to CE accelerate disease progression and shorten survival by disrupting neurotransmitter release and compromising neuronal connectivity [46]. Dysregulation of STMN2 and UNC13A splicing has significant clinical implications, as it directly contributes to motor neuron dysfunction and accelerates ALS progression.

Table 1.

Representative fALS-associated gene mutations and treatments

Gene	Mutation	Gene therapy	Purpose	Delivery	Outcome	References
SOD1	G93A	CRISPR-Cas9	KO	AAV	Mutant SOD1 reduction, and restored motor function	[87,129]
SOD1	G93A	CRISPR-Cas9	KO	Plasmid	Decreased mutant SOD1 expression leading to a disease-free condition	[130]
SOD1	G93A	BE	KO	AAV	Reduced rate of muscle atrophy, decreased muscle denervation, improved neuromuscular function	[131]
C9orf72	G4C2 expansion	CRISPR-Cas9	Deletion of repeats	Plasmid	Prevented RNA foci formation and resistance to excitotoxicity	[132,133]
C9orf72	G4C2 expansion	CRISPR-Cas9 with Donor template	Wild-type conversion	Plasmid	Prevented RNA foci formation, improved cell survival and the response to cellular stress	[134]
C9orf72	G4C2 expansion	CRISPR-Cas9	KO	AAV	Reduction of RNA foci, poly-dipeptides, and haploinsufficiency	[88]
FUS	G1566A	CRISPR-Cas9 with Donor template	Wild-type conversion	Plasmid	Mutant FUS reduction	[135]
FUS	R521H P525L	CRISPR-Cas9 with Donor template	Wild-type conversion	Plasmid	Corrected DNA ligation defects in ALS patient-derived iPSC	[89,136]
TARDBP	M337V	CRISPR-Cas9 with Donor template	Wild-type conversion	Plasmid	Restored BDNF secretion and synaptic plasticity by preventing SORT1 mis-splicing	[137]

SOD1 is a critical antioxidant enzyme that neutralizes free superoxide radicals. A byproduct of hydrogen peroxide metabolism, superoxide radicals serve as a signaling molecule that activates downstream antioxidant pathways [47]. SOD1 was the first fALS-associated gene identified. Mutations in SOD1 disrupt mitochondrial function and intracellular calcium homeostasis, thereby exacerbating neuronal degeneration [48]. FUS is a multifunctional RNA-binding protein that regulates gene expression and RNA processing. FUS maintains genomic stability by participating in DNA repair pathways. Impaired nuclear transport of the FUS protein, resulting from mutations in the C-terminal nuclear localization sequence, is the primary pathogenic driver of fALS, leading to aberrant cytoplasmic sequestration [49]. C9orf72 mutations are the most common in fALS and are present in approximately 40% of fALS cases. The normal GGGGCC (G4C2) hexanucleotide repeat in the C9orf72 gene typically ranges from two to ten, with an expansion of more than 30 repeats considered pathogenic. The abnormal expansion of G4C2 repeats forms RNA foci that sequester RNA-binding proteins, including TDP-43 and heterogeneous nuclear ribonucleoproteins (hnRNP), thereby perturbing RNA processing in neurons [50]. Despite the clear genetic mechanism, approximately 90% of ALS cases are sporadic and are not linked to inherited genetic mutations. sALS pathogenesis is due to a combination of environmental and lifestyle factors that contribute to disease progression. These risk factors interact with age-related cellular vulnerabilities in motor neurons that drive ALS progression. Occupational exposure to toxic materials, such as pesticides, solvents, and heavy metals, contributes to the development of sALS [51,52]. Smoking is a risk factor for sALS as it mediates vascular damage and pro-inflammatory signaling [53]. Aging is a major risk factor for sALS and contributes to its onset and progression via multiple interrelated biological processes. Aging-associated cellular senescence in glial cells and neurons alters the central nervous system microenvironment by promoting neuroinflammation and reducing regenerative capacity [54]. Motor neurons are particularly vulnerable to oxidative stress due to the high metabolic demands imposed by their extended axons. Aging further exacerbates motor neuron vulnerability by attenuating endogenous antioxidant defense mechanisms and increasing reactive oxygen species (ROS) levels. This imbalance facilitates oxidative proteostasis stress and the accumulation of DNA damage, ultimately lowering the threshold for neurodegeneration. Aging leads to mitochondrial dysfunction, which impairs energy metabolism and calcium homeostasis, both of which are critical for maintaining neuronal survival and modulating membrane excitability [55]. Age-related epigenetic drift alters gene expression, which is crucial for neuronal maintenance and protein homeostasis, thereby impairing neuroregenerative capacity [56].

Pathogenesis

ALS pathogenesis is characterized by a cascade of molecular and cellular dysfunctions within the motor neurons, ultimately disrupting the NMJ and facilitating neuromuscular degeneration. ALS pathogenesis involves multiple cellular processes. Dysfunction of the ubiquitin-proteasome system and the autophagy-lysosomal pathway impairs the clearance of misfolded or damaged proteins [57,58]. The accumulation of toxic and misfolded proteins leads to the collapse of proteostasis, a hallmark of neurodegenerative diseases. Evidence for a link between impaired cellular clearance and ALS pathogenesis is also supported by the transcriptional downregulation of genes governing protein degradation pathways [59]. Dysregulation of axonal transport is a critical contributor to axonal degeneration in neurodegenerative diseases. The destabilization of microtubules and alterations of motor proteins impair axonal transport mechanisms, thereby compromising axonal integrity and synaptic function in ALS [60]. This failure is further exacerbated by the loss of nuclear TDP-43-dependent mis-splicing of STMN2 and UNC13A [14,61]. Neuroinflammation, a key feature of ALS pathogenesis, is characterized by the activation of microglia and astrocytes in response to motor neuron injury. An increase in microglia has been observed near the corticospinal tract in post-mortem analyses of patients with ALS [62]. Reactive astrocyte-associated genes are upregulated in postmortem spinal cord samples from patients with ALS [63]. Microglia and astrocytes are activated and release proinflammatory cytokines in response to neuronal stress or injury [64]. Although the initial inflammatory response serves to mitigate cellular and neuronal damage, persistent activation and chronic cytokine release shift the cellular environment toward excessive oxidative stress, thereby disrupting neuronal homeostasis and amplifying neurotoxicity. An excessive oxidative environment due to mitochondrial dysfunction contributes to neuronal vulnerability in ALS. Neurons derived from induced pluripotent stem cells (iPSC) of patients with ALS exhibit abnormal mitochondrial morphology and impaired calcium-buffering capacity [65]. Mitochondrial abnormalities compromise cellular ATP production, thereby impairing the bioenergetic demands that are essential for motor neuron survival. Neurons with mitochondrial dysregulation exhibit defective axonal transport, increased ROS production, and increased susceptibility to oxidative stress [66].

Current Medications

Current pharmacological treatments only slow the progression of ALS or alleviate symptoms, offering modest clinical advantages (Table 2). Therefore, the development of novel therapeutic strategies to reverse ALS progression remains an urgent and unmet medical need. Riluzole was the first FDA-approved drug for the treatment of ALS. It mitigates excitotoxicity by inhibiting glutamate release from presynaptic nerve terminals [67]. Excessive excitotoxic signaling leads to glutamate-induced calcium overload, creating a toxic cellular environment that contributes to motor neuron degeneration in ALS [68]. Clinical trials have demonstrated that riluzole extends the median survival of patients with ALS by approximately three months, with a more pronounced therapeutic benefit in individuals with bulbar-onset disease [69]. Edaravone is a free radical scavenger that mitigates oxidative stress in motor neurons. Clinical studies have shown that edaravone treatment modestly slows down functional decline, particularly in patients with early-stage ALS [70]. Tofersen, an ASO therapy designed to target SOD1 mRNA, is the first FDA-approved gene-targeted therapy for ALS. Tofersen triggers endogenous RNase H activity to cleave the mRNA, effectively lowering the levels of pathogenic SOD1 protein in patients with SOD1 mutations. Although tofersen does not selectively target the mutant SOD1 mRNA, it effectively reduces the levels of both the toxic mutant SOD1 protein and neurofilament light chain, suggesting a significant neuroprotective effect in ALS [71]. More recently, sodium phenylbutyrate and taurursodiol (PB-TURSO), a combination therapy aimed at mitigating endoplasmic reticulum stress and enhancing mitochondrial function, has been shown to delay functional decline in early clinical studies [9]. Despite these promising initial findings, the therapy failed to meet key endpoints in the phase III clinical trial, prompting its withdrawal from the market.

Table 2.

Current therapeutic approaches and clinical outcomes in ALS

Therapy	Mechanism / target	Status	Animal study / clinical outcome	Key references
Riluzole (Rilutek, Tiglutik, Exservan)	Inhibits glutamate release to reduce excitotoxicity	FDA-approved (1995)	Extends survival by ~3 months; greater benefit in bulbar-onset and fast-progressing patients.	[138,139]
Edaravone (Radicava)	Scavenges free radicals to reduce oxidative stress	FDA-approved (2017)	Slows functional decline in early-stage and fast-progressing patients.	[140,141]
Tofersen (Qalsody)	ASO targeting mutant SOD1 mRNA	FDA-approved (2023)	Reduces SOD1 protein and neurofilament light chain levels; slows respiratory decline.	[71,142]
PB-TURSO (Relyvrio)	Targets ER and mitochondrial stress	Withdrawn from Market (US) (2022)	Improved survival / function in Phase 2; withdrawn after Phase 3 (PHOENIX), showed no ALSFRS-R benefit.	[143]
Masitinib	Tyrosine kinase inhibitor targeting immune cells to reduce neuroinflammation	Ongoing phase 3 clinical trials	Slows progression and improves survival in a patient subgroup.	[144,145]
ION363 (Jacifusen)	ASO targeting FUS mRNA	Ongoing phase 3 clinical trials	Reduces FUS protein levels and delays progression in animal models.	[80]
QRL-101	Small Molecule (Potassium channel opener, targets motor neuron hyperexcitability)	Phase I	Reduces neuronal hyperexcitability to slow ALS progression.	[146]
AMX0114	ASO targeting calpain-2 (CAPN2) to prevent axonal degeneration	Phase I	Reduced calpain-2 levels and improved motor neuron survival in animal models; granted FDA fast track designation.	[147]
Gene editing: CRISPR / Cas9	Correcting mutations (e.g., C9ORF72 repeat expansion)	Preclinical	Potential for permanent, single-dose correction of genetic ALS mutations.	[88]
AAV gene therapy	Viral vectors delivering neurotrophic factors (e.g., IGF-1, GDNF)	Preclinical / early phase I	Provides direct neuroprotection and survival signals to motor neurons.	[148,149]
Stem cell therapy	Neural progenitor or mesenchymal stem cell transplantation		Prevents neuronal damage and disease progression.	[150-152]
Neuroprotective agents	Growth factors, anti inflammatory agents, metabolic stabilizers		Reduces mitochondrial dysfunction, inflammation, or oxidative stress	[153,154]
Supportive care	Respiratory and nutritional support		Improves quality of life, prolongs survival, reduces complications	[76,155]

The therapeutic effects of the current FDA-approved treatments for ALS are limited, and these drugs do not completely halt or reverse disease progression, only achieving a modest delay in functional decline. Consequently, neuroprotective agents, including brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), and anti-inflammatory drugs, have been investigated as therapeutic strategies for preventing neurodegeneration [72,73]. Stem cell therapy is currently used for a broad spectrum of diseases including hematological disorders, cardiovascular diseases, and autoimmune conditions [74]. Stem cell applications are specifically designed to replace the lost motor neurons and provide essential neurotrophic support in ALS. Mesenchymal stem cells, neural stem cells, and induced pluripotent stem cells have been investigated in preclinical and early-phase clinical settings for the treatment of ALS. Although stem cell transplantation attenuates ALS progression and improves motor function, the establishment of long-term safety profiles, optimization of delivery strategies, and reproducibility of therapeutic efficacy remain significant challenges [75]. Multidisciplinary supportive care is essential for managing ALS symptoms in the absence of curative treatments. Non-invasive ventilation, nutritional support, and palliative care mitigate secondary complications and improve the quality of life in patients with ALS [76].

Gene Targeted Therapy

Antisense oligonucleotides

ASOs are short, single-stranded nucleic acids designed to hybridize with complementary RNA sequences. The therapeutic efficacy of ASOs relies on their sequence-dependent design, which precisely modulates target gene expression [14]. ASO treatment has emerged as a promising therapeutic platform since it can target toxic mutant genes and prevent aberrant mRNA splicing in ALS. Tofersen treatment has demonstrated clear target engagement by reducing toxic mutant SOD1 protein levels and neuronal injury biomarkers in patients with ALS [71,77]. ASO targeting G4C2 expanded C9orf72 prevents the formation of toxic RNA foci and cytoplasmic TDP-43 aggregation [78]. Treatment with G2C4 ASO targeting G4C2 repeats prevents transcriptomic alterations, including cryptic mis-splicing associated with TDP-43 proteinopathy in C9orf72 patient-derived iPSC neurons [79]. Non-allele-specific ASO treatment downregulates FUS mRNA and reduces FUS protein levels, delaying motor neuron degeneration in a pathogenic FUS knock-in mouse model [80]. ASO treatment effectively reduces mutant FUS aggregates within the central nervous system of patients harboring the FUS^P525L mutation [80].

ASOs can also modulate pre-mRNA splicing by sterically hindering the binding of splicing factors. Specifically, ASOs can block CE, sterically mimicking the nuclear TDP-43 and preventing CE inclusion in the STMN2 and UNC13A transcripts. ASOs targeting sequences proximal to the STMN2 CE splice sites restore full-length STMN2 protein production and rescue axonal integrity in both cellular and animal models [49]. Similarly, ASOs targeting UNC13A CE-splicing acceptors and donors prevent CE inclusion and restore UNC13A protein levels and synaptic integrity following TDP-43 knockdown [15].

Genome editing approaches

Genome editing technologies, including CRISPR-Cas9, base editing, and prime editing, represent a transformative approach for curative therapies. These platforms enable the precise modification of pathogenic mutations, aberrant regulatory elements, and splicing motifs, offering the potential for single-dose interventions for durable and permanent therapeutic effects. Casgevy, the first FDA-approved medicine for sickle cell disease in 2023, was based on CRISPR-Cas9 genome-editing technology [81,82]. Casgevy utilizes the CRISPR-Cas9 system to modify and correct the genetic defect in patients’ hematopoietic stem and progenitor cells ex vivo before transplanting them back as functionally corrected cells. In vivo gene-editing therapies have also been actively investigated in clinical trials for applications in oncology, immunodeficiency, and cardiovascular diseases [83-85]. Although several gene therapies have been approved, in vivo genome-editing treatments have yet to receive final approval from the FDA. In 2025, Musunuru et al. treated a patient using a customized base-editing therapy to correct the carbamoyl phosphate synthetase I Q335X variant [86]. The research team first developed patient-specific cell lines and mouse models to validate the editing efficiency and safety of personalized genome-editing treatments. The therapy was authorized by the Investigational New Drug, and the patient received the first infusion at seven months of age. Genome editing has been successfully applied in preclinical ALS models to knockout mutant SOD1, resulting in significant amelioration of motor deficits and prolonged survival in SOD1 mutant mice [87]. The delivery of CRISPR-Cas9 and gRNAs targeting both upstream and downstream regions of G4C2 repeats in C9ORF72 results in deletion of the G4C2 repeats, thereby reducing toxic RNA foci formation and poly-dipeptide protein accumulation [88]. The FUS^P525L mutation in ALS patient-derived cells increases cytoplasmic FUS levels. Correction of the mutant allele using CRISPR/Cas9 and wild-type FUS^P525 donor plasmids prevents cytoplasmic FUS accumulation and rescues DNA ligation defects [89]. Prime editing expands the field of genome editing by combining a reverse transcriptase and a donor template with a modified CRISPR-Cas9 system, enabling precise insertions, deletions, and multiple base substitutions. The prime editor is particularly well-suited for correcting larger or more complex genetic mutations relevant to ALS pathogenesis. Prime editing disrupts the CE donor splice site of UNC13A, preventing CE inclusion upon TDP-43 knockdown [90]. Prime editing corrects the fALS-associated SOD1^R115G to wild-type SOD1 in patient-derived iPSCs [91].

Base editing strategy to correct mis-splicing

TDP-43 sterically blocks the access of splicing machinery to the cryptic splice sites in STMN2 and UNC13A, thereby preventing CE inclusion. The delivery of catalytically inactive Cas13 (dCas13) with gRNAs targeting cryptic splice sites blocks CE inclusion and prevents pathogenic splicing [14]. ASOs targeting cryptic splice sites and the surrounding regions prevent CE inclusion in STMN2 and UNC13A mRNA, thereby restoring functional STMN2 and UNC13A in the absence of TDP-43. However, the effects of dCas13-mediated translational repression and ASO treatment are transient, thus lifelong administration of these molecules is required, which carries risks of complications [92]. Targeted disruption of cryptic splice sites via genome editing offers a durable and curative single-dose therapy. Although conventional CRISPR-Cas9 systems can achieve a high on-target efficiency, their reliance on double-strand breaks (DSBs) is problematic since DSBs can trigger error-prone DNA repair, which results in unintended indels. Conversely, prime editing avoids DSBs, but is currently limited by relatively low editing efficiency and inconsistency across target sites, cell types, and delivery systems [93,94]. Base editing enables the precise conversion of single nucleotides without inducing DSBs, thus minimizing undesired indels. The on-target efficiency of base editing is significantly higher than that of prime editing. Furthermore, the development of base editors utilizing engineered deaminases attenuates the off-target burden, providing enhanced safety for therapeutic applications compared with nuclease-based methods [95]. Since most fALS-associated mutations are single-nucleotide variants (SNVs), base editing is a promising modality for targeting common pathogenic fALS mutations in SOD1, FUS, and TARDBP (Figure 1B). The disruption of cryptic splice sites via base editing can prevent CE inclusion in STMN2 and UNC13A, thus offering a potential therapeutic strategy for sALS. The pre-mRNA splicing mechanism involves identification of splice sites and transesterification reactions to remove introns and join exons. The large spliceosome complex recognizes splice sites, extracts introns, and brings the two exons together. Splice site modification successfully prevents CE inclusion [14]. In this study, we used base editors and gRNAs targeting STMN2 CE-splicing acceptor AG motifs (Figure 2A). We used an adenine base editor (ABE) to convert adenine (A) to guanine (G) and a cytosine base editor (CBE) to convert cytosine (C) to thymine (T). We used an engineered N2A cell line carrying a humanized Stmn2 gene fragment. TDP-43 binding to the GU-rich motif sequence is replaced with a bacteriophage MS2 aptamer sequence that allows STMN2 CE splicing regulation by the MS2 coat protein, which provides a steric block analogous to that of TDP-43 [14]. Full-length Stmn2 mRNA expression was significantly downregulated in N2A^MS2/HOMO. We compared the top candidate ASO among the 250 potential ASOs targeting the cryptic splice site in STMN2. ASO treatment restores approximately 20% of full-length Stmn2 mRNA expression in N2A^MS2/HET [14]. Base editor-mediated disruption of the cryptic splice site in N2A^MS2/HOMO mice restored fulllength Stmn2 mRNA levels to near N2A^MS2/HET (Figure 2B). We further evaluated two ABEs and four CBEs paired with three different sgRNAs to address the varying PAM preferences of the different Cas9 backbones. All base-editing strategies achieved over 80% disruption of the splicing motif (Figure 2C). This splicing disruption restored over 70% of the full-length Stmn2 mRNA and downregulated over 90% of the truncated Stmn2 mRNA (Figure 2D). Notably, we observed the restoration of over 60% of STMN2 protein levels (Figure 2E), which exceeded the established threshold for functional rescue. Previous studies have demonstrated that 25% of wild-type STMN2 levels are sufficient to support axonal regrowth following injury in human motor neurons [14]

Figure 2. Mechan i sms of ALS pathology and therapeutic gene-targeting strategies.

ALS is a progressive neurodegenerative disorder characterized by the selective loss of motor neurons, ultimately leading to muscle atrophy and paralysis. A hallmark of ALS is the nuclear depletion of TDP-43. Cytoplasmic TDP-43 aggregation results in aberrant splicing and CE inclusion within STMN2 and UNC13A transcripts. Inclusion of these CEs generates truncated mRNAs that are either degraded by nonsensemediated decay or translated into nonfunctional protein products, thereby depleting functional STMN2 and UNC13A proteins, thus neuronal homeostasis is disrupted. STMN2 plays a critical role in microtubule dynamics required for axonal outgrowth and regeneration, whereas UNC13A is essential for synaptic vesicle priming and neurotransmitter release. Therapeutic strategies have been developed to restore normal splicing and gene function of STMN2 and UNC13A. Base editing can be employed to disrupt canonical splice motifs that drive CE inclusion, thereby preserving correct transcript processing. Alternatively, ASOs designed to target sequences adjacent to the cryptic splice sites sterically block CE recognition and promote restoration of fulllength STMN2 and UNC13A mRNAs. In addition to TDP-43 dysfunction, over 40 genes have been identified as risk factors for ALS. Among these, mutations in FUS, SOD1, C9orf72, and TARDBP are responsible for up to 70% of fALS cases. Notably, most ALS-associated mutations are single-nucleotide mutations, which represent promising targets for correction using base editing technologies.

Figure 3. Base editing restore full leng th STMN2.

(A) Schematic representation of the genomic STMN2 CE in red. (B) BEs are used to disrupt exon CE splicing motif to prevent its inclusion and the resulting truncation of STMN2. CE splicing is disrupted by BEs to prevent CE inclusion and Stmn2 truncation. CE splicing disruption shows higher level of full-length Stmn2 mRNA restoration compared to ASO treatment. (C) Splicing motif editing outcomes at the CE splicing acceptor site are achieved using combinations of two ABEs and four CBEs paired with two different sgRNAs. (D) Full-length Stmn2 mRNA levels are restored following editing in N2A^MS2/HOMO as measured by qRT-PCR and normalized to N2A^WT. Truncated Stmn2 mRNA, resulting from the inclusion of CE, is downregulated after splicing disruption in N2A^MS2/HOMO as measured by qRT-PCR and normalized to N2A^MS2/HOMO treated with unrelated sgRNA. (E) Full-length STMN2 proteins are restored in N2A^MS2/HOMO via CE splicing disruption. For all qRTPCR, western blot and editing analyses, each data point represents independently treated wells of cells. Error bars indicate the standard error of the mean (SEM).

Limitations of Gene Therapies

Limitations of correcting TDP-43-related mis-splicing

Cryptic splicing of STMN2 and UNC13A is one of the most well-characterized consequences of TDP-43 nuclear loss [61]. ASOs blocking the cryptic splice site establish the mechanistic rationale underlying clinical-stage STMN2 restoration [14]. Similarly, ASOs that suppress UNC13A CE inclusion can restore synaptic functions, and ASOs that correct KCNQ2 mis-splicing can rescue hyperexcitability [15,96]. Furthermore, an engineered therapeutic U7 small nuclear RNA (tU7) that suppresses mis-splicing of STMN2 and UNC13A rescues neuronal function and axonal regeneration in TDP-43-depleted neurons and in mouse models [97,98]. The small size of tU7 constructs makes multiplexing feasible, allowing multiple mis-spliced genes to be targeted simultaneously. Despite the preclinical success of tU7, biological heterogeneity and multifactorial pathophysiology of ALS suggest that the correction of TDP-43-related splicing defects alone may not be sufficient to reverse disease progression, particularly in sALS. Since sALS pathogenesis is multifactorial, the restoration of neuronal functions through STMN2 and UNC13A correction alone does not address other mechanisms implicated in disease progression, including excitotoxicity, oxidative stress, mitochondrial dysfunction, and protein aggregation. Restoring STMN2 and UNC13A functions may be necessary to delay progression when administered at the early stage; however, it may not be sufficient to halt neurodegeneration in all patients with sALS. Although sALS pathogenesis is multifactorial, the KJ Muldoon case demonstrates that a rapid-turnaround personalized base-editing pipeline is feasible [86].

Off-target risks

Despite the promise of gene therapy, several translational barriers remain, including the risk of off-target editing and innate immunogenicity elicited by bacterial Cas9 nucleases. Base editors generate unintended edits through guide-RNA-dependent off-target activity. Base editors can recognize and edit R-loop hotspots that occur naturally at actively transcribed genomic regions [99]. Base editors can target RNA, and high-fidelity TadA-derived deaminase vari-ants successfully attenuate RNA off-target effects [100]. Prime editors introduce unintended DNA edits less frequently than base editors and Cas9 nucleases. However, low-frequency off-target events can produce clinically consequential structural variations [101]. Recent applications of suppressor tRNA systems as genome editing tools provide a complementary strategy for mitigating off-target effects by strictly constraining the duration of editor activity [102]. Using this approach, a premature stop codon was engineered into the Cas9-encoding transcript. Translation of the full-length catalytically active protein depends on the co-expression of a suppressor tRNA capable of reading through the stop codon. Since the suppressor tRNA component can be delivered or expressed transiently, it creates a self-limiting circuit.

Figure 4. Mechanisms of neuroprotection and muscle rescue by exercise training in ALS Exercise exerts multifaceted neuroprotective and myogenic effects, positioning it as a critical therapeutic strategy to enhance functional recovery in individuals with ALS.

Exercise training promotes motor neuron health and function by increasing the expression of crucial neurotrophic factors like BDNF and IGF-1 which are essential for motor neuron survival, synaptic plasticity, and axonal regeneration. The type and intensity of exercise are critical determinants of therapeutic efficacy in ALS interventions. Moderate physical activity can create an anti-inflammatory environment, shifting the immune system towards a more protective state. Resistance training promotes muscle hypertrophy and improves glucose metabolism, thereby counteracting the catabolic muscle wasting that drives functional decline in ALS. Aerobic exercise enhances mitochondrial biogenesis and function, leading to increased cellular energy capacity and reduced oxidative stress, a hallmark of ALS pathology. Moreover, moderate physical activity fosters an anti-inflammatory milieu by shifting immune responses toward a more protective phenotype.

ASO-based therapeutics exhibit hybridization-dependent and independent off-target effects. These phenomena occur when an ASO anneals to unintended RNA transcripts through partial sequence complementarity. Even minor sequence homologies or tolerated base-pair mismatches can trigger the RNase H-mediated degradation of non-target mRNAs [103]. Alternatively, non-cleaving steric-blocking ASOs may bind to non-target transcripts to perturb pre-mRNA splicing kinetics or obstruct ribosomal translation. Transcriptome-wide RNA sequencing has revealed that off-target transcript depletion can perturb essential metabolic pathways, leading to sequence-specific cellular dysregulation and organ toxicity [103]. Sequence-independent toxicity stems directly from the chemical architecture incorporated into the oligonucleotide backbone and ribose sugar modifications. Chemical modifications such as phosphorothioate linkages stabilize ASOs, but they also facilitate plasma protein binding and promote non-specific intracellular protein interactions [104].

Delivery challenges

The efficient delivery to upper and lower motor neurons remains a critical challenge in ALS gene therapy [105]. Unlike adeno-associated virus (AAV) vectors, ASOs lack an intrinsic targeting specificity for cell types. Intrathecally delivered ASOs remain in the central nervous system (CNS). Intrathecal administration bypasses the blood-brain barrier to achieve high CNS bioavailability; however, a measurable, low amount of ASO also reaches systemic circulation [106]. Since ALS pathology spans the bulbar, cervical, thoracic, and lumbar motor neurons simultaneously, a broad ASO distribution is advantageous for patients with ALS. Base editor cassettes exceed the AAV packaging capacity, necessitating dual-AAV split-intein strategies, in which the editor is divided into two vectors that must be co-transduced into the same cell. The AAV9 serotype is widely used to deliver genome-editing components to neurons. However, neuronal transduction efficiency following intravenous AAV9 administration is significantly reduced in adults compared to neonates, limiting its therapeutic utility in the typical ALS patient population. One approach to solve this biodistribution problem is AAV-PHP.eB, an engineered capsid variant derived from AAV9 that dramatically enhances blood-brain barrier penetration and CNS transduction in adult rats [107]. Although clinical genome editing still faces significant delivery and implementation bottlenecks, it has the potential to slow or attenuate ALS progression, particularly when administered at an early disease stage before extensive neuronal loss has occurred. No clinical genome-editing trials have been conducted for ALS yet. However, evidence from related neurodegenerative diseases, such as spinal muscular atrophy (SMA), supports this therapeutic premise. P0 delivery of a base editor targeting SMN2 successfully rescued survival motor neuron protein levels and significantly increased lifespan in a preclinical mouse model of SMA [108].

Therapeutic Role of Exercise

Mechanisms of neuroprotection and myogenic rescue

Exercise exerts neuroprotective and myogenic effects, thus serving as a critical therapeutic modality to enhance functional recovery in individuals with ALS (Table 3). Accumulating evidence suggests that regular physical activity enhances the neuromuscular microenvironment by modulating metabolic homeostasis and enhancing activity-dependent neurotrophic support. Exercise upregulates the expression of the neurotrophic factors BDNF and IGF-1, which are critical for maintaining motor neuron survival, promoting synaptic plasticity, and facilitating axonal regeneration [109,110]. BDNF and IGF-1 promote neuronal resilience and support glial cell function to maintain a healthy neural environment. These neuroprotective mechanisms are largely derived from studies conducted in healthy individuals. In healthy or disuse-atrophied muscles, resistance exercise promotes hypertrophy and neuromuscular adaptations that increase muscle strength and improve balance and coordination. However, muscle atrophy is not a disuse phenomenon in patients with ALS and is largely due to the progressive denervation of muscle fibers as motor units are lost. Evidence remains limited regarding whether resistance exercise can induce sufficient hypertrophy in already-denervated ALS muscles. Resistance exercise prevents insulin resistance and enhances glucose metabolism, thereby counteracting catabolic muscle wasting, which significantly contributes to functional decline in ALS [111]. Furthermore, sustained physical activity optimizes mitochondrial biogenesis and function, potentially buffering motor neurons against the bioenergetic failure characteristics of ALS. Additionally, aerobic exercise stimulates mitochondrial biogenesis and improves function by upregulating the transcriptional coactivator PGC-1α, thereby enhancing oxidative phosphorylation efficiency and reducing cellular energy deficits [112]. Aerobic exercise strengthens the endogenous antioxidant defense system, thereby mitigating ROS accumulation, a key contributor to motor neuron degeneration [113]. Moderate-intensity or sustained exercise induces protective cellular adaptations against oxidative stress. Concurrently, moderate physical activity induces an anti-inflammatory environment and shifts the immune profile toward a protective phenotype [114]. Thus, exercise-induced adaptations provide a strong rationale for incorporating structured physical training programs in ALS care.

Table 3.

Therapeutic role of exercise

Exercise effect	Mechanism / insight	Key references
Resistance exercise	Upregulation of BDNF and IGF-1 for motor neuron survival and synaptic plasticity	[156,157]
	Stabilization of NMJs and promotion of axonal sprouting and reinnervation	[158]
	Muscle hypertrophy and metabolic recovery	[159]
Aerobic exercise	Enhancement of mitochondrial biogenesis and antioxidant defense (SOD1 and Glutathione peroxidase)	[160,161]
	Reduction of oxidative stress and inflammation may delay neurodegenerative cascades	[162]
Preclinical & clinical evidence	Moderate treadmill training improves motor coordination and extends survival in SOD1 mice	[125]
	Clinical trials show improved ALSFRS-R scores and reduced fatigue with structured exercise	[20,116]
	Guidelines recommend low-to-moderate aerobic / resistance exercise tailored to disease stage	[163]

Exercise prescription and supportive care across the ALS stages

Since neurodegeneration is progressive, exercise prescriptions must be matched to the ALS stage at the time of treatment. Efficient collateral reinnervation compensates for early focal denervation; therefore, the measured strength remains largely within normal limits despite active denervation and reinnervation cycling in the affected region during the early stages of ALS [115]. The timing and volume of exercise interventions are crucial for delaying NMJ denervation, as motor unit remodeling is a dynamic process rather than a simple unidirectional terminal consequence of motor neuron death in ALS. Exercise intervention at an early stage, before extensive denervation and motor neuron loss, slows disease progression [116]. Fast-fatigable motor units are preferentially vulnerable, whereas slow-oxidative units display relative resilience, resulting in fiber type grouping and a phenotypic shift toward slower and more oxidative muscle fibers during ALS progression [117]. Moderate-intensity resistance training prevents the loss of fast-fatigable motor units. It preserves the strength and functional capacity of the remaining motor units and delays the rate of functional decline; however, it does not reverse the underlying denervation process or halt disease progression.

During the middle stage of ALS, muscle weakness typically propagates contiguously from the site of onset to adjacent motor regions. Specifically, bulbar-onset disease characteristically progresses to the upper extremities before the lower limbs, whereas limb-onset disease exhibits a horizontal spread within the affected region [118]. Reduced voluntary muscle activity predisposes patients to disuse atrophy and progressive shortening of the muscle and connective tissue, which can lead to joint stiffness, contractures, and pain. As ALS progresses, exercise interventions shift from active strengthening to passive range of motion modalities and targeted stretching, rather than active training programs.

Preclinical and clinical evidence

Emerging evidence suggests that regular moderate-intensity exercise exerts a neuroprotective effect, potentially reducing the risk or delaying the onset of various neurodegenerative disorders. However, the relationship between physical activity and ALS pathogenesis remains controversial. Conflicting findings exist, particularly concerning the adverse effects of high-intensity exercise [119,120]. Although moderate activity is considered beneficial for maintaining neuromuscular functions, high-intensity professional-level physical activity increases the incidence of ALS. Observational studies and animal model studies suggest that an active lifestyle influences disease susceptibility in individuals with a genetic predisposition to ALS [121,122]. Exercise volume and intensity are critical factors in ALS management [123]. Excessive exercise induces muscle damage and potentially accelerates disease onset or progression, whereas moderate-intensity aerobic exercise exerts neuroprotective effects without overstressing vulnerable motor circuits [124]. Moderate-intensity exercise has demonstrated a consistent therapeutic potential in ALS, as supported by both animal and human studies. Moderate-intensity exercise delays disease onset, enhances motor coordination, and prolongs survival in SOD1G93A transgenic mice [125]. These benefits are mainly due to the enhanced preservation of the NMJ, improved mitochondrial function, and increased levels of neurotrophic factors. Clinical exercise intervention trials have reported that structured physical activity is safe and enhances muscle function in patients with ALS. Combining moderate-intensity aerobic and resistance training significantly improves ALS Functional Rating Scale-Revised (ALSFRS-R) scores and reduces fatigue scores [116]. Exercise improves mobility and respiratory functions in individuals with ALS by maintaining muscle strength and supporting respiratory capacity [19,20].

Synergistic Effect of Gene-targeted Therapy with Exercise Rehabilitation

Current clinical rehabilitation guidelines for ALS recommend a combination of moderate aerobic exercise and light resistance training. Specifically, personalized exercise prescriptions should account for ALS stage, neuromuscular function, and fatigue tolerance to ensure both safety and optimal therapeutic outcomes. ALS gene therapies targeting cryptic splicing sites of STMN2 and UNC13A via ASOs and snRNPs restore axonal integrity and regeneration capacity across diverse ALS models, including sALS patient-derived iPSCs [14,15]. However, exercise rehabilitation following ALS gene therapy has not yet been studied, as the STMN2 ASO clinical trial remains in the early stages. ANQUR (QRL-201-01), a first-in-class Phase 1/2 clinical trial of STMN2 ASO therapy, evaluated only patients with early-stage ALS. ASO distribution was observed across the spinal cord and motor cortex. STMN2 mis-splicing was corrected, and STMN2 protein levels were significantly increased. This therapy also produced a statistically significant and clinically meaningful reduction in the ALS biomarker levels.

ASO gene therapy for neuromuscular diseases has been extensively studied in SMA, a disease caused by mis-splicing. Combined exercise intervention with splice-modified SMA gene therapy resulted in functional gains and upregulation of skeletal muscle growth pathway signals [126]. A previous study enrolled adults with genetically confirmed type 3 SMA who exhibited a limited capacity for intensive activity but could walk independently, representing a phenotypic profile comparable to that of patients with early-stage ALS. Combining gene therapy with targeted physical interventions in non-ambulatory children with type 2 SMA having a disease severity comparable to that of middle-stage ALS enhances motor performance and reduces serum and cerebrospinal fluid levels of phosphorylated neurofilament heavy chain [127].

Future Directions and Conclusions

A comprehensive understanding of the heterogeneous landscape of ALS pathology is required to develop a multifaceted therapeutic approach. The strategic integration of precision genetic correction with functional rehabilitation, including personalized exercise interventions, aims to address both the underlying molecular etiology and the progressive motor dysfunction characteristics of ALS. Currently, FDA-approved drugs offer only modest, temporary neuroprotective effects; therefore, lifelong treatment is required. Gene-targeted therapies can halt the progression of motor neuron dysfunction by directly correcting fALS-associated genes and restoring mis-spliced STMN2 and UNC13A via a single administration, offering a significant advantage over current chronic treatments. The proposed gene-targeted therapy via base editing is fundamentally limited by its inability to reverse the established neuromuscular damage. Thus, reversing pre-existing neuromuscular atrophy or functional decline remains a significant challenge. Exercise interventions promote neuromuscular remodeling and functional recovery. To fully translate genetic correction and molecular stabilization into clinical recovery, integration with structured exercise rehabilitation is essential. The combination of exercise and gene therapy presents a promising therapeutic paradigm for ALS. Gene-targeted therapies are administered at an early stage to halt neurodegeneration and preserve motor neuron function. This neuromuscular stabilization subsequently allows personalized exercise rehabilitation to promote motor reinnervation, facilitate NMJ remodeling, and support skeletal muscle hypertrophy. Exercise not only facilitates muscular adaptation but also enhances neurobiological recovery by amplifying neurotrophic support, modulating systemic and neural inflammation, and reinforcing synaptic stability at the NMJ. These effects may act as potential synergists in gene-targeted therapies to correct the underlying mechanisms of ALS. However, this combined effect has not been directly demonstrated in patients with ALS. In the absence of gene-targeted treatments, exercise rehabilitation approaches for patients with ALS remain controversial. Strenuous and repeated physical activity is considered an environmental risk factor for ALS because the resultant excess ROS exacerbates the characteristic oxidative stress pathology in ALS [128]. This dual-phase strategy addresses both the underlying genetic pathology and functional motor deficits through integrated neurobiological and physiological recovery. However, the clinical application of genome editing therapy still faces significant obstacles. The development of neuron-specific adeno-associated viruses and lipid nanoparticle-based delivery systems has improved the efficiency, cell-type specificity, and safety of delivering genome-editing tools to the central nervous system. Integrating structure-based design, phage-assisted evolution, and artificial intelligence enables the optimization of precise genome-editing tools with minimal off-target effects for therapeutic applications. These innovations are critical for enhancing the clinical applications of ALS gene therapies. In summary, ALS is a complex, multifactorial neurodegenerative disease that requires a multidisciplinary therapeutic approach. Gene-targeted therapies enable the direct correction of genetic mutations and splicing abnormalities that drive ALS onset and progression, while exercise-based interventions concurrently provide critical functional recovery. Ultimately, this integrative strategy redefines the standard of care for ALS, shifting from symptom management to proactive, restorative care through the synchronization of genetic and physiological therapies. The integration of genetic- and exercise-based approaches offers a promising pathway toward personalized and functional restorative care for individuals living with ALS. Nevertheless, ALS gene therapy remains in its early clinical stages, and further preclinical and clinical studies are required to directly evaluate this therapeutic concept.