Preclinical studies are performed on a number of organisms, which scientists call "animal models of the disease." This concept is very vague and can involve everything from immortalized cancer cells to nematodes or fish. The most serious work is done on several standardized and commercial mouse models. This makes it possible in theory to compare work between laboratories, although this remains difficult in practice. However, commercial mouse models of disease are expensive and are almost useless for diseases like ALS, because the nervous system of mice is very different from the human nervous system. However, in preclinical studies, scientists look for clues that a drug might be useful, but it is not yet possible to prove that a drug will be effective in humans. One of the best things they can do at this stage is to show that a drug has a positive effect on several unrelated commercial animal models. The endoplasmic reticulum (ER) is an important organelle in cells that is involved in protein conformation. This step occurs after protein synthesis by ribosomes and after conformation, the new protein will be sent to its final destination by the Golgi apparatus. Protein conformation requires energy, so when disease occurs, the ER may not be able to properly conform the new proteins.

The accumulation of unfolded proteins leads to ER stress, followed by an adaptive response via activation of the unfolded protein response (UPR). Since folded proteins require energy, the unfolded protein response significantly slows down the production of new proteins. This is a way to cope with temporary stressful events, but it is not sustainable, as a cell that does not produce proteins is in a kind of stasis and will die quickly. Indeed, prolonged cellular stress activates apoptosis signaling leading to cell death.

Several studies have shown that impaired endoplasmic reticulum (ER) proteostasis is a pathogenic feature of ALS/FTD. Several drugs targeting the UPR in ALS have been proposed (GSK2606414, ISRIB, Guanabenz, Sephin1, Trazodone, KIRA), but none seem to be effective in ALS at this point.

There are different strategies, one is to stop the prolonged deleterious UPR in the hope that somehow the stressor has disappeared and the cell is healthy again. Another, on the contrary, tries to force an unfolded protein response state on all cells in the hope that the cell will be able to clear the backlog of accumulated misfolded proteins. However, the involvement of the UPR and the mechanisms by which ER stress contributes to pathogenesis are not entirely clear and can have contrasting or even opposing effects. Contributing to this complexity is that the UPR is actually several mechanisms.

The transcription factor XBP1s has several roles, one of them being that of regulator of the unfolded protein response. In a new publication, scientists provide evidence of suboptimal activation of the UPR in mouse models of ALS/FTD under experimental ER stress.

They designed a genetic therapy so that nervous system cells in ALS/FTD mouse models express the active form of XBP1 (XBP1s). XBP1s expression improved motor performance and extended lifespan in SOD1 mutant mice, associated with reduced protein aggregation.

It is important to note that AAV-XBP1 administration also attenuated disease progression in mouse models of TDP-43 and C9orf72 pathogenesis. As noted at the beginning of this text, most preclinical work in a single animal model is a bit suspect, especially when the animal model is not standardized but performed by administering a chemical that affects the nervous system.

ALS SOD1 disease is probably very different from TDP-43 and C9orf72 diseases. As SOD1 is an anti-oxidant, a mutated SOD1 protein probably protect less neurons from metabolism by-products. TDP-43 protein has many roles but one is to repair DNA in pluripotent stem cell-derived motor neurons. Most ALS patients have misfolded, aggregated fragments of TDP-43 in cell's cytosol which is weird as normally TDP-43 should be in cell's nucleus where it could repair DNA. C9orf72 is different again, in this disease the cellular ribosomes produce the wrong proteins from correct RNA, a so-called frameshift effect.

It is not clear how an XBP1s drug could benefit these three variants of ALS. However, if this is confirmed in humans, it would be good news because today, only one drug benefits ALS patients (Tofersen), but it benefits less than 1% of them. Having a drug that would benefit most patients would be extraordinary.

But we are not there yet, a first step would be to understand the mechanism of action of this drug in ALS

It's 2025, Happy New Year!

Since late 2018 this blog has comments on research on ALS, Parkinson's, and Alzheimer's diseases. My goal initially was to write a post every two days, with newly published research on Pubmed as input. This goal was impossible to reach because there is an immense activity but little valuable research on these topics.

Most articles are produced with an optic where quality is not important as long it's obscured by jargon. As publishing an article cost anywhere between $1000 and $4000, this is an incredible waste of money. Another aspect is that the articles about drugs' effects on immortalized cells, worms, or fishes, do not provide any hint that a drug might be useful for humans.

At a minimum such research to apply to humans must use animal models that are as large as humans and with a similar central nervous system. Only upper primates fit these requirements and the cost and ethics aspects are that kind of research almost never happen.

So I will try for a few months to write posts that briefly talk about publications that I feel have some merit.

Let's go!

• A medical case report recounts that an ALS patient was given a GLP1-inhibitor (a category of drugs including Ozempic). Indeed the "case" deteriorated quickly. Sometimes patients make bad encounters in white coats.

• Some good news came for ALS patients with a familial form. More than half of familial ALS cases are due to a nasty dysfunction in the mechanism that produces proteins. This study explores a novel approach to combat C9ORF72-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) using a CRISPR-Cas13-based RNA-targeting system. C9ORF72 mutations contribute to those diseases through three mechanisms: loss of C9ORF72 protein function, RNA toxicity from repeat-containing transcripts, and toxicity from dipeptide repeat (DPR) proteins. Current therapies, such as antisense oligonucleotides (ASOs) and miRNAs, face limitations, including transient effects and suboptimal targeting. The researchers developed RfxCas13d, a compact CRISPR-Cas13 variant, to target and degrade the pathogenic G4C2 repeat RNA in cellular and animal models. When delivered to the brain of a transgenic rodent model, this Cas13-based platform curbed the expression of the G4C2 repeats without affecting normal C9ORF72 levels.

• Another study demonstrates the potential of a CRISPR-CasRx-based approach for targeting both sense and antisense C9orf72 repeat transcripts. ASOs for the G4C2 repeat RNA developed by Wave Life Sciences and Ionis Pharmaceuticals and Biogen failed to show a benefit in human trials. Though the exact reason for this remains unknown, these ASOs targeted only the G4C2 (sense) repeat RNA and were thus presumed to not affect the G2C4 (antisense) transcript. This last study has the same overall goal as the first one but it targets both sense and antisense C9orf72 repeat transcripts. Yet the First study's RfxCas13d is a multiplexable enzyme. Thus, it has also the capacity to simultaneously target both the G4C2 (sense) and G2C4 (antisense) repeat RNAs from a single vector. Indeed there is a long road to transform these findings into efficient drugs, but it's a step in the right direction.

• In younger, healthy cells, the "normal" metabolic process is typically oxidative phosphorylation (OXPHOS), which occurs in the mitochondria. Healthy cells maintain a slightly alkaline intracellular pH (around 7.2 in the cytoplasm). However, during aging, cells may shift towards glycolysis (a process common in senescent cells), where the cytoplasm, not mitochondria consumes glucose to produce ATP with lactic acid as a side product. As neurodegenerative diseases are, in most cases, diseases of aged people, one layperson would expect that the cell shift in metabolism from mitochondria to cytoplasm and subsequent acidification are of the utmost importance. Unfortunately, it is not, and as usual, when scientists have no idea about something, they tell that this shift in aging metabolism is due to a combination of multiple factors. Joyal Xavier and colleagues wanted to understand the mechanisms associated with TDP-43 aggregation. TDP-43 expressing cell lines were exposed to either an acidic environment, a neutral environment, or sodium arsenate. Asparaginyl endopeptidase (AEP) has been implicated in the misfolding and aggregation of TDP-43 and other proteins implicated in neurodegenerative diseases because it is an enzyme that can cleave proteins in toxic fragments. They have observed the localization of TDP-43 in the mitochondria under normal pH conditions. However, under acidic conditions and after sodium arsenate exposure, they observed an increase in TDP43 levels in the mitochondria and nucleus. Alternatively, they observed a decrease in TDP43 in the mitochondria and nucleus following treatment with an asparaginyl endopeptidase inhibitor. My conclusion is that not much has been learned, yet it is a neglected research avenue that has some potential.

Les personnes qui présentent des problèmes de santé sont exposées à une stigmatisation, consciente ou inconsciente. La stigmatisation peut être ressentie ou effective. Dans le cas de la SLA/maladie dite "de Charcot", il y a une profonde dissonance entre la personne qui en général conserve toutes ses facultés mentales, mais subit une évolution si rapide de la maladie qu'il est difficile de s'y adapter et par ailleurs les interlocuteurs qui voyant un corps amaigri, sans force, assimilent la difficulté à parler, la bave et la tête penchante à des facultés intellectuelles défaillantes. Par ailleurs nos sociétés présentent incorrectement la santé comme étant l’état naturel, et donc est toujours accusatrice envers les malades qui auraient donc dilapidé leur « capital santé ». On trouve cela aussi chez les malades du cancer à qui bizarrement les médecins intiment sérieusement de « se battre » contre leur cancer comme si c’était de leur faute s’ils étaient malades et qu’il fallait qu’ils se battent pour obtenir une forme de rédemption.

La stigmatisation des patients atteint de la sclérose latérale amyotrophique/maladie du motoneurone (SLA/MND) augmente leur retrait social et réduit leur qualité de vie ainsi que l’utilisation des technologies et appareils d’assistance qui est si importante pour leur relatif confort et leur survie à long terme.

Je me rappelle un malade qui se plaignait avec humour du personnel médical qui haussait le ton pour lui parler comme s'il était sourd, quand il ne l'ignorait tout simplement pas et s’adressait à son accompagnateur pour lui demander comment lui, le malade, allait.

D'autres malades signalaient qu'ils étaient ignorés dans les conversations car inaudibles, jusqu'à ce qu'ils achètent un système d'amplification de la parole.

Par ailleurs, avoir la tête inclinée, baver, amène des regards insistants et dérangeants des personnes rencontrées quand elles ne sont pas des familiers du malade.

L'étude faisant l'objet de ce post rend compte de l'influence d'une série de ces facteurs sur la stigmatisation auto-perçue rapportée, si ces influences restent importantes au fil du temps et comment, le cas échéant, la stigmatisation varie au fil du temps. Elle est dérivée de l'étude Trajectories of Outcomes in Neurological Conditions-ALS (TONiC-ALS) au Royaume-Uni.

Les données collectées entre 2013 et 2019 ont été utilisées pour cette analyse afin d'éviter l'influence éventuelle de la pandémie de Covid sur les comportements. Les participants ayant complété un questionnaire de base étaient éligibles pour un suivi avec des questionnaires répétés à au moins 4 mois d'intervalle, avec un intervalle de 11 mois entre le début et le premier suivi. Les chercheurs ont suivi les participants sur 30 mois.

Au total, 1059 personnes atteintes de SLA/MND ont contribué à cette analyse. Avec un âge moyen de 65 ans, la durée moyenne depuis le diagnostic était de deux ans. Les deux tiers des malades étaient des hommes. La plupart des patients étaient mariés ou vivaient avec leur partenaire. Plus de la moitié étaient à un stade avancé de leur maladie. Un quart d'entre eux avait une maladie caractérisée par début bulbaire.

Le questionnaire portait sur les sujets suivants.

• La capacité physique, la fatigue, l'essoufflement.
• Les symptômes évidents comme la spasticité, les spasmes musculaires. Les crampes, la tête tombante, la bave ;
• La stigmatisation ressentie et effective.

Près de la moitié des personnes interrogées ont indiqué avoir éprouvé un essoufflement plus ou moins important. La plupart des participants ont également évoqué une raideur musculaire et une fatigue intense.

Plus de 80% des personnes ont indiqué avoir subi une forme de stigmatisation liée à leur maladie. Elles se sont senties gênées par leurs limitations physiques et ont parfois eu l'impression que les autres les jugeaient. Cette stigmatisation était particulièrement marquée chez les femmes, les personnes plus jeunes et celles dont la maladie avait débuté au niveau bulbaire.

La stigmatisation touche une grande partie des personnes atteintes de SLA/MND. Plus de 80% des participants ont déclaré en avoir souffert à un certain degré. Les rires et pleurs incontrôlés, les spasmes musculaires ou les troubles de la parole augmentent le risque de stigmatisation. Les patients plus jeunes présentant un début bulbaire et sans partenaire sont plus vulnérables. À l'inverse, un âge plus avancé et le fait d'être en couple peuvent réduire cette stigmatisation.

De plus, l'estime de soi joue un rôle crucial. Plus l'estime de soi est faible, plus la stigmatisation est élevée.

Durant les 30 mois de l'étude il a été observé que le niveau de stigmatisation pouvait varier au fil du temps.

Les chercheurs ont identifié trois groupes de personnes :

• Un groupe important (plus de 70%) : Ces personnes ont un niveau de stigmatisation élevé dès le début de l'étude et celui-ci a tendance à augmenter avec le temps. Elles ont généralement une moins bonne santé et une estime de soi plus faible.
• Les deux autres groupes : Ces personnes ont soit un niveau de stigmatisation faible et stable, soit un niveau qui évolue différemment.

L’étude comporte évidemment des limites. L’étude actuelle se limite au Royaume-Uni et concerne principalement des patients caucasiens.

En conclusion, la stigmatisation ressentie et effective est fréquemment perçue par les personnes atteintes de SLA/MND. Les personnes plus jeunes et celles présentant un début bulbaire, ainsi que celles présentant une labilité émotionnelle, de la fatigue et de la spasticité ou des stades cliniques plus avancés sont plus à risque de cette stigmatisation.

Introduction This is a well-done study of ALS patients, but it will not provide new information to specialists in the field.

The survival time of patients after a diagnosis of ALS is variable, although death generally occurs about 2 to 5 years after the onset of symptoms, with a mean survival of 20 to 50 months, and only about 5 to 10% of those affected survive 10 years or more. In addition, earlier age at symptom onset and diagnosis, spinal onset, higher initial ALSFRS-R score, or higher body mass index (BMI) have been associated with longer survival. In contrast, older age, bulbar onset, cognitive impairment or depression, and poorer nutritional status are associated with shorter survival.

Although several authors have described the clinical and epidemiological characteristics and factors related to the survival of patients with ALS, few studies have been conducted in the Spanish population. This study is therefore one of the few to evaluate the epidemiological and clinical characteristics and prognostic factors of ALS in Spain, and it provides similar results to previous population studies.

A population-based registry data analysis over a long study period provides up-to-date, representative, and complete information on patients with ALS, which is useful for planning the necessary resources for affected individuals and their families. Therefore, this study aimed to determine the incidence and prevalence of patients with ALS, as well as their main characteristics, and to analyze the factors associated with the evolution and survival of these individuals using information from the Rare Disease Registry in the Region of Murcia (RM), located in the southeast of Spain.

Study population

An observational study was conducted on patients with a confirmed or probable diagnosis of ALS according to the El Escorial criteria and registered in the Rare Disease Information System (SIER) of the RM from January 2008 to December 2021. The data collected from each patient included the following:

• Data include gender, country of birth, date of birth, death of the patient (yes/no) and date of death.
• Family history of the disease, i.e. those including a family member with a diagnosis of ALS. The associated genetic mutation was collected in patients who underwent genetic study.
• Characteristics included year of diagnosis, date of symptom onset, and initial disease presentation (bulbar, spinal, bulbospinal, or respiratory). Time from symptom onset to diagnosis (years) and from symptom onset to death (years) were also recorded.
• Initial clinical manifestations collected were: muscle weakness (cervical, upper limbs, lower limbs, or both), dysarthria, dysphagia, dyspnea, gait alteration and clumsiness, muscle atrophy (upper limbs, lower limbs, or all limbs), muscle cramps, loss of dexterity, fasciculations (lingual, upper limbs, lower limbs, mixed), spasticity, and emotional lability (Citation35).
• Information on riluzole treatment, family support, palliative care, and the patient's last wishes were obtained. Finally, data were collected on the recognition of disability and/or dependency.

Statistical analysis

Demographic, genetic, and clinical characteristics of people with ALS were summarized using descriptive statistics. In addition, different hypothesis contrast tests were used depending on the type of variables and the normality of their data distribution. Survival was calculated from the age of symptom onset to the age of death (end event) or until December 31, 2021, or until loss to follow-up.

Results

781 cases of ALS were recorded in the SIER, 508 were of which were classified as confirmed or probable cases, including 374 incidents from 2008 to 2021.

The standardized incidence rate (SIR) was approximately 2/100,000 person-years. It was higher in men than in women. An increase in incidence was observed with age, with a maximum of data between 75 and 84 years, followed by an overall decrease. However, in men, the highest incidence was in the 65-74 age group. Throughout the study, incidence rates ranged from 2/100,000 person-years in 2008 to 2.77/100,000 in 2021), with the latter year being the year with the highest incidence recorded.

There was a family history of the disease in 28 patients (7.5%). Among patients for whom information on the causative genetic mutation was available, 55.5% were associated with the C9orf72 gene, 22.2% with the FUS gene, and the remaining 22.2% with other genes.

According to the site of onset, spinal ALS was predominant in half of the patients, followed by bulbar ALS in one-third of the cases. Dual pathologies (bulbar and spinal) were considerably less frequent and cases where the onset of the disease was characterized by respiratory symptoms were rare. In the remaining 8.3% of the cases, this information was not available.

The more frequent site of onset in men was spinal ALS, while in women it was bulbar ALS but less clearly. In analyses by age group, spinal onset predominated up to 74 years, after which bulbar onset had the highest incidence.

The mean time from symptom onset to diagnosis was less than 1 year, with no significant differences between the sexes. However, when analyzed by site of onset (bulbar or spinal), the diagnostic delay was slightly shorter for bulbar ALS.

Overall, the most common clinical manifestations at disease onset were muscle weakness (71.1%), followed by fasciculations (66.0%), muscle atrophy (61.2%), and gait alteration/clumsiness (53.0%). Patients with bulbar ALS had more dysarthria and dysphagia as their initial symptom (over 80% in both cases), while those classified as spinal ALS had mainly muscle weakness, atrophy, fasciculations, and gait alteration/clumsiness.

Interestingly, only 9 out of 10 patients were treated with riluzole, and more distressingly, less than half of the cases had their disability recognized. The average time from diagnosis of ALS to recognition of disability was one year, and the average time to dependency was one and a half years.

Half of the patients received palliative care, three-quarters of them had family support, and more than a third recorded their last wishes. Among these, most of them refused to receive palliative measures but accepted final sedation, while 15% of them on the contrary accepted any measure that could have prolonged their life.

During the study period, 297 people died (8 out of 10), half of them were men, and the average age at death was 70 years, without significant differences between genders.

The mean number of years between the onset of symptoms and death was 2.6 and the median was 2 years (there were more early deaths than deaths after these two years). 85% of patients survived more than 1 year after diagnosis, 12% more than 5 years, and 1% more than 10 years, which is lower than the 5 to 10% reported by other authors.

Here is a summary of an interesting article on how ALS clinical trials could be improved.

Introduction

Clinical trials typically proceed sequentially, through early, middle, and late phases, often referred to as Phases 1, 2, and 3. Phase 2 trials are generally designed to gather information about the safety, tolerability, and dosing of an experimental treatment, and to determine whether the therapeutic agent shows sufficient promise to warrant further study in a large, randomized, controlled Phase 3 study. In the field of amyotrophic lateral sclerosis (ALS), approximately several dozen drugs showed “promise” in phase 2 but failed in phase 3.

Much has been written about the many potential reasons why so many trials have led to so few effective treatments and how we might learn from this experience.

Duration

Historically, phase 2 trials in ALS have varied in duration, but a 6-month placebo-controlled phase followed by an open-label extension (OLE) seems to have become a common standard, for example the Healey Platform trial. The phase 3 VALOR study of tofersen in SOD1 ALS provides useful information on the length of time needed for a clinical trial in ALS. In this 6-month trial, significant reductions in CSF SOD1 protein levels (a marker of target engagement) and plasma neurofilament light chain (NfL) (a marker of axonal degeneration rate) were observed at 12 weeks. A meaningful clinical benefit did not emerge until 12 months in an integrated analysis of double-blind and open-label extension (OLE) data.

The long latency is notable given that the SOD1 ASO targets a biological mechanism that causes disease. This study showed that clinical benefits may take time to be detectable. Longer treatment periods may be required for clinical effects to become apparent for therapies that target more downstream biological mechanisms.

The VALOR study also showed that a significant reduction in NfL was detected over a shorter time period than meaningful clinical effects, providing an early confidence signal, later reflected in the FDA’s groundbreaking recognition of NfL as a “reasonable surrogate marker predicting clinical benefit in ALS” in its decision to grant accelerated approval to tofersen. The problem of a long latency to show clinical benefit is not unique to the ALSFRS-R.

A short study duration therefore risks missing potential delayed clinical effects, increasing the likelihood of a false negative result. This risk can be partially mitigated by implementing an OLE (non-randomized extended drug availability), which allows time for delayed effects to become evident during the extension phase. A long OLE, however, cannot fully compensate for a short placebo-controlled period.

But the longer the OLE period, the more similar the groups become, diluting a potentially effective treatment effect and possibly increasing the risk of statistical error. The results of these studies are confounded by incomplete follow-up, differences between completers and non-completers, and selection bias in those eligible for treatment.

Outcome measures

The ALSFRS-R measures the patient's functional independence with a set of activities that reflect bulbar, fine motor, gross motor, and respiratory muscle function. It is a relatively subjective measure of patient functioning, and a slower rate of decline, or a higher score, correlates with longer survival. The heterogeneity in the rate of disease progression among patients, manifested by enormous variation in the rate of change in the ALSFRS-R, generally makes phase 2 trials that rely on the ALSFRS-R or similar subjective measures of insignificance. The use of the ALSFRS-R is preferable in phase 3 trials that aim to answer questions of clinical efficacy.

In addition, the selection of the ALSFRS-R as the primary outcome measure for a phase 2 trial suggests a desire to demonstrate clinical efficacy. An overreliance on the ALSFRS-R as the primary outcome measure may also lead investigators to seek drug approval based on a single phase 2 trial of small size, as was the case for AMX0035.

If the ALSFRS-R is to be used in phase 2 trials, these results need to be supported by biomarkers, such as baseline blood NfL and the ENCALS prediction score. Although much is not yet known about NfL, it is undoubtedly one of the most promising candidates to date to help select participants for a phase 3 study.

Missing Data

For both trial duration and primary endpoint selection, the question arises as to how best to deal with missing data, whether due to death, treatment interruption, or patient “evaporation.”

Strategies such as the last observation carried forward (LOCF) used in the masitinib phase 2/3 trials, the edaravone phase 3 trials, and the post-hoc analyses of the CENTAUR AMX0035 trial data are subject to bias given the assumption that the outcome is constant after treatment is stopped. This is difficult to justify for diseases such as ALS, which are progressive over time, particularly when instruments such as the ALSFRS-R are used to measure the outcome.

This problem was well illustrated in the FDA’s analysis of the CENTAUR trial data, where differential treatment of deaths with accompanying missing data showed a loss of statistical significance.

The Dangers of Statistical Manipulation

Multiplicity is an important consideration in the analysis of clinical trial data. It occurs when multiple significance tests are performed, for example, opportunistic and dishonest selection of different outcomes such as measuring outcomes at multiple time points, using multiple doses, or different study populations and subgroups. Performing a statistical test at p < 0.05 has a 5% chance of finding a false positive on one type of measurement, but increases to 40% for performing ten statistical tests.

Interpretation and communication

The lack of biological and mechanistic information on many failed drugs significantly limits the lessons that can be learned from them.

The absence of primary and secondary outcomes in the main study population, but the discovery of a “hit” in one (or more) exploratory outcomes in a subpopulation, even if pre-specified, especially when financial considerations are taken into account, leads to a real risk of over-optimistic interpretation and unbalanced (and dishonest) communication of results. The release of the results of several recent trials provides a useful recent example.

Not only is there a risk that the discovery of false positives will encourage large, necessarily costly, and time-consuming phase 3 trials, but also a demand from patients for expanded access programs (EAPs) based on the promise of new and hypothetical therapies. Moreover, the appropriation of significant funds by political personnel for such purposes, motivated by “advocacy” by patient organizations and manipulation of opinion via social media, can divert valuable research funds from more promising therapeutic candidates and clinical trials. There is also a risk that the ALS community will be given false hopes about the potential clinical benefits of these investigational compounds based on minimal data.

Although "post-hoc" analysis of phase 2 trial data can sometimes lead to the generation of new hypotheses that could be tested in a future study, a distinction must be made between phase 3 trials that are based on a hypothesis that was tested in phase 2 and a hypothesis that was generated on the basis of phase 2 data and is, therefore, more fragile because it did not benefit from preclinical testing.

The risks associated with predicting phase 3 trials on the results of post-hoc exploratory analyses of phase 2 data are well illustrated by the experience with dexpramipexole, reldesemtiv, and NurOwn. Overreliance on clinical endpoints, short duration of placebo-controlled follow-up, and multiplicity, combined with overly optimistic reporting, have jeopardized the entry criteria and predictive value of phase 2 results for phase 3 outcomes. This problem was also clearly illustrated by the major negative phase 3 results for edaravone, AMX0035, and tauroursodeoxycholic acid. Each of these studies was preceded by positive clinical results in small, short trials, which were the primary drivers of the decision to proceed to phase 3.

Basing decisions on biological and mechanistic considerations could significantly reduce the risks of initiating Phase 3. While there is a risk that go-ahead criteria based on biological markers, such as NfL or other mechanistic markers, may not guarantee translation to clinically meaningful Phase 3 results, this approach could help to select better which drugs to test.

Premature Approval of Drugs

Regulatory approval of drugs based on Phase 2 data carries risks and benefits. It is certainly permissible for a company or group to advocate for early access to a drug with a favorable safety and tolerability profile while a confirmatory Phase 3 trial is underway, but approval of a drug based on limited evidence should not be confused with proof of efficacy.

My conclusion One development that seems likely to the author of this post is that future ALS clinical trials will address a smaller (and more homogeneous) population. This will ultimately make it even more difficult to conduct trials when the population with ALS available for trials is already very small.

Spinal muscular atrophy (SMA) is a disease whose manifestations have some similarities with ALS, however, it has a well-identified genetic origin (SMN1 gene) and as a result, several drugs have been approved. These drugs improve the health of patients but have various drawbacks.

This rare disease causes the loss of motor neurons and progressive muscle atrophy. It is usually diagnosed in early childhood and, if left untreated, it often leads to death. It can also appear later in life and in this case the disease progresses more slowly.

The common feature is a progressive weakness of voluntary muscles, with the muscles of the arms, legs and airways being affected first. Associated problems can include poor head control, difficulty swallowing, scoliosis, and joint contractures. Although there is a large literature on the split hand phenomenon in ALS, knowledge remains limited for other motor neuron diseases, including SMA.

Early in ALS it is common for the thenar muscles (thumb muscles) to be affected and lose their usual volume, visually dividing the palm into two sections. This is oddly described as the split hand phenomenon or monkey hand phenomenon.

This phenomenon reflects the selective vulnerability of motor neurons characteristic of the disease. Conditions such as ALS, while also affecting motor neurons, tend to present with the classic split hand pattern, highlighting the differential pathophysiological mechanisms at play. However, the explanations for why these muscles are affected early in the disease are no clearer than in ALS. Furthermore, age-related atrophy can also present with the split hand phenomenon, complicating the diagnosis of ALS in older patients.

Muscle disuse is a common cause of muscle atrophy. The rate of muscle atrophy due to disuse is about 0.5% of total muscle mass per day. Older adults are most vulnerable to dramatic muscle loss with immobility. In SMA, as in ALS, loss of motor neuron function leads to muscle atrophy. A new study compared these losses in ALS and SMA.

To assess muscle loss in motor neuron diseases, the number of motor units is studied. A motor unit includes a motor neuron and all the skeletal muscle fibers innervated by the neuron's axon terminals, including the neuromuscular junctions between the neuron and the fibers. Groups of motor units often work together as a motor pool to coordinate the contractions of a single muscle.

The number of motor units per muscle can change due to aging, disease, or injury.

Motor unit number estimation (MUNE) is a technique that uses electromyography to estimate the number of motor units in a muscle.

Motor unit number estimation (MUNE) methods, such as MScanFit MUNE, provide accurate results. This study uses MScanFit MUNE to compare patterns of motor unit loss in SMA, ALS, and healthy controls. Key findings include:

Patients with SMA had more severe degeneration of the hypothenar muscles compared to the thenar muscles. The authors call this: The reverse split-hand phenomenon, in reference to the split-hand phenomenon in ALS. Patients with ALS had a traditional split-hand phenomenon, with more severe involvement of the thenar muscles.

Reinnervation in SMA: Evidence of compensatory nerve sprouting in the ADM muscle has been noted in SMA but not in ALS, highlighting distinct pathophysiological mechanisms in these two diseases.

For SMA, the APB muscle has emerged as an optimal biomarker to monitor disease progression and therapeutic response due to its resistance to degeneration.

Curiously, although the authors confirmed the correlation between MScanFit MUNE neurophysiological parameters and disease severity in SMA patients, they did not find convincing correlations between MUNE neurophysiological parameters and clinical variables in ALS patients, particularly with the ALSFRS-R scale. On this issue, although several studies have reported the correlation between MUNE values ​​and the ALSFRS-R scale, others have not confirmed it.

Limitations and future directions The small cohort of AMS in the study and the lack of longitudinal data (over a period of several years) limit the conclusions. Future research should examine whether the reverse split hand phenomenon is exclusive to SMA and clarify why certain hand muscles are more vulnerable.

In this blog, I avoid studies that are not done on humans, firstly because the further away from humans and primates, the less sincere the scientific studies are. Then it is well known that the pre-clinical studies published are all extremely positive in order to attract investors (if possible private) who will finance clinical studies.

2,4-dinitrophenol (DNP)

The study examined here explores whether small doses of 2,4-dinitrophenol, a chemical used in the manufacture of pesticides and slimming drugs because it decreases the metabolic action of mitochondria, could help protect motor neurons, preserve muscle function and slow the progression of amyotrophic lateral sclerosis (ALS) in a mouse model of the disease. The scientists' guiding idea therefore seems to be to slow down the disease, by slowing down the metabolism. This seems absolutely counter-intuitive but the scientists assure that they have had good results. The effective dose of 2,4-dinitrophenol was very low (0.5–1 mg/kg, human equivalent dose 2.5–5 mg/day), making it safer for potential use in humans. Dinitrophenol acts as a proton transporter in the mitochondrial membrane, inhibiting oxidative phosphorylation of ATP and making energy production less efficient. This is because some of the energy that is normally produced from cellular respiration is wasted as heat. This inefficiency is proportional to the dose of dinitrophenol that is absorbed. Thus, as the dose increases, energy production becomes less efficient: metabolism is then activated - more fat is burned - to compensate for the inefficiency and meet energy demands.

The researchers used hSOD1G93A mice, a common model of ALS, to test the effects of 2,4-dinitrophenol on motor skills, muscle strength, and disease progression. However, it is important to remember that most ALS patients do not have this mutation and that its notoriety is simply because it was the first mutation to be associated with ALS and that for more than 10 years (from 1993 to 2006) no other deleterious mutations were discovered in ALS.

Results

Mice treated with microdoses of 2,4-dinitrophenol (0.5–1 mg/kg) showed better motor coordination and better results on tests measuring muscle strength, compared to untreated mice. Early treatment initiation (before symptoms appeared) delayed the onset of motor decline, while late treatment initiation (after symptoms appeared) improved motor skills (which were already impaired by the disease) and slowed disease progression. Treated mice retained their ability to perform tasks such as running at 20 cm/s for longer than untreated diseased mice. In some cases, the mice regained lost motor skills, which is unusual in ALS research.

Although ALS damages the connections between nerves and muscles (neuromuscular junctions), treatment with 2,4-dinitrophenol preserved these connections. Treated mice retained a higher number of motor units (groups of muscle fibers controlled by a single neuron), indicating that motor neuron loss was reduced.

Reduced Cellular Stress

2,4-dinitrophenol reduced oxidative stress, a harmful process linked to the progression of ALS. This was demonstrated by lower levels of damaged proteins in treated muscles. While ​​slowing down an ALS patient’s metabolism seems pretty criminal, reducing cellular stress is a very good idea.

The drug also reduced inflammation and activated pathways (like Akt/mTOR) involved in muscle growth and repair.

How would 2,4-dinitrophenol work?

2,4-dinitrophenol acts on mitochondria, the energy producers of cells, by slightly lowering their membrane potential (∆Ψm). This mild “uncoupling” reduces the production of harmful reactive oxygen species (ROS), which can damage cells. 2,4-dinitrophenol may also help clear damaged mitochondria and promote the formation of healthy mitochondria, further protecting neurons and muscles.

Future Directions

While the mouse results are promising, translating these findings to humans requires more research. The study also highlighted some limitations:

• It focused on one type of ALS model (hSOD1G93A) that affects less than 2% of patients.

• It did not address potential differences in drug responses between male and female mice, which could be significant.

• Administering a metabolic reducer to ALS patients still seems like a dangerous notion.

In recent years, research has shown that physical exercise has many benefits for the entire body, beyond muscle growth. There has been much discussion in recent years about the value of physical activity programs in the case of Alzheimer's or Parkinson's disease.

Researchers at MIT wrote about experiments that might lend credence to the idea that mechanical stimulation could one day be beneficial in ALS or other MND diseases.

Muscles release various biochemical factors, called myokines, which circulate in the bloodstream. These molecules establish a kind of dialogue between different tissues and this allows them to collectively adapt to a new environment. Myokine receptors are found in muscle, fat, liver, pancreas, bone, heart, immune system and brain cells. The location of these receptors reflects the fact that myokines have multiple functions. First, they are involved in the metabolic changes associated with exercise, as well as in the metabolic changes that follow adaptation to training. To study these effects specifically on motor neurons, the cells that transmit movement commands from the brain to muscles, MIT researchers developed a series of in vitro systems where they could precisely control and observe the effects of muscle contractions.

In 2023, Raman and his colleagues reported that they could restore mobility in mice that had suffered traumatic muscle injury by first implanting muscle tissue at the site of the injury and then exercising the new tissue by repeatedly stimulating it with light. Over time, they found that the exercised graft helped the mice regain motor function, reaching levels of activity comparable to those of healthy mice. This meant not only that the new muscle tissue had become functional, but also that there were somehow new connections between the lower motor neurons and the new muscles. In other words, the exercise was not only beneficial for the new muscle but also for the local motor neuron that develops synapses to connect to muscle fibers.

Then the group wondered: Could exercise’s purely physical impacts have a similar benefit on motor neurons?

This claim was met with some skepticism.

So the MIT team designed experiments in which the neurons were repeatedly pulled back and forth, similar to the way muscles contract and expand during exercise. Angel Bu is the first author, while Ritu Raman is the senior author; the other authors are from MIT’s Department of Mechanical Engineering and MIT’s Koch Institute for Integrative Cancer Research. The authors matured a set of motor neurons on a gel that was a kind of carpet into which they embedded tiny magnets. They then used an external magnet to shake the carpet—and the neurons—back and forth. In this way, they made the neurons work, for 30 minutes a day.

The researchers demonstrated that the physical force generated during muscle contraction has direct mechanical effects on motor neurons, promoting growth in both a biochemical and mechanical way. And the two effects, myokine release and motor neuron work, have similar effects.

These results could have important implications for the treatment of motor neuron diseases, such as amyotrophic lateral sclerosis (ALS) or spinal muscular atrophy, where motor neurons progressively lose their function. Therapies that mechanically stimulate muscle contractions could encourage nerve growth and regeneration, potentially slowing the progression of these diseases or facilitating recovery after nerve damage.

Of course, this study is extremely preliminary, it is carried out in vitro. We cannot even talk about micro-organs. This is basic research indeed, the authors didn't talk about applications in ALS/MND diseases. Another limitation of this study is that the authors did not explore a wide variety of mechanical or biochemical stimulation protocols with different frequencies, magnitudes, and durations.

If these mechanisms were confirmed in preclinical studies with primates and then clinical studies with humans, exercise protocols could be refined to maximize the biochemical and mechanical benefits for motor neurons, potentially improving motor function or slowing disease progression in patients with motor neuron diseases.

For example, patients could benefit from muscle stimulation devices that could help maintain or even regenerate motor neuron pathways. Mechanical muscle stimulation could indeed be a way to mimic the combined biochemical and mechanical effects of muscle contractions in patients with weakened muscles, potentially helping to slow neuronal degeneration or even stimulate nerve repair.

Electrical stimulators already exist for physiotherapy and rehabilitation, and future protocols could incorporate fine-tuning to produce exercise-like contractions that not only provide muscle benefits but also encourage motor neuron activity. Given that MND patients vary greatly in progression and severity, personalized electrical stimulation programs would be essential. Clinicians could develop individualized regimens, perhaps informed by biomarkers or real-time feedback, to maximize neuron growth-promoting effects without overloading the system.

Future research could test whether electrical muscle stimulation in MND patients produces benefits similar to biochemical and mechanical stimulation observed in vitro. If effective, this could lead to new physiotherapy protocols or devices aimed at improving the quality of life and motor function of people with MND.