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.

Until Tofersen from Biogen, ALS drugs were only slightly slowing the disease. Tofersen aims to lower the levels of a specific mutation of SOD1. This therapy is probably a lifeboat for the patients with the matching SOD1 mutation. It's certainly slowing the disease progression, but only for a tiny portion of ALS patients less than 2%.

Not all patients with the right SOD1 mutation react to Tofersen similarly.

• People have two SOD1 genes in their cells and sometimes only one allele is mutated and the other can make up for the defective one. There are also other proteins named SOD2 and SOD3 that can assume partly the functions of SOD1.

• In the worst case with ASO medications, ALS patients are merely exchanging a defective protein with a lower production of the same protein. This is not a great perspective, a genetic therapy that makes cells produce the correct version of SOD1 would be better. Yet genetic therapies have their share of problems, including low efficiency and increased cancer risk.

All members of this protein family, transform a byproduct of the mitochondrial electron transport chain, into hydrogen peroxide and diatomic oxygen. Yet those two chemical species are themselves quite reactive. SOD1 is located in the cytoplasm of cells, SOD2 in their mitochondria, and SOD3 is extracellular.

In that case, where there is still one functional allele, it would be nice to check SOD1 levels in the body of patients treated with Tofersen. If it's too low (because of Tofersen) the therapy renders itself ineffective. This could be done by analyzing blood, but scientists reckon that checking SOD1 in CSF would be a better idea.

The discovery of children developing SOD1 Deficiency Syndrome (ISODDES) which is characterized by injury to the motor system, suggests that a too-low SOD1 antioxidant activity may be deleterious in humans. Measuring SOD1 activity in cerebrospinal fluid (CSF) in Tofersen-treated patients is recommended but difficult due to low concentration and the presence of the isoenzyme SOD3.

To assess SOD1 activity, the scientists propose to remove SOD3 from CSF samples with antibodies and subsequently measure the SOD1 activity. To propose this as a standard procedure for human beings is a bit weird. Repeatedly piercing the membranes that protect the spinal cord sounds like an unhealthy proposal, particularly if it's done to patients having motor neuron disease.

A recent publication provides a detailed overview of recent advances and challenges in the development of RNA therapies for neurodegenerative diseases, particularly for amyotrophic lateral sclerosis (ALS). Early immunotherapies targeting amyloid-β in Alzheimer's disease initially showed reductions in amyloid plaques but failed to prevent cognitive decline. The FDA recently approved lecanemab as the first disease-modifying drug for Alzheimer's disease. However, its benefits appear to be limited to the early stages of the disease, as it does not stop neurodegeneration or improve cognition. This highlights the difficulty of modifying neurodegenerative diseases, which often progress despite treatment.

Most cases of ALS are recognized as proteinopathies involving RNA dysregulation, but in others, such as those with mutations in superoxide dismutase 1 (SOD1), these abnormalities are absent, suggesting different pathogenetic pathways.

Nucleic acid-based therapies (NATs) represent an emerging treatment class that targets RNA rather than proteins. These agents act by degrading disease-associated mRNA or altering translation processes. For example, ASOs inhibit translation by disrupting ribosome assembly or degrading mRNA.

Although ASO approaches are both reasonable and scientifically sound, discernible clinical benefit has not always been observed in humans.

Three clinical trials using ASOs to reduce huntingtin (HTT) protein in Huntington’s disease have been halted because the therapies did not consistently reduce mutant HTT levels or improve clinical outcomes. A trial of one ASO, tominersen, caused unexpected worsening in patients who received higher doses. This has raised concerns about potential ASO toxicity due to off-target effects, immune responses, or loss of normal HTT function, which is essential for cellular health.

ASOs targeting toxic genes in ALS, such as TDP-43 in ALS, have shown promise in preclinical studies in extending life and restoring motor function in animal models. Yet, inhibitions of SOD1 and C9orf72 in mice show motor deficits and memory impairment over time, warning researchers of the potential risks of long-term ASO treatments. Clinical trials, such as the Phase III study of tofersen (an ASO targeting SOD1), have demonstrated a reduction in SOD1 mRNA, although clinical (i.e. visible) benefit has not been established.

Results from a Phase III trial of the ASO tofersen, which targets SOD1 mRNA in ALS, were reported in 2022. In this study, a total of 108 participants were enrolled, 60 of whom were classified in the faster progression subgroup. Approximately 7% of participants receiving tofersen experienced serious neurological adverse events, including myelitis, chemical or aseptic meningitis, and lumbar radiculopathy, but the pharmaceutical and medical community has highlighted the case of a Swedish patient who saw real benefit from his therapy.

A new study, ATLAS (NCT04856982), aims to test tofersen in asymptomatic, and some are thought to be presymptomatic, carriers of the SOD1 mutation to determine whether early intervention can delay the onset of ALS.

ASO-mediated inactivation in neurodegenerative diseases faces major challenges. By the time symptoms of ALS appear, motor neuron damage may be too advanced. Symptoms appear because compensatory mechanisms are exhausted. This is similar to Parkinson’s disease, where symptoms only appear after significant neuronal loss.

It is also likely that current ASOs are not very selective, and may reduce the production of essential proteins, causing side effects. Targeting mutations or aberrant transcripts specifically with more selective ASOs, such as those used in the PRECISION-HD trials, could help preserve healthy protein function.

Identifying sensitive biomarkers, such as elevated plasma TDP-43 or cryptic HDGFL2 levels, could help diagnose ALS before symptoms appear. This could allow for timely therapeutic interventions to slow or prevent neurodegeneration before it becomes irreversible.

In summary, RNA-based therapies such as ASOs offer hope for neurodegenerative diseases but face significant challenges.

Readers of this blog probably know the story of the drug NP001. One phase I and two phase II trials were conducted by Neuraltus in ALS patients (NCT01281631 and NCT02794857). These were both 6-month studies, the usual clinical trial duration. Phase 2A was completed in 2012, and Phase 2B in 2017. Both failed. Now some people want to revive this drug, through a new biotech named Neuvivo.

What the authors of a new publication did was to try to find a subset of patients that showed some longer survival with NP001 in those old trials.

This is a widely used technique by unsuccessful companies, but it is statistically meaningless.

The authors found a subset of patients who had inflammation and a longer survival. Yet this analysis would be comically wrong if we were not speaking of dying people. For example, the authors claim that survival of ALS patients with inflammation is 16 months longer than in the placebo arm. At 72 months there were only 3 people in the inflammation subset and two people in the placebo arm. Nobody can say anything about these numbers. If we use the same criteria, it shows that NP001 worsened the condition in all pALS with respect to the placebo branch, as starting from 72 months there were fewer survivors in the NP001 arm than in the placebo.

In addition, one could read the subset of pALS with inflammation as them having a comorbidity. If you prescribe an inflammation therapy to people having inflammation, they will improve a bit, which would be reflected in longer survival to ALS.

The proposed mechanism of action is vague (as usual, at least here there is a proposal): They said that NP001 is converted by macrophages to taurine chloramine, a regulator of inflammation. As the authors assert that persistent immune activation in patients with ALS is the cause of loss of muscle, an anti-inflammatory drug would help.

There are few publications about taurine chloramine, but, when taurine is in the presence of highly toxic hypochlorous acid, it generates the less toxic taurine chloramine. It's the result of the body's mitigation to a poison.