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.

The current paper is about an untested hypothesis. Scientists have proposed thousands of assumptions about the etiology of ALS, and the same is true for many other diseases. Single-authored papers are often dismissed, as are papers that make wild hypotheses without trying to test them. I mention this paper because the single author is a remarkable scientist in the field, not one of the countless hacks who write a paper on ALS today with very little knowledge of the disease and will never write about it again.

Another reason might be because it may have some relation with a drug developed by Richard B. Silverman, and P. Hande Ozdinler at Northwestern University. AKAVA Therapeutics, started last year by Silverman, is carrying out studies of the drug AKV9 (ex NU-9).

This article discusses the possible relationship between sleep, the glymphatic system, and neurodegenerative diseases. It suggests that sleep issues might exacerbate ALS disease progression by impairing the brain's waste-clearance mechanisms and compromising neuronal health, but it does not describe any experiment. It also tells that neuron health is diminished when the organism is sleep-deprived, in particular neurons experience dendritic spine loss.

Sleep is crucial for brain health because the clearance of metabolic waste and the remodeling of synapses happens during sleep. Many ALS and Parkinson's patients experience sleep disturbances. Disrupted sleep patterns, especially those associated with conditions like sleep apnea, a condition where upper airways collapse during sleep, can lead to impaired glymphatic function. The author equals poor glymphatic function with accumulation of agglomerates of misfolded proteins in cellular cytosol. I am not sure there is any evidence of this relation.

The glymphatic system is responsible for clearing waste products from the brain, primarily during sleep. It is facilitated by cerebrospinal fluid (CSF) circulation. During sleep, the glymphatic system operates optimally, removing waste products from the brain. Impaired glymphatic clearance, especially when sleep is disrupted, might be a significant contributor to protein buildup and possibly subsequent neurodegeneration.

Evidence from studies shows a faster CSF clearance during sleep, suggesting that adequate sleep is crucial for maintaining brain health. Dysfunction of this system can contribute to the accumulation of toxic proteins, such as amyloid-beta and tau, associated with neurodegenerative diseases. Yet this clearance happens in the periphery of the brain, so it's hard to see how a good clearance would improve the health of those neurons that are deep inside the brain.

Early signs of neurodegeneration in ALS include the loss of dendritic spines. A dendritic spine is a small membrane protrusion from a neuron's dendrite that typically receives input from a single axon at the synapse. Motor neurons in the spinal cord, for example, can have a dense arrangement of dendritic spines in certain regions, as these neurons need to process a large number of excitatory and inhibitory signals to regulate muscle activity effectively. Sleep plays a vital role in spine pruning and remodeling, ensuring healthy neuronal connectivity.

Synaptic connections, especially dendritic spines, are dynamic and undergo constant remodeling, particularly during sleep. This process is crucial for maintaining neuronal network stability and function. Sleep deprivation or sleep apnea disrupts spine pruning, leading to excessive or unhealthy connections, which stresses neurons and hampers brain connectivity. Experiments show that even brief sleep deprivation reduces spine elimination, resulting in abnormal spine density and neuronal hyperactivity in brain areas like the hippocampus. This disruption may have a profound impact on memory and cognitive function.

Therefore investigating the relationship between sleep, glymphatic function, and biomarkers in CSF could lead to earlier diagnosis and more effective disease monitoring.

Yet, sleep is not routinely assessed in clinical diagnostics for neurodegeneration. Integrating sleep studies into patient assessments could enhance diagnostic precision and enable targeted interventions. Moreover, understanding the molecular changes in CSF associated with sleep problems could provide valuable biomarkers for monitoring disease progression. There’s potential for developing therapies focused on improving sleep quality, as addressing hypoxia and improving glymphatic function might reduce protein buildup and protect against neuronal damage.

A couple of days ago, I complained about the lack of publications on ALS metabolism in skeletal muscles, which represent only a tiny fraction of the huge number of ALS (mostly useless) publications.

Here is one article describing the evolution of the masseter muscle, one of the muscles of mastication, during the disease course in a SOD1 mice model. Why study the masseter muscle in ALS? Because it is one of the few skeletal muscles that is not affected by the disease. The authors observed that, despite a decrease in limb motor functions, the feeding function of these mice was preserved until the late stages of the disease. Remarkably, the masseter muscle showed no reduction in muscle volume, wet weight, or muscle fiber cross-sectional area. Furthermore, no changes were observed in muscle fiber types, indicating a possible resistance of the masseter muscle to ALS-induced impairment. A potential reason for the lack of atrophy in the masseter muscle could be its higher number of muscle satellite cells compared to that of the gastrocnemius muscle. This abundance may promote the maintenance of muscle fiber nuclei, thereby contributing to muscle tissue regeneration.

What they are saying in the background is: * Something is stressing the skeletal muscles in ALS, which looks quite a reasonable assumption to me. * Maybe it would be possible to design an ALS therapy targeting muscle satellite cells. This looks less likely to me.

While the authors promote the idea that the disease may, at least partly, start in muscles, I can't help myself thinking that maybe the reason it is preserved is simply that this muscle (as for eye movements) is activated by the trigeminal nerve which is usually preserved in ALS.

It seems to me that in spinal ALS, the longer motoneurones fail early (hands, feet) and the shorter ones survive longer. Indeed in bulbar ALS, the situation is reversed, but ALS mice models attempt only to model spinal ALS. So in my opinion, the authors should have considered that the lack of wasting of mice's masseter muscle may stem from a still functioning trigeminal nerve.

We previously reported that Memantine was found ineffective in an ALS clinical trial for the fifth time. Several articles about persistent failure in ALS clinical trials appeared in the last issue of The Lancet Journal.

Trial designs for motor neuron disease in the 21st century

A new era of drug discovery for amyotrophic lateral sclerosis

Scientists attribute Memantine's (and the many other drugs that were tried) lack of efficacy to the "complexity of the pathophysiological mechanisms."

In simpler words, they have no idea why it failed, yet it was tested for the fifth time in ALS, so in a rational world, they should, on the contrary, have expected it to fail. In addition, no pre-clinical studies have shown any special value of Memantine in ALS.

And it's not only about Memantine, hundreds of drugs with dozens of different mechanisms of action have been trialed in ALS, as well as in other neurodegenerative diseases. For example, in the same journal issue, there are the results of the ROCK-ALS phase II clinical trial which has a purported mechanism of action entirely different from the usual suspects (glutamate excitotoxicity, impaired proteostasis, autophagy, and neuroinflammation).

Clearly, scientists know nearly nothing about these diseases, otherwise, they would concentrate their efforts on specific drugs.

It is time to reconsider century-old and unquestioned assumptions about these diseases. What makes ALS patients die? Skeletal muscle wasting which leads to respiratory failure. Efforts should concentrate in this direction. We also know that ALS is not always a death sentence, for example Stephen Hawking lived 76 years and 55 years with the disease. We know that a BMI in the 27 range helps for survivability, yet publications on ALS metabolism in skeletal muscles represent only a tiny fraction of the huge amount of ALS publications. In 2023 there were only 23 publications on this topic, versus 2507 publications on ALS.

Why this situation? Laboratories and CRO are not organized to study whole-body mechanisms in large mammals. It would cost a lot, universities and biotech prefer to work on small rodents or even worse on immortalized cell lines.

There is also the question of the time span, most studies are conducted within 6 months, or even two months, because students are used as a cheap workforce. You can't detect any statistically meaningful clinical change in neurodegenerative diseases in two months.

Studies must last at least one year and use large mammals, if possible mammals which have a corticospinal tract similar to ours, with direct connection between upper and lower motor neurons for fine control of skeletal muscles such as in hands..

A recent publication poses a question that has become increasingly pressing in the face of numerous unsuccessful trials for the treatment of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. "Why is the treatment and management of amyotrophic lateral sclerosis so difficult?"

The article suggests that when a phase II clinical trial succeeds while its phase III trial fails, it's because they have a different profile of patient population.

The authors argue that because they recruit fewer patients, the characteristics of patients enrolled in phase II trials are more homogeneous than those in phase III trials, which aim to recruit hundreds of participants. This is contrary to what statistics teaches.

I also find this hypothesis unlikely, given the constraints on patient recruitment and the sensitivity of principal investigators to the fragility of ALS diagnoses and the variability of patient phenotypes.

The authors also propose specifically that edaravone and Relyvrio (AMX0035) phase II studies yielded better results than their phase III studies. However, the phase II trials for these two drugs did not provide clear evidence of a therapeutic benefit, only showing marginal improvements in the ALSFR-R criterion, which is known to be influenced by non-medical factors such as access to better equipment. Relyvrio/AMX0035 in particuliar benefited from the intense pressure by ALS organisations. It should be noted that one of these organisations would have financially greatly benefited in a market authorization.

Furthermore, post-hoc analyses, which are often favored by drug manufacturers, are statistically unreliable. It is too easy to select favorable results from a small sample and attribute them to a common characteristic, which is why large-scale clinical trials are necessary.

In my opinion, it is time to recognize that we are on the wrong track in relying on molecular biology experts to develop treatments for neurodegenerative diseases. The current pharmacological approach is heavily influenced by our understanding of communicable diseases, where identifying the pathogen and suppressing it can lead to recovery. Molecular biology is conceptually far removed from medicine, as it ignores cellular mechanisms, tissue-level interactions, physiological systems, and the complex interplay between organs.

I believe that we would be better served by acknowledging that neurodegenerative diseases are the result of a complex interplay of factors, including a patient's medical history, lifestyle, and environmental exposures. Each patient over the age of 50 likely has a unique combination of age-related neurological diseases, with some having a history of strokes, high-intensity sports, environmental toxins, or head trauma. Some may have also had a history of substance abuse or smoking.

In summary, I believe that neurodegenerative diseases are the result of a complex interplay of factors in a patient's history, rather than a single molecular event. Therefore, funding for most molecular biology efforts should be gradually shifted to regenerative medicine, which addresses the restoration of damaged tissues and organs.

Vitamin B12 injections are sometimes proposed by neurologists to ALS patients. Patients often decide to start the treatment because of the perceived low risk of side effects and the potential benefit to their quality of life. It is typically shipped as a sealed frozen package with several vials containing a 25-mg injectable dose. Patients are typically advised to inject 50 mg of B12 daily, which is 100 times the daily recommended dose. Usually, ALS patients recognize some benefits from the injections, such as increased energy, reduced fatigue, and improved balance. However, the high cost of injection, lack of insurance coverage, and inconsistent syringes are significant challenges faced by patients.

High-dose methylcobalamin treatment involves intramuscular injection of 25mg to 50mg of methylcobalamin twice a week, which is 50 to 100 times the dose of existing drug injections.

A phase II/III clinical trial for ALS patients was started in Japan, and the results were published in 2019. 373 ALS patients who had been onset for less than 3 years were recruited for a methylcobalamin clinical trial with three branches where patients have daily administrated 50mg, 25mg, or a placebo. It was conducted over 3.5 years. As a result, the methylcobalamin group showed a tendency to show better results in terms of the decline in ALSFRS-R, but the difference was not significant, and overall efficacy could not be demonstrated to Japanese authorities.

However, when a subanalysis was conducted only for patients who were enrolled within 12 months of onset (close to diagnostic), the 50 mg group, the 25 mg group, and the placebo group showed less decline in ALSFRS-R and a longer time to the primary endpoint. Post-analysis is frowned on because in small groups there are always statistical flukes and it's easy to cherry-pick some of these to prove whatever. But here the size of the trial was a bit larger than usual so there was more confidence in the findings.

The difference in decline in ALSFRS-R between the 50 mg group and the placebo group was statistically significant. Based on these results, a clinical trial (JETALS trial) was conducted in 2017 to confirm the reproducibility of the subanalysis, and the results were announced in May 2022. Results were reported on this blog.

In the JETALS study, 130 ALS patients within 12 months of onset were recruited and assigned to a twice-weekly 50 mg group or a placebo group. As a result, the reduction in ALSFRS-R score at 16 weeks was −2.66 in the methylcobalamin 50 mg group and −4.63 in the placebo group, which was significantly better in the active drug group.

There was no difference in side effects of the drug between placebo or methylcobalamin-treated participants. There was a marked reduction in serum homocysteine levels. Homocysteine is neurotoxic and has been associated with ALS cases but also with Alzheimer's and Parkinson's diseases. It may be a byproduct of methionine metabolism and there are a few studies that discuss the influence of diet on homocysteine via methionine in diet. High levels of methionine can be found in eggs, meat, and fish; sesame seeds, Brazil nuts.

These results are better than most previous drug results in ALS, but indeed it does not stop the disease progression. Based on these results, it was announced in January 2024 that a new drug application for methylcobalamin had been submitted in Japan.

Eisai Co. announced last week that it has obtained manufacturing and marketing authorization approval for amyotrophic lateral sclerosis (ALS) treatment “Rozebalamin® for Injection 25 mg” (mecobalamin) in Japan as a treatment for slowing progression of functional impairment in amyotrophic lateral sclerosis.

It should be noted that although there were statistically significant reductions in ALSFRS-R, other measures such as muscle strength, forced vital capacity, and the ALSAQ-40 total score, were not changed. This is a bit confusing as ALSFRS-R and ALSAQ-40 while not identical are similar enough, ALSAQ-40 adds a well-being dimension to the usual questionnaire. How could ALSFRS-R show an improvement if it's not reflected in ALSAQ-40?

As UK's Alsa-Mnd remarks, as the drug was only tested on participants early in the disease process, it is unclear if the treatment would be appropriate for participants with more advanced diseases.

In addition, Alsa-Mnd says it may not have been a truly blinded trial as methylcobalamin treatment results in a marked change in urine color which could mean that participants may have known whether they were receiving a placebo or methylcobalamin, and that could have influenced results (including a potential “nocebo” effect). This is supported by the fact that the placebo group appeared to worsen their rate of disease progression once the trial commenced.

It's possible that regulation agencies are afraid of the considerable political pressure from patient organizations who accuse them of being inactive, and that as for Alzheimer's disease and (temporarily) for AMX0035/Relyvrio they prefer to authorize new drugs even if they are ineffective, instead of waiting decades for an effective drug.

If our readers do not belong to academic or pharmaceutical circles, they certainly think that rationality guides the choice of drugs tested in clinical trials. They also certainly think a drug is tested in a clinical trial only if pre-clinical works show a strong signal of efficacy in the targeted disease.

We live in a human, imperfect world, but sometimes it borders on stupidity. Let's discuss the case of memantine. It's a drug that has been known for 60 years. It was bizarrely applied to a large variety of mostly unrelated diseases, like diabetes, OCD, autism, depression, Parkinson's, and Alzheimer's diseases as well as COVID-19.

In all these cases it had consistently shown it was ineffective. If one is especially interested in ALS, it's interesting to note that there is no published preclinical work on memantine in ALS.

Yet there were 5 clinical trials of memantine in ALS!

The latest had just published its results/ Two of them were phase III clinical trials, the others were phase II, so it cost probably $50M overall.

What is behind this strange behavior? Are we so irrational as a species to make repetitively so impressively huge mistakes?

One layperson may be troubled to learn that in ALS only, there were more than 500 unsuccessful clinical trials.

Every week academics are claiming to have made breakthroughs in neurodegenerative diseases. Obviously, most if not all of these claims were wrong.

It seems that academic and pharmaceutical scientists are just throwing spaghetti at the wall to see if it sticks. Most of them are paid well at the end of the month for doing crappy work, so why bother working harder?

Jean-Pierre Le Rouzic (my email is at the bottom of the page)