Memantine – yet another failed Autism Trial

Memantine (Namenda/ Ebixa) is an Alzheimer’s drug that has been used off-label in autism for many years; but does it actually work?

More than a thousand people with autism have completed clinical trials and yet more trials are in progress. 

A few years ago, at the FDA’s request, the producer of the drug, Forest Laboratories, funded two clinical trials enrolling 903 children with autism.  The results were never fully published because the trials were deemed to have failed to find any positive effect and a note to reflect this is included in each pack of Namenda.

A quick look at ClinicalTrials.gov website shows yet more autism trials in the pipeline.

What is going on?

When Dr Chez made a trial in 2007 he found Memantine to be effective; he has since moved on to stem cell therapy which he also finds to be effective.

The latest study to be published includes Dr Hardan from Stanford, who published that study showing NAC to be effective in autism.  This time his study shows no positive effect.

If you look on the clinical trials site you can see some data for the primary endpoint used in the very big trial funded by Forest Laboratories.  It seems to show 517 responders.

By the time the results were reviewed in detail the conclusion drawn by Forest was “there was no statistically significant difference in the loss of therapeutic response rates between patients randomized to remain on full-dose memantine (n=153) and those randomized to switch to placebo”. 

In other words it does not work.

The drug itself now carries this note:-

8.4 Pediatric Use

The safety and effectiveness of memantine in pediatric patients have not been established.

Memantine failed to demonstrate efficacy in two 12-week controlled clinical studies of 578 pediatric patients aged 6-12 years with autism spectrum disorders (ASD), including autism, Asperger’s disorder, and Pervasive Development Disorder — Not Otherwise Specified (PDD-NOS). Memantine has not been studied in pediatric patients under 6 years of age or over 12 years of age. Memantine treatment was initiated at 3 mg/day and the dose was escalated to the target dose (weight-based) by week 6. Oral doses of memantine 3, 6, 9, or 15 mg extended-release capsules were administered once daily to patients with weights < 20 kg, 20-39 kg, 40-59 kg and ≥ 60 kg, respectively.

In a randomized, 12-week double-blind, placebo-controlled parallel study (Study A) in patients with autism, there was no statistically significant difference in the Social Responsiveness Scale (SRS) total raw score between patients randomized to memantine (n=54) and those randomized to placebo (n=53). In a 12-week responder-enriched randomized withdrawal study (Study B) in 471 patients with ASD, there was no statistically significant difference in the loss of therapeutic response rates between patients randomized to remain on full-dose memantine (n=153) and those randomized to switch to placebo (n=158).

So if it does not work, why do researchers continue to carry out further trials, like the recent one below, including Hardan?

Safety and Efficacy of Memantine in Children with Autism: Randomized, Placebo-Controlled Study and Open-Label Extension

OBJECTIVE:

Abnormal glutamatergic neurotransmission is implicated in the pathophysiology of autism spectrum disorder (ASD). In this study, the safety, tolerability, and efficacy of the glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist memantine (once-daily extended-release [ER]) were investigated in children with autism in a randomized, placebo-controlled, 12 week trial and a 48 week open-label extension.

METHODS:

A total of 121 children 6-12 years of age with Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text Revision (DSM-IV-TR)-defined autistic disorder were randomized (1:1) to placebo or memantine ER for 12 weeks; 104 children entered the subsequent extension trial. Maximum memantine doses were determined by body weight and ranged from 3 to 15 mg/day.

RESULTS:

There was one serious adverse event (SAE) (affective disorder, with memantine) in the 12 week study and one SAE (lobar pneumonia) in the 48 week extension; both were deemed unrelated to treatment. Other AEs were considered mild or moderate and most were deemed not related to treatment. No clinically significant changes occurred in clinical laboratory values, vital signs, or electrocardiogram (ECG). There was no significant between-group difference on the primary efficacy outcome of caregiver/parent ratings on the Social Responsiveness Scale (SRS), although an improvement over baseline at Week 12 was observed in both groups. A trend for improvement at the end of the 48 week extension was observed. No improvements in the active group were observed on any of the secondary end-points, with one communication measure showing significant worsening with memantine compared with placebo (p = 0.02) after 12 weeks.

CONCLUSIONS:

This trial did not demonstrate clinical efficacy of memantine ER in autism; however, the tolerability and safety data were reassuring. Our results could inform future trial design in this population and may facilitate the investigation of memantine ER for other clinical applications.

  

Dr Chez? 

So how reliable then are Dr Chez’s other findings?  He is a "big name" in autism research.

Back in 2007 Dr Chez published a very positive study on the use of Memantine in autism. 

Memantine as adjunctive therapy in children diagnosed with autistic spectrum disorders: an observationof initial clinical response and maintenance tolerability.

 

Abstract

Autism and Pervasive Developmental Disorder Not Otherwise Specified are common developmental problems often seen by child neurologists. There are currently no cures for these lifelong and socially impairing conditions that affect core domains of human behavior such as language, social interaction, and social awareness. The etiology may be multifactorial and may include autoimmune, genetic, neuroanatomic, and possibly excessive glutaminergic mechanisms. Because memantine is a moderate affinity antagonist of the N-methylD-aspartic acid (NMDA) glutamate receptor, this drug was hypothesized to potentially modulate learning, block excessive glutamate effects that can include neuroinflammatory activity, and influence neuroglial activity in autism and Pervasive Developmental Disorder Not Otherwise Specified. Open-label add-on therapy was offered to 151 patients with prior diagnoses of autism or Pervasive Developmental Disorder Not Otherwise Specified over a 21-month period. To generate a clinician-derived Clinical Global Impression Improvement score for language, behavior, and self-stimulatory behaviors, the primary author observed the subjects and questioned their caretakers within 4 to 8 weeks of the initiation of therapy. Chronic maintenance therapy with the drug was continued if there were no negative side effects. Results showed significant improvements in open-label use for language function, social behavior, and self-stimulatory behaviors, although self-stimulatory behaviors comparatively improved to a lesser degree. Chronic use so far appears to have no serious side effects.

Making sense of Memantine

Personally, I think it likely that Memantine may indeed have a positive effect in some people with autism.  For most people it probably does no good, but no harm, so it is a harmless placebo that may make the parents feel better and gives the doctor something to prescribe.

Memantine and the very similar Galantamine probably do deserve a place in the long list of drugs and supplements that may be effective in some people.  But how great is that “effect”?  I suspect this is the problem; it is big enough for Dr Chez but not big enough for the others.

I suspect this will be a recurring problem in almost all future autism drug trials.  What is a responder?  How big an effect is a worthwhile effect?

I think a better approach would be to focus on the so-called responders identified by Dr Chez and others.  Document the claimed positive effects and then see if these effects continue when the responders are given a dummy placebo.

This is the approach I use in my trials; when I stop a therapy, I look to see if there is a change.  When you suspend an effective therapy things should get worse.

The hundreds or thousands of kids currently on Memantine should do the same; take a break and see if there is any change, be it positive or negative. 

Many people believe no valid treatments for autism exist and that those thinking otherwise are all deluded.

I think that many people are giving their kids drugs and supplements of no therapeutic value and in some cases are making the situation worse.

However, effective therapies do exist for many people with autism and they stand up to scrutiny.  The effect is apparent to third parties, like teachers and therapists, and when you stop the therapy the positive effect is lost and people notice, only to return when it is restarted.  Then you know it is not wishful thinking and at that point what the FDA says does not really matter and you do not need bother with what subsequent trials say.

So when a reader asked me what I thought about the recent “failed” trial of NAC, to treat social impairment in autism, I took a very relaxed view.  If they had identified 50 kids with classic autism and stereotypy and looked at whether NAC reduced this, I would take note.  They choose the wrong primary endpoint, social impairment, and wasted a lot of money.

A randomized placebo-controlled pilot study of N-acetylcysteine in youth with autism spectrum disorder

Conclusions
The results of this trial indicate that NAC treatment was well tolerated, had the expected effect of boosting GSH production, but had no significant impact on social impairment in youth with ASD.

      

I only wait to see what happens when Ben Ari publishes the results of his large trial on Bumetanide.  Whatever data they choose to collect, is it going to convince the European Medicines Agency that it is an effective therapy?  I hope so, but nothing would surprise me.

I would love to know how Dr Chez rationalizes the fact that so many others cannot replicate his positive research findings.  But he keeps on going.

Rather off-topic, a recent comment on my post on Clonidine, informed us that this drug, often prescribed off-label in autism and ADHD, really is acting as a sedative to calm the person down. So no effect on core autism.  Sedation does have a role to play in some people’s disorders.  Very low doses of Mirtazapine (Remeron) are also sedating via its effect of central H1 receptors; it occurred to me that this might be a safe long term therapy for some "out of control" people with severe autism; likely safer than the usual antipsychotics.