There have been several anti-glutamatergic agents that have been examined in ALS, and, in fact, the one drug that has prolonged survival is an anti-glutaminergic drug - Rilutek. Rilutek inhibits the release of glutamate and has prolonged the survival in the ALS mouse model. It has now been tested in two clinical trials in humans. There are now several other antiglutamate drugs that have been tested. Topamax, neurontin, low dose lamictal (lamotrogine), and dextromethorophan have shown no benefit. A drug by Lilly was promising but has not yet gone to trial (LY300164) or Talampanel. There is now an investigator driven effort to bring Talampanel to trial. Another drug that likely modifies glutamate by altering the transport protein for it is Ceftriaxone. A clinical trial of Ceftriaxone has recently been initiated. Finally, NAALADase ( N-acetylated alpha linked acidic dipeptidase) is a good candidate drug since it may simultaneously reduce glutamate production and decrease its release in the brain. However there have been no studies in humans yet.

Antiglutamate Strategies

Anti Glutamate Drug	Clinical Findings
Rilutek	Prolongs survival
LY300164 (Talampanel)	Encouraging Phase II
Topiramate	Negative
Gabapentin	No efficacy
Dextromethorphan	No efficacy
Lamotrigine	No efficacy (low dose)
Ceftriaxone	Enrolling Phase II-III
Memantine	Enrolling Phase II
NAALADase	Positive animal, no human studies

Trophic (growth inducing) factors that help to protect neurons from cell death have been studied in patients with ALS. To date, these neurotrophic factors in ALS have not shown clear benefits. There are ongoing trials of IGF-1, or Myotrophin, in process.

Another agent that may block apoptosis is now in a large Phase III trial headed by Dr. Paul Gordon at Columbia University; the antibiotic minocycline. This agent is an antibiotic that protects the mitochondria and helps to block the release of the protein Cytochrome C from the mitochondria (the energy powerhouse of all cells). Cytochrome C provides the signal to initiate cell death and minocycline appears to block this signal. It was recently shown to be effective in ALS mice.

TCH346 is a novel compound recently investigated as a treatment for ALS which did not have any efficacy. TCH346 interacts with a protein enzyme (GAPDH) which has recently been implicated in programmed cell death and this interaction seems to be important for the effect of TCH346 in models of nerve degeneration. TCH346 prevents the degeneration of neurons in a variety of tissue culture and animal models of programmed cell death. These preclinical findings provided the rationale for study of TCH346 in ALS.

Neurotrophic factors are chemicals in the body that preserve and nourish nerve cells including motor nerve cells. One possible way nerve cells die in ALS may relate to a lack of neurotrophins or an altered response by neurotrophins. These substances block or delay cell death or apoptosis. To date, neurotrophic factors including Xaliproden, BDNF, CNTF, Growth Hormone, and GDNF have not shown clear benefits. IGF1 (brand name Myotrophin) is a neurotrophic factor and like other neurotrophic factors, IGF1 has shown some protective effects on nerve cells in laboratory experiments. Previously Myotrophin was tested in patients with ALS in Europe and the United States but results of these trials conflicted, with the U.S. patients showing some benefit, while negative results were found in the European patients. The differences have been attributed to study design problems, and the U.S. Food and Drug Administration has asked for a third clinical trial to resolve the issue of Myotrophin’s safety and effectiveness in ALS. The present study is a longer study (two years) than the previous studies and will assess more direct measures of muscle strength. The objective of this study is to determine whether Myotrophin slows the progression of weakness in ALS. People may not notice a difference in symptoms, as Myotrophin is not expected to halt or reverse the weakness in ALS, but rather to slow its course. This is a double-blind, placebo-controlled study. The coordinating center is at the Mayo Clinic.

Buspirone is a commonly used antianxiety agent that is generally well tolerated. Its mechanism of action for treating anxiety is unknown but it has high affinity for serotonin receptors (special docking sites on brain cells). Buspirone may also mimic or stimulate the activity of endogenous (inside the body) neurotrophins (nerve-nourishing substances), such a nerve growth factor (NGF) and brain-derived growth factor (BDNF). Because of these actions, preliminary studies were conducted in mice with ALS. Initial results demonstrated improvements in pulmonary function compared to untreated littermates. It is theorized that buspirone treatment will result in short-term benefits in pulmonary function in patients with ALS. A double-masked, randomized, placebo-controlled clinical trial in which patients are assigned to receive buspirone or placebo has been initiated at Johns Hopkins University. Pulmonary function and respiratory symptoms will be followed over the course of this study.

Anti-Apoptotic and Neuroprotective Stategies

Anti-apoptotic/Neurotrophic	Results in Patients
Xaliproden (SR57746A)	Not clear
BDNF (subcutaneous)	Negative (two trials)
BDNF (intrathecal)	Negative
IGF-1 (Myotrophin)	1 positive, 1 negative, 1 in progress
CNTF	Negative
GDNF	Safety Concerns
Growth Hormone	Negative
TCH 346	Negative
Neuroimmunophilins	Not tested yet
Minocycline	Completed enrollment
Arimoclomol	Phase IIa completed

There have been several trials of antioxidants and mitochondrial buttressing agents as treatments in ALS. First several antioxidants have been tried in small studies, Vitamin E, N-acetylcysteine and deprenyl. Recently creatine has demonstrated neuroprotection in a mouse model of ALS but failed to show an effect in two recent trials in people with ALS. Co-enzyme Q10 has moderate benefit in mouse model of ALS and is also being tried in ALS patients in an ongoing clinical study at Columbia University. There will be a new trial of high doses of a liquid preparation of co-enzyme Q10 that has better absorption starting in the fall. Tamoxifen, an agent used in breast carcinoma patients, may also help to protect mitochondria and Phase II clinical trials have shown promising results. Aeolus Pharmaceuticals recently completed the initial Phase I clinical trial of their investigational drug, AEOL 10150, in people living with ALS. AEOL 10150 is part of a new class of small molecule catalytic antioxidants that destroy oxygen-derived free radicals. In pre-clinical animal studies, the catalytic antioxidants have been shown improve survival in ALS mice. Pramiprexole, an anti-Parkinsonian agent, has anti-oxidant actions and is now in a small Phase II trial in ALS patients. Hyperbaric oxygen has shown promising effects in a small group of patients as well. Arimoclomol is an agent that increases a neuroprotective protein called heat-shock protein. This provides both an anti-oxidant action and neurotrophic action. A Phase IIa trial has just been completed and a wider, efficacy directed Phase IIb trial is to start over the next 6 months.

Table 6: Anti Oxidants and Mitochondrial Buttressing Agents

Drug	Clinical Findings
Vitamin E	No effect
N-acetylcysteine	No effect
Deprenyl	No effect
Creatine low dose	No effect
Co-enzyme Q10	Phase II study
Manganoporphyrin AEOL 10150	Phase I
Pramiprexole	Phase II
Arimoclomol	Phase II
Hyperbaric oxygen	Phase I-II

Based on evidence that ALS may in part be due to autoimmune mechanisms, Dr. Stanley Appel at Baylor, is examining the effects of bone marrow transplantation in ALS. Recently, the clinical trial of Celebrex has been completed but showed no efficacy. Celebrex inhibits an inflammatory modulating protein called COX 2. COX 2 is present in the spinal cord and may play a role in releasing glutamate from cells in the spinal cord and also may promote oxidative damage to nerve cells. It has been shown that COX 2 expression is increased in the ALS mouse model and in spinal cords of ALS patients. COX 2 inhibitors have been shown to decrease glutamate toxicity in culture models and Celebrex, increased the survival in ALS mice. Other COX 2 inhibitors (Nimesulide) may come to trial in the future.

Other drugs that modify the inflammatory reaction in the brain include minocycline, Copaxone, Thalidomide, Lenolidomide, Celastrol and ONO 2506 (an analogue of depakote). These drugs capitalize on strategies to decrease the activity of the cells in the nervous system that cause damage at times of inflammation including microglia and astrocytes. Alternatively, they may block the molecules released by these cells responsible for the damage including molecules like TNF alpha or COX 2. Minocycline modifies the response of microglia, an inflammatory cell in the nervous system. Copaxone, a drug that modifies the inflammatory response in multiple sclerosis has shown neuroprotective effects in the mouse model of ALS and is presently in a Phase II trial in ALS patients. Thalidomide and its less toxic analogue lenolidomide, inhibit inflammation and TNF alpha. Thalidomide worked in the mouse model of ALS and a small Phase II trial is underway in people with ALS using the less toxic analogue of thalidomide, lenolidamide. ONO 2506 has a similar structure to depakote, an FDA approved anti-seizure medication. These drugs modify astrocyte reaction and decrease glutamate release. The ONO 2506 compound recently completed Phase II testing and there is a Phase III trial starting in Europe. Depakote is in a small Phase II study in the US. Celastrol is both an anti-inflammatory and anti-oxidant because it that blocks TNF alpha and IL1 beta molecules which increase inflammatory damage to nerve cells and decreases nitrous oxide (NO) which causes oxidative damage. Nimesulide is a potential drug candidate because it can inhibit COX 2. In animals it decreased COX 2 and slowed motor loss.

Table 7: Anti-Inflammatory Strategies

Drug	Results in Patients
Celebrex	No benefit
Copaxone	Enrolling Phase II
Lenalidomide	Enrolling Phase II
ONO 2506	Enrolling Phase II-III
Atorvastatin (Lipitor)	Enrolling Phase II
Celastrol	Animal studies
Nimesulide	Animal studies

Anti-viral agents:
The human immunodeficiency virus (HIV), which causes AIDS (acquired immunodeficiency syndrome), can cause an ALS-like syndrome that improves with treatment with antiviral drugs. Given this recent report of an ALS like illness in HIV infected patients a trial was carried out at Beth Israel Hospital with the antiviral agent Indinavir. Unfortunately, there was no effect on disease.

Oxandrolone:
Oxandrolone is a synthetic steroid of the “anabolic,” or tissue-building, type. It is similar in structure to the male hormone testosterone. Oxandrolone was tested in 12 people with ALS in an open label trial by Dr. Jeffrey Rothstein. It appears to have prevented a decrease in strength in some muscle groups, although it did not slow the weight loss associated with the disease, which was the primary question for this trial. The number of participants was not large enough for any definitive conclusions but provided enough information to consider Oxandrolone in conjunction with other compounds. It was well tolerated with few side effects.

Marinol
Dronabinol (brand name Marinol) is a marijuana-derived compound approved by the U.S. Food and Drug Administration for treatment in AIDS and cancer. Dr. Deborah Gelinas and Dr. Robert Miller from the MDA/ALS Center at California Pacific Medical Center in San Francisco have examined the drug in 20 people with ALS. During the three-month study the drug was well tolerated and there were improvements in sleep, appetite and spasticity (muscle tightness) noted. The researchers feel that the compound merits further study for its possible symptom relief and perhaps as a neuroprotective agent.

Stem Cell Safety Trial
A procedure in which bone marrow stem cells were taken from seven Italian ALS patients and implanted into their spinal cords appears to be safe and well tolerated, physician-investigator Letizia Mazzini announced. Establishing safety was the purpose of the trial. The seven patients, who apparently received stem cell transfers in October 2001, had no major problems, with the exception of pain after surgery.

Scriptaid
Scriptaid inhibits aggregation

Trehalose
Trehalose is a natural disaccharide used to prevent protein denaturation in freeze dried products and may prevent formation of mutant SOD aggregates.

Phenylbutyrate
Phenylbutyrate is used for hyperammonemia. It inhibits histone deacetylase and leads to increased gene transcription. It extended animal life by 21.9% in trials.

Tamoxifen
Tamoxifen inhibits protein kinase C, which mediates inflammation, It extends life in viral induced motor neuron death. Prolonged survival in Phase II study at 10-20-30-and 40 mg.

Other Drug Candidate	Clinical Findings
Scriptaid	No animal/human
Trehalose	No animal/human
Na Phenylbutyrate	Phase I-II
Sodium Valproate	Phase II
Tamoxifen	Phase II
Celastrol	Multidrug Trials: Creatine and Celebrex
Nimesulide