**5. Clinical trials in ALS**

8 Amyotrophic Lateral Sclerosis

 Anti-aggregation drugs. Cellular aggregates of proteins, such as the Bunina bodies, occur in the neuronal somata of ALS patients. The prevention of these cellular aggregates may also increase the survival of motor neurons. The subcellular component involved in the degradation of aggregates is the endoplasmic reticulum (ER). Defects in ER function may contribute to the formation of the protein aggregates, as well as the

 Suppliers of cellular energy. In ALS, mitochondrial dysfunction contributes to the cellular energy loss. Thus the prevention of neuronal energy depletion may increase

 Anti-oxidants. The generation of reactive oxygen species (ROS), such as H2O2, can produce major damage to the neuron. Thus specialized cellular systems exist in the cell to prevent oxidative damage. One of these systems include [Cu,Zn]-superoxide

SOD1 reduction techniques. The clearance of the mutated and dysfunctional SOD1

 Inducers of intraaxonal transport. Molecules that signal damage in the bouton terminal are transported to the neuronal soma. In ALS, this transport is retricted, thus the

Drugs supporting nerve-muscle transmission. Defects in the transmission at the

 Stabilizers of the neuro-vascular unit. The loss of proteins at the tight junctions may disrupt the neuro-vascular unit. Thus molecules stabilizing the tight junctions may

 Anti-inflammatory compounds. Neuroinflammation plays a role in the chronic detrimental processes occurring in the immediate microenvironment of the neuron. Neuroprotectants. Since neurodegeneration is the general mechanism in ALS progression, neuroprotective drugs may prevent or slow down neuronal break-

 Anti-apoptotic compounds. Cell death is the ultimate reason in the apoptotic cascade. Thus compounds preventing cell death may contribute to increased survival of motor

 Growth factors. Growth factors such as G-CSF, VEGF, GDNF and others can both stimulate the growth of novel neurons (neurogenesis) and the repair of damaged

Various techniques whereby muscles can be strengthened even in an environment

Gene therapy. In these approaches, the expression of endogenous proteins, such as

 Stem cell therapies. The transplantation of various sources, such as bone-marrow derived stem cells (BMSC), mesenchymal stem cells (MSC), or neuronal stem cells (NSC), may support the microenvironment and thus the survival of motor neurons, or

where motor neurons are degenerating, thus maintaining motor function.

supply new motor neurons by replacing apoptotic cells.

dismutase-1 (SOD1), of which mutations in humans can induce ALS.

protein may also positively influence motor neuron survival.

damage information reaches the peri-nuclear area only delayed.

neuromuscular junction may contribute to disease progress.

ameliorate the supply of neurons with substrates.

concentration.

down.

neurons.

neurons (neuroregeneration).

growth factors, are used to increase

inhibition of the proteasome.

and prolong neuronal survival.

transporters type-2 (EAAT2), which is regulating most of the extracellular glutamate

### **5.1 Programmed failure in clinical trials for ALS?**

In the typical process of drug development, preclinical data such as biochemical assays, cellular assays, and rodent models for the disease, lead to positive results with regard to predefined outcome parameters, for example, the increase in muscle strength, or survival time. For all of the drugs listed in the next section, promising preclinical data have been provided and published (for review, see (Ludolph & Sperfeld, 2005)). But why did the majority of the clinical trials fail, when preclinical data have been so promising?

Three major points came to my notice, when reviewing the literature: First, the animal models (mouse, rat, drosophila etc.) may either not sufficiently reflect the human pathology, or the animal pathology does not reflect human conditions (discussed in Green, 2002; Kiernan et al., 2011; Scott et al., 2008). Second, "ALS" is a clinical but not a pathophysiological entity. Thus, the inter-personal variability between patients is too big, and the inclusion criteria are too broad. Third, the design of the clinical trials may be insufficient (Aggarwal & Cudkowicz, 2008; Fornai et al., 2011; Kiernan et al., 2011; Maragakis, 2009), including:


In future clinical trials, these issues should be discussed and included into the design of clinical ALS trials (Borasio, 1997).

### **5.2 Consensus guidelines for ALS trials**

Therefore, a round table has been established to agree on minimal criteria for a "good" clinical trial (Miller et al., 1999). Of note, there have been substantial efforts also in other diseases such as stroke research to agree on clinical and pre-clinical guidelines for research, such as the "Stroke Therapy Academic Industry Roundtable (STAIR)" (STAIR - Stroke Treatment Academic Industry Roundtable, 2006).

In the following paragraphs, I will shortly summarize the consensus guidelines for ALS trial. The prerequisite for any ALS trial should be a substantial diagnosis according to the criteria defined by the World Federation of Neurology (see above). Moreover, the inclusion criteria should be handled strictly, including that both sporadic and familial ALS can be entered into the trial. The age of the patients should be limited between 18 and 85 years of age. Symptoms should show a disease progression within the first six months after onset, but not more than five years. Additionally, also exclusion criteria have been defined, for example, the patients should not show sensory abnormalities, dementia, other neurological diseases, they should not suffer from any uncompensated medical illness, substance abuse, or psychiatric illness. Of note, the patients should not be taking any other investigational drug.

The endpoints of the trial must be defined in advance, for example, survival time, muscle strength, or ventilator dependence are common endpoints. All trials should include a control group.

The quality of life should be assessed in every efficacy trial. The statistical analysis must be sound and planned with sufficient power. Any co-medication must be carefully reconsidered.

Amyotrophic Lateral Sclerosis: An Introduction to Treatment and Trials 11

AEOL-10150 is a metalloporphyrin scavenging reactive oxygen species (ROS) (Orrell, 2006). It has been tested for safety and tolerability in three phase I trials, but further development

Amantadine shows a weak NMDA receptor antagonism and anti-cholinergic effects. In a cross-over study with guanidine, no benefits for ALS patients have been described (Munsat

Anakinra is a recombinant antibody directed against the interleukin-1 receptor (IL-1R). IL-1 is involved in sustaining the neuroinflammatory process. Treatment with anakinra in the G93A-SOD1 transgenic mouse model of ALS extended the lifespan of the animals and decreased neuroinflammation (Meissner et al., 2010). Thus blocking of the IL-1R may be a potential target in decreasing the speed of ALS progression (van der Meer & Simon, 2010). Currently, a phase II study (NCT01277315), designed as a riluzole add-on study,

In a systematic review, no evidence for a benefit of anti-oxidant treatment with regard to survival, neither alone, nor in combination, has been described (Orrell et al., 2008). The antioxidants administered in ALS patients included vitamin E, acetylcysteine, L-methionine,

The small molecule arimoclomol is a co-inducer of heat-shock proteins (Phukan, 2010), namely of HSP70 (Brown, 2007). Thus it may be used to increase endogenous cellular protein repair and to prevent misfolding, or aggregation, of proteins by activating molecular

Arimoclomol was tested in two phase II studies to evaluate safety and efficacy in ALS patients (NCT00561366) and to find a dose range and to determine pharmacokinetic

Currently, arimoclomol is tested in a phase II/III trial in patients with SOD1-positive fALS

Arundic acid is an enantiomeric, three carbon atom homolog of valproic acid, with anti-

It was tested in two phase II studies, designed as riluzole add-on, in clinical ALS trials for long-term safety (NCT00694941) and safety and efficacy (NCT00403104). The original evaluation of the trials did not show statistically significant differences between groups, but the subgroup analysis showed a possible positive effect for patients in early stages, namely within 14 months after onset of symptoms. On the other hand, patients with longer disease

parameters (NCT00244244) (Cudkowicz et al., 2008; Lanka et al., 2009).

inflammatory and anti-glutamatergic effects (de Paulis, 2003).

onset showed negative outcome (Thomas Meyer, 2005).

**5.3.3 Amantadine (1-adamantylamine, 1-aminoadamantane)** 

investigates the safety and tolerability of anakinra in ALS.

**5.3.2 AEOL-10150** 

has been halted.

et al., 1981).

**5.3.4 Anakinra** 

**5.3.5 Antioxidants** 

**5.3.6 Arimoclomol (BRX-220)** 

**5.3.7 Arundic acid (ONO-2506)** 

chaperones (Kalmar & Greensmith, 2009).

and selenium.

(NCT00706147).

Since there has been an early release of information about the efficacy in clinical ALS trials, which had to be revoked after thorough analysis, any information with regard to the efficacy of an investigational drug should only be released when peer-reviewed publication is at least imminent (with the exception of scientific meetings). The investigator is responsible for any conflict of interest.

The design of ALS trials should comprehend three phases (Brooks, 1997). In phase I, toxicity and pharmacokinetics is tested. In phase II (pilot, exploratory, or screening trials) information is gathered about dose finding, preliminary efficacy, and further safety observations. In phase III, definitive efficacy and safety is evaluated. Phase I trials should incorporate a placebo control group and the follow-up should be at least six months. Phase II trials may use placebo controls, historic controls, or a crossover design. If the prospective therapeutic value aims at improvement of signs and symptoms, such as increased muscle strength or ameliorated function, the follow-up should be at least six months, whereas trials aiming at stabilization or slowing of deterioration should observe the patients' condition for at least 12 months (Bedlack, 2010). All phase III trials should be placebo-controlled. The endpoints should include at least the survival time, assessment of strength measured by maximum voluntary isometric contraction, pulmonary function, and functional performance by the ALS rating scale. Of course, an independent data and safety monitoring board should be established.

Of note, since survival times are rather short, many patients feel desperate and take unapproved medication out of the reach of a clinical trial. By establishing these consensus guidelines, this potentially dangerous drug use may be reduced (Ross, 2009).

### **5.3 Overview over drug candidates in clinical ALS trials**

In the following "inventory" of clinical trials in ALS, I will give an overview over drug candidates used in ALS trials. I have included all interventional clinical trials registered at Clinicaltrials.gov (http://clinicaltrials.gov/). Information on these trials can be obtained by accessing the website http://ClinicalTrials.gov/show/NCTxxx, where xxx stands for the registration number shown below.

Since there have been various clinical trials in the era before Clinicaltrials.gov required registration, and before a consensus conference established criteria for ALS trials (Miller et al., 1999), I have included some information on earlier trials. On the other hand, I excluded case reports, trials with nutritional supplements, and non-pharmacological therapeutic procedures such as plasma exchange, whole-body irridation, hyperbaric oxygenation, balneotherapy, cervico-dorsal electroshock therapy, adrenal cortex injection or stem cell injection, even when the stem cells are used as vehicles and vectors for the expression of biologicals.

Of note, this inventory is neither comprehensive, nor does it contain all available references due to space restriction. It is mainly based on a selective literature search in the PubMed database, and summarizes recent reviews in the field (Carlesi et al., 2011; Miller et al., 2005; Siciliano et al., 2010; Zinman & Cudkowicz, 2011; Zoccolella et al., 2009).

### **5.3.1 N-acetylcysteine**

The anti-oxidant N-acetylcysteine did not show efficacy in a phase II clinical trial (Louwerse et al., 1995).
