Albert A. Yen

Mutant SOD1G93A microglia are more neurotoxic relative to wild-type microglia

Recent studies suggest that microglia over‐expressing mutant human superoxide dismutase (mSOD1G93A) may contribute to motoneuron death in a transgenic mouse model of familial amyotrophic lateral sclerosis. To further assess the relative neurotoxicity of wild‐type microglia, mSOD1G93A microglia, and microglia over‐expressing wild‐type human SOD1, we used primary cultures of microglia and motoneurons in the presence and absence of lipopolysaccharide stimulation. Following activation with lipopolysaccharide, mSOD1G93A microglia released more nitric oxide, more superoxide, and less insulin‐like growth factor‐1 than wild‐type microglia. In microglia/motoneuron co‐cultures, mSOD1G93A microglia induced more motoneuron death and decreased neurite numbers and length compared with wild‐type microglia. Mutant SOD1G93A microglia also induced more motoneuron injury than microglia over‐expressing wild‐type human SOD1 in microglia/motoneuron co‐cultures. Motoneuron survival was inversely correlated with nitrate + nitrite concentrations in mSOD1G93A co‐cultures, suggesting the important role of nitric oxide in microglia‐induced motoneuron injury. Thus, relative to wild‐type microglia, mSOD1G93A microglia were more neurotoxic and induced more motoneuron injury than similarly treated wild‐type microglia.

Oxidative Stress: A common denominator in the pathogenesis of amyotrophic lateral sclerosis

Purpose of reviewAmyotrophic lateral sclerosis, or Lou Gehrig disease, is a progressive neurodegenerative disease of adult onset characterized by a loss of motor neurons in the spinal cord and motor cortex. In the last several years, substantial progress has been made in defining the pathogenesis of motor neuron injury and relationships between disease mechanisms and the selective vulnerability of the motor neuron in both familial and sporadic forms of amyotrophic lateral sclerosis. Recent findingsCurrent theories have shifted from a neuron-centered pathology to a focus on the interaction between motor neurons and glia, and their respective contributions to pathways implicated in amyotrophic lateral sclerosis. Although multiple mechanisms clearly can contribute to the pathogenesis of motor neuron injury, recent advances suggest that oxidative stress may play a significant role in the amplification, and possibly the initiation, of disease. SummaryThis article reviews the clinical aspects of amyotrophic lateral sclerosis and potential mechanisms of disease pathogenesis in the context of recent data supporting a major role for oxidative stress throughout the disease course. Evidence suggesting an important role for intercellular signaling is emphasized.

HFE mutations are not strongly associated with sporadic ALS

The presence of oxidative damage and increased iron deposition in CNS tissues of ALS patients prompted the authors to examine the prevalence of two common HFE gene mutations linked to iron accumulation and consequent oxidative stress. The prevalence of the C282Y and H63D mutations was nearly identical in 51 ALS patients and 47 normal control subjects. The presence of either mutation did not significantly affect the age at onset or rate of progression in ALS.

Predictability of disease progression in amyotrophic lateral sclerosis

The aim of this study was to determine the predictors of disease progression in a group of 832 patients with the diagnosis of definite or probable amyotrophic lateral sclerosis (ALS). Disease progression was defined as the time to 20‐point change in Appel ALS (AALS) score. The effects of individual prognostic factors on disease progression were assessed with the Kaplan–Meier life‐table method. In addition, the prognostic value of each factor was estimated using both univariate and multivariate Cox proportional hazard analyses. The median time to a 20‐point change in AALS score in our patient population was 9 months. Age, site of symptom onset, time between first symptom and first examination, total AALS score at first examination, and AALS preslope (rate of disease progression between first symptom and first examination) were significant and independent covariates of disease progression in our population. Identification of predictors of disease progression will facilitate better design of therapeutic trials, permitting the use of disease progression as a primary endpoint and improving baseline stratification of patient populations. Muscle Nerve, 2006

ALSFRS AND APPEL ALS SCORES : DISCORDANCE WITH DISEASE PROGRESSION

Progression of disease and effectiveness of therapy in patients with amyotrophic lateral sclerosis (ALS) are determined by both questionnaire‐ and examination‐based measures. To determine whether both types of measurement tools are equally predictive at all stages of disease, we compared questionnaire‐based ALS Functional Rating Scale (ALSFRS) scores to the examination‐based Appel ALS (AALS) scores at different stages of disease. Same‐day scores were obtained during 174 visits in 62 patients with definite or probable ALS. Using normalized scores, correlation between the scales and predictability were best in mildly affected patients. Predictions of ALSFRS based on AALS scores were less than half as precise in the later stages of disease. Both scales showed significant change with disease progression, but ALSFRS consistently underestimated disease severity defined by AALS (P < 0.001). Questionnaire‐based measurements should be compared against objective scales at all stages of disease severity before they are accepted as primary endpoint measures. Muscle Nerve, 2008

The value of database controls in pilot or futility studies in ALS

Objective: To evaluate the use and reliability of database controls in place of a placebo group in pilot or “futility” ALS trials. Methods: We compared the rates of disease progression in the placebo arm of the clinical phase III US Insulin-like Growth Factor-I Trial (n = 90) with the rates of disease progression of 207 patients with ALS selected from 1,600 ALS database patients using the same inclusion criteria. Results: The mean rates of change in the Appel ALS (AALS) score were nearly identical in the placebo group (4.70 points/month) and in the database group (4.79 points/month). In addition, there was no significant difference in the median time to achieving a 20-point progression in AALS score: 143 days for database match vs 146 days for the placebo group (log rank p = 0.88). Furthermore, in the multivariate Cox analysis, both the rate at which the disease had progressed prior to first exam (preslope) (p < 0.001) and first exam AALS total score (p = 0.01) were shown to be covariates of subsequent rate of disease progression. Conclusion: The similarity in disease progression between placebo arm of clinical phase III trial and matched database group suggests the value of historical databases in futility trials. However, the proposed study design requires appropriate matching of study patients with database controls. Based on our results, we suggest matching by stage of the disease and rate of clinical decline in a contemporaneous ALS population.

Slower disease progression and prolonged survival in contemporary patients with amyotrophic lateral sclerosis.

BACKGROUND In recent years, considerable effort has been made to improve the treatment of patients with amyotrophic lateral sclerosis (ALS). However, despite the increased use of supportive measures, controversy still exists about overall trends in disease progression and survival. OBJECTIVE To analyze whether survival and disease progression in patients with ALS have changed during the past 20 years. DESIGN By using the Kaplan-Meier life-table method, we compared disease progression (measured as time to a 20-point increase in the Appel ALS score) and survival in 1041 patients diagnosed as having ALS between January 1, 1984, and January 1, 1999 (historical group, n = 647), and between January 2, 1999, and November 1, 2004 (contemporary group, n = 394). The Cox proportional hazards model was used for univariate and multivariate analyses. RESULTS The median survival from symptom onset was 4.32 years (95% confidence interval [CI], 3.81-4.84 years) in the contemporary group compared with 3.22 years (95% CI, 3.04-3.41 years) in the historical group (P<.001). The contemporary patients progressed more slowly (10 months to a 20-point increase; 95% CI, 9-13 months) compared with patients in the historical group (9 months to a 20-point increase; 95% CI, 8-9 months) (P<.001). In the multivariate Cox proportional hazards model, the observed outcome improvement over time was independent of confounding factors, such as age, sex, diagnostic delay, site of symptom onset, baseline forced vital capacity, and baseline Appel ALS score, and independent of the use of potentially outcome-modifying therapies (riluzole, noninvasive ventilation, and percutaneous gastrostomy). CONCLUSIONS Contemporary patients had significantly prolonged survival and slower disease progression compared with patients from the historical group. The improved outcome seemed independent of specific ALS outcome-modifying therapies, but we cannot rule out an effect of comorbid conditions, which could have influenced medical treatment and survival. Nevertheless, our observations suggest the possibility that disease course has changed and that ALS is becoming less aggressive over time. Further studies are needed to determine whether there has been a fundamental change in the natural history of the disease or whether our results are because of other unmeasured aspects of improved multidisciplinary care.

Design using historical controls

Over the last 20 years, our clinic has evaluated and followed over 2100 patients, recording clinical data for each patient, and assessing the extent of dysfunction and rates of progression. This historical database provides a unique benchmark for carrying out ‘futility design’ experiments as described by Dr. Palesch, to assess whether therapies are sufficiently promising to warrant intensive investigation. This futility design could weed out ineffective drugs that probably should not proceed to Phase III studies, and permits a concentrated effort on drugs that have an increased likelihood of demonstrating efficacy. More than 1,000 patients have had two or more examinations, for a total of 6,000 examinations. Seventyfive percent of the patients had probable or definite ALS, and 9% were familial. Approximately 25% of patients presented with bulbar onset. The higher the age of onset, the more likely that patients will present with bulbar compromise. Females are more likely than males to present with bulbar compromise. In general, recent additions to our database have substantiated our prior publication, with one exception: we now agree that bulbar onset is associated with shorter survival at all ages, including both older and younger patients. The major question to be addressed in this discussion is how a historical database can be used most effectively in drug trials with the futility design. What are the relative strengths and limitations of such an approach? When evaluating the plotted clinical progression, we noted that many patients display a small lag before the course becomes linear. If you look at the design (Figure 1), the time from first symptom to a screening examination is the preslope. Next, we have from screening to baseline and then the 0–3 month prediction, which is very similar to when preslope is used. If you look at the pre-slope predicted versus the actual progression, there is very poor correlation. Similarly, if you compare the screening-to-baseline predicted to actual progression, there is also poor correlation. The best correlation with subsequent progression was found by using sequential examination scores from the first three months after the baseline examination. That gives us some confidence that it may be possible to use our database to weed out those drugs that are likely to be ineffective. We have used our database in validation studies as well as in determining potential efficacy of drugs to proceed to Phase III studies. First, to validate the database, we took all the placebo data from the Myotrophin (IGF-1) trial and looked at it in relation to our database. There were 90 placebo patients in the American trial, and there clearly was a statistical difference in slope of 25–26%. However, the placebos, intriguingly, matched our database when selecting patients with the same criteria (Figure 2, top). The same was done for riluzole. We had 199 patients who were on riluzole for at least six months, and we matched them against 459 patients who were not on riluzole, not on IGF, nor in any of our trials. Interestingly, we found no statistical difference in rate of progression (Figure 2, bottom). These have been the arguments that favor the use of a historical database, with some examples. I would like to highlight a point raised by Dr. Nigel Leigh which is that we have been very successful in our clinics – so successful that you might not be able to use a historical database. That is a reasonable concern; if you examine the data from 1983–87, compared to 1997–2001, the more-recent patients survived longer. Realizing that the introduction of newer medications and the wider use of supportive therapies may have contributed to improved patient survival, we excluded patients who were in the riluzole study and other patients who had been on riluzole or on myotrophin. Moreover, we tried to account for possible effects from BiPap respiratory assistance. However, we still found an improvement. Indeed, when comparing outcomes from the earlier time periods, 1983–87 and 1990–94, there was already an improvement in survival (Figure 3). In addition to survival time, improvement was also seen in the rates of disease progression; the patients from 1997–2001 changed less per month than the patients in the 1983–87 group. This improvement in survival and rate of progression raises a difficulty if we go back and use old database patients for the historical control, even for rejecting futility. This bias is not usually mentioned when the use of a historical database is being considered. Nevertheless, if looking for a substantial change, say 30%, comparison of efficacy of a tested compound to a historical database may still be a useful and meaningful first step, and may represent an appropriate ‘futility design’.