The future of multiple sclerosis therapies: redesigning multiple sclerosis clinical trials in a new therapeutic eraa

Due to past success in testing and gaining regulatory approval for a variety of therapies in multiple sclerosis (MS), the conduct of future clinical trials has become increasingly problematic. An international workshop has met to discuss the issues facing the MS clinical trial community and to examine possible new strategies for the design of trials. Particular focus has been placed on trials that either avoid the use of a placebo because of ethical considerations or on designs that allow new therapies to be studied more rapidly or with fewer patients than needed in a conventional placebo-controlled trial. The discussions resulting from the workshop should provide a basis for the examination and implementation of innovative clinical trial designs in MS.

Proof of concept studies for tissue-protective agents in multiple sclerosis

BACKGROUND

There is considerable interest in tissue-protective treatments for multiple sclerosis (MS).

METHODS AND OBJECTIVES

We convened a group of MS clinical trialists and related researchers to discuss designs for proof of concept studies utilizing currently available data and assessment methods.

RESULTS

Our favored design was a randomized, double-blind, parallel-group study of active treatment versus placebo focusing on changes in brain volume from a post-baseline scan (3-6 months after starting treatment) to the final visit 1 year later. Study designs aimed at reducing residual deficits following acute exacerbations are less straightforward, depending greatly on the anticipated rapidity of treatment effect onset.

CONCLUSIONS

The next step would be to perform one or more studies of potential tissue-protective agents with these designs in mind, creating the longitudinal data necessary to refine endpoint selection, eligibility criteria, and sample size estimates for future trials.

Differential diagnosis of suspected multiple sclerosis: a consensus approach

BACKGROUND AND OBJECTIVES

Diagnosis of multiple sclerosis (MS) requires exclusion of diseases that could better explain the clinical and paraclinical findings. A systematic process for exclusion of alternative diagnoses has not been defined. An International Panel of MS experts developed consensus perspectives on MS differential diagnosis.

METHODS

Using available literature and consensus, we developed guidelines for MS differential diagnosis, focusing on exclusion of potential MS mimics, diagnosis of common initial isolated clinical syndromes, and differentiating between MS and non-MS idiopathic inflammatory demyelinating diseases.

RESULTS

We present recommendations for 1) clinical and paraclinical red flags suggesting alternative diagnoses to MS; 2) more precise definition of "clinically isolated syndromes" (CIS), often the first presentations of MS or its alternatives; 3) algorithms for diagnosis of three common CISs related to MS in the optic nerves, brainstem, and spinal cord; and 4) a classification scheme and diagnosis criteria for idiopathic inflammatory demyelinating disorders of the central nervous system.

CONCLUSIONS

Differential diagnosis leading to MS or alternatives is complex and a strong evidence base is lacking. Consensus-determined guidelines provide a practical path for diagnosis and will be useful for the non-MS specialist neurologist. Recommendations are made for future research to validate and support these guidelines. Guidance on the differential diagnosis process when MS is under consideration will enhance diagnostic accuracy and precision.

Magnetic resonance imaging as a surrogate outcome for multiple sclerosis relapses

BACKGROUND

Magnetic resonance imaging (MRI) of lesions in the brain may be the best current candidate for a surrogate biological marker of clinical outcomes in relapsing remitting multiple sclerosis (MS), based on its role as an objective indicator of disease pathology. No biological surrogate marker has yet been validated for MS clinical outcomes.

OBJECTIVE

The objective of this study was to use a multi-phased study to determine if a valid surrogate relationship could be demonstrated between counts of contrast enhancing lesions (CELs) and occurrence of relapses in MS.

METHODS

We examined correlations for the concurrent and predictive relationship between CELs over 6 months and MS relapses over the same 6 months and an additional 6 months (total: 12 months), using available data on untreated patients from a large clinical trial and natural history database.

RESULTS

Concurrent and predictive correlations were inadequate to justify continuation of this study to the planned additional phases required to demonstrate a surrogate relationship between CELs and MS relapses.

CONCLUSIONS

Confidence intervals for correlations between CELs and MS relapses exclude the possibility that CELs can be a good surrogate for relapses over the time scales we investigated. Further exploration of surrogacy between MRI measures and MS clinical outcomes may require improved datasets, the development of MRI techniques that couple better to clinical disease, and the ability to test a wide range of imaging- and clinically-based hypotheses for surrogacy.

Stem cell therapy in multiple sclerosis: promise and controversy

Stem cells offer the potential for regeneration of lost tissue in neurological disease, including multiple sclerosis (MS). Their development in vitro and their use in vivo in animal models of degenerative neurological disease and recent first efforts in human clinical trials were the topics of a recent international meeting sponsored by the Multiple Sclerosis International Federation and the National Multiple Sclerosis Society on “Stem Cells & MS: Prospects and Strategies” Participants reviewed the current state of knowledge about the potential use of stem and progenitor cells in MS and other degenerative neurological disorders and outlined a series of urgent fundamental and applied clinical research priorities that should allow the potential of regeneration of damaged tissue in MS to be assessed and pursued.

Recommended diagnostic criteria for multiple sclerosis: guidelines from the International Panel on the diagnosis of multiple sclerosis

The International Panel on MS Diagnosis presents revised diagnostic criteria for multiple sclerosis (MS). The focus remains on the objective demonstration of dissemination of lesions in both time and space. Magnetic resonance imaging is integrated with dinical and other paraclinical diagnostic methods. The revised criteria facilitate the diagnosis of MS in patients with a variety of presentations, including "monosymptomatic" disease suggestive of MS, disease with a typical relapsing-remitting course, and disease with insidious progression, without clear attacks and remissions. Previously used terms such as "clinically definite" and "probable MS" are no longer recommended. The outcome of a diagnostic evaluation is either MS, "possible MS" (for those at risk for MS, but for whom diagnostic evaluation is equivocal), or "not MS."

Placebo-controlled clinical trials in multiple sclerosis: ethical considerations. National Multiple Sclerosis Society (USA) Task Force on Placebo-Controlled Clinical Trials in MS

The availability of partially effective therapies for some forms of multiple sclerosis (MS) raises practical and ethical issues for future placebo-controlled clinical trials. An international Task Force of clinicians, statisticians, ethicists and regulators was convened to discuss these issues and develop consensus. The Task Force concluded that placebo-controlled clinical trials in forms of MS for which partially effective therapies exist were ethical, so long as study subjects were fully apprised of the availability of such therapies and were encouraged to pursue them outside of a clinical trial. Patients who decline to utilize available treatments, after proper education and counseling, or those that fail all therapies can be considered to have no treatment alternatives and thus may participate in a placebo-controlled trial.

The Multiple Sclerosis Functional Composite Measure (MSFC): an integrated approach to MS clinical outcome assessment. National MS Society Clinical Outcomes Assessment Task Force

Clinical outcome assessment in Multiple Sclerosis (MS) is challenging due to the diversity and fluctuating nature of MS symptoms. Traditional clinical scales such as the EDSS are inadequate in their assessment of key clinical dimensions of MS (e.g. , cognitive function), and they have psychometric limitations as well. Based on analyses of pooled data from natural history studies and from placebo groups in clinical trials, the National MS Society's Clinical Outcomes Assessment Task Force recently proposed a new multidimensional clinical outcome measure, the MS Functional Composite (MSFC). The MSFC comprises quantitative functional measures of three key clinical dimensions of MS: leg function/ambulation, arm/hand function, and cognitive function. Scores on component measures are converted to standard scores (z-scores), which are averaged to form a single MSFC score. Preliminary analyses confirm that: (1) the three clinical dimensions of the MSFC are relatively independent; (2) the MSFC is sensitive to clinical changes over 1- and 2-year intervals; and (3) the MSFC has acceptable criterion validity (i.e., predicts both concurrent and subsequent EDSS change). The advantages and potential limitations of incorporating quantitative functional outcome measures such as the MSFC into collaborative databases are discussed.

The role of magnetic resonance techniques in understanding and managing multiple sclerosis

Magnetic resonance (MR) techniques have had a major impact in the last 10-15 years in understanding and managing multiple sclerosis. This review summarizes the current uses of MR in multiple sclerosis, based on the proceedings of a recent international workshop, under four headings: (i) technical issues; (ii) role in diagnosis; (iii) natural history studies in understanding the disease; (iv) application in clinical trials. The theory and methodology of relevant technical issues is outlined, in order to provide a framework with which to understand the potential and limitations of MR in addressing biological and clinical questions in multiple sclerosis. The principles underlying signal-to-noise and contrast-to-noise ratio are discussed, along with the techniques and clinical results for conventional and fast spin echo T2-weighted imaging, fluid-attenuated inversion recovery, detection of blood-brain barrier break down and hypointense lesions on T1-weighted images, magnetization transfer, T2 decay-curve analysis, MR spectroscopy, spinal cord imaging, diffusion imaging, and quantification of lesion load and atrophy. MRI has an extremely valuable role in confirming the clinical diagnosis of multiple sclerosis. T2-weighted brain imaging remains the standard diagnostic tool, but in some instances it is usefully complemented with gadolinium enhancement and spinal imaging. The caveat that the diagnosis of multiple sclerosis remains primarily a clinical one cannot be over-emphasized. Serial MRI studies have added much to our understanding of the natural history and pathophysiology of the disease. Blood-brain barrier breakdown is a consistent early feature of new lesion development in relapsing-remitting and secondary progressive multiple, sclerosis, and this usually correlates with active inflammation and myelin breakdown. A number of the acute MR changes are reversible, but chronic persistent abnormalities in a number of MR parameters, such as reduced N-acetyl aspartate, low magnetization transfer ratios, atrophy and T1-hypointensity, suggest the presence of demyelination and/or axonal degeneration in many chronic lesions. The presence and extent of T2-weighted MRI abnormalities at first presentation with a clinically isolated syndrome suggestive of demyelination strongly predicts the risk of developing clinically definite multiple sclerosis in the next few years. In established multiple sclerosis, however, the correlations between T2 abnormalities and disability are modest. This poor relationship partly relates to the discrepancy between lesion site and function in attempting to correlate locomotor disability with brain MRI findings. However, the correlations between brain lesion load and cognitive dysfunction in multiple sclerosis, whilst more evident, are still modest. A more important limitation is the low pathological specificity of abnormalities seen on T2-weighted images. Stronger correlations have been found between disability and new putative MR markers for demyelination and/or axonal degeneration. Serial studies using multiple MR techniques are now needed to further clarify pathophysiological mechanisms in multiple sclerosis. Serial MR has become an important tool in monitoring treatment efficacy. It provides data which can be readily analysed in a blinded fashion and which directly inspects the pathological evolution; it also enables a rapid and sensitive measure of treatment outcome in early relapsing-remitting and secondary progressive disease. Because of the modest clinical correlations it is, however, still appropriate that the definitive determinant of treatment efficacy remains a clinical one. Further work is needed to address issues of quality control in serial studies, statistical calculation of appropriate sample sizes, and optimization of the nature and frequency of MR outcomes measured.

Defining the clinical course of multiple sclerosis: results of an international survey. National Multiple Sclerosis Society (USA) Advisory Committee on Clinical Trials of New Agents in Multiple Sclerosis

Standardization of terminology used to describe the pattern and course of MS is essential for mutual understanding between clinicians and investigators. It is particularly important in design of, and recruitment for, clinical trials statistically powered for expected outcomes for given patient populations with narrowly defined entry criteria. For agents that prove safe and effective for MS, knowledge of the patient populations in definitive clinical trials assists clinicians in determining who may ultimately benefit from use of the medication. An international survey of clinicians involved with MS revealed areas of consensus about some terms classically used to describe types of the disease and other areas for which there was lack of consensus. In this report, we provide a summary of the survey results and propose standardized definitions for the most common clinical courses of patients with MS.

Guidelines for the use of magnetic resonance techniques in monitoring the treatment of multiple sclerosis. US National MS Society Task Force

Because of the major difficulties in measuring clinical end points in multiple sclerosis (MS) treatment trials, there has been much enthusiasm for using magnetic resonance imaging (MRI) findings as an alternative outcome. To provide international consensus guidelines for the use of MRI in MS clinical trials, a task force of the US National MS Society was convened. The recommendations of the task force are presented in this review. Given the high sensitivity for detecting pathological activity in relapsing-remitting and secondary progressive MS, monthly T2-weighted and gadolinium-enhanced brain MRI is an excellent tool for short-term exploratory trials of new agents where it serves as the primary end point; in particular, failure to demonstrate a reduction in lesion activity avoids the time, cost, and risks of a larger clinical end point study. However, conventional MRI findings have a limited correlation with disability in established MS. The primary end point of a definitive trial should therefore be clinical, although serial MRI at 6- to 12-month intervals is a useful secondary end point in providing an index of pathological progression. In trials of patients presenting with clinically isolated syndromes suggestive of MS, MRI findings can be used in the entry criteria, and as a secondary outcome measure, but conversion to clinically definite MS should be the primary outcome. The pathological substrates of irreversible disability are demyelination and axonal loss. Putative magnetic resonance markers for these processes include decreased N-acetylaspartate on proton magnetic resonance spectroscopy, decreased magnetization transfer ratios, hypointensity on T1-weighted images, and loss of short T2 water fractions, some of which relate more closely to disability than conventional MRI findings. Further technical developments should lead to more accurate quantitation, greater pathological specificity, and stronger clinical correlations.

Outcomes assessment in multiple sclerosis clinical trials: a critical analysis

The feasibility and precision of clinical trials for the treatment of MS must be improved. Subsequent to the approval by the Food and Drug Administration of the United States of interferon beta-Ib as a safe and effective, though not curative, treatment for relapsing-remitting MS, the testing of other agents in this disease has been undertaken or is anticipated. This report summarises the discussions and recommendations of an international workshop held to review critically the elements of current MS therapeutic trials and to identify the most important aspects of clinical evaluation, study design and data analysis that would allow agents for MS to be tested as accurately, rapidly and economically as possible. While acknowledging the many uncertainties about the pathophysiology and natural history of MS, the workshop participants made recommendations about the preferred components to be used in the design of trials which may be different depending on the treatment goal and agent studied. It was concluded that the formulation of a useful clinical trial design must be based on specific guidelines for clinical scales and imaging for which task forces were recommended and subsequently appointed.

Advances in the understanding and treatment of multiple sclerosis. Boston, Massachusetts, USA, 28-29 October 1992

Basic and applied research on multiple sclerosis (MS) has become increasingly focused on the development and testing of new therapeutic agents for this devastating disease. After a generation or more of exposing patients to non-specific immunoregulatory and other agents that have been, at best, of minimum benefit and significant potential or actual toxicity, attention has turned to attempts to identify treatment modalities that might be used in a more specific, effective and safe fashion. This trend has not been lost on the emerging biotechnology industry, which tends to view MS as both a disease to be explored on its own and as a disease whose solution may also open doors into other chronic diseases of purported autoimmune etiology, such as rheumatoid arthritis, type I diabetes, and others. These trends toward an increasing biotechnological approach to MS, coupled with an academic and industrial focus on the disease, were the clear motivations behind a recent two-day conference entitled "Advances in the Understanding and Treatment of Multiple Sclerosis" held in Boston and sponsored by a commercial meeting planner, International Business Communications USA Conferences, Inc.

Neurological consequences of immune dysfunction: Lessons from HIV infection and multiple sclerosis

In a recent workshop held on Sanibel Island, Florida (18-21 January 1992), the two most common neuroimmunologic diseases of young adults, multiple sclerosis (MS) and HIV encephalopathy, were jointly discussed. The logic of assembling investigators from these two fields was based not on an assumed etiologic connection between MS and retroviral infection of the central nervous system (CNS), but rather in the hope of uncovering potential common pathogenic mechanisms, particularly as might relate to trafficking of mononuclear cells into the central nervous system, the distribution and function of macrophages and microglia, the structure and function of the blood-brain barrier, and the role of cytokines released by activated cells. Multiple sclerosis is a disease without a known etiologic agent or pathogenesis. While the causative agent for HIV leukoencephalopathy is known, the pathogenesis of the disease remains entirely enigmatic (a topic covered by R. Johnson). This meeting brought together two different groups of investigators to compare and contrast the diseases and to share perspectives, paradigms, and data with the aim of cross-fertilizing the disciplines and generating healthy hybrids.

Revised estimate of the prevalence of multiple sclerosis in the United States

Using three adjustments, we have revised a 1976 prevalence count for multiple sclerosis in the United States. The adjustments were made to data from a US national survey; they used 1990 population projections from the US Bureau of the Census, and results of investigations conducted in Weld and Larimer Countries, Colorado, and Olmsted County, Minnesota. It is estimated that approximately 250,000 to 350,000 persons in the United States in 1990 had physician-diagnosed multiple sclerosis.

[3H]-2-deoxyglucose autoradiography in a molluscan nervous system

We have used [3H]2-deoxyglucose autoradiography to correlate the labeling of individual neurons with electrical activity within the central nervous system of a terrestrial mollusc, Limax maximus. In an electrically quiescent control preparation where a single neuron is impaled with a glass microelectrode but not stimulated, several somata are uniformly labeled at 3-5 times background. In preparations where a single cell is impaled and stimulated, one or more somata are heavily labeled with [3H]2-deoxyglucose at 10-50 times tissue background. This technique may be useful for surveying metabolically active neurons during spontaneous and driven electrical activity.

Localization of[3H]-2-deoxyglucose in single molluscan neurones

The glucose analogue 2-deoxyglucose (2-DG) can be used quantitatively to measure metabolic activity and is widely used qualitatively for mapping functional activity in the brain. The resolution (meaning the full width at half maximum of the grain density distribution around a line source) of the technique using [14C]-2-DG and X-ray film is limited to about 100 micrometers. Attempts have been made to improve the resolution using [3H]-2-DG (ref. 6) and cellular resolution has been achieved in the goldfish retina and with cultured mouse neurones. An anatomical technique for mapping the metabolic activity of individual neurones would be useful for studying invertebrate central nervous systems, which are relatively simple and stereotyped compared to vertebrate brains. The [3H]-2-DG technique was applied to an invertebrate in a study of the Drosophila visual system, though without cellular resolution. We present here modifications of the [3H]-2-DG technique to demonstrate localization of 2-DG in single neurones of Limax maximus, a gastropod mollusc, with a resolution of less than 1 micrometer.

Feeding motor programme in Limax. II. Modulation by sensory inputs in intact animals and isolated central nervous systems

The sources of variability in feeding motor programme (FMP) of the terrestrial slug, Limax maximus, were examined in relation to: (1) changes in load on the feeding apparatus; (2) changes in concentration of attractive food stimuli; and (3) changes in satiety signalled by feedback from the gut. These sources of variability, which affect both timing of the central pattern generator for feeding and probability of occurrence of FMP, were compared in intact animals and in isolated brain preparations. The load on feeding apparatus of intact animals is altered by varying the hardness of their food. An animal will show a higher ‘bite cycle’ frequency on soft food as compared with hard food. In physiological preparations, weights attached to buccal muscles similarly increase load. Cycle frequency of FMP triggered by food extracts is increased when buccal muscles are unloaded compared with FMP when muscles are loaded. Increasing the chemostimulant concentration of food results in greater numbers of intact animals feeding for longer periods. Increasing the food extract concentration used to trigger FMP in physiological preparations causes similar increases in feeding duration. Intact animals use cues from gut distention to indicate satiation and terminate feeding. Inflation of the crop in physiological preparations causes an early termination of feeding activity, along with decreased FMP cycle frequency.

Feeding motor program in Limax. I. Neuromuscular correlates and control by chemosensory input

The feeding motor program(FMP) of the terrestrial slug Limax maximus was examined in vivo and in vitro. The feeding pattern of intact animals shows an initial increase in bite frequency followed by a plateau phase. Recordings obtained from semi-intact preparations of the lips, brain, and buccal mass established the correlation of activity in buccal ganglion nerve roots with the protraction-retraction bite cycle. A preparation of the lips, cerebral ganglia, and buccal ganglia was developed, such that, repetitive chemostimulation of the lips yields reproducible bouts of FMP. Sources of proprioceptive feedback from buccal muscles were demonstrated. The feasibility of computer scoring of the FMP is documented. The results demonstrate that aspects of in vivo feeding behavior are retained and identifiable in highly dissected, in vivo preparations.