AMERICAN SOCIETY FOR EXPERIMENTAL NEUROTHERAPEUTICS ABSTRACTS

Editor’s Note: We believe our readers will ben- When Is Surrogate Marker Clinically efit from knowing about the annual ASENT (Ameri- Useful? Statistical and Clinical Significance can Society for Experimental Neurotherapeutics) May Not Be the Same meeting and having available the abstracts from this meeting. Emphasizing therapy in neurology Daniel F. Hayes, MD is the objective of ASENT and thus this information is both timely and important. ew molecular markers have gained widespread Roger N. Rosenberg, MD clinical use in the practice of clinical oncology. In F therapeutic clinical investigations, standardized ter- minology for type of study (phases 1, 2, and 3), efficacy (complete, partial response), and toxic effects (grading Abstracts From the Program of the Second scales) have been accepted. In contrast, tumor marker stud- ies have been performed haphazardly. In 1996, the Ameri- Annual Meeting of the American Society can Society of Clinical Oncology convened a Tumor Marker for Experimental Neurotherapeutics, Expert Panel to establish practice guidelines for breast and Washington, DC, March 23-25, 2000. colon cancer (J Clin Oncol. 1996;14:2843-2877). Several members of the panel coauthored a proposed Tumor Marker Utility Grading System (TMUGS) that was used to evaluate each marker (Hayes, et al. J Natl Cancer Inst. Some Statistical Issues in the Design 1996;88:1456-1466). The TMUGS provides a framework of Cancer Clinical Trials With to define the marker designation, how it is assayed, and Surrogate End Points the proposed clinical use (risk, screening, differential di- agnosis, prognosis, and monitoring). For each use, the Steve Piantadosi, MD marker only has clinical utility if it influences a clinical decision that results in an improvement in overall sur- urrogate end points are widely used for the devel- vival, disease-free survival, quality of life, and/or cost. A opment of new therapies in cancer and many other semiquantitative scale, ranging from 0 to 3+, was gener- chronic diseases. Surrogate outcomes are particu- S ated to grade the clinical utility. Routine clinical use is rec- larly useful because they greatly increase the efficiency of ommended for tumor markers that are assigned grades of developmental clinical trials. In particular, they can shorten 2+to 3+. The assigned grade is supported by a scale of lev- the time required to observe treatment effects and reduce els of evidence (LOE). Grades should only be assigned in the sample size required for some trials. As a conse- the presence of LOE I or II data, preferably the former. Lev- quence, surrogate end points can reduce costs and speed els of evidence I and II studies provide a measure not only up the development time for new therapies. To be useful, of the reliability (statistical significance) of the observed a surrogate end point should be strongly associated with relative prognostic (outcome independent of therapy) or the definitive outcome, lie in the causal pathway for the predictive (outcome related to specific therapy) values but definitive outcome, should manifest early in the course of also of the magnitude of difference between groups of pa- follow-up, and should be relatively easy to measure. How- tients identified by marker positivity or negativity (Hayes, ever, the defining characteristic is that the surrogate out- et al. Br Ca Res Tr. 1998;52:304; Hayes. Eur J Cancer. come should be affected by treatment in the same way (di- 2000;36:302-306). Ultimately, these considerations will rection and relative magnitude) as the definitive outcome. help evaluate the clinical utility of novel surrogate mark- It is this last characteristic that is difficult to verify. Even ers more rapidly, leading to improved patient care. when a surrogate outcome is judged to be appropriate for a particular treatment, different therapies for the same dis- ease could potentially invalidate a given surrogate out- come. There are numerous examples of the apparently suc- Surrogate Markers: The AIDS Clinical Trials cessful application of surrogate outcomes in cancer. However, there are other circumstances in which the tra- Donna Mildvan, MD ditionally employed surrogate (tumor shrinkage) is not ap- propriate. Furthermore, for other diseases, such as car- linical trials during early anti-HIV (human im- diovascular disease and AIDS (acquired immune deficiency munodeficiency virus) drug development were syndrome), the putative surrogate outcome may be wholly C designed as large-scale studies, using mortal- inadequate. All of these ideas were discussed in more depth ity and progression to AIDS (acquired immunodefi- during the presentation. ciency syndrome) as end points. Representing the only

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 end points of relevance at the time, clinical end points tions) will provide important information about the defined “clinical efficacy” for new drug approvals but ne- identity of that confer risk to neuropsychiatric dis- cessitated cumbersome, prolonged, and costly trials, of- orders and genes involved in their pathogenesis. The ten requiring years to initiate and complete. Resulting de- development of genetic markers will aid in understand- lays in defining useful therapies had real and implied ing the developmental time and the molecular and impact on the ever-widening AIDS epidemic and led to anatomical substrates of neuropsychiatric disorders. The a concerted effort to accelerate new drug development application of genetic markers in clinical studies will through identification of surrogate end points, that is, bio- ultimately enhance the power of neuroimaging and markers that could be used to substitute for clinical end cognitive markers as tools to understand disease patho- points in trials of antiretroviral drug efficacy. With the genesis and will aid in the development and assessment advent of highly sensitive molecular tools for the detec- of new preventive strategies and therapeutic inter- tion and quantitation of circulating HIV-1 RNA in all in- ventions for CNS disorders. Examples of the application fected individuals, a key advance was made. The quan- of neuroimaging, cognitive, and genetic markers in titation of HIV-1 RNA together with the CD4 cell count clinical studies of neuropsychiatric disorders were (the end organ of HIV attack) were validated as useful presented. biomarkers in that they were shown to predict clinical outcome in longitudinal studies of untreated HIV infec- tion (type 0 marker). Each of these markers responded to effective antiretroviral therapy (type 1 marker) and to- Traumatic Brain Injury— gether they accounted for a substantial proportion of the Biochemical Markers clinical benefit mediated by therapy (type 2 marker; Mild- van, et al. Clin Infect Dis. 1997;24:764-774). These find- Bertil Romner, MD, PhD ings have been so consistent across trials and popula- tions that they resulted in a paradigm shift for new drug he severity of traumatic brain injury after head approvals based on “antiretroviral efficacy.” This has trans- injury is difficult to assess because specific mea- lated into an accelerated drug development/approval pro- T sures of the presence and severity of such inju- cess for anti-HIV therapies, which ultimately resulted in ries have been unavailable. Computed tomographic scans dramatically improved patient outcomes. The extent to reveal a brain injury in 8% to 22% of patients with mi- which the AIDS model may be extrapolated to other dis- nor head injuries. Magnetic resonance imaging is more ciplines was discussed. sensitive but availability is limited. Single photon emis- sion computed tomographic scans demonstrate abnor- malities in more than 50% of patients, but this measure of regional blood flow is not necessarily related to struc- Neuroimaging and Genetic Markers tural damage of the brain. There is a major need for a in CNS Disorders biological marker for the severity of traumatic brain in- jury, especially in mild injury in the medical-legal con- Linda Brady, PhD text in which it may be desirable or necessary to prove that disability or neuropsychological impairment after a dvances in technology and basic biology have traumatic event is really due to the head injury. The need provided opportunities to develop neuro- for an early prognostic indicator exists so that therapies A imaging and genetic biomarkers to study CNS can be selected. (central nervous system) disorders. Functional imaging Biochemical markers of brain lesions and/or ischemia of brain metabolic activity, biochemistry, and circuitry quantify secondary cerebral injury, identify toxic media- reveals normal and abnormal physiological conditions tors, optimize target-controlled therapy or neuroprotec- and the molecular basis for CNS disorders. The applica- tive agents, and possibly to facilitate economical and/or tion of MRS (magnetic resonance spectroscopy) and ethical decision making. Problems in relying on bio- MRI (magnetic resonance imaging), and PET (positron chemical markers, such as S100, neuron specific eno- emission tomographic) and SPECT (single photon lase (NSE), aldolase C40, glial fibrillary acid emission computed tomographic) radiotracers to image (GFAP), creatine kinase (CK), adenylate kinase (AK), my- CNS receptors and other signaling molecules has elin basic protein (MBP), and ␶ , include the following: provided new opportunities to assess the onset and (1) No currently used markers are unique to the brain. progression of CNS disorders and to monitor the (2) Sex, age, species variability, and possibly neurologi- effectiveness of treatments. Cognitive biomarkers (eg, cal disease influence production of a marker. (3) Type attention, working memory, and eye movement) have and extent of the injury and localization of the marker been applied to prospectively assess biological suscepti- in the cell affect marker release. Moreover, several mark- bility in populations at risk for developing neuro- ers are physiologically released. (4) Concentrations of bio- psychiatric disorders. Cognitive markers may also be chemical markers found are dependent on rate of diffu- useful in assessing new treatments and long-term func- sion and CSF (cerebrospinal fluid) volume and flow. tional outcome in neuropsychiatric and neuro- (5) Kidney and liver function affect clearance of the bio- degenerative disorders. chemical markers and little is known about their clear- Advances in genomic technologies (completion of the ance from the CSF. (6) Assay properties need to be stan- and a catalog of human sequence varia- dardized to avoid variations.

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 ods have been proven to be useful for clinical trials. The Functional MRI Case Study: general problems with current imaging technology for Monitoring Stroke in Humans assessment of stroke treatments were discussed as well as feasible objectives for future studies. Gregory Sorensen, MD

euroimaging already plays an important role in Signature MRI Drug Effects in MS: the diagnosis and management of acute ische- the Demand for Composite MRI Outcomes N mic stroke. Magnetic resonance imaging (MRI) has also established itself as a surrogate end point in ani- Jerry S. Wolinsky, MD mal models of ischemia. Recent developments have al- lowed a transition of these MRI techniques from ani- agnetic resonance imaging (MRI), an estab- mals to humans. Ongoing work indicates that computed lished secondary outcome for multiple scle- tomography (CT) and MRI may be able to assess tissue rosis (MS) clinical trials, looms on the near status at an early stage and serve as an indicator of ad- M horizon as a primary outcome of therapeutic efficacy. It ditional tissue at risk. Furthermore, additional statisti- provides a window on pathology. Gadolinium enhance- cal modeling appears to increase the power of these tech- ments, reflecting blood-brain barrier dysfunction com- niques. mon in early disease, are easily quantified. Tissue in- The ability of these imaging techniques to help iden- volvement or disease burden is represented by increased tify individual differences appears promising. Such ap- signal intensity on T2-weighted images, and hypoin- proaches may allow for the determination of efficacy with tense lesions on T1-weighted images capture the most smaller numbers of patients than that found in tradi- extensive destruction. These are complemented by global tional approaches. Furthermore, these approaches may atrophy measures, advanced imaging, and spectro- allow for the establishment of the biological effect of novel scopic assessment of neuronal and integrity. All therapies. reflect different aspects of the complex pathologic pro- While these techniques are still under development, cess that ultimately compromises function. As recent stud- they do seem to indicate that, as in other neurologic dis- ies show, therapy may differentially affect the progres- eases, imaging has the possibility of greatly enhancing sion of these parameters. The interferons have early and our insight into the pathophysiologic mechanism of hu- profound effects on enhancement but lesser effects on man acute cerebral ischemia. disease burden and delayed effects on atrophy. Glat- iramer has delayed and modest effects on enhancement but still affects disease burden. Linomide has dose- Clinical End Points for Stroke Trials dependent effects on both enhancements and hypoin- tense lesions. Cladribine has profound and long-lasting Justin A. Zivin, MD, PhD effects on enhancements not mirrored on disease bur- den. These varied patterns support an unweighted MRI he only proven acute stroke treatments act by composite incorporating different measures of the patho- restoring blood flow to the ischemic brain re- logic process as potentially preferable for monitoring MS T gion. Numerous neuroprotective drugs are ef- trials, especially when pharmacological drug mecha- fective in animal models but have failed in clinical tri- nisms are incompletely understood. als. A reason for many of these failures is that preclinical investigations optimize the treatment conditions and such protocols often differ substantially from methods that are The Relationship Between Acute Disease feasible for patient management. Identification of the criti- cal treatment variables is essential to improve the trial Activity on MRI as Reflected by Blood-Brain designs and clinical rating scales, but they are rather in- Barrier Disruption and Clinical Measures efficient for this purpose. Specifically, we would like to of Disease Activity identify surrogate end points that can be used in phase 2 trials to facilitate protocol designs for phase 3 studies. Henry McFarland, MD An important advantage for investigations of possible stroke treatments is that the cause of the disorder is well he last decade has seen a steady increase in in- understood—it is simply a mechanical disruption of blood terest in using magnetic resonance imaging (MRI) supply. Detailed mechanistic understanding at the mo- T measures to monitor disease activity in mul- lecular level is not required to generate useful therapies, tiple sclerosis (MS). While MRI unquestionably pro- although that would be helpful. No single abnormality vides an important tool for studying the natural history has been identified that is responsible for irreversible is- of MS and is useful as a biological marker for disease in chemic nervous system damage. studies of disease mechanisms, the use of MRI as a sur- Clinical investigation can employ empiric methods for rogate outcome measure has been problematic. The strin- developing valid biomarkers. Imaging techniques show gent criteria for a validated surrogate that includes evi- some promise for providing useable surrogate end points dence that the surrogate predicts future levels of clinical to identify salvageable tissue. However, no such meth- disease activity and that the effect of various classes of

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 treatments on clinical disease can be accounted for by kinson disease (PD). For example, in the appropriate clini- their effect on the surrogate outcome have not been met cal setting, numerous telencephalic ␤- peptide- at any stage of MS. It is evident that MRI does reflect the rich senile plaques and ␶-rich neurofibrillary tangles (NFTs) underlying pathological conditions of the disease and in are diagnostic of AD, while Lewy bodies (LBs) formed by this regard may, under some conditions, be acceptable ␣-synuclein (␣-syn) in substantia nigra neurons are sig- as an invalidated surrogate-outcome measure. In the early natures of PD. However, filamentous ␶ lesions are the char- stages of relapsing-remitting MS, conventional imaging acteristic neuropathological feature of several other neu- techniques, such as burden of disease on T2-weighted rodegenerative disorders, referred to as tauopathies, while images and the number of contrast enhancing lesions, filamentous ␣-syn inclusions are hallmarks of another group appear to have value but more advance imaging tech- of diverse neurodegenerative diseases known as synucle- niques will be needed to reflect the pathological changes inopathies. Moreover, AD and PD commonly cooccur in the leading to progression of the disease. The design of clini- same patient, and ␣-syn is a major component of LBs in an cal trials using MRI as a primary outcome measure pre- AD-like cognitive disorder known as dementia with LBs and sent important difficulties and possibilities for error. Fu- in the LB variant of AD. Further, ␣-syn positive LBs occur ture research will need to focus on how MRI can best be in more than 60% of familial AD brains and in more than used to monitor disease in patients with MS. 50% of Down syndrome brains, thereby linking mutations in the and ␤-amyloid precursor protein genes as well as trisomy 21 to the pathogenesis of ␣-syn lesions. Although the role of LBs and NFTs in the mechanisms of Unraveling the Genetics brain degeneration has been controversial for many years, of Alzheimer Disease the recent discovery of pathogenic ␣-syn mutations in familial PD as well as pathogenic ␶-gene mutations in Rudolph Tanzi, PhD familial frontotemporal dementia with parkinsonism linked to 17 provides unequivocal evidence that ab- lzheimer disease (AD) is the most common cause normal ␣-syn and ␶ cause neurodegenerative disease. Clari- of dementia in the elderly. While roughly 5% of fication of how alterations in ␣-syn and ␶ genes and/or pro- A AD occurs in people younger than 60 years of teins lead to the onset/progression of synucleinopathies and age, less than half of these cases are caused by autoso- tauopathies, respectively, could advance understanding of mal dominant mutations in the ␤-amyloid protein pre- these disorders and the development of more effective thera- cursor (APP) and presenilin (PSEN1 and PSEN2) genes. pies. This presentation reviewed recent insights into the For late-onset AD, a growing number of common pub- pathobiological features of synucleinopathies and tauopa- lic polymorphisms (CPP) appear to confer increased risk thies that could be exploited for the development of diag- for AD but are neither necessary nor sufficient to cause nostic biomarkers of these 2 distinct categories of neuro- AD. The most well-established, late-onset AD genetic risk degenerative disease. factor is apolipoprotein E (APOE). In addition, we re- cently described CPPs in ␣2-macroglobulin (␣2M) that confer increased risk for AD. While early-onset AD gene mutations increase the production of ␤-amyloid pep- Using Registration of Serial MRI tide, the principal component of senile plaques in the AD to Measure Atrophy Progression in Alzheimer Disease and Related Disorders brain, CPPs in APOE and ␣2M influence the accumula- tion of ␤-amyloid peptide by modulating clearance/ degradation and the rate of aggregation of the peptide into Nick Fox, MD amyloid plaques. We have recently completed (with Cen- ter of Inherited Disease Research at National Institutes he advent of therapies for Alzheimer disease (AD) of Health, Bethesda, Md) a high resolution (9 cM) ge- and related disorders has increased interest in nome screen of more than 400 families to localize addi- T biological markers of early disease and in sur- tional genetic risk factors for AD. Candidate genes lo- rogate measures of disease progression. Magnetic reso- calized in regions of chromosomal hits are being assessed nance imaging (MRI) has potential in both these areas. primarily by family-based association techniques. The re- Direct in vivo imaging of specific molecular pathologi- sults of these ongoing analyses were discussed. cal features (eg, ␤-amyloid plaques and neurofibrillary tangles in the AD brain) is not yet possible. However, MRI can be used to measure a surrogate marker of neuronal damage, that is, atrophy. Imaging studies have shown Biochemical Markers of Neurodegenerative marked regional (eg, hippocampus and entorhinal cor- Diseases: ␶ and Synucleins tex) and global (whole brain and ventricles) atrophies to be a consistent feature of AD. Because of the wide nor- John Trojanowski, MD, PhD mal variation in cerebral structure, there is considerable overlap in these measures when mildly affected patients he aggregation of brain into filamentous and matched controls are compared. Rates of atrophy from lesions is emerging as a common mechanistic serial imaging allow individuals to form their own T theme in sporadic and hereditary neurodegenera- control avoiding problems of intersubject morphologi- tive disorders, including Alzheimer disease (AD) and Par- cal variability.

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 Registration (positional matching) of serial MRI is the brink of new protective and restorative therapies for now possible to subvoxel (0.2 to 0.4 mm) levels and PD, neuroimaging offers the potential to provide an permits direct measurement of rates of atrophy. The objective end point for therapeutic trials on disease methods are automated and unbiased, independent of progression. ora priori decisions about regions of interest, and avoid laborious manual measurements. Rates of cere- bral loss derived in this way are highly reproducible (to 0.2% of brain volume), are significantly raised in AD (2.5%±1.1%/y vs controls 0.3%±0.4%/y), and are Can We Measure ALS? sensitive even in early cases. Rates of loss correlate with cognitive decline in untreated patients with AD. Hiroshi Mitsumoto, MD These techniques, together with volumetry, may prove useful both in diagnosis and in tracking disease n dealing with a disease like amyotrophic lateral scle- progression. rosis (ALS) that has no fully known cause and no I cure, clinical trials are becoming the sole vehicle of hope to identify effective treatments. The World Federa- tion of Neurology Committee of Motor Neuron Disease Imaging in Parkinson Disease—a Window has published revised diagnostic criteria for ALS and to Neurodegeneration, a Tool to Assess guidelines on the design and conduct of clinical trials in Neuroprotection? ALS. These criteria and guidelines are helpful since we have no diagnostic or surrogate markers in ALS. Given Kenneth Marek, MD this, clinical trialists must rely on currently available mea- surement techniques, including survival rate, neuromus- arkinson disease (PD) has been a model neuro- cular assessments, clinimetrics, and quality of life (QoL). degenerative disorder in which advances in neu- Survival has been used in several clinical trials, such as P roscience have informed, and in turn, have been riluzole, SR57746A, and new brain-derived neuro- informed by clinical neurology. In vivo imaging of the trophic factor (BDNF) trials, but this has inherent prob- nigrostriatal dopamine system has provided a tool to lems. Tufts quantitative neuromuscular evaluation bridge developments in basic neuroscience and clinical (TQNE), including the maximal voluntary isometric neurology and to identify markers for the chronic muscle contraction (MVIC), expresses a direct clinical degenerative process in PD. During the last decade, feature of ALS; however, it has not been able to demon- neuroreceptor imaging has been used to monitor dis- strate positive results in trials, such as ciliary neuro- ease onset, severity, and progression, and the physi- trophic factor (CNTF), BDNF, and gabapentin. The use ological conditions of the degenerative process. Several of TQNE remains important, though in investigator- markers, most focused on the dopamine system, using driven trials. Among all measurement techniques, forced positron emmission tomography (PET) and single pho- or slow vital capacity and ALS functional rating scale (ALS- ton emmission computed tomography (SPECT) tech- FRS) appear the most universally accepted evaluation nology have been used to asses PD. The 2 most mature techniques in ALS trials. For QoL measurements, only imaging biomarkers are F-Dopa ([18F]-6-fluoro-L-Dopa) generic QoL instruments have been available until PET, which measures dopamine function, and [123I] recently. Now ALS-specific QoL tools, such as the ALS ␤-CIT SPECT, which tags the dopamine transporter. In assessment questionnaire-40 (ALSAQ-40), have just been numerous studies, these ligands have demonstrated introduced. dopamine striatal deficits that identify symptomatic and The use of objective quantitative measurements of lower presymptomatic subjects and that correlate with sever- motor neuron and upper motor neuron functions are im- ity of PD. More recently, longitudinal imaging studies perative to directing the focus of clinical trials in ALS. have shown that the dopamine loss in PD occurs at a Motor unit number estimate (MUNE) has been devel- rate of approximately 10%/y and have suggested that oped by 2 fundamentally different concepts and meth- the preclinical phase of PD was 5 to 10 years. Ongoing odologies: statistical methods and multipoint stimula- studies are evaluating whether the rate of loss of tion methods. Although there are pros and cons for these F-Dopa or ␤-CIT differs in response to several putative 2 techniques, the importance of these measurement tech- neuroprotective or restorative therapies. These studies niques in clinical trials must be emphasized. For mea- will further elucidate the use of neuroreceptor imaging suring upper motor neuron function, we introduce the as a biomarker or surrogate end point for disease pro- use of 2 novel methods. One is magnetic resonance spec- gression. As genetic and environmental at-risk groups troscopy imaging (MRSI), demonstrating a relative or ab- for PD are identified, imaging studies will also be cru- solute amount of N-acetyl aspartate, analyzing the ana- cial in establishing the onset of neurodegeneration and tomical neuronal (neurons and neuritis) tissue in the whether potential protective treatments are effective brain; the other is transcranial magnetic stimulation even prior to symptoms. In a slowly, but variably, pro- (TMS), analyzing electrophysiological excitability and de- gressive neurodegenerative disorder like PD, imaging scending tract integrity. Further studies of these 2 tech- may be particularly useful in establishing at-risk groups niques are absolutely essential to establish the reliabil- for rapid or slow progression of disease and assessing ity and validity in assessing the disease evolution in ALS. therapies directed at each group. As we are poised on In the near future, we should be able to measure ALS more

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 objectively than before for identifying therapeutic agents (CNS) drug development by giving an overview of for this disease. some phase 1/2a study results in which these tech- niques were applied. The possibility of defining at the earliest time the potential of the CNS active com- pound passing the blood-brain barrier, if it does (its Monitoring minimal active dose and dose/time effects), is in Central and Peripheral addressed. The ways to obtain more powerful assess- Nervous System Injury ments of its pharmacological activity and pharmacody- namic profile are also shown as well as inputs toward A. A. Cameron, W. Huang, J. Chang, L. Pham, C. R. Ill, potential therapeutic indications. Finally, to show the W. Young, D. J. Carlo predictive power of these techniques, the link between the surrogate markers, and the clinical outcomes are rauma to the central nervous system (CNS) examined. Examples of discriminating between elec- and peripheral nervous system (PNS) cause an trophysiological techniques based on their relative T inflammatory response that is dichotomous advantages and applications are given depending on and may support or inhibit subsequent regenerative the characteristics of the compound and aims of the capacity. However, very little is known about the pat- study. In addition to the above mentioned uses, elec- terns of gene expression in the injured tissues, nuclei, trophysiological markers may also provide an impor- or ganglia. We have used complementary DNA micro- tant warning of possible adverse effects and use in arrays to monitor gene expression in models of diagnosis of CNS diseases. peripheral nerve regeneration and spinal cord trauma and in peripheral and central glia. The expression pro- file of the regenerating dorsal root ganglion (DRG) Generation of Human Neural Stem Cell showed a number of gene groups whose function is consistent with metabolic activation and neurite elon- Lines and Brain Transplantation gation. The absence of cell cycle–related gene activa- in Animal Models of Parkinson tion and tissue mitosis in the DRG suggests the exist- Disease and Multiple Sclerosis ence of a modified form of the cell cycle, the “regeneration cycle.” In addition, a cluster of 111 Seung U. Kim, Eiji Nakagawa, Atsushi Nagai, genes up-regulated in the DRG were identical to genes Evan Y. Snyder, Jai K. Ryu, Jin Kim, Myong A. Lee, down-regulated in activated Schwann cells (and a sub- In H. Mook, Byong K. Jin set of oligodendrocytes), indicating that components of the gene-expression program are highly conserved eural stem cells (NSCs) of the central nervous and can be reciprocally regulated. The gene expression system (CNS) have recently aroused a great profile in the injured spinal cord following methyl- N deal of interest not only because of their prednisolone treatment is consistent with the reduc- importance in basic research of neural development but tion in messenger RNA and protein synthesis levels also for their therapeutic potential for neurological dis- and the provision of neuroprotection through the eases. Previously we have produced immortalized cell up-regulation of genes encoding antioxidants, growth lines of human NSCs (Flax, et al. Nat Biotech. factors, and matrix proteins. Gene-expression moni- 1998;16:1033). Recently we have produced several toring is useful in characterization of the genetic more clones of human NSC lines via retrovirus- response following PNS or CNS trauma and for the mediated v-myc transfer into embryonic human telen- identification of leads for the development of novel cephalon cells. One of the NSC lines, HB 1/C4, is main- therapeutic targets. tained as a stable cell line and remains uncommitted, undifferentiated, multipotent, and express nestin and vimentin, which are phenotypes specific for NSCs. Immortalized human NSCs have clinical utility for cell Electrophysiological Surrogate Markers replacement and gene therapy for patients suffering in Clinical Development of CNS from degenerative, developmental, and acquired neuro- Active Compounds logical diseases. The HB 1/C4 cells carrying β-gal gene were stereotaxically implanted into brains of parkinso- F. D’Aniello, T. Lincker, R. Luthringer, M. Toussaint, nian model rats and of myelin-mutant shiverer mice. P. Boeyjinga, L. Staner, J. P. Macher Two to 6 weeks postoperation, implanted human NSCs were found to migrate extensively, integrate into host onsidering that to optimize drug develop- brain, and develop into neurons and/or glial cells as ment, it is important to anticipate go/no-go shown by immunohistochemistry. These results C decisions. Our aim is to show the usefulness indicate that human NSCs are capable of survival, of electrophysiological markers in early clinical phase migration, and differentiation in animal models of Par- decision-making studies. In particular, our purpose is kinson disease and multiple sclerosis. (Supported by to illustrate the usefulness of wake electroencephalog- the Canadian Myelin Research Initiative, Mississauga, raphy (wake EEG) and polysomnography (sleep EEG) Ontario, and Korea Social Engineering Foundation, techniques in optimizing central nervous system South Korea.)

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©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 and differentiated into functional dopaminergic (DA) neu- Transdermal Delivery of Interferon rons capable to compensate the motor asymmetry in- beta-1a by Transfersomes and Its Effects duced by 6-hydroxydopamine in a rat model of Parkin- on Surrogate Markers son disease (Studer, et al. Nat Neurosci. 1998;1:290-295). In this model, we have now examined the survival and differentiation of human expanded precursors trans- B. Scorneaux, J. Lehmann, G. Payne, G. Cevc, M. Rother planted into the denervated striatum. Human precur- sors from the mesencephalon gave rise to TH positive (+) oninvasive delivery of interferon-beta (IFN-␤) neurons in vitro and in vivo. Six weeks after transplan- may reduce adverse events at the injection site, tation, the number of TH+positive neurons in the graft N including necrosis, reduce systemic adverse ef- was correlated with the degree of recovery of rotational fects potentially linked to the pharmacokinetics after in- behavior following amphetamine stimulation. Further- jection, be less immunogenic (less neutralizing antibod- more, cortical progenitors could also be differentiated into ies), and increase patient acceptance. Transfersomes (Tfs) TH+neurons in vitro, and they partly maintained this phe- were used to deliver IFN-␤ transdermally. Transfer- notype after transplantation. These results provide ad- somes are novel self-regulating drug carriers that can de- ditional basis for future clinical applications of in vitro liver macromolecules across the intact skin (Cevc, et al. expanded CNS precursors. J Controlled Release. 1995;36:3-16). The main objective of this pilot study was to investigate if IFN-␤ associated with Tfs produces systemic levels of IFN-␤. The second aim was to study surrogate markers for drug effects (se- rum ␤2-microglobulin and urine neopterin) and ad- Dose-Dependent Neuroprotection of verse effects (body temperature). Normal pigs were treated Taigabine After 2-Hour Middle Cerebral with a single epicutaneous dose of 4.6ϫ106 U/kg body Artery Embolization in the Rat weight IFN-␤ in Tfs, or with 3.8ϫ105 U/kg body weight IFN-␤ solution subcutaneously. This was compared to empty vehicles epicutaneously and subcutaneously. In- Y. Yang, Q. Li, C. X. Wang, A. Shuaib terferon-␤ Tfs produced plasma levels with a Cmax (peak arterial plasma concentrations)of 6 hours as compared -Aminobutyric acid (GABA) is a potent and ubiq- with 2 hours for subcutaneous injection. The area un- ␥ uitous inhibitor in the central neuronal system der the curve (AUC) was lower for epicutaneous appli- (CNS), and enhancement of its inhibitory activ- cation by a factor of about 3. Interferon-␤ Tfs produced ity may protect ischemic neurons. In a current study, we evaluate the neuroprotective effect of a novel GABA ago- comparably higher amounts of neopterin and ␤2- microglobulin, indicating a better biopotency; in con- nist, taigabine, in a reversible focal cerebral ischemia model trast, IFN-␤ Tfs were less pyrogenic. The results of this of rats subjected to 2-hour middle cerebral artery embo- study indicate that Tf-mediated transdermal IFN-␤ de- lization with a filament. Taigabine was given at 10, 20, livery could become a valuable alternative to subcuta- and 40 mg/kg intraperitoneally at 1 hour after the onset neous injection. More recent work using IFN-␣ Tfs of reperfusion. Neurobehavioral outcome was exam- showed that the bioavailability could be substantially in- ined at 1 hour and 24 hours, respectively, after reperfu- creased by an improved formulation. sion. The percentage of brain infarction volume was cal- culated from the coronal brain sections, which were stained with 2,3,5-triphenyltetrazolium chloride (TTC) at 72 hours after cerebral ischemia. Significant neuro- Transplantation of Human Expanded logical improvement was observed only in animals treated Progenitors From Midbrain and Neocortex with taigabine at a dose of 20 or 40 mg/kg (both PϽ.05). Into a Rat Model of Parkinson Disease Postischemic treatment of taigabine displayed a dose- dependent reduction in brain infarct size, but only taiga- R. Sa´nchez-Pernaute, L. Studer, Conrad Messam, bine given at 20 and 40 mg/kg showed significant dif- K. S. Bankiewicz, R. D. G. McKay ferences when compared with that of the control group (control, 28.7±11.0; 10 mg/kg, 19.5±10.8, P=.07; 20 mg/ he use of in vitro expanded precursors of the cen- kg, 12.3±9.7, P=.006; and 40 mg/kg, PϽ.001). The re- tral nervous system (CNS) might overcome some sults from this study suggest that postischemic admin- T of the current limitations for neural transplan- istration of taigabine is neuroprotective in the focal tation. Rat midbrain precursors can be proliferated in vitro cerebral ischemia model.

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