VIEWS & REVIEWS
`
`Mechanisms of action of disease-modifying
`agents and brain volume changes in
`multiple sclerosis
`
`R. Zivadinov, MD,
`PhD
`A.T. Reder, MD
`M. Filippi, MD
`A. Minagar, MD
`O. Stu¨ve, MD, PhD
`H. Lassmann, MD
`M.K. Racke, MD
`M.G. Dwyer
`E.M. Frohman, MD,
`PhD
`O. Khan, MD
`
`Address correspondence and
`reprint requests to Dr. Robert
`Zivadinov, Buffalo Neuroimaging
`Analysis Center, Jacobs
`Neurological Institute, 100 High
`Street, Buffalo, NY 14203
`rzivadinov@thejni.org
`
`ABSTRACT
`Disease-modifying agents (DMAs), including interferon beta (IFN␤) and glatiramer acetate (GA),
`are the mainstays of long-term treatment of multiple sclerosis (MS). Other potent anti-
`inflammatory agents like natalizumab and different types of chemotherapeutics are increasingly
`being used for treatment of MS, particularly in patients with breakthrough disease activity. Brain
`volume (BV) loss occurs early in the disease process, accelerates over time, and may be only
`partially affected by DMA therapy. Low-dose, low frequency IFN␤administered once weekly and
`GA appear to partially reduce BV decline over the second and third years of treatment. High dose,
`high frequency IFN␤ demonstrated no clear effect on BV loss during this time period. Current
`evidence suggests that changes in BV after immunoablation may not be due entirely to the reso-
`lution of edema but may be related to potential chemotoxicity of high dose cyclophosphamide.
`Natalizumab reduces the development of BV decline in the second and third years of treatment.
`IV immunoglobulin showed a positive effect on decelerating BV reduction in relapsing and ad-
`vanced stages of MS. These differences between DMAs may be explained by the extent of their
`therapeutic effects on inflammation and on the balance between inhibition or promotion of remy-
`elination and neuronal repair in the CNS. We described the mechanisms of action by which DMAs
`induce accelerated, non–tissue-related BV loss (pseudoatrophy) in the short term but, in the long
`run, may still potentially lead to permanent BV decline. The effects of corticosteroid therapy on
`changes in BV in patients with MS help clarify the mechanisms through which potent anti-
`inflammatory treatments may prevent, stabilize, or induce BV loss.
`Neurology® 2008;71:136–144
`
`GLOSSARY
`AHSCT ⫽ autologous hematopoietic stem cell transplantation; BBB ⫽ blood–brain barrier; BV ⫽ brain volume; CIS ⫽ clinically
`isolated syndrome; DB ⫽ double-blind; DMAs ⫽ disease-modifying agents; GA ⫽ glatiramer acetate; GM ⫽ gray matter;
`IFN␤ ⫽ interferon beta; IM ⫽ intramuscular; IVIg ⫽ intravenous immunoglobulin; IVMP ⫽ IV methylprednisolone; MS ⫽
`multiple sclerosis; NA ⫽ normal appearing; NS ⫽ not significant; OLC ⫽ open label controlled; PG ⫽ parallel group; PLC ⫽
`placebo-controlled; PP ⫽ primary progressive; RR ⫽ relapsing-remitting; S ⫽ significant; SC ⫽ subcutaneous; SP ⫽ second-
`ary progressive; WM ⫽ white matter.
`
`MRI characteristics of multiple sclerosis (MS) include multifocal white matter (WM) and gray
`matter (GM) lesions, presence of brain atrophy, and occult changes in normal appearing (NA)
`WM and NAGM.1,2 Brain atrophy appears early in the disease process, with measurable
`changes occurring within a few years of diagnosis.
`There is no clear distinction in the MS literature between the terms “brain atrophy” and
`“brain volume (BV) loss.” Changes in BV in MS can occur principally by two mechanisms: 1)
`changes in the degree of brain edema; this is clearly associated with inflammation, and 2) tissue
`loss (such as myelin, axons, and possibly also astrocytes) or regeneration (such as remyelina-
`tion). Other mechanisms of BV loss may also play significant roles (table 1). In the early stage
`of an MS lesion there is already loss of tissue.3 This is superimposed on blood– brain barrier
`
`From Buffalo Neuroimaging Analysis Center (R.Z., M.G.D.), The Jacobs Neurological Institute, Department of Neurology, State University of New
`York, Buffalo; Department of Neurology (A.T.R.), University of Chicago, IL; Neuroimaging Research Unit (M.F.), Department of Neurology,
`Scientific Institute and University Ospedale San Raffaele, Milan, Italy; Department of Neurology (A.M.), Louisiana State University Health Sciences
`Center, Shreveport; Neurology Section (O.S.), VA North Texas Health Care System, Medical Service, Dallas, TX; Center for Brain Research (H.L.),
`Medical University of Vienna, Wien, Austria; Department of Neurology (M.K.R.), The Ohio State University, Columbus; Departments of Neurology
`and Ophthalmology (E.M.F.), University of Texas Southwestern Medical Center at Dallas; and Department of Neurology (O.K.), Multiple Sclerosis
`Center, Wayne State University School of Medicine, Detroit, MI.
`Disclosure: The authors report no disclosures.
`
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`Table 1
`
`Mechanisms that may decrease brain volume in multiple sclerosis
`
`Beneficial
`
`Non–tissue-related
`(fluid shifts)
`
`Fluctuating
`
`Demyelination (reduced via
`remyelination); loss of glial cells
`(reduced via recruitment and
`differentiation)
`
`Irreversible
`
`Axonal loss;
`Wallerian
`degeneration
`
`Natural history
`
`DMA-related
`
`DMA-induced
`pseudoatrophy
`
`Resolution of
`inflammation
`and edema
`
`Change in electrolyte
`balance and vascular
`permeability; dehydration
`
`Inhibition of “good”
`inflammation
`
`Chemotoxicity;
`protein catabolism
`
`DMA ⫽ disease-modifying agent.
`
`(BBB) damage and edema, which may com-
`pensate in part for loss of BV from tissue de-
`struction.4 Focal edema in new lesions may
`mask reductions in BV caused by true atro-
`phy, especially in the WM where inflamma-
`tion is more pronounced.5 In the later stages
`of MS, there is additional massive cortical de-
`myelination and a diffuse axonal loss in the
`NAWM contributing to loss of BV.6 The lack
`of efficacy by immunomodulatory treatments
`in this stage of the disease process may be due
`to the fact that either these drugs do not reach
`the inflammatory process behind the closed
`BBB, or that their effects are insufficient to
`cope with the existing inflammatory process.
`Another explanation for the lack of effect of
`immunomodulatory therapies in progressive
`MS is that the pathogenesis of this disease
`type is not inflammatory.7 Remyelination,
`however, may be extensive in a subset of pa-
`tients with MS.8 Thus there is indeed the pos-
`sibility that loss of BV may in part be reduced
`by remyelination within the lesions and NA
`brain tissue.
`Dynamic changes in BV in MS are there-
`fore a composite of volume-gaining and
`volume-losing processes that are influenced
`by the extent of inflammatory, neurodegen-
`erative, and remyelinating processes, po-
`tency of anti-inflammatory therapy, and
`their real neuroprotective effect. Inflamma-
`tion also transiently increases BV, which
`confounds the interpretation of real BV
`changes (table 1). On the other hand, po-
`tent anti-inflammatory therapies may re-
`duce BV in the short term by reducing
`inflammation, causing accelerated, non–
`
`tissue-related BV decline called pseudoatro-
`phy (table 1).
`Current disease-modifying agents (DMAs)
`for MS include interferon beta (IFN␤) 1a,
`IFN␤-1b, glatiramer acetate, natalizumab,
`and mitoxantrone. Their effect on BV
`changes is likely to differ. At the present time,
`mechanisms by which DMAs may prevent or
`slow down BV loss are not fully understood,
`and are therefore not a topic in this review
`article. Theoretically, DMAs’ molecular
`mechanisms of action could decelerate BV
`loss by reducing inflammation and possibly
`promoting remyelination and repair. Possible
`mechanisms for repair failure include reduced
`differentiation or recruitment of oligodendro-
`cytes as a consequence of immune cell at-
`tack,9,10 an imbalance of growth factors,11 or
`the release by immune cells of molecules/
`signals that inhibit remyelination.12 It is cur-
`rently a topic of intense debate as to if, how,
`and to what extent anti-inflammatory inter-
`ventions can alter oligodendrocyte death. The
`evidence is currently inconclusive. No direct
`clinical evidence in support of neuroprotec-
`tion or oligodendrocyte protection exists at
`this time with currently available DMAs.
`This review examines the mechanisms in MS
`by which different DMAs may induce acceler-
`ated, non–tissue-related BV loss (pseudoatro-
`phy) and induce permanent BV loss in the mid
`to long term (⬎2 years).
`
`EFFECTS OF MS TREATMENTS ON BV
`CHANGES: CLINICAL FINDINGS The optimal
`methodology for MRI-based assessment of BV
`changes is still debated.13-16 Available studies differ in
`terms of types of BV techniques, measures, acquisi-
`
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`Table 2
`
`Effect of disease-modifying agents on brain volume (BV) changes in multiple sclerosis (MS) in
`placebo-controlled and open-label controlled studies
`
`Trial design
`
`Duration, mo
`(no. of patients)
`
`Disease type
`
`Treatment effect on BV
`
`S (12–24 mo)
`
`S (12–24 mo), S (24–36 mo)
`
`S (0–36 mo)
`
`NS
`
`NS
`
`NS
`
`S (9–18 mo), S (0–18 mo)
`
`S (0–24 mo)
`
`S (0–80.4 mo)
`
`S (0–60 mo)
`
`S (12–24 mo)
`
`S (0–12 mo)
`
`S (0–24 mo)
`
`S (0–24 mo)
`
`NS
`
`NS
`
`NS
`
`Treatment
`
`IM IFN-␤-1a
`(30 ␮g weekly)14
`
`IM IFN-␤-1a
`(30 ␮g vs 60 ␮g weekly)20
`
`IM IFN-␤-1a
`(30 ␮g weekly vs no treatment)25
`
`SC IFN-␤-1a
`(66 ␮g or 132 ␮g weekly)18
`
`PLC
`
`DB, PG
`
`OLC
`
`PLC
`
`24 (140)
`
`36 (386)
`
`36 (54)
`
`24 (519)
`
`RRMS
`
`RRMS
`
`RRMS
`
`RRMS
`
`SC IFN-␤-1a
`(66 ␮g or 132 ␮g weekly)24
`
`PLC, OLC
`(baseline vs FU)
`
`84–96 (382)
`
`RRMS
`
`GA (20 mg daily)31
`
`GA (20 mg daily)13
`
`GA (20 mg daily)33
`
`GA (20 mg daily)33
`
`PLC in the 0–9 mo;
`OLC in the 9–18 mo
`
`PLC in the 0–9 mo;
`OLC in the 9–18 mo
`
`PLC
`
`OLC
`(baseline vs FU)
`
`IVMP (1 g daily for 5 d)17
`
`Natalizumab15
`
`IVIg40
`
`SC IFN-␤-1a (22 ␮g weekly)26
`
`IVIg41
`
`SC IFN-␤-1b (875 ␮g weekly)19
`
`Cladribine (0.7 or 2.1 mg/kg)42
`
`IM IFN-␤-1a (60 ␮g weekly)27
`
`OLC
`
`PLC
`
`PLC
`
`PLC
`
`PLC
`
`PLC
`
`PLC
`
`PLC
`
`18 (239)
`
`18 (194)
`
`24 (27)
`
`80.4 (135)
`
`60 (81)
`
`24 (942)
`
`12 (127)
`
`24 (163)
`
`24 (318)
`
`36 (95)
`
`12 (159)
`
`24 (50)
`
`RRMS
`
`RRMS
`
`RRMS
`
`RRMS
`
`RRMS
`
`RRMS
`
`RRMS
`
`CIS
`
`SPMS
`
`SPMS
`
`SPMS, PPMS
`
`PPMS
`
`Changes in BV are not comparable across trials due to differences in MRI analysis techniques, disease type, trial designs,
`and patient populations. Open-label, uncontrolled studies, using brain volume measures to determine efficacy of disease-
`modifying agents, were not included in this table. Current evidence suggests that mobilization with high doses of cyclo-
`phosphamide during autologous hematopoietic stem cell transplantation increases the rate of BV loss compared with the
`rate prior to treatment.35-37 Alemtuzumab did not show a significant effect on brain volume decline in patients with sec-
`ondary progressive MS over 18 months.43
`IM ⫽ intramuscular; IFN-␤ ⫽ interferon beta; PLC ⫽ placebo-controlled; RR ⫽ relapsing remitting; S ⫽ significant; DB ⫽
`double-blind; PG ⫽ parallel group; OLC ⫽ open label controlled; NS ⫽ not significant; GA ⫽ glatiramer acetate; IVMP ⫽ IV
`methylprednisolone; IVIg ⫽ intravenous immunoglobulin; CIS ⫽ clinically isolated syndrome; SP ⫽ secondary progressive;
`PP ⫽ primary progressive; SC ⫽ subcutaneous.
`
`tion MRI schemes, and methods of image postpro-
`cessing. Therefore, changes in BV are not directly
`comparable across trials due to differences in MRI
`analysis techniques, disease type, trial designs, and
`patient populations.
`
`Corticosteroids. In a controlled, single-blind study of
`prolonged IV methylprednisolone (IVMP) pulse
`therapy, 81 patients with relapsing-remitting (RR)
`MS were randomized to receive IVMP every 4
`months for 3 years followed by IVMP administration
`every 6 months for an additional 2 years or by IVMP
`administered only for relapses (control group).17 Pa-
`tients treated with prolonged pulse IVMP did not
`lose BV, whereas the control group experienced sig-
`nificant BV decline over 5 years.
`
`Interferon ␤. Clinical effects of IFN␤on BV changes
`in MS have been determined in the pivotal phase III
`
`trials of IM IFN␤-1a,14 SC IFN␤-1a,18 and SC
`IFN␤-1b,19 as well as in other large, randomized,20
`and open-label studies (table 2).21-25
`In a preplanned analysis of the pivotal trial of IM
`IFN␤-1a for RRMS (n ⫽ 140), there was a 55% reduc-
`tion in the rate of BV loss in the IM IFN␤ 1a-treated
`group in the second year of treatment, compared with
`the placebo group.14 However, there was no significant
`effect over the first year, or over the entire study peri-
`od.14 In a large subgroup analysis of the European IM
`IFN␤-1a Dose Comparison trial, comparison of annu-
`alized BV rates between the pretreatment and treatment
`periods of combined treatment groups showed signifi-
`cant reduction in the BV rate in the second and third
`years.20 In a large cohort of patients with clinically iso-
`lated syndrome, once weekly 22 ␮g SC IFN␤-1a re-
`duced the rate of BV loss at 2 years.26 Only one
`
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`exploratory, randomized, placebo-controlled trial27 in-
`vestigated the effect of IFN␤-1a on BV loss in 50 pa-
`tients with primary progressive (PP) MS. No significant
`treatment effect was observed, as measured over 2 years.
`The effect of IM IFN␤-1a on BV changes in secondary
`progressive (SP) MS (IMPACT study)28 is unknown.
`In the post hoc analysis of the pivotal trial of SC
`IFN␤-1a 66 or 132 ␮cg weekly for relapsing MS (n
`⫽ 519), there was no significant treatment effect on
`BV decline over 2 years.18 Extended open label re-
`sults of this study after a long-term follow-up (7– 8
`years) showed that loss of BV over the first 24
`months was significantly greater in patients originally
`randomized to 132 ␮cg SC weekly compared to
`those in the late treatment group or the 66 ␮cg SC
`weekly group.24 BV declined significantly across all
`treatment groups, with a median relative reduction
`of 3.9% at long-term follow-up. There was no differ-
`ence in the loss of BV between 132 ␮cg or 66 ␮cg
`weekly compared to those in the late treatment
`group. The effect of SC IFN␤-1a on BV changes in
`SPMS (SPECTRIMS study)29 is unknown.
`In a small, open-label, 3-year follow-up study of
`30 patients with RRMS who received SC IFN␤-1b 8
`MIU every other day, no significant difference in BV
`loss over any yearly interval was observed (although
`BV loss appeared to accumulate in the first year, sta-
`bilize in the second year, and again increase slightly
`in the third year).21 No control group was used. No
`significant treatment effect of SC IFN␤-1b 8 MIU
`every other day on BV loss in patients with SPMS (n
`⫽ 95) was detected in a subgroup of patients partici-
`pating in the European IFN␤-1b trial in SPMS.19
`Preliminary data from a single-center, randomized,
`placebo-controlled trial of IFN␤-1b in 49 patients
`with PPMS and 24 patients with transitional pro-
`gressive MS30 did not report any treatment effect on
`BV decline over the 2-year study period.
`Different other open-label studies in RR and
`SPMS using IFN␤ showed no effectiveness on slow-
`ing down BV decline.22,23
`
`Glatiramer acetate. In a post hoc study of a Europe-
`an/Canadian GA trial of 239 patients randomized to
`GA or placebo over a 9-month double-blind period,
`followed by a 9-month open-label period during
`which all patients received GA, there were no signif-
`icant differences in BV loss between GA and placebo
`treatment using a semiautomated analysis tech-
`nique.31 However, a treatment effect was identified
`in a re-analysis of the data using a fully automated
`technique.13
`In an open-label study of 135 patients enrolled in
`the extension of the original GA pivotal trial, patients
`
`originally randomized to the placebo had larger CSF
`volumes, indicating more BV loss compared with pa-
`tients originally assigned to GA treatment.32 In an-
`other small, one-site, open-label study of 27 patients
`from the GA pivotal trial, GA reduced the rate of BV
`decline over 2 years.33 The effect of GA on BV changes
`in the PPMS (PROMISE study)34 is unknown.
`
`Natalizumab. The AFFIRM study showed that na-
`talizumab did not prevent BV decline over 3 years
`compared to placebo; however, natalizumab signifi-
`cantly prevented BV loss in the second year of treat-
`ment (⫺0.24% in natalizumab arm vs ⫺0.43% in
`the placebo arm, p ⫽ 0.004).15
`
`Chemotherapeutics. High-dose cyclophosphamide
`(4–8 g/m2) used for mobilization during autologous
`hematopoietic stem cell transplantation (AHSCT) in-
`creases the rate of BV loss compared with the rate prior
`to treatment.35,36 There was an average annual decrease
`in BV of about 1.9% over 24 months, despite clinical
`and MRI inflammatory stability in 10 patients with
`rapidly evolving MS treated with AHSCT.36 A 5-year
`follow-up of 9 patients with MS treated with AHSCT
`showed a slower BV loss after the second year following
`treatment.37 In 9 patients with MS undergoing immu-
`noablation and AHSCT,35 from baseline to month 1
`after treatment, BV decline was 10 times faster than the
`rate of decline prior to treatment. BV loss was ⫺1.6%
`in the first year, ⫺0.9% in the second, and ⫺0.8% in
`the third. These observations suggest that changes in
`BV after immunoablation may not be due entirely to
`the resolution of edema but may be related to potential
`chemotoxicity of high dose cyclophosphamide.
`In another study that used low doses of cyclo-
`phosphamide (800 mg/m2), there was no accelerated
`BV loss.38
`
`IV immunoglobulin. The only DMA that showed a
`positive effect on decelerating BV loss in SPMS is IV
`immunoglobulin (IVIg). Preliminary data from a sub-
`cohort of 43 patients participating in the European-
`Canadian, randomized, placebo-controlled trial of IVIg
`treatment in SPMS showed that, over the 2-year study
`period, BV reduction was smaller in IVIg- than in
`placebo-treated patients, with a significant difference in
`infratentorial BV.39 Monthly application of high-dose
`IVIg to 318 patients with SPMS—in the European
`Study on Immunoglobulin in MS—showed that the
`partial cerebral fraction decreased significantly less
`with IVIg than with placebo treatment (final visit:
`⫺0.63% vs ⫺0.89%; p ⫽ 0.009).40 Otherwise, this
`trial was negative from both clinical and MRI points
`of view. A recent multicenter, randomized, double-
`blind, placebo-controlled trial study investigated the
`effect of IVIg in RRMS (PRIVIG study). Of 127
`patients, 44 patients received treatment with 0.2 g/kg
`
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`of IVIg, 42 patients with 0.4 g/kg of IVIg, and 41
`patients received placebo every 4 weeks for 48
`weeks.41 IVIg failed to support the superiority over
`placebo treatment for all clinical and MRI outcomes,
`except for a smaller reduction in BVs (median, IVIg
`0.2 g/kg, ⫺0.79%; IVIg 0.4 g/kg, ⫺0.35%; placebo,
`⫺0.98%). One possible explanation may be that
`chronic IVIg treatment increases protein content,
`which results in increased osmotic pressure and water
`content in the brain that might be responsible for
`lower BV loss. The pathophysiologic causes and con-
`sequences of these observations are not fully under-
`stood.
`
`Cladribine and alemtuzumab in progressive MS. A
`post hoc analysis of a multicenter, randomized,
`double-blind, placebo-controlled trial of patients
`with progressive MS (70% of whom had a SP and
`30% PP disease course) did not show treatment ef-
`fect by cladribine on BV changes over 1 year.42 Ale-
`mtuzumab, a humanized monoclonal antibody
`which targets the CD52 antigen, was associated with
`a reduction in the number and volume of enhancing
`lesions, but a significant decrease in BV was observed
`in patients with SPMS over 18 months.43
`
`MECHANISMS BY WHICH BIOLOGIC FAC-
`TORS (FLUID STATUS, NUTRITION, AND
`BODY HABITUS) INDUCE SHORT- AND LONG-
`TERM BV FLUCTUATIONS Only a few MRI stud-
`ies have investigated the effects of fluid status,
`nutrition, and body habitus on BV fluctuations in
`healthy people. Potentially confounding biologic fac-
`tors include dehydration-rehydration, intake of alco-
`hol, and diet.44
`cerebral dehydration-
`The mechanism of
`rehydration may explain short-term BV fluctuations
`in healthy people.45 In normal conditions, the water
`content of the human body fluctuates on the order of
`3% of the total body weight.46 Dehydration caused
`by thirst leads to a shrinking of astrocytes, the key
`cells for water movement between the cellular, vascu-
`lar, and ventricular compartments of the brain.47
`Several protective regulating mechanisms (angioten-
`sin, vasopressin, brain natriuretic peptide, and aqua-
`porin) maintain brain osmotic homeostasis during
`these short-term fluid shifts.48 Duning et al.46 investi-
`gated how fluid loss and fluid intake affect BV mea-
`surement. The BV was assessed before and after
`thirsting for 16 hours, and 20 to 30 minutes after
`drinking 1.5 L of mineral water. This study showed
`that hydration status can affect the measurement of
`BV. Lack of fluid intake for 16 hours decreased BV
`by 0.55%, and after rehydration increased BV by
`0.72%. These findings are important for better inter-
`pretation of disease-related conditions in which small
`
`changes in BV are considered important diagnostic
`parameters (i.e., in neurodegenerative disease).49,50
`Therefore, hydration status should be considered as
`an important confounding factor for serial longitudi-
`nal MS studies of BV measurement in the short- to
`mid-term.
`Advances in research on chronic alcoholism and
`brain atrophy have identified another possible mech-
`anism of BV loss in patients with alcoholism. It has
`been demonstrated that chronic alcoholism is associ-
`ated with hypercortisolemia and low serum zinc lev-
`els.51 After toxic insults of chronic alcoholism there
`are metabolic as well as regionally distinct morpho-
`logic capacities for partial brain recovery, and early
`measurable benefits of therapeutic sobriety.52 Under-
`standing these recovery mechanisms is valuable in
`models of brain regeneration.
`Dietary habits may also influence BV measure-
`ment.47,53 Evidence of BV loss in undernourished
`subjects with anorexia nervosa supports the protein-
`loss theory.44 The reduction in BV that occurs in the
`underweight anorexic state could be explained by de-
`creased serum proteins resulting in decreased colloi-
`dal osmotic pressure and a shift of fluid from the
`intravascular space into the subarachnoid spaces, and
`decreased protein synthesis resulting in loss of den-
`dritic spines, reduction in the number of synaptic
`junctions, and delayed synaptogenesis. Insulin-like
`growth factor -1 may be related to changes in brain
`tissue in patients with anorexia nervosa.53
`
`MECHANISMS WHEREBY ANTI-INFLAMMATORY
`TREATMENTS MAY LEAD TO ACCELERATED,
`NON–TISSUE-RELATED BV LOSS (PSEUDOATRO-
`PHY) Pseudoatrophy can be defined as an accelerated
`BV reduction with no associated loss of cell structures.
`It is not clear whether pseudoatrophy is inseparable
`from true BV decline or represents only accelerated wa-
`ter loss (fluid shifts), and whether it influences long-
`term clinical outcomes. It
`is not clear whether
`pseudoatrophy is a temporary phenomenon, as it has
`not been convincingly demonstrated that, when DMAs
`are discontinued, the BV would return to the pretreat-
`ment level. Two types of pseudoatrophy may be in-
`duced by potent
`anti-inflammatory
`treatments
`(beneficial and non–tissue-related) (table 1).
`It is unknown whether the extent of the pseudoat-
`rophy depends on class and type of DMA, along with
`dose, frequency of administration, and delivery
`method. The most
`likely explanation of
`the
`pseudoatrophy during MS therapy is that loss of BV
`is from loss of intracellular water.
`
`Change in electrolyte balance, vascular permeability,
`and dehydration. Potent anti-inflammatory treat-
`ments affect the electrolyte balance by reducing ab-
`
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`normal vascular permeability and promoting water
`and sodium diuresis in the brain (table 1). DMAs
`may initially reduce edema and inflammation, in-
`ducing pseudoatrophy that confounds any real treat-
`ment effect of DMAs on this MRI endpoint in the
`first year of treatment. Studies of the short-term ef-
`fects of IFN-␤s on changes in BV (0 – 6 months)
`have rarely been reported. In a large subgroup analy-
`sis of the European IM IFN␤-1a Dose Comparison
`trial (n ⫽ 138), 68% of the first-year decrease in the
`brain parenchyma fraction occurred during the first
`4 months of treatment (baseline to month 4 was
`⫺0.48% and month 4 to month 12 was ⫺0.23%).20
`Corticosteroids produce a transient and non–
`tissue-related change in the appearance of BV (en-
`larged ventricles and subarachnoid spaces) in the
`short term.44 This corticosteroid-induced pseudoat-
`rophy has been well documented in various patient
`populations.54-58
`The development of pseudoatrophy suggests that
`yearly measurement of BV loss may not be optimal
`for assessing changes in BV after therapeutic inter-
`vention. In future treatment trials, the 3- to 6-month
`MRI scan should be considered a baseline scan, in
`order to eliminate pseudoatrophy. In a post hoc
`study of 147 patients who participated in the
`placebo-controlled combination ASA (Avonex-
`Steroids-Azathioprine) trial and who received bi-
`monthly scans in the first 24 months, we showed that
`GM volume decreased at a higher rate over 2 years
`(⫺2.6%) than whole BV (⫺1.2%) or WM volume
`(⫹0.7%), and was less influenced by the pseudoatro-
`phy phenomenon.5 Therefore, GM volume loss may
`be a more reliable marker of disease and treatment-
`related volume changes. It is difficult to compare the
`natural history estimated rate of BV change in the
`treatment group prior to therapy with the on-study
`BV loss rate in the placebo group, after the pseudoat-
`rophy is stabilized, because pathologic change in BV
`does not occur at a linear constant rate, and the de-
`gree and duration of the pseudoatrophy effect may be
`substantially different between DMAs.
`
`Resolution of inflammation and edema. Different
`DMAs may alter the balance of beneficial and detri-
`mental mechanisms specific to pretreatment disease
`characteristics. For example,
`in patients with
`gadolinium-positive (Gd⫹) lesions at baseline, the
`decline in BV increased with high-dose, high-
`frequency IFN␤-1b compared to placebo, whereas
`patients without Gd⫹ lesions at baseline benefited
`from IFN␤-1b treatment.19A possible explanation
`may be that IFN␤-1b reduced the level of inflamma-
`tory activity (reflected by Gd⫹ lesions), which in
`turn reduced BV.
`
`MECHANISMS BY WHICH ANTI-INFLAMMATORY
`TREATMENTS MAY LEAD TO IRREVERSIBLE BV
`LOSS Potent anti-inflammatory treatments may in-
`duce fluctuating or irreversible changes in BV (table 1).
`
`Chemotherapy-induced neuronal toxicity. In the Ca-
`nadian AHSCT study, there was a decrease in BV by
`a median value of 3.2% during a median time inter-
`val of 2.4 months, which represented a very high me-
`dian annualized rate of BV loss of 15.1%/year.35 The
`loss in BV was irreversible. The BV loss was not sec-
`ondary to water shifts.35 No association was found
`between loss in BV and change in parenchymal water
`in a recent report that investigated whether the acute
`brain BV loss following immunoablation and AH-
`SCT for MS is associated with a loss of myelin, wa-
`ter, or axons.59 Patients with the largest BV loss
`exhibited increases in T2 relaxation time. This study
`suggests that parenchymal water loss is not responsi-
`ble for the rapid development of permanent BV loss
`in patients treated with AHSCT. More likely, the
`direct cytotoxic effect of the potent chemotherapy
`may be responsible for this BV loss.
`
`Parenchymal water loss vs protein catabolism. Corti-
`costeroids with long-term daily treatment at low
`doses may induce BV loss.44 One of the most signifi-
`cant mechanisms for this effect is the induction of
`protein catabolism, which may lead to reduced BV in
`patients with anorexia,47,53 patients with alcohol-
`ism,51,52 and patients with Cushing disease.44 Patients
`with non-neurologic autoimmune diseases,44 treated
`with prolonged daily use of corticosteroids over the mid
`to long term, showed significant BV loss. On the other
`hand, high-dose pulsed IVMP in MS at 3- to 4-month
`intervals prevented BV loss.17 This suggests that fre-
`quency of administration of anti-inflammatory treat-
`ment is an important factor in the dynamics of change
`in the parenchymal water that may trigger the protein
`catabolism or other mechanisms over the long term.
`
`The effect of “good” vs “bad” inflammation on remy-
`elination. Remyelination in MS must take place in a
`hostile proinflammatory environment that typically
`initiates and sustains demyelination.8 Paradoxically,
`inflammation can promote remyelination in some
`models.60 Potent, frequently administered unselec-
`tive anti-inflammatory treatments may not prevent
`BV loss over the long term because they reduce neu-
`roprotective effects of inflammation.
`Because inflammation induces some beneficial
`processes, potent anti-inflammatory treatments over
`long periods of time may suppress growth factors or
`prevent migration of stem cells that promote remy-
`elination. Inflammatory CNS injury also promotes
`neuronal repair by increasing neurotrophin secre-
`tion.60 BDNF is expressed throughout MS lesions,
`
`Neurology 71 July 8, 2008
`
`141
`
`Page 6 of 9
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`YEDA EXHIBIT NO. 2024
`MYLAN PHARM. v YEDA
`IPR2017-00195
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`

`

`and neurons as well as infiltrating T cells may be a
`source of BDNF.60 This hypothesis highlights the
`importance of balancing “good” and “bad” inflam-
`mation because infiltrating T cells may provide neu-
`rotrophic factors.
`
`CONCLUSIONS Treatment with DMAs in the
`short term may affect BV by inducing pseudoatro-
`phy, and in the long term by slowing BV loss. The
`long-term effects of anti-inflammatory treatments af-
`fect the balance of “good” and “bad” inflammation
`in MS differently. Reducing “bad” inflammation
`may prevent future demyelination but evidence sug-
`gests that demyelination and BV loss occur at an
`early disease stage. Once initiated, these processes in-
`duce remyelination and may be vulnerable to over-
`suppression of certain regulatory cytokines and
`inhibition of neurotrophins. Longer, controlled
`studies on the effects of different DMA dosing regi-
`mens on BV changes should improve our under-
`standing of this phenomenon.
`
`ACKNOWLEDGMENT
`The authors thank Professor Franz Fazekas for providing supporting data
`not yet published. They also thank Eve Salczynski for technical support in
`the preparation of this manuscript.
`
`DISCLOSURE
`Dr. Zivadinov served as a consultant for Teva and Biogen. Dr. Zivadi-
`nov has served on the speakers’ bureaus of Teva and Biogen. Dr.
`Zivadinov has received honoraria from Teva, Biogen, EMD Serono,
`and Pfizer. Dr. Zivadinov has received research or grant support from
`Teva, Biogen, Aspreva, and Genzyme. Dr. Reder is on Advisory
`Board/Consultant for: Abbott Laboratories, Immunoscience, Parsip-
`pany, NJ; American Medical Association, Chicago, IL; Astra Merck,
`Wayne, PA; Athena Neurosciences, South San Francisco, CA; Aventis
`Pharma, Bridgewater, NJ; Berlex Laboratories, Richmond, CA; Bio-
`gen and Biogen/Idec, Cambridge, MA; BioMS Medical Corp., Edm-
`onton, Alberta, Canada; Blue Cross, Blue Shield, Chicago, IL;
`Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT; Care-
`mark Rx, Northbrook, IL; Centocor, Inc., Malvern, PA; Cephalon,
`Inc., Delaware, MD; Connectics/Connective Therapeutics, Palo Alto,
`CA; CroMedica Global Inc., Victoria, BC; Elan Pharmaceuticals, Inc.,
`San Diego, CA; Genentech, South San Francisco, CA; Genzyme Cor-
`poration, San Antonio, TX; GlaxoSmithKline, Research Triangle
`Park, NC; Hoechst Marion Roussel Canada Research, Inc., Leval,
`Quebec; Hoffman-LaRoche, Nutley, NJ; Idec, San Diego, CA; Immu-
`nex, Seattle, WA; Institute for Health Care Quality, Minneapolis,
`MN; Johnson & Johnson, Pharmaceutical Research & Development,
`LLC, Raritan, NJ; Kalobios, San Francisco; NARCOMS, Yale Univer-
`sity, New Haven, CT; Barrow Neurological Institute, Phoenix, AZ;
`National Multiple Sclerosis Society & Paralyzed Veterans of America,
`“Pain Panel,” New York, NY; Neurocrine Biosciences, San Diego, CA;
`Novartis Corporation, New York, NY; Parke-Davis, Morris Plains,
`NJ; Pfizer Inc., New York, NY; Pharmacia & Upjohn, Kalamazoo,
`MI; Protein Design Labs, Inc., Delaware; Quantum Biotechnologies,
`Inc., Leval, Quebec; Quintiles, Inc., San Diego, CA; RENEW study
`(post-marketing study of Novantrone in MS); Serono; Sandoz (now
`Novartis) & Novartis, East Hanover, NJ; Sention, Inc., Providence,
`RI; Serono, Norwell, MA; Smith Kline-Beecham, Philadelphia, PA;
`Specialized Therapeutics, a division of Berlipharm, Inc., Montville,
`NJ; Takeda Pharmaceuticals, Lincolnshire, IL; and Teva-Marion,
`Kansas City, MO. Dr. Filippi has served as a consultant for Teva,
`Bayer Schering AG, Genmab, Bioge