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1 Clinical Neurology and Neurosurgery 112 (2010) Contents lists available at ScienceDirect Clinical Neurology and Neurosurgery journal homepage: Review Therapy of MS Reza Vosoughi, Mark S. Freedman The Ottawa Hospital, General Campus, Ottawa, Ont., Canada article info abstract Article history: Received 28 February 2010 Accepted 4 March 2010 Available online 1 April 2010 Keywords: Multiple sclerosis Treatment Therapy Disease-modifying Relapsing remitting multiple sclerosis Emerging therapies The era of disease-modifying drugs (DMDs) in multiple sclerosis (MS) treatment began in the 1990s, first with interferon- (IFN ), and the number of agents has increased steadily since then. Currently, there are six different parenteral formulations approved for MS treatment and many other oral and parenteral ones are in different stages of investigation or awaiting approval by federal agencies. All of these medications have demonstrated partial efficacy along with different side effect profiles. Increasing our understanding about the natural behaviour of MS and its different types and stages, diversity of different therapies, their strength and weaknesses, and their serious and sometimes life-threatening side effects have created challenges for treating physicians; making the choice of individualized optimal treatment increasingly more complicated. In this review, we will summarize present and future treatment options and also address clinical challenges we are regularly facing in arriving at treatment choices for our patients Elsevier B.V. All rights reserved. Contents 1. Introduction Treatment of relapsing remitting multiple sclerosis Approved treatments First-line agents Second-line agents Stem cell transplantation in MS Rationale for early treatment of MS after the first demyelination episode Clinical treatment strategies in RRMS: induction vs. escalation, treatment optimization Disease-modifying agents in progressive MS Emerging therapies Fingolimod (FTY 720) Gilenia Cladribine Teriflunomide Dimethyl fumarate (BG00012) Laquinimod Minocycline Statins Alemtuzumab Rituximab Daclizumab Conclusion References Abbreviations: AHSCT, autologous hematopoietic stem cell transplantation; ARR, absolute risk reduction; BBB, blood-brain barrier; CDMS, clinically definite multiple sclerosis; CIS, clinically isolated syndrome; CNS, central nervous system; CHF, congestive heart failure; DMD, disease-modifying drugs; EAE, experimental autoimmune encephalomyelitis; EBV, Epstein-barr virus; EDSS, expanded disability status scale; eod, every other day; GA, glatiramer acetate; G-CSF, granulocyte colony-stimulating factor; Gd, gadolinium; GdE, gadolinium-enhancing; IFN, interferon; IM = im, intramuscular; IV = iv, intravenous; LVEF, left ventricular ejection fraction; MIU, million international units; MS, multiple sclerosis; mab, monoclonal antibody; MBP, myelin basic protein; mcg = g, microgram; MHC, major histocompatibility complex; MOG, myelin oligodendrocyte glycoprotein; MSC, mesenchymal stem cell; NAbs, neutralizing antibodies; OCT, optic coherence tomography; PLP, proteolipid protein; PML, progressive multi-focal leukoencephalopathy; PPMS, primary progressive multiple sclerosis; qw, every week; RRMS, relapsing remitting multiple sclerosis; SC = sc, subcutaneous; SPMS, secondary progressive multiple sclerosis; tiw, three times a week; TNF, tumor necrosis factor. Corresponding author. Tel.: addresses: [email protected], [email protected] (R. Vosoughi) /$ see front matter 2010 Elsevier B.V. All rights reserved. doi: /j.clineuro

2 366 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) Introduction Multiple sclerosis (MS) is the leading cause of acquired neurological disability in young adults and the most common demyelinating disorder of the central nervous system. It is an inflammatory disease that affects the myelin of both gray and white matter, which eventually leads to the loss of neurons and axons the pathological substrate of progressive disability. An international panel of neurologists has outlined four distinct clinical disease patterns in MS: relapsing remitting (RRMS); secondary progressive (SPMS); primary progressive (PPMS); and progressive relapsing (PRMS) [1]. At onset, over 80% of MS patients have a RRMS disease course, about 50% of whom will develop SPMS after years disease duration. Although approximately 15% of MS patients develop PPMS, relapse-like activity (PRMS) will develop over time in about 5% of these patients. Relapsing remitting MS, which is the most common phenotype, starts with a single mono- or multi-focal demyelinating episode (clinically isolated syndrome, CIS) with partial or full recovery. Similar or varied types of relapses occur in time after this initial attack. This stage of the disease is dominated by overt inflammation and demyelination, manifesting as clinical attacks and the formation of new MRI lesions; though subclinically damage to neurons and axons is slowly amassing, gradually diminishing the ability to sustain further events without acquiring disability. After some years, most but not all patients with RRMS evolve into a slowly progressing phase with or without superimposed relapses (SPMS). At this stage of the disease inflammation appears less prominent, and instead the accumulated damage to neurons and axons starts to show itself clinically as neurological progression. The other clinical type of MS which is primary progressive MS (PPMS) is recognized by its progressive course from the outset, with a paucity of inflammation detected in the CNS compared with RRMS. Some of these patients still have clinical and radiological evidence of inflammation, but unfortunately for this subtype of the disease there is still no proven effective treatment. 2. Treatment of relapsing remitting multiple sclerosis 2.1. Approved treatments First-line agents Interferon-ˇ. Of the type I interferons, interferon- (IFN ) is one of the first-line agents in the treatment of CIS and MS. Interferons were first tried in MS, regardless of their type, because of their antiviral activities. The clinical trial with type II interferon (interferon- ) was very influential, because it showed a proinflammatory effect of this interferon and increased disease activity [2,3]. Different preparations of interferon- (another type I interferon used primarily for the treatment of severe viral disease or cancer) have been tested over time to treat MS, and despite having some favourable effects on MRI and clinical disease activity in some trials, conflicting overall results [4 10] have diminished enthusiasm for this interferon compared to that of IFN. There are three different formulations of IFN, which are already approved for the treatment of RRMS: IFN -1a, 6 MIU (30 g), IM weekly injection (Avonex ), IFN -1a, 22 and 44 g, SC injections thrice-a-week injections (Rebif ), and IFN -1b, 8 MIU (250 g), SC alternate day injections (Betaseron ). Nowadays, these three interferons along with glatiramer acetate are the first-line DMDs in the treatment of MS, having the support of class I evidence from several phase III trials [11 18]. Though the exact mechanism(s) of action of IFN beneficial to MS is not known, it seems that among many different biological actions, the effects on immune function are the most plausible ones. IFN has been shown to reduce antigen presentation [19], reduce and modulate co-stimulatory molecules on dendritic and other cell types [20,21], inhibit proliferation and suppression of Th1 cells and upregulate IL-10 production [22], and in general shift the cytokine profile of production from proinflammatory to anti-inflammatory cytokines [23,24] along with decreased T-cell migration possibly due to reduced MMP expression [25,26]. IFN probably also stimulates regulatory T-cells acting to better keep the autoimmune disease in check IFNˇ-1b (Betaseron ). IFN -1b was the first immunomodulatory therapy approved for the treatment of relapsing remitting (RR) multiple sclerosis (MS) in 1993 [11,12] and currently is the only IFN licensed for use in North America for secondary progressive (SP) MS [27]. It is produced by recombinant DNA technology in the bacterial cell (Escherichia coli) [28]. The initial 1993 phase III study was a double-blind placebocontrolled phase 3 trial Interferon-beta Multiple Sclerosis Study Group trial [11,12]. It included 372 patients with EDSS score and at least two relapses in the preceding 2 years. Patients were randomized to receive placebo or IFN -1b (50 or 250 g subcutaneously every other day) for 2 years. The primary end point, the clinical relapse rate, was significantly reduced in the both IFN treated groups compared to the placebo control group (high dosage vs. placebo p = ; low dosage vs. placebo p = 0.01) and in (high dosage vs. low dosage group p = ), suggesting a dosage effect. The MRI results supported the clinical findings, showing a significant reduction of T2-active scans (high dosage vs. placebo p = ; low dosage vs. placebo p = 0.04), appearance of new T2 lesions (high dosage vs. placebo p = ; low dosage vs. placebo p = 0.03) and MRI burden of disease (high dosage vs. placebo p < 0.001; low dosage vs. placebo p = 0.04). For the secondary end point, the number of patients with EDSS progression, the difference was not statistically significant between treatment and placebo groups, owing probably to a significant attrition of patients over the scheduled 5-year observation period. To evaluate long-term safety and efficacy of IFN -1b in RRMS patients, a multicentre, open-label, observational study was conducted for up to 16 years of follow-up using cross-sectional data collection from patients having participated in the pivotal trial [29]. The final results of this longer follow-up study suggested that early and continuous long-term treatment with IFN -1b was favourable, since relapse frequency reduction remained similar to the pivotal study (<40%), and progression of disability, evaluated as those reaching the EDSS 6 milestone (unable to walk without assistance), was even slower in patients exposed for a longer period compared to other groups with a shorter period of treatment. These reported results were confirmed by a more recently published longterm observational study showing that IFN- 1b treated patients have a significant reduction in the incidence of secondary progression, EDSS 4.0 and 6.0, compared with untreated patients, during a follow-up lasting up to 7 years [30]. The most common side effects of IFN -1b are lymphopenia, injection-site reaction, asthenia, flu-like symptoms, headache, pain, and elevated liver enzymes. More serious adverse events are rare but include depression, suicidal ideation, and injection-site necrosis, which may mandate immediate withdrawal of the drug IFNˇ-1a SC (Rebif ). This interferon- preparation is also produced using DNA technology, but unlike IFN -1b, it is produced in mammalian Chinese hamster ovary cells, which adds glycosylation to the final product which has a significantly higher specific activity [31]. It was approved for treatment of RRMS in 1998 in Europe and Canada, and only in 2002 in the USA, when it was able to show superiority over the other approved IFN -1a (Avonex ) product in the EVIDENCE trial [18]. This IFN was tested as a once-weekly injections in the OWIMS (once-weekly interferon for MS) study; a large (n = 293),

3 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) randomized, double-blind, placebo-controlled trial performed to determine whether IFN -1a (22 or 44 mcg sc) administered at a low dosing frequency (qw) was effective in patients with RRMS [32,33]. Low-frequency weekly administration was the proven dosage for the other IFN -1a (Avonex ) (see below); however, 1-year data from the OWIMS study showed significant treatment effects on MRI measures only, with only a trend towards relapse rate reduction in the IFN -1a, 44 mcg sc qw, group [32]. The Prevention of Relapses and Disability by Interferon- -1a Subcutaneously in Multiple Sclerosis study (PRISMS study) [15] that led to approval of IFN -1a SC in RRMS was a multicentre controlled trial wherein 560 patients with an EDSS score between 1.0 and 5.0 and at least two relapses in the preceding 2 years were randomized to 2-year treatment with placebo or IFN -1a (22 or 44 g subcutaneously three times weekly). After 2 years of treatment, both doses of IFN -1a showed significant benefits compared with placebo in all major outcome measures (relapse rate, disability progression, MRI activity). There was a non-significant trend towards greater efficacy with the 44- g dose than with the 22- g dose on most clinical measures, and a statistically significant dose-effect favouring the higher dose in terms of impact on the number of T2- active lesions. In addition, although 22 g IFN -1a tiw was more effective than placebo, the subgroup of patients with more severe disease (baseline EDSS score > 3.0) responded significantly only to the higher dose. After 2 years, patients who had initially received placebo in the PRISMS study were re-randomized to receive active treatment (22 or 44 g SC tiw) and were followed for an additional 2 years. By the end of year 4, patients who had switched from placebo to 22 or 44 g IFN -1a had experienced a 54% reduction in annual relapse rate, compared with the end of year 2 [34]. Furthermore, after 4 years, the trend evident at 2 years, favouring the higher dose, approached significance for annual relapse rates (0.8 for 22 mcg vs for 44 mcg; p = 0.069). The mean annualized relapse rate was significantly lower in patients who had received IFN -1a for the full 4 years compared with those who had received placebo for the first 2 years. Relapse rates fell progressively with each additional year on therapy. Additionally, patients who received the highest cumulative dose of therapy had the lowest rate of disability progression [35]. In terms of side effects, the most commonly reported adverse reactions were: injection-site reaction, flu-like symptoms, elevated liver enzymes and haematological abnormalities. Injection-site necrosis was rare. The most serious adverse reactions were similar to IFN -1b, a psychiatric disorder, including depression and suicidal ideation or attempt IFNˇ-1a IM (Avonex ). Similar to Rebif, this IFN - 1a is also produced in Chinese hamster ovary cells and was approved for treatment in RRMS in 1996 following the results of a pivotal study designed by the Multiple Sclerosis Collaborative Research Group (MSCRG). They randomized 301 patients with EDSS score of and at least two relapses in the preceding 3 years, to receive placebo or IFN -1a (30 g intramuscularly once weekly) for 2 years [36,37]. This trial was stopped earlier than originally intended and only 57% of patients completed the full 2 years on study medication. Many results were then calculated using this subset of patients (but the totally enrolled subset and therefore such an analysis did not follow the intention-to-treat principle). However, after 2 years, the group that received IFN -1a did show an effect on the primary endpoint of the trial: the progression rate, when compared with placebo. A modest reduction in relapse rate (18% for the total group, 32% if only the 2 year completers were included) and a reduction in the median number of active (gadolinium-enhancing) MRI lesions were seen in a subset of patients. The most common reported side effects of the drug were flulike symptoms including myalgia, fever, fatigue, headache, chills, nausea, and vomiting. Paresthesiae, hypertonia, and myasthenia have also been reported. Like the other -interferons depression, suicidal ideation, and new or worsening psychiatric disorders are increased in patients receiving this treatment and need careful follow up. Hepatic failure, hepatitis, and elevated liver enzymes have also been reported Glatiramer acetate (Copaxone ). Glatiramer acetate (GA) is a synthetic amino acid polymer composed of random sequences of four amino acids (tyrosine, glutamate, alanine, and lysine), approved in 1997 for treatment of RRMS. GA has been shown to be effective in preventing and suppressing experimental allergic encephalomyelitis (EAE) [38,39]. Daily injection of GA, which is a peptide mixture rather than a chemical substance, might be considered as an example of therapeutic vaccination. Its beneficial effects in RRMS are thought to stem from the modification of immune processes implicated in the pathogenesis of the disease. Its relevant effects possibly explaining the clinical efficacy in MS include: high affinity MHC binding in the periphery [40], induction of regulatory T-cell by a shift from Th1 type to Th2 and Th3 type [41 43], dose-dependent inhibition of MBP-specific T-cell response [44,45], Th2-type cell migration through the blood-brain barrier (BBB) [46], cross reactivity of GA induced T-cells with MBP, MOG, and PLP [47 49], bystander suppression [50 52] and neuroprotection due to increased production of brain-derived neurotrophic factor (BDNF) by GA-specific T-cells [53,54]. In the initial phase II trial in RRMS patients, GA reduced relapse rates by 76% [55]. Further clinical development confirmed this finding: The relapse rates were reduced by a third and a high proportion of patients became relapse-free in a multicentred, placebo-controlled phase 3 trial [56]. Unfortunately, MRI was not used in the initial phase III trial, prompting a second short trial [62] to show the effects of GA on several MRI metrics. That trial also demonstrated a similar response on relapse rate, but neither the original phase III nor this follow-up MRI trial was able to demonstrate an effect at slowing EDSS progression according to the standard definition. Long-term follow-up of the original phase III trial patients was able to show the benefits of early GA introduction compared with delayed therapy [57 60], similar to that of Rebif above. Lesion burden assessed by MRI has shown a beneficial profile for GA in RRMS patients. In these trials GA reduced the frequency of new enhancing lesions and lesion load compared to baseline pretreatment measures [61,62]. Generally, it is viewed that GA has the most favourable adverse effect profile compared with the other therapeutic options available for MS. Unlike IFN, GA does not cause liver function abnormalities or leukopenia, and is not associated with depression. The typical flu-like reaction characteristic of IFN does not occur with GA, however, approximately 15% of patients experience a selflimited, post-injection systemic reaction characterized by chest tightness, flushing, anxiety, dyspnea, and palpitations. This reaction is unpredictable, can occur at any time during treatment, and may be mistaken for cardiac ischemia, but is of no consequences. Skin site reactions may occur and hives are not uncommon. Laboratory values do not need to be monitored in patients treated with GA Neutralizing antibodies (NAbs). Biopharmaceuticals can induce the formation of antibodies, which interact and bind with or possibly neutralize the biological effect of such drugs and are therefore termed binding antibodies or BAbs or neutralizing antibodies or NAbs [63] NAbs to IFNˇ. The first detailed report on IFN induced NAbs in MS was published in 1996 [64]. The prevalence

4 368 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) of NAbs against different IFN preparations varies widely. NAbs frequencies in IFN -lb treated patients were often reported to be highest [17,65,66] but more recent studies could not detect a substantial difference from subcutaneous IFN -la [67]. IFN -la given intramuscularly induces significantly less NAbs than any other IFN formulation, at least in the short term. Factors that might contribute include frequency and route of injection as well as Nabs assay setting [68,69]. The route of administration produces varying immunogenicity, with sc > im > iv [69,70]. The preparation itself is a factor, but even within one product differences can occur [69,71]. For example, after a change in the formulation and production process of Avonex (intramuscular IFN -la) the frequency of NAbpositive patients dropped from 22% to 2% [72,73]. A similar effect, although to a lesser extent, was observed with a new formulation of Rebif (subcutaneous IFN -la) [74]. In contrast to other forms of immunization, NAbs develop relatively slowly and (depending on the definition of NAb positivity) can take up to 2 years to occur for the first time [75]. Low titres of NAbs may disappear with maintenance of treatment but high titres of NAbs have a higher chance of persistence [76,77]. There are several prospective studies investigating the effect of NAbs on the clinical outcome in terms of relapses, mainly in RRMS but also in patients with progressive MS [64,65,73,78 86]. The majority of studies with longer observation periods have demonstrated significantly higher relapse rate, decreased number of relapse-free patients, and shorter time to first relapse in NAb-positive patients. But, most of the studies with an observation period of less than 2 years did not detect a difference in relapse rates between NAb-positive and NAb-negative patients. Most MRI studies revealed a significant difference between NAb-negative and NAb-positive patients, with higher activity in the latter group. MRI changes generally occurred earlier than clinical NAb effects [18]. All of these studies suffer from the same criticism in that characteristics of NAb+ patients are not known a priori and only declare themselves after the appearance of NAbs. There may be other factors that associate with both the propensity to develop NAbs and to have a more active disease course. Two guideline papers have been issued by independent neurological organizations, one by the European Federation of Neurological Societies (EFNS) [87] and one by the American Academy of Neurology [88]. There are several lines of agreement between the two guidelines: NAbs occur during treatment with IFN. There is lower prevalence of NAbs in patients treated with intramuscular IFN -la compared with the other preparations. NAbs are associated with a reduction in the clinical and MRI effects of IFN, specifically at high titres. Given that there is no unified assay for the measurement of NAbs, NAbs disappear over time and there is even some suggestion that patients developing NAbs might have a stronger response to IFN, especially early on [89], many do not measure NAbs routinely and their usefulness overall is still somewhat undecided [89] Antibodies against glatiramer acetate. Several studies have investigated the presence of antibodies against glatiramer acetate; in most studies, the majority or all patients were found to be seropositive [90,91]. The biological meaning of these antibodies remains unknown, since the pathway leading to the clinical effect of this drug is still obscure. But, a recently published study indicates that although neutralizing activity of anti-ga antibodies is not significant, the clinical efficacy of GA treatment could be associated with a decrease in anti-ga IgG2 isotype in long-term GA-treated patients [92] Change in the response to treatment over time. It has been noted that with each new trial over time the response to treatment using either IFN or GA is improving (see Figs. 1 and 2). The exact reason for this is not known, but it is obviously not because the medications have changed. Likely it has to do with earlier diagnosis and the eventual enrolment of patients with less advanced disease, emphasizing the need for early introduction of disease-modifying medications to achieve the greatest result Comparison of efficacy of first-line agents. The relative efficacy of approved first-line DMDs has been a topic of great interest, but it was recognized that simply comparing the results across the individual studies was a flawed process [93]. The various trials were quite different in terms of their study designs, clinical and paraclinical endpoints, patient characteristics, and placebo-effect size. Although systematic comparison of these different studies is still possible with application of Evidence-Based Medicine principles [93], the most valid source of data on this matter has come from direct comparative head-to-head trials. Until 2007, only two clinical studies had directly compared the efficacy and tolerability of different immunomodulatory treatments. These were the EVIDENCE study [18], which compared interferon- 1a SC 44 g to interferon- -1a IM over 1 year; and the INCOMIN study [17], comparing interferon- -1b SC to interferon- 1a IM over 2 years. Both these studies demonstrated that high-dose subcutaneous INF was more effective than intramuscular IFN. The EVIDENCE study [18] was a randomized multicentre trial, which compared IFN -1a SC, 44 g toifn -1a IM, and after 24 weeks, 74.9% of patients receiving IFN -1a 44 g tiw remained relapse-free compared with 63.3% of those given 30 g qw. The odds ratio for remaining relapse-free was 1.9 (95% CI, ; p = ) at 24 weeks and 1.5 (95% CI, ; p = 0.009) at 48 weeks, favouring 44 g tiw. Patients receiving 44 g tiw had fewer active MRI lesions (p < at 24 and 48 weeks) compared with those receiving 30 g qw. Injection-site reactions were more frequent with 44 g tiw (83% vs. 28%, p < 0.001), as were asymptomatic abnormalities of liver enzymes (18% vs. 9%, p = 0.002) and altered leukocyte counts (11% vs. 5%, p = 0.003) compared with the 30 g qw dosage. Neutralizing antibodies developed in 25% of 44 g tiw patients and in 2% of patients receiving 30 gqw. INCOMIN was a prospective, randomized, multicentre study [17], and after 2 years, 51% of individuals receiving IFN -1b remained relapse-free compared with only 36% given IFN -1a (relative risk of relapse 0.76; 95% CI ; p = 0.03); and respectively, 55% compared with 26%, remained free from new T2 lesions at MRI (relative risk of new T2 lesion 0.6; ; p < ). In both groups, the differences between the two treatments increased during the second year. There were also significant differences in favour of IFN -1b in most of the secondary outcome measures, including delay of confirmed disease progression. Recently, three additional studies compared the efficacy of glatiramer acetate (GA) with that of high-dose subcutaneous IFN. These were the REGARD trial [94], which compared GA to IFN 1a SC 44 mg (Rebif ), the BECOME [95,96] and BEYOND [97] trials, which both compared GA to IFN -1b (Betaferon ). The BECOME trial was a small, single-centre, investigator-driven study using MRI outcome measures, whereas the BEYOND and REGARD trials were large, multicentre, industry-sponsored studies using clinical outcome measures. The primary outcome measure in the REGARD study was time to first relapse, determined using a Cox proportional hazard model [94]. The secondary endpoints of the REGARD study were related to MRI measures and were restricted to a sub-population of patients who underwent serial MRI scans. These were the number of new or enlarged T2 lesions accumulating over the course of the study, the mean number of gadolinium-enhancing lesions per patient and per

5 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) Fig. 1. Change in efficacy responses over time in IFN MS trials. scan, and the change in volume for both these lesion types. In terms of primary endpoint, there was no significant difference in time to first relapse between the two treatment groups. With respect to the subpopulation of patients with serial MRI evaluations, no difference was observed in the number of new or enlarging T2 lesions per patient per scan or in the number of new T1-hypointense lesions between the two groups, but a statistically significant difference (p < 0.001) of 42% in the number of gadolinium-enhancing lesions/patient/scan in favour of the IFN treatment group was noted. The overall proportion of patients reporting adverse events was similar in the two treatment groups although they were of different nature. The primary outcome measure for BECOME was the mean number of combined active lesions per scan per patient [95]. Combined active lesions were defined as either gadolinium-enhancing T1- lesions or new non-enhancing T2/FLAIR lesions. The final analysis of the data demonstrated that the mean number of combined active lesions declined over 1 year in both treatment groups, with no significant inter-group difference. Similarly, no differences in any of the secondary MRI outcome measures were observed between the two treatment groups. Although insufficiently powered to detect differences in clinical outcome, annualized relapse rates and disability progression were similar in the IFN and GA treatment groups [96]. The BEYOND study was a much larger study [97] which tested two hypotheses, first whether the higher dose of 500 g of IFN - 1b would have superior efficacy to the standard dose of 250 g, and secondly whether either dose would show superiority to GA. Therefore, the study included 2244 treatment-naïve patients with RRMS from 198 study centres worldwide who were randomized in a ratio of 2:2:1 to one of three treatment arms, namely IFN 500 g (n = 899), IFN 250 g (n = 897) or GA (n = 448). This is in fact the Fig. 2. Change in efficacy responses over time in GA MS trials.

6 370 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) largest randomized study in RRMS reported to date. The primary outcome measure was the hazard ratio for multiple relapses determined with the Anderson Gill extension of the Cox proportional hazards model. Secondary outcomes included time to confirmed EDSS progression and the development of T1-hypointense lesions ( black holes ). In the primary outcome evaluation, the hazard ratio for multiple relapses in all three pair-wise comparisons was not significantly different from unity, indicating no difference in relapse risk between any of the three treatments. With respect to MRI outcomes [98], no significant differences were observed for most measures. In particular, no significant differences between the groups in the number or volume of T1 Gd-enhancing lesions at study end, in the accumulation of T1-hypointense lesions ( black holes ) or in changes in total brain volume between the three treatment groups. Exceptions were the cumulative number of T2 lesions up to the last scan and the relative increase in T2 lesion volume, which were both significantly higher in the GA group than in either of the IFN groups; however the differences observed were relatively small Second-line agents Mitoxantrone (Novantrone ). Mitoxantrone, originally developed in the 1970s as an anti-neoplastic agent, is chemically related to the anthracyclines such as doxorubicin and daunorubicin and has both potent immunosuppressive and immunomodulatory properties. Mitoxantrone intercalates with DNA, causing singleand double-stranded breaks, and also inhibits DNA repair via inhibition of topoisomerase II. In addition to its immunosuppressive effects on proliferating cells, particularly B- and T-lymphocytes, and macrophages [99 102], several early immunomodulatory properties have been described, including decreased secretion of interferon, TNF- and interleukin IL-2 [102]. Mitoxantrone also induces apoptosis and necrosis of B-lymphocytes and monocytes [103,104]. Different trials have confirmed its efficacy in RRMS and early SPMS cases especially in the ones with highly active or rapidly worsening disease. An Italian, multicentre, randomized, single-blinded, placebo-controlled trial conducted in eight centres evaluated the efficacy of mitoxantrone over 2 years in 51 patients with RRMS [105]. The patients were randomized to 1 year of either mitoxantrone therapy 8 mg/m 2 of intravenous mitoxantrone every month or placebo. There was a significant difference between the two groups of patients in terms of primary endpoint of the study which was a 1-point EDSS progression (p = 0.02). In terms of the secondary endpoints, there was a statistically significant difference for the mean annual number of exacerbations (0.9 vs. 2.6, p < 0.001), and the number of exacerbation-free patients (p < 0.01). Follow-up analysis showed a 52% reduction in new T2 lesions in the mitoxantrone group, compared with the placebo group (7.3 vs. 3.5, p = 0.05). The French British, multicentre, randomized, MRI controlled (but clinically unblinded and not placebo-controlled) trial evaluated the efficacy of mitoxantrone over 6 months, in a group of 42 patients with aggressively active clinical and radiological disease [106]. Eligible patients had experienced either two MS relapses with sequelae, or progression of two points on the EDSS during the previous 12 months. All patients had at least one new active lesion on 3-monthly Gd+ MRI scans during a 2-month baseline period. Six patients in the control group and four patients in the mitoxantrone group had SPMS; the remainder had RRMS. Patients were randomized to 6 months of treatment with 20 mg mitoxantrone plus 1 g methylprednisolone every month, or 1 g methylprednisolone every month. The primary endpoint of the study was the percentage of patients without new Gd+ MRI lesions. There was a significant difference by month 6 between the mitoxantrone and non-mitoxantrone treated group (90% vs. 31%, p < 0.001). The secondary endpoint was the mean monthly number of new Gd+ lesions which was lower at all timepoints in the mitoxantrone treated group and the differences were significant from month 1 to 6 (month 1 4, p < 0.05; month 5, p < 0.01; month 6, p < 0.001). Globally, over 6 months, there was an 85% reduction in new enhancing lesions in the mitoxantrone group. Similarly, comparison of the T2-weighted images at the study end with those at month 0 identified an 80% reduction of new T2 lesions in the mitoxantrone group. Clinical assessment of the patients, though unblinded, showed a clear benefit in the mitoxantrone group. EDSS score in the mitoxantrone group continuously improved, while in the nonmitoxantrone group it deteriorated and resulted in the drop-out of five patients. During the treatment period, there were few relapses in mitoxantrone treated group (7 vs. 31), and more exacerbationfree patients. The European multicentre, double-blind, Phase III MIMS trial involved 194 patients randomly assigned to treatment with placebo, mitoxantrone 5 mg/m 2 or mitoxantrone 12 mg/m 2, administered intravenously every 3 months for 24 months [107]. The primary efficacy outcome consisted of five clinical measures (change in EDSS score, change in ambulatory index score, number of relapses treated with glucocorticoids, time to first severe relapse treated with glucocorticoids, and change in Standardized Neurological Status score). A significant treatment effect (p < ) was detected with the primary outcome. Treatment effects for the 5 mg/m 2 mitoxantrone recipients were generally intermediate between those observed in 12 mg/m 2 mitoxantrone and placebo recipients. Over 24 months, confirmed neurological progression was observed in significantly fewer patients receiving 12 mg/m 2 dosages relative to those on placebo (8.3% vs. 22%, p = 0.04). Annualized relapse rates were significantly lower in the 12 mg/m 2 mitoxantrone group relative to placebo in year 1 (0.42 vs. 1.15, p < ), and year 2 (0.27 vs. 0.85, p = ). Significantly more patients in the 12 mg/m 2 mitoxantrone group did not experience any relapse over 24 months relative to the placebo group (57% vs. 36%, p = 0.021). Significantly fewer patients receiving 12 mg/m 2 mitoxantrone demonstrated Gd+ lesions at 24 months relative to baseline (29.4% vs. 3.2%; p = 0.003), but not to placebo (3.2% vs. 15.6%; p = 0.065). The mean increase in the number of T2-weighted lesions was 0.29 in those receiving the 12 mg/m 2 mitoxantrone dosage and 1.94 in placebo recipients (p = 0.027). The important issue of mitoxantrone treatment and its potential utility in rapidly deteriorating MS patients (described as the malignant form of MS) was addressed by Edan et al. [106]. The strong and rapid reduction in the inflammatory process observed with mitoxantrone (20 mg monthly, for 6 months) and methylprednisolone (1 g monthly, for 6 months) in combination suggests a potential role for this regimen as rescue therapy in very active MS cases. Similar results were observed by Debouverie et al. [108] in clinical practice. They pointed out that, among the predictive parameters of mitoxantrone effectiveness, the number of relapses in separate areas within the 24 months before treatment was the strongest parameter in predicting clinical improvement. As part of a MS treatment escalation strategy in patients with very active MS, mitoxantrone might be considered as a first-line therapy, but these patients are, in general, non-responders to other approved disease-modifying drugs used in MS. Mitoxantrone might be an attractive, though temporary, option for RRMS patients who are non-responders to IFN -1a, -1b or GA. Usual mitoxantrone side effects include nausea and vomiting; alopecia is usually very mild [109]. Leucopenia develops between days 10 and 14 after a single large dose and persists for 4 7 days with full recovery usually occurs between days 18 and 21 [110].

7 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) Mitoxantrone can have serious and life-threatening side effects: cardiotoxicity has been reported in cancer and MS patients receiving mitoxantrone as an immunosuppressive chemotherapeutic agent [107, ] and characterized by changes in electrocardiogram (ECG), asymptomatic decrease in measures of left ventricular ejection fraction (LVEF), or symptomatic congestive heart failure (CHF). The mechanism of cardiotoxicity is not completely understood, but it is associated with higher cumulative dosed of the drug. It happens even years after initiation of treatment [118,119] and long-term monitoring and follow up of patients especially after cumulative doses of 100 mg/m 2 is mandatory. Therapy-related acute myelogenous leukemia is another complication reported in cancer and MS patients treated with this medication [ ] that mostly become evident between 2 and 4 years after therapy. Its overall incidence is estimated 1.04% for all of the topoisomerase II inhibitors but less for mitoxantrone in MS [119]. Gonadal dysfunction is another delayed side effect of chemotherapy that should be discussed with young patients. In women, it can result in amenorrhea which can be transitory or permanent. The risk of permanent gonadal dysfunction in female increases with age [127]. InMS patients transient and permanent amenorrhea is reported in 11.8% and 10.7% consecutively [119]. In contrast, gonadal dysfunction in males receiving mitoxantrone is mainly limited to decreased sperm count for the period of treatment with rapid recovery 3 4 months after ending of treatment [128] Natalizumab (Tysabri ). Natalizumab is the first monoclonal antibody (mab) especially developed for the treatment of RRMS and approved for therapy in 2004 and 2006, respectively [129]. Natalizumab is a humanized mab directed against the 4- chain of 4 1 integrin [130] which is also known as very late activating antigen-4 (VLA-4). VLA-4 is expressed on the surface of all leukocytes with the exception of neutrophils. Natalizumab acts as an antagonist with VLA-4 and it inhibits the binding of leukocytes to vascular cell adhesion molecules (VCAM)-1 and fibtronectin (FN). Thus, lymphocytes are prevented from infiltrating the target tissue [131,132]. After promising results in phase II trials [133,134], two-phase III trials were conducted. In a randomized, phase III, placebo-controlled trial (AFFIRM), 942 patients with relapsing MS who had active disease received either 300 mg natalizumab or placebo every 4 weeks for 2 years [135]. The patients on natalizumab therapy met the primary endpoints: the drug was associated with a 68% reduction in relapse rate at 1 year (p < 0.001) and a 42% decrease in the rate of disability progression at 2 years (p < 0.001). With regard to MRI lesion activity, natalizumab reduced Gd+ lesions by 92% (p < 0.001), the accumulation of new or enlarging hyperintense lesions on T2- weighted MRI by 83% (p < 0.001), and new T1-hypointense lesions by 76% (p < 0.001). Brain atrophy was greater at 1 year in the treated patients but less so at 2 years compared with placebo patients. In a second phase III trial (SENTINEL) [136], 1171 patients who had at least one relapse in the previous year while on IFN -1a im qw therapy were randomly assigned to receive 300 mg natalizumab or placebo as an add-on therapy every 4 weeks for 2 years. The combination therapy fulfilled the primary endpoints which was a lower annualized relapse rate compared with IFN -1a alone (0.35 vs. 0.75; p < 0.001) and fewer new or enlarging T2-weighted MRI lesions (p < 0.001). At 2 years, the combination therapy resulted in a 24% reduction in the relative risk of sustained disability progression (p = 0.02). Based on these two clinical trials, natalizumab is now approved at a monthly dose of 300 mg and is given as a monthly infusion [137]. The most common adverse reaction to natalizumab is headache and fatigue. Other common adverse reactions are: arthralgia, urinary tract infection, lower respiratory tracts infections, gastroenteritis, vaginitis, extremity pain, diarrhea, and hypersensitivity reactions (mainly rash and urticaria). The gravest adverse event with this medication is the development of a fatal opportunistic brain oligodendrocytes infection by JC virus called progressive multi-focal encephalopathy or PML. Two cases of PML were diagnosed in MS patients treated with natalizumab in the SENTINEL study with both patients being treated with natalizumab and INF - 1a IM; no other risk factors were evident [138,139]. These cases resulted in withdrawal of natalizumab from the market. Postmortem, a third case of PML was identified in a patient treated with natalizumab for Crohn s disease [140]. PML typically presents itself by a subacute progressive dementia, and focal neurological deficits including motor dysfunction, and vision loss; the disease is usually fatal. Natalizumab was eventually re-launched as a second-line therapy for patients with relapsing MS, with a restricted indication for patients with very active or breakthrough relapsing MS. It is only available through restricted distribution programmes. After reintroduction, new cases of PML were reported using natalizumab as monotherapy with the count now past 35 cases worldwide. Based on accumulated experience, the risk of PML increases with longterm treatment duration. It seems that subclinical reactivation of JC virus is much more common in MS patients receiving natalizumab. In an observational study on 19 patients, the frequency of JC virus-positive urine samples was markedly increased, from 19% at baseline to 63% after 12 months of therapy with natalizumab (p = 0.02) [141]. NAbs against natalizumab occur less frequently (6%) than IFN, but are associated with a clear loss of clinical and radiological efficacy and confer susceptibility to subsequent allergic reactions of the drug [142]. Measurement of NAbs to natalizumab is part of the routine management with that agent and is tested up front after the first or second infusion Stem cell transplantation in MS Following promising studies in animal models of immunemediated diseases [143], immunosuppression followed by either allogeneic or autologous hematopoietic stem cell transplantation (AHSCT) has been tested as a novel strategy in severe forms of MS [ ]. Allogeneic transplantation in severe autoimmune disease has been thought to be feasible in particular cases [ ], however is not acceptable for most patients because of the high incidence of severe complications such as acute and chronic graft vs. host disease leading to a mortality exceeding 20% [149]. Peripheral blood is currently the preferred source of AHSCs identified by the expression of the surface antigen CD34, and mobilized by the use of cyclophosphamide, followed by G-CSF. Peripheral blood stem cells can also be mobilized with G-CSF alone, but has been associated with severe flares of MS [150], probably due to cytokine release, which can be prevented by the concomitant administration of steroids or cyclophosphamide [151]. AHSCs are re-infused to patients days following conditioning (usually variable chemotherapy agents) which serves to eradicate the autoreactive disease-causing immune system in the peripheral blood, bone marrow, lymphoid tissue and even the CNS. Since the earliest studies, over 400 patients have been transplanted worldwide [152]. Neurological outcome in AHSCT has been assessed in small phase I/II studies done by single-centres [145, ] and by collaborative efforts of various teams from several countries [151, ]. Transplant-related mortality has dropped from 6% in the first reported cohorts to approximately 1% [152]. Two retrospective reports on patients with MS registered in the European Bone Marrow Transplantation (EBMT) database were published in 2002 and 2006 [146,170]. Treated patients were severely disabled with high EDSS scores (ranging from 4.5 to 9.5), and a long disease duration (median 7 years, range 1 29 years); most cases were secondary progressive (60 70%; 20% with primary

8 372 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) progression), and only about 20% were in the relapsing remitting stage. Despite generally short follow-ups and use of diverse conditioning regimens some data and indications can be extracted from these studies. After a follow-up period of 3 years, a median of 60 70% of treated cases did not progress (progression-free survival [PFS] assessed by EDSS score). Some patients improved, but in most cases, the EDSS score remained stable, which was significant in that these patients had usually worsened by at least 1 point on EDSS in the year before transplantation, despite the administration of conventional therapy. The range of stable or improved cases varied from 36% to 85% at 3 years. More severely disabled patients, with a high pre-transplantation disability score (EDSS > 6) generally continued to deteriorate and progress despite the treatment, whereas less disabled cases (EDSS 6) responded better and did not show any increase in disability in the follow-up period [158]. Of particular interest is the very favourable outcome of the socalled malignant forms of MS after AHSCT [ ]; this term applied to severe cases of MS who have a rapidly evolving clinical course with progression to severe disability or even death in a short period of time, usually less than 5 years [175]. Though other therapies have been attempted for such patients [176,177], AHSCT has been reported to be effective in halting progression of the disease, often with an unexpected recovery from the previous disability. AHSCT has the capacity to completely suppress gadolinium Gd-enhancing MRI activity, and this effect is maintained with time. No other treatment for MS has this profound and persistent effect on inflammation, without any maintenance treatment. Many studies have supported this remarkable MRI stabilization [151,154,158,161,162,165,166]. Patients most likely to benefit from AHSCT are considered to be relatively young, ambulatory, with a relapsing remitting or a relapsing progressive clinical course, who has failed the conventional approved immunomodulatory therapies including natalizumab or conventional immunosuppressive drugs (cyclophosphamide or mitoxantrone), with MRI signs of inflammation, shown by Gd-enhancing activity. Patients with malignant forms of MS, who rapidly deteriorate over the course of months or a few years, who accumulate severe disability and who are unresponsive to all the available treatments (including plasma exchange), are likely to be good candidates. Patients who are compromised (non-ambulatory (EDSS > 6.5)) with an established progressive clinical course without relapses or MRI inflammatory activity probably should not be treated. Therapy with AHSCT early in the clinical course raises ethical issues because of the associated toxic effects [178], therefore only severe cases with a poor prognosis of advanced disability and dependence within a short period of time should be considered for treatment, and such cases should be enrolled in prospective, approved clinical studies. Mesenchymal stem cell transplantation for MS is another promising treatment. It has been reported that intravenous injection of mesenchymal stem cells (MSCs) can ameliorate EAE, without the use of any chemotherapy or immunosuppressive medications [179]. Human MSCs suppress T-lymphocyte proliferation induced by cellular or non-specific mitogenic stimuli [180]. Because MSCs can be easily obtained and expanded from bone marrow, their direct immunomodulatory effect independent of chemotherapeutics can be desirable for treatment of immune-mediated diseases. Although the exact mechanism(s) is unclear, MSC-mediated immunosuppression probably occurs through both direct cell contact and cytokine secretion [181]. In fact, treatment of human immunemediated diseases with intravenous infusion of MSCs has already begun following a report of rapid resolution of severe GVHD after transplant of MSCs from the patient s haplo-identical mother [182]. Clinical trials with MSCT have now begun and are expanding internationally [183]. 3. Rationale for early treatment of MS after the first demyelination episode Evidence supporting that presence of early and irreversible axonal damage in CNS of MS patients (even before the clinical onset of the disease) [ ], coupled with the apparently reduced benefit of treatment later in the disease, suggests treatment with disease-modifying therapies should begin early in the disease course, even after the first clinical episode of demyelination (CIS). In fact, several lines of evidence have corroborated this notion. Of the available treatments, IFN -1a 30 mcg im qw (Avonex ) and IFN -1b 250 mcg sc eod (Betaseron ) as well as GA (Copaxone ) [187] have all been shown to be effective treatments for CIS. Lowdose IFN -1a 22 mcg sc qw (Rebif ) has also demonstrated efficacy in CIS [188] and an ongoing study called REFLEX is testing this dose of IFN against the standard dose of IFN -1a 44 mcg sc tiw (Rebif ). Three large clinical trials have shown that IFN treatments are effective in CIS patients (Controlled High-Risk Avonex Multiple Sclerosis Prevention Study (CHAMPS), Early Treatment of MS (ETOMS), and Betaferon in Newly Emerging Multiple Sclerosis for Initial Treatment (BENEFIT)) [ ]. The CHAMPS study enrolled 383 CIS patients with monofocal disease randomized to two groups: 193 were given once-weekly IFN -1a 30 g IM, and 190 were given weekly placebo injections [189]. Development of CDMS was defined by the occurrence of a second attack, or an increase of at least 1.5 points on the EDSS. At 3 years, the cumulative probability of CDMS was significantly lower in the IFN -1a group than in the placebo group (rate ratio 0.56; p = 0.002). In the ETOMS trial [188], 309 CIS patients were randomized to once-weekly injections of IFN -1a 22 g, SC (n = 154) or placebo (n = 155). A significantly higher proportion of patients in the placebo group than the IFN -1a group (45% vs. 34%, respectively; rate ratio 0.65; p = 0.047) converted from CIS to CDMS (as defined by the occurrence of a second clinical attack) over the 2- year course of the study. The BENEFIT study [190], randomized 468 CIS patients to two groups receiving injections of either IFN -1b 250 g, sc (n = 292), or placebo (n = 176) every other day. As in the other two studies, the IFN group showed a significantly lower rate of conversion from CIS to CDMS, as defined by a second event or an increase of at least 1.5 points on the EDSS. According to proportional hazards regression, the 2-year cumulative probability for CDMS was 28% in the IFN - 1b group and 45% in the placebo group (rate ratio 0.5; p < ). In addition to defining CDMS by the Poser criteria, the BENEFIT study also employed the new International Criteria [192] to define progression to MS. In this analysis, again, treatment with IFN -1b was associated with a reduction in the progression to McDonald MS within 2 years, compared with placebo (rate ratio 0.54; p < ). In the PRECISE study [187], a randomized, double-blind, multicentre trial, 481 patients presenting with a clinically isolated syndrome with monofocal manifestation, and two or more T2- weighted brain lesions measuring 6 mm or more, were randomly assigned to receive either subcutaneous glatiramer acetate 20 mg per day or placebo for up to 36 months, unless they converted to clinically definite multiple sclerosis. The primary endpoint was time to clinically definite multiple sclerosis, based on a second clinical attack. Analysis was by intention-to-treat. Glatiramer acetate reduced the risk of developing clinically definite multiple sclerosis by 45% compared with placebo (hazard ratio 0.55, 95% CI ; p = ). The time for 25% of patients to convert to clinically definite disease was prolonged by 115%, from 336 days for placebo to 722 days for glatiramer acetate. A randomized, double-blind, placebo-controlled, multicentre trial, called the REFLEX study (REbif FLEXible dosing in early MS), is ongoing which evaluates two different doses of this IFN in CIS [193]. Patients receive either the new formulation of Rebif

9 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) mcg sc tiw vs. qw vs. placebo for a period of 24 months, unless they suffer from a second attack leading to a diagnosis of clinically definite MS. This study, will also examine the impact of treatment on cognitive function and includes an optic coherence tomography (OCT) substudy to assess retinal nerve fibre thickness, a marker of axonal loss. As the first trial to compare the effects of qw vs. tiw dosing in CIS, the REFLEX study is likely to provide valuable information on treatment optimization for patients who are at risk of developing MS. As the CIS stage represents the first opportunity for treatment in most patients, and the greatest impact of these first-line therapies is early, many neurologists will advocate starting therapy at this point. Between one-half and two-thirds of placebo-treated CIS patients (who have MRI evidence of multi-focal disease) will progress to MS within 6 months [190]. The BENEFIT study clearly demonstrated that a head start of only 1.33 months was enough to delay significant progress [191]. It may well be that this head start will confer a much greater delay 25 years later. 4. Clinical treatment strategies in RRMS: induction vs. escalation, treatment optimization The current therapeutic paradigm in RRMS consists of starting with an immunomodulatory treatment, either IFN or GA and then advancing up a therapeutic pyramid in case of inadequate response until disease activity is adequately controlled (escalation therapy). The successive steps of this treatment strategy might be first to switch between first-line therapies, and then to escalate to a more aggressive therapy such as immunosuppression with mitoxantrone or monoclonal antibodies. All these latter agents have been shown to reduce mean relapse rates by 60% or more, but have significant toxicity issues compared to the first-line treatments. There are still several caveats concerning such an escalation strategy. First, standard immunomodulatory therapies are only modestly effective and a significant proportion of patients will fail on first-line therapy over the longer term, generally as a result of ongoing disease activity. In addition, patients may only be selected for a more efficacious therapy if they are considered to have failed two first-line therapies, which may take 2 years or more to establish. Delaying initiation of more effective treatment may allow development of irreversible disability before optimal treatment is established. Finally, physicians may be reluctant to advance up the therapeutic pyramid due to apprehension about increased risk. For all these reasons, following an escalation strategy, which is the usual algorithm may lead to a substantial delay in treatment for patients who may already be advancing to the end of their therapeutic window of opportunity for treatment with anti-inflammatory type medication. Alternatively, early treatment of RRMS cases with more potent immunosuppressive therapies with subsequent switch to weaker immunomodulatory agents (induction therapy) might translate into a greater efficacy down the road, but at the expense of potentially more serious side effects up front. For patients who present near the end of their window this approach takes advantage of the little time that is left for the anti-inflammatory drugs to work. There are several parameters that help us to assess the MS disease severity and patient s prognosis. Natural history studies have allowed a number of risk factors for poor prognosis to be identified. In a systematic review of such studies, Langer-Gould et al. identified sphincter symptoms at onset, incomplete recovery from the first attack, and a short interval between the first and second attack as being the clinical variables most strongly and consistently associated with poor prognosis [194]. Among magnetic resonance imaging (MRI) variables, a high T2 lesion load at diagno- Table 1 Prognostic features in early MS. Better prognosis Poorer prognosis Caucasian Afro-American or non-white Monofocal onset Multi-focal onset Onset with optic neuritis or isolated sensory symptoms Onset with motor, cerebellar, or bladder/bowel symptoms Low relapse rate in first 2 5 years High relapse rate in first 2 5 years Long interval to 2nd relapse Short inter-attack latency No or low disability at 5 years Disability at 5 years Low lesion load on MRI Abnormal MRI 2 contrast lesions 9 T2 lesions sis and rapid accrual of T2 lesions in the early years of disease are associated with more disability later in the disease course [195]. Different prognostic factors in early MS are summarized in Table 1 [196,197]. Though each of these variables individually has limited prognostic value, those patients presenting with several of these clinical and radiological features are likely to be at higher risk for early disability [198], either secondary to accumulating relapserelated disability or earlier evolution into the SPMS stage. In early relapsing remitting multiple sclerosis (RRMS), in the absence of clear biological markers for prognosis, such factors should be considered to identify patients at greatest risk at the time of diagnosis or early in their treatment in order to make informed decisions about the potential benefit of drugs with significant toxicities. One issue that arises in escalation treatment strategy is the definition of suboptimal response to DMD. All of the first-line agents reduce the frequency of relapses and inflammatory brain lesion activity on magnetic resonance imaging (MRI) and may delay accumulation of disability, but are only partially effective. It is unreasonable, therefore, to expect that current therapies will completely shut off disease activity in patients. Some disease breakthrough inevitably will occur, but one needs to know whether the level of continued disease activity is significant enough to warrant a change in therapy possibly to an agent with greater risk or toxicity, or mild enough to be comfortable maintaining the status quo. Suboptimally controlled MS may be defined as unacceptably higher levels of MS disease activity despite current ongoing treatment, which beckons a change in management. Although creating this distinction on paper may seem simple, differentiating what might be considered still within the spectrum of DMD efficacy vs. suboptimally controlled MS in practice remains challenging. Because all current agents were deemed beneficial based on a favourable comparison with placebo-treated patients, the absence of a placebo-comparator patient for each individual starting treatment makes it difficult to know what his or her disease activity might have been without treatment. Instead, a patient s ontreatment disease behaviour is compared with his or her disease behaviour before treatment. If a patient is experiencing disease activity on a treatment, his or her condition might well be better than it would have been without that treatment, but this determination is often difficult to make because MS can change its course unexpectedly in a given patient. To optimize treatment in the absence of validated, evidence-based guidelines, several groups created algorithms to identify suboptimal responses [ ]. One analog model assessed response to treatment based on relapse activity, disease progression, and MRI findings [199]. The three parameters were rated by the level of concern (i.e., notable, worrisome, or actionable). The authors recommended that treatment be reconsidered in a patient with all three parameters rated notable, with two parameters rated worrisome, or with one parameter rated actionable. Later refinements modified the criteria for MRI findings [201,202]. The Canadian MS Working Group has defined three

10 374 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) levels of concern (low, medium, high) based on relapse outcome, EDSS changes, and MRI outcomes with regards to considering DMD modification [201]. They agreed that MRI findings alone should not be used to determine treatment failure, but they could be used to support relapse and disease progression outcomes [201]. The International Working Group for Treatment Optimization in MS placed more emphasis on disease progression, and considered a change in treatment after worrisome changes in disease progression coupled with notable changes in relapse or MRI findings [202]. This group felt that notable changes in all three parameters were not sufficient for changing treatment but warranted close monitoring of the patient. None of the paradigms for identifying suboptimally controlled MS has been prospectively validated. However, retrospective evaluations of the Canadian treatment optimization recommendations (TORs) attempted to predict which treated patients fared poorly over time [203,204]. The Canadian TOR accurately identified a subgroup of patients from the Prevention of relapses and disability by IFN -1a subcutaneously in MS study after 1 year who experienced continued disease activity in years 3 and 4 while on treatment [203]. Similar results were observed after applying the recommendations to patients receiving IFN -1a intramuscular [204]. Several groups have created treatment algorithms for patients who have a suboptimal response to or tolerability issues with a given MS therapy [ ]. Recognition of a suboptimal response to therapy and the timing and choice of therapy switches in patients with breakthrough disease remain challenging for clinicians who treat MS patients. A paucity of evidence-based data to guide evaluation of continued disease activity while taking a given DMD as directed creates a gap for rendering treatment decisions. Several studies have examined switches between first-line agents in patients with suboptimal response. Some indirect and direct evidence suggests that patients with suboptimal response to IFN may benefit from increasing the dose of IFN [17,18,35,209]. Other studies have shown that switching patients between first-line DMDs (IFN to GA and vice versa and from one IFN agent to another) reduced clinical disease activity in patients with suboptimally controlled MS, but these latter studies were small, observational, and uncontrolled [ ]. Several studies have shown the benefit of mitoxantrone on disease activity in patients with suboptimal response to first-line DMD [211,213,214]. Some benefits on disease stabilization and patient-reported quality of life have also been reported for highdose cyclophosphamide [215]. However, these results should be considered preliminary because cyclophosphamide is currently not indicated for the treatment of MS. Many preliminary studies have provided favourable results for various combination regimens. However, several subsequent large, randomized, controlled trials have had negative or conflicting results. Therefore, the usefulness of combination therapy in MS remains uncertain [216]. The most robust study of combination therapy in patients with suboptimal response was the SENTINEL study that showed significant benefits for IFN -1a IM and natalizumab combination therapy in patients with suboptimal response to IFN -1a im vs. continued IFN -1a im monotherapy [137]. However, the occurrence of two cases of PML in this study has made physicians wary of combining anything with natalizumab, although subsequent cases of PML on natalizumab monotherapy lessen such a theoretical concern. The Avonex Combination Therapy (ACT) study was a randomized controlled study in which patients with RRMS had at least one relapse despite treatment with IFN -1a IM in the year prior to entry and were given a combination regimen of continued IFN - 1a IM with methotrexate and/or intravenous methylprednisolone (IVMP) [217,218]. Results yielded only modest trends supporting some outcomes for IVMP combination therapy, but did not demonstrate significant benefit for the addition of either the low-dose oral methotrexate regimen or a 3-day course of 1 g IVMP every other month to continued therapy with IFN -1a IM [218]. For the most part, studies of combination therapy with IFN have not been controlled other than comparing the disease activity on combination therapy (i.e., after treatment) with disease activity on monotherapy (i.e., before treatment). Unfortunately, the natural history of each patient s disease after treatment is not known and complicates interpretation of these results. Despite encouraging data, the results and designs of these studies are not robust enough to definitively conclude which switches in therapy are best for patients with suboptimally controlled MS and need to be confirmed by larger, randomized, controlled clinical studies. Although larger studies are currently under consideration, there are ethical issues regarding patients being randomized to continue a medication that may already be suboptimally controlling their disease. After establishing that a change in treatment may be warranted, several factors need to be considered when selecting the next treatment, including safety profile, monitoring requirements, patient lifestyle factors that might influence treatment adherence, or even the development of NAbs. The definition of suboptimal response may change as the disease progresses and is influenced by other factors. Patients transitioning to more progressive disease may be nearing the end of the window of opportunity for immunomodulatory treatment and may require intervention with more aggressive agents [219]. Mitoxantrone is approved for worsening RRMS and SPMS [218,220] and should be considered in such patients given its proven efficacy for reducing disease activity in this patient population [107]. Natalizumab should also be considered as second-line therapy for patients with suboptimal response to first-line DMDs [221]. 5. Disease-modifying agents in progressive MS Different therapeutic agents have been tested for progressive MS cases without promising results. Despite the efficacy of IFN in RRMS, therapy in SPMS patients seems to be only effective in the subgroup of patients who continue to experience acute inflammatory episodes [79,81,222]. In SPMS cases without clinical evidence of acute inflammatory activity, the effectiveness of therapy is generally not apparent [79,81,222,223]. Of all of the SPMS trials, only the European trial [81] with IFN -1b showed a significant reduction in disability as measured by the EDSS and, even in this trial, the therapeutic effect was only significant in the subgroup of patients who continued to experience acute attacks. The same subgroup of patients in the North American trial showed a treatment benefit, although the effect in the entire cohort was non-significant [79]. Similarly, the SPMS trial of IFN -1a sc 44 and 22 mcg, although non-significant as a whole, showed a benefit on disability progression in patients who were still experiencing relapses [81]. IFN is now only recommended for use in SPMS patients who are still experiencing relapses [224]. No significant clinical improvement in the course of the disease with GA has been demonstrated for SPMS patients [225]. Mitoxantrone was approved by the Food and Drug Administration at a dosage of 12 mg/m 2 every 3 months up to a maximum cumulative dose of 140 mg/m 2 (allowing a period of treatment of about 3 years), in patients with SPMS [107]. But, there are no convincing data demonstrating the efficacy of mitoxantrone in SPMS patients with slow worsening of disability without superimposed relapses. The MIMS study [107] (in which 25.5% patients with SPMS were without superimposed relapses) was not designed or powered to detect a treatment effect in this MS population. More data are warranted before mitoxantrone can be recommended as therapy for cases of progressive MS with-

11 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) out superimposed relapses. Currently its use should be restricted to cases where inflammatory activity can be demonstrated either clinically (relapses, rapid worsening of disability) or by MRI (Gd+ lesions). The outlook for PPMS is not optimistic as well. Trials on different preparations of IFN, despite showing some effects on MRI parameters of the disease, did not affect disability progression as the primary outcome measure [ ]. The largest ever randomized, placebo-controlled study in PPMS with GA failed to show an overall significant effect on disease progression [230]. There are no robust data to recommend the use of mitoxantrone therapy in PPMS, and results of mitoxantrone studies in PPMS patients have been largely disappointing [108,231]. The same is true for many other trials on PPMS [ ]. 6. Emerging therapies Multiple new oral or parenteral medications are under trial for treatment as DMD in MS and some of them like Cladribine, Fingolimod, or Teriflunomide may join the list of first-line DMDs if prove to be safe and effective Fingolimod (FTY 720) Gilenia The mechanism of action of this drug is through modulation of sphingosine-1-phosphate (S1P) receptors in lymphoid and neural tissues. Sphingosine-based phospholipids are abundant structural components of cell membranes and have chemoattractive function for lymphoid cells. Resting T-cell and B-cells express high levels of S1P receptor (subtype 1) and lymphocyte egress from lymph nodes and thymus is dependent on this receptor function [237,238]. Fingolimod-phosphate (which forms after in vivo phosphorylation of fingolimod) is a structural analogue of S1P and after binding to lymphocytes S1P receptors results in their internalization and renders lymphocytes insensitive to S1P signalling, thereby trapping them in secondary lymphoid organs [239]. Fingolimod administration produces a rapid, reversible decrease in circulating lymphocytes, but does not result in immunosuppression since it does not impair T-and B-cell activation, proliferation and effective function. Interruption of lymphocyte recirculation between CNS and secondary lymphoid organs is probably responsible for its clinical benefit in MS. S1P receptors are also widely expressed in CNS and they might potentially have neuroprotective effects [240]. Interaction of fingolimod with widely expressed S1P receptors in other tissues probably accounts for its adverse effects. The potency of this agent has already been demonstrated in human organ transplantation [241]. Furthermore, preclinical studies in various EAE models demonstrated its efficacy [ ]. Fingolimod has shown promising and persistent effectiveness in a phase II trial (with a 2-year extension) compared to placebo [245,246]. Two large phase III studies of FTY720 in MS have been completed. The FREEDOMS study (FTY720 Research Evaluating Effects of Daily Oral therapy in Multiple Sclerosis) was a double-blind and randomized study, recruiting 1033 RRMS cases to investigate the effects of two doses of fingolimod (0.5 and 1.25 mg/day) treatment vs. placebo for 24 months [247]. The primary end point was the annualized relapse rate, defined as the number of confirmed relapses per year. The key secondary end point was the time to confirmed disability progression, defined as an increase of one point in the EDSS score (or half a point if the baseline EDSS score was equal to 5.5), confirmed after 3 months, with an absence of relapse at the time of assessment and with all EDSS scores measured during that time meeting the criteria for disability progression. The annualized relapse rate was 0.18 with 0.5 mg of fingolimod, 0.16 with 1.25 mg of fingolimod, and 0.40 with placebo (p < for either dose vs. placebo). Fingolimod at doses of 0.5 and 1.25 mg significantly reduced the risk of disability progression over the 24- month period (hazard ratio, 0.70 and 0.68, respectively; p = 0.02 vs. placebo, for both comparisons). The cumulative probability of disability progression (confirmed after 3 months) was 17.7% with 0.5 mg of fingolimod, 16.6% with 1.25 mg of fingolimod, and 24.1% with placebo. Both fingolimod doses were superior to placebo with regard to MRI-related measures (number of new or enlarged lesions on T2-weighted images, gadolinium-enhancing lesions, and brain-volume loss; p < for all comparisons at 24 months). Causes of study discontinuation and adverse events related to fingolimod included bradycardia and atrioventricular conduction block at the time of fingolimod initiation, macular edema, elevated liver-enzyme levels, and mild hypertension. The other completed study is TRANSFORMS (the Trial Assessing Injectable Interferon vs. FTY720 Oral in Relapsing Remitting Multiple Sclerosis), assessed the efficacy of different doses of FTY720 (1.25 and 0.5 mg) against an active agent: IFN -1a IM, Avonex [248]. This study was a 12-month, randomized, doubleblind, double-dummy, and multicentre study with central MRI review and independent EDSS raters RRMS were randomized to three above-mentioned groups with annualized relapse rate as primary endpoint. Secondary outcomes include relapse-related endpoints, MRI-related endpoints, and disability endpoints. The annualized relapse rate (ARR) was significantly lower in both high dose (0.16, p < ) and low dose (0.20, p = ) fingolimod-treated groups vs. IFN -1a IM (0.33). The number of MRI gadolinium-enhancing lesions at 12 months was significantly lower in both high dose (0.14, p < ) and low dose (0.23, p < ) fingolimod-treated patients comparing with IFN -1a IM (0.51). Number of new/newly enlarged T2 lesions over 12 months was also lower in both Group of fingolimod-treated patients comparing to IFN -1a IM, but only reached statistical significance in high-dose group (1.25 mg fingolimod: 1.4, p = ; 0.5 mg fingolimod: 2.1, p = ; IFN -1a IM: 2.1). Disability outcomes were also not significantly different between different treatment groups. Because of ubiquity of S1P receptors in body, fingolimod can have several though non-serious adverse side effects including: nasopharyngitis, dyspnea, headache, diarrhea, nausea, and asymptomatic elevations of liver enzymes. Fingolimod treatment produced bradycardia with the first dose and a mild decrease in forced expiratory volume in 1 second. Eight cases of macular edema have been seen in TRANSFORMS study (one in IFN -1a, and 7 in fingolimod-treated patients), though most of these were subclinical and detected on OCT. The total number of infections were no different in cases and controls, but there were two fatal viral infections during the study: one owed itself to a primary infection and dissemination of varicella (chicken pox) while being treated with high-dose corticosteroid for MS relapse, and another was a case of Herpes encephalitis [249] Cladribine Cladribine is an adenosine deaminase-resistant analogue of purine nucleoside. After intracellular phosphorylation, its active triphosphate form accumulates in lymphocyted and monocytes and results in disruption of DNA synthesis and repair and ultimately apoptosis [250,251]. It results in profound and long-lasting lymphocyte depletion mainly affecting CD4+ T-cells [252]. It is licensed for treatment of hairy cell leukemia (since 1993), and in some countries for chronic lymphocytic leukemia. Parenteral form Cladribine has shown some efficacy in treatment of RRMS [251,253] but the

12 376 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) results of studies on progressive MS have been more conflicting [234,252, ]. Oral form of Cladribine has been tested in RRMS patients and the result of CLARITY study (Cladribine Tablets Treating Multiple Sclerosis Orally) which is a phase III multinational double-blind placebo-controlled clinical trial [258], enrolling 1,326 RRMS patients (as per revised McDonald criteria) [259]. Participants were randomized to receive high-dose (1.4 mg/kg in year 1 and 0.7 mg/kg in year 2) or low-dose (0.7 mg/kg in years 1 and 2) oral cladribine or placebo. The primary outcome was efficacy of cladribine in relapse reduction comparing to placebo over 96 weeks of study. There were many secondary objectives including: MRI parameters (reduction of T1 gadolinium-enhancing lesions, active T2 lesions, combined unique lesions), relapse-free patients, and time to disability progression on EDSS. The annualized relapse rate (ARR) showed significant decrease in both high dose (54.5%, p < 0.001) and low dose (57.6%, p < 0.001) cladribine treated groups vs. placebo (ARR = 0.33 in placebo, 0.15 in high dose, and 0.14 in Low-dose group). The proportion of relapse-free patients was significantly more in both high dose (78.9%, OR = 2.43, p < 0.001) and low dose (79.7%, OR = 2.53, p < 0.001) cladribine treated groups vs. placebo (60.9%). Both doses of Cladribine showed almost 30% reduction in risk of developing disability progression at any time point over 96 weeks of study (high-dose HR = 0.69, 95% CI = , p = 0.026; low-dose HR 0.67, 95% CI = , p = 0.018). Both doses of the drug also met all secondary MRI-related outcomes (T1- enhancing lesions, active T 2 lesions and combined unique lesions) with p < In terms of side effects, the drug use was not associated with hepato-, neuro- or nephrotoxicity. Expectedly, lymphopenia was more common in treated patients comparing with placebo, and resulted in discontinuation of drug in some cases mainly high-dose group. Opportunistic infections has not been a major side effect of this drug in MS patients because doses planned for use in MS, cladribine preferentially targets both CD4+ and CD8+ T-cells and also impacts on B-cells, but has only minor effects on natural killer (NK) cells [234,251]. The relative preservation of these key cell types would allow maintenance of innate immune function during treatment and may explain the low number of infections observed after cladribine treatment despite a reduction in lymphocyte numbers [234,260]. Four cases of cancer have been reported in CLARITY study: one in situ cervical carcinoma, one metastatic pancreatic carcinoma, one ovarian cancer, and one skin melanoma. It is not clear what, if any risk there is for malignancy while taking this agent Teriflunomide Teriflunomide is the active metabolite of leflunomide that is used for treatment of rheumatoid arthritis. It blocks de novo pyrimidine synthesis by non-competitive and reversible inhibition of the mitochondrial enzyme dihydro-orotate dehydrogenase in T- cell, B-cells and other rapidly dividing cell populations, leading to decrease of DNA synthesis [261,262]. Teriflunomide has been found to suppress clinical and pathological manifestations of the experimental autoimmune encephalomyelitis (EAE), probably via the inhibition of the cytokines tumor necrosis factor (TNF) alpha and interleukin (IL)-2 [263,264]. In 2006, the first randomized, double-blind, placebo-controlled phase II study to assess efficacy and safety of oral teriflunomide in MS patients with relapses was published [265]. One hundred and seventy nine patients with relapsing remitting MS (n = 157) or secondary progressive MS with relapses (n = 22) and EDSS score of <6 were randomized to receive either placebo (n = 61), teriflunomide 7 mg/day (n = 61) or teriflunomide 14 mg/day (n = 57). Patients were required to have two documented relapses within the previous 3 years and one during the preceding year. The primary efficacy endpoint was the number of combined unique (CU) active lesions (a combination score of the number of new and persisting Gd-T1 and T2 lesions) per MRI scan during the 36-week treatment phase. Secondary outcomes were MRI-based and included the number of T1-lesions, the number of T2 lesions, the number of patients with CU active, T1- and T2-active lesions and the percentage change from baseline to endpoint in burden of disease (measured in T2 lesion volume). Secondary clinical measures included the number of patients with MS relapses, the annualized relapse rate, and the number of relapsing patients requiring a course of steroids. Treatment with either teriflunomide 7 or 14 mg/day resulted in the significant suppression of 61.1% or 61.3%, respectively (p < 0.03 or p < 0.01) of MRI activity measured in the mean number of CU active lesions per scan. Regarding secondary MRI-endpoints, teriflunomide 7 or 14 mg/day also significantly reduced the median number of T1 and T2 lesions per scan over the treatment period. In addition, the number of patients with T1, CU active and T2 lesions was lower in both of the teriflunomidetreated groups. Finally, the burden of disease measured in the median change from baseline was significantly diminished in the teriflunomide 14 mg/day group ( 4.1% vs. 5.2%, p < 0.02). The proportion of patients showing an increase in disability measured on the EDSS score at endpoint vs. baseline was significantly lower in the 14 mg/day teriflunomide group compared with placebo (7.4% vs. 21.3%; p < 0.04). Annualized relapse rates were lower in both treatment groups compared to placebo without reaching statistical significance. Although not significant, a greater proportion of patients (77% vs. 62%) were relapse-free in the 14 mg teriflunomide group and less patients in this group required steroids compared to placebo (14% vs. 23%). Different phase 2 and 3 trials are ongoing for this treatment in RRMS and CIS [193]. Different designs of the teriflunomide trials (use as monotherapy, add-on to IFN or GA, comparison with placebo, or IFN ) will give us valuable information about this treatment in MS in near future. Teriflunomide was generally safe and well tolerated. Adverse effects more frequent in teriflunomide-treated participants included nasopharyngitis, alopecia, nausea, limb pain, diarrhea, and arthralgia. Hepatic necrosis and pancytopenia were reported in patients with rheumatoid arthritis who were taking teriflunomide. An additional potential safety issue is teratogenicity in animals. Female subjects are advised not to become pregnant and males are cautioned not to father a child during therapy. Without washout with cholestyramine or activated charcoal, it may take up to 2 years for plasma levels to reach less than 0.02 mg/l, the level expected to present minimal teratogenic risk Dimethyl fumarate (BG00012) Fumaric acid esters are a group of simple structured compounds that have been used since long time ago in treatment of psoriasis [266,267], and different clinical trials have shown their benefits in psoriasis [ ]. Dimethyl fumarate is a second-generation fumarate derivative with improved tolerability. Exact mechanism of action of these group of medication is not know [271] but it is hypothesized that they affect nuclear transcriptional factors and result in regulation of immune function and response to oxidative stress [272,273]. Dimethyl fumarate and its primary metabolite monomethyl fumarate affect several type of cells in the immune system, but specifically result in apoptosis of active T-cells and shift in cytokine profile of Th1 to Th2 [274,275]. Dimethyl fumarate inhibits clinical and histopathologic features of EAE through both anti-inflammatory and neuroprotective actions [276,277]. The largest published data on BG00012 in RRMS is the randomized, double-blind, placebo-controlled, dose-ranging phase 2b study by Kappos et al. [278]. 257 participants with RRMS were randomized to receive oral placebo or 120, 360, or 720 mg of dimethyl fumarate per day, for 24 weeks. In 24 weeks extension period of the

13 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) study, patients treated with placebo received BG mg per day. The primary endpoint was total number of new gadoliniumenhancing (GdE) lesions on brain MRI scans at weeks 12, 16, 20, and 24. Additional endpoints included cumulative number of new GdE lesions (weeks 4 24), new or enlarging T2-hyperintense lesions, new T1-hypointense lesions at week 24, and annualized relapse rate. Treatment with BG mg three times daily reduced by 69% the mean total number of new GdE lesions from week 12 to 24 compared with placebo (1.4 vs. 4.5, p < ). It also reduced number of new or enlarging T2-hyperintense (p = ) and new T1-hypointense (p = 0.014) lesions compared with placebo. BG00012 reduced annualized relapse rate by 32% (0.44 vs for placebo; p = 0.272). Adverse events more common in patients given BG00012 than in those given placebo included abdominal pain, flushing, and hot flush. Dose-related adverse events in patients on BG00012 were headache, fatigue, and feeling hot. Infections were reported in similar proportions of BG00012 and placebo patients (34% in both groups). There are 2 ongoing 2-year phase 3 trials of dimethyl fumarate that will further elucidate the potential of BG12 in the treatment of RRMS [193] Laquinimod Laquinimod is a once-daily oral immunomodulatory agent derived from linomide. Promising results with linomide were demonstrated in EAE and preliminary clinical trials [279]. However, a phase 3 trial of linomide was terminated shortly after enrollment completion owing to unanticipated toxicity, including pericarditis, pleural effusion, myocardial infarction, possible pulmonary embolism, pancreatitis, and death [280]. A multicentre, randomized, double-blind, placebo-controlled phase 2 study in RRMS and SPMS demonstrated that daily doses of 0.3 mg of laquinimod reduced cumulative active MRI lesion number during 24 weeks, the primary outcome measure, in the perprotocol cohort (n = 187; mean, 5.2 vs. 9.4 lesions; 44% reduction; p =.0498), with a non-significant trend in the intention-to-treat cohort (n = 209; mean, 5.5 vs. 9.3 lesions; 41% reduction; p =.17) [281]. The 0.1-mg daily dose was ineffective. Benefit was more prominent in the subgroup of participants with at least 1 GdE lesion at baseline (approximately 70% of the per-protocol group), with a 52% reduction in cumulative active MRI lesions during 24 weeks (p =.005). In a multicentre, randomized, double-blind, placebo-controlled phase 2b trial with 306 participants, a higher laquinimod dose (0.6 mg per day) significantly reduced mean cumulative GdE lesions per scan at weeks 24, 28, 32, and 36 compared with placebo (2.6 vs. 4.2 lesions; 40.4% reduction; p =.005), while the 0.3-mg/day dose was not effective [282]. Benefit was seen on several other MRI measures with a non-significant trend on relapse rate. In an open-label extension study, benefit of 0.6 mg of laquinimod per day was recapitulated in participants who switched from placebo and persisted in participants who continued taking laquinimod. In general, laquinimod has been well tolerated. Mild self-limited dosedependent increases with liver enzymes were seen in both phase 2 studies. A single case of Budd-Chiari syndrome developed after 1 month of exposure in the phase 2b study in a participant with the factor V Leiden mutation. No clinical evidence of a proinflammatory effect was seen. Currently there are three phase 3 ongoing trials assessing this medication in RRMS patients, one comparing laquinomod with placebo and another with IFN -1a [193] Minocycline Minocycline is a semisynthetic tetracycline antibiotic with extensive clinical experience supporting safety and tolerability. Minocycline crosses the blood brain barrier, and biologic actions of minocycline potentially of benefit in MS include inhibition of microglial activation, apoptosis, inducible nitrous oxide and free radicals, mitogenactivated kinases, proinflammatory cytokine production by T-cells, and matrix metalloproteinase activity [283]. Small pilot studies on minocycline in RRMS patients either as monotherapy or add-on to GA has shown beneficial effects of this drug on MRI activity of MS disease [284,285]. A phase 2 study assessing the add-on effect of minocycline to GA in RRMS patients has finished. Another phase 2 trial assessing the effectiveness of this drug as add-on to IFN -1a SC, in RRMS, and a phase 3 placebocontrolled study on this drug in CIS are recruiting [193] Statins Statins, in addition to their lipid-lowering effects, has many immunomodulatory actions that might be beneficial in MS patients. These immunomodulatory effects include: decreased production of Th1 cytokines (IL-2, IL-12, interferon, and tumor necrosis factor ), increased production of Th2 cytokines (IL-4, IL-5, IL-10, and transforming growth factor ), generation of Th2 cells, decreased major histocompatibility complex class II expression by antigenpresenting cells, decreased co-stimulatory molecule expression, decreased antigen-specific T-cell activation, and decreased adhesion molecule and chemokine receptor expression by activated lymphocytes [ ]. Oral statins have been effective in preventing or reverting EAE [286]. They have been used for long time in medical practice and there is no issue with their long-term safety. An open-label, single-arm cross-over study of 30 participants with RRMS showed a 44% reduction in the number of GdE lesions on MRI at months 4, 5, and 6 of treatment with 80 mg of simvastatin daily vs. pre-treatment (mean, 1.30 vs lesions, p < 0.001) [289]. A second study with a similar design evaluated 41 participants with RRMS, including 16 taking IFN [288]. Treatment with 80 mg of atorvastatin daily produced a 24% reduction in GdE lesions on monthly MRI at months 6 9 compared with months 2 to0 (mean, 1.52 vs lesions, p = 0.003). But, a recent small, randomized, double-blind, pilot study compared daily oral atorvastatin (40 or 80 mg) with placebo combined with 44 g of subcutaneous IFN -1a 3 times weekly in 26 participants with RRMS, have given conflicting results [290]. Prior to the study, participants received IFN -1a on average for 2 years and were clinically stable for at least 6 months. Surprisingly, during the 9-month study, participants treated with either dose of atorvastatin exhibited significantly increased risk of new T2-hyperintense or GdE MRI lesions, or clinical relapse. Certainly, results of phase 2 studies on this drug in PRMS (add-on to IFN ) and CIS (placebo-controlled) will clarify this contradiction [193] Alemtuzumab Alemtuzumab (also known as Campath-1H) is a humanized monoclonal antibody (mab), originally generated for the treatment of lymphoid malignancies [291]. This mab targets the CD52- antigen on the surface of more than 95% of T and B lymphocytes, monocytes and macrophages [292,293]. It depletes target antigen carrying cells through complement-mediated lysis, antibodydependent cell toxicity, induction of apoptosis, and results in leukopenia [291,294,295]. A single injection of it results in rapid and prolonged decrease in lymphocyte count. Lymphocytes regenerate, but the speed and degree of recovery varies between cell types: CD4+ T-cells are particularly slow to recover, taking 5 years to reach pre-treatment levels [296]. Pilot studies between 1991 and 2002 at University of Cambridge demonstrated potent suppression of MS relapses and lesion activity on magnetic resonance imaging (MRI) by alemtuzumab in both

14 378 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) relapsing remitting and secondary progressive cases but no benefit on disability accrual in progressive MS [ ]. A phase II study (CAMMS223) comparing high- and low-dose alemtuzumab (12 and 24 mg intravenous alemtuzumab for 5 days at month 0, 3 days at month 12, and for some participants, 3 days at month 24) vs. high-dose IFN (Rebif ) was conducted on 334 patients with early, active relapsing remitting MS. CAMMS-223 was a commercially sponsored, multicentre, randomized, single-blind trial with results revealing strong efficacy data in favour of alemtuzumab [299]. Two primary endpoints were examined: relapse rate and time to accumulation of clinically significant disability as measured by EDSS. Two treatment cycles of alemtuzumab with an annual interval led to a highly significant 75% reduction in relapse rate and a 60% reduction in sustained disability. In addition, the EDSS of those treated with alemtuzumab improved by 0.39 points, whereas those receiving Rebif continued to acquire disability by points (p < ), both from a mean baseline score of 2.0. These clinical observations were paralleled by changes in brain volume as measured by MRI: increased MRI-T1 brain volume was seen between 12 and 36 months post-alemtuzumab suggesting a restoration of brain structure, whereas brain atrophy progressed in those treated with Rebif. Infusion-related cytokine release was common in patients and the cause of pyrexia, headache, malaise and rash. Infections were more common in alemtuzumab patients vs. those receiving Rebif (65.7% vs. 46.7%) but it was mainly due to mild and moderate respiratory symptoms. Unexpectedly no case of serious infectious side effects including PML has been reported in MS patients. Cancer was no more common in alemtuzumab patients but reported single case of non-ebv-associated Burkitt s lymphoma might be related to this treatment. Secondary autoimmune diseases happening month to years after treatment were the major untoward adverse effect of this medication: 20 30% of patients develop thyroid problems, mainly Graves disease; 2.8% developed ITP (idiopathic thrombocytopenic purpura). Currently, two large multicentre phase III trial are underway (CAREMS I/II, sponsor: BayerScheringPharma/Genzyme) [193] Rituximab Rituximab is a chimeric mouse-human mab targeting CD20, a surface antigen expressed on pre-b-cells and mature B-cells [300]. It destroys target cells by complement- and antibody-mediated cell lysis and apotosis [301] and its intravenous infusion results in rapid decrease of circulation B-cells. It is approved for treatment of non-hodgkin lymphoma [302], and is a second-line treatment for rheumatoid arthritis [303]. Several lines of evidence point towards the contributing role of humoral immunity in MS patients [ ]. The contribution of B-cells to autoimmunity in MS is not only by their antibody production, but also their antigen presentation to T-cells and expression of co-stimulatory molecules B7-1 and B7-2 (which activate resting T-cells) [312]. Rapid clinical and radiologic response to rituximab in MS patients cannot be explained by its effect on antibody production; because of longer half-life of antibodies in blood, and lack of CD-20 expression on plasma cells which are the principal source of antibodies. Therefore its mechanism of action probably involves other above-mentioned functions of B-cell in MS pathogenesis [313,314]. Surprisingly, after injection of the drug to MS patients there is a reduction of both B-cell and T-cell numbers in CSF [315,316]. In a multicentre, randomized, double-blind, placebo-controlled phase 2 trial, 104 participants with RRMS received 1000 mg of intravenous rituximab or placebo on days 1 and 15 and were followed up for 48 weeks [317]. The primary end point was the sum of the number of gadolinium-enhancing lesions on serial T1-weighted brain MRIs. Proportion of patients with relapses and the annualized rate of relapse were among key secondary endpoints. Total number of Gd-enhancing lesions were significantly lower at weeks 12, 16, 20, and 24 in rituximab treated patients vs. placebo (mean, 5.5 vs. 0.5 lesions, p < 0.001), showing a relative reduction of 91%. The proportion of patients with relapses was reduced in the rituximab group at week 24 (14.5% vs. 34.3% in the placebo group; p = 0.02) and week 48 (20.3% vs. 40.0%, p = 0.04). Patients in the placebo group were more likely to have had a relapse at week 24 (relative risk, 2.3; 90% CI, ) and at week 48 (relative risk, 1.9; 90% CI, ). Patients in the rituximab group, as compared with those in the placebo group, had a lower annualized rate of relapse at 24 weeks (0.37 vs. 0.84, p = 0.04) but not at 48 weeks (0.37 vs. 0.72, p = 0.08). Initial rituximab infusions produce fever, rigors, tachycardia, dyspnea, headache, pruritus, and rashes, probably due to cytokine release. The infusion reactions rarely were severe and concomitant corticosteroid administration reduces these symptoms. In this study, rituximab was associated with rapid depletion of circulating B-cells that remained nearly complete (>95%) until week 24, with gradual partial return thereafter. Therefore, increased risk of infection is a potential concern but most infections were mild and occurred equally in treatment groups and no opportunistic infections were seen. There was no case of PML in MS patients treated with rituximab, but it is reported with other underlying condition treated with rituximab [ ]. Of patients who received rituximab, 24.6% develop human antichimeric antibodies at week 48. Though there was no relationship to adverse effects or efficacy, these antibodies may be an issue with repeated administration. Therefore, future development in MS will use ocrelizumab, a humanized anti-cd20 mab. A 6-month phase 2 study comparing 2 doses of intravenous ocrelizumab, placebo, and intramuscular IFN -1a in RRMS is in progress [193] Daclizumab Daclizumab is a humanized mab directed against the subunit of IL-2 receptor CD25 on activated lymphocytes. Blocking CD25 on these cells down regulates B-cell and T-cell proliferation by decreasing secretion of proinflammatory cytokines; a critical step in antigen-specific immune responses [321]. Studies in MS patients suggested that daclizumab s clinical benefit was mediated through generation of CD56+ natural killer cells with regulatory effects [322]. Interestingly, this drug also blocks CD25 on regulatory T-cells CD4+CD25+ (Treg) which have antiinflammatory properties in MS pathogenesis, and their number diminish after treatment in MS patients [323]. It is approved to treat acute renal allograft rejection. Clinical trials that have tested effectiveness of this drug in MS have been consistently showing positive results [ ]. A multicentre, randomized, double-blind, placebo-controlled phase 2 study enrolled 230 participants with relapsing MS and continued activity despite treatment with interferon-beta [324]. Participants continued to take interferon-beta and were randomized to receive 2-mg/kg subcutaneous daclizumab every 2 weeks, 1-mg/kg daclizumab alternating with placebo (I-mg every 4 weeks), or placebo for 24 weeks, with 48 weeks of subsequent follow-up. Primary outcome of the study was number of Gdenhancing lesions on MRI which showed 72% reduction (p = 0.004) in high-dose group and a non-significant 25% reduction in the low-dose group. Annualized relapse rate as a secondary outcome, showed a 35% reduction in both treatment groups (intention-totreat analysis) but did not reach statistical significance; however the study was not powered for this endpoint. Daclizumab was generally safe and well tolerated in the relatively short studies to date. In the phase 2 study, there was no overall increased risk of infections. No opportunistic infections including PML, no malignancy or autoimmune side effects were reported. The main adverse effects

15 R. Vosoughi, M.S. Freedman / Clinical Neurology and Neurosurgery 112 (2010) were cutaneous reactions and possibly increased severity of common infections. A phase II multicentre, randomized, double-blind, placebo-controlled trial is evaluating this drug in MS patients as a monotherapy [193]. 7. Conclusion It has not even been 20 years that we have had effective medications that alter the natural course of MS and though ultimately we sense that the control of early disease will prevent later disease progression, this is still unknown. There is a general sense that most of the medications, if taken consistently by patients, can effectively control disease and delay or even prevent the development of SPMS. Some recent data suggest that this is in fact the case, but longer term data is only starting to emerge. Using a novel statistical approach called a propensity score, Trojano et al. compared a group of over a thousand patients taking IFN with that of a similarly sized population of untreated patients and concluded that IFN slows the progression of RRMS [328]. Using a patient unique approach to selection of treatment, monitoring for suboptimal response and a switch to a different medication to re-achieve disease control and the advent of more novel, effective therapies, MS has reached a stage where complete disease control is reality. References [1] Lublin FD, Reingold SC. 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. Neurology 1996;46(4): [2] Pantich HS, Hirsch RL, Schindler J, Johnson KP. Treatment of multiple sclerosis with gamma-interferons: exacerbations associated with activation on immune system. 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