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Background: Vaccines are the-omit complex biological preparations that are meant to be used as a treatment or preventive measures against any specific disease condition. Vaccine research and development is a tedious, time and cost consuming process because of stringent quality assessment procedures. Every year approximately 80-85 % of the world’s children receive vaccines;however, regardless of this success rate each year, approximately more than 3 million die from vaccine-preventable diseases in most of the-omit developing countries. Today the entire world is facing a pandemic COVID-19 and the researchers are putting their best effort to bring a vaccine into the market. Developing a vaccine is a tedious process and emerging vaccine into the market requires a whole lot of process. Purpose: The current study aimed to evaluate the vaccine approval processes of two international pharmaceutical regulatory giants and develop a road map for the progress of vaccines in emerging countries to face the challenges posed by COVID-19. Methods: This article expresses the brief updated report of the regulatory approval pathways involved in the vaccines registration process in the United States of America (USA) the European Union (EU). The comparison study serves to understand the regulatory issues involved during the life-cycle of the vaccine approval process in the USA and the EU. Authors advocate the necessity of harmonised guidelines for the vaccine approval process in developing countries. Conclusion: Authors insist on broad global partnerships between the developed and emerging countries for the supply of affordable vaccines across the globe to face the pandemic called COVID-19. © 2021, Association of Pharmaceutical Teachers of India. All rights reserved.

Objective: To report on safety and effectiveness of subcutaneous cladribine (Litak®) in multiple sclerosis (MS) patients. Methods: Litak® was offered to MS-patients irrespective of disease course. Litak® 10 mg was administered for 3–4 days during week 1. Based on lymphocyte count at week 4, patients received another 0–3 doses at week 5. A second course was administered 11 months later. Follow-up included adverse events, relapses, expanded disability status scale (EDSS), 9-hole-peg and Timed-25-foot-walking tests, no-evidence-of-disease-activity (NEDA), no-evidence-of-progression-or-active-disease (NEPAD), MRI, cerebrospinal fluid (CSF) neurofilament light chain (NfL), and lymphocyte counts. Results: In all, 208 patients received at least one course of treatment. Age at baseline was 44 (17–72) years and EDSS 0–8.5. Cladribine was generally well tolerated. One myocardial infarction, one breast cancer, and three severe skin reactions occurred without long-term sequelae. Two patients died (one pneumonia, one encephalitis). Lymphopenia grade 3 occurred in 5% and grade 4 in 0.5%. In 94 out of 116 pwMS with baseline and follow-up (BaFU) data after two treatment courses, EDSS remained stable or improved. At 18 months, 64% of patients with relapsing MS and BaFU data ( n = 39) had NEDA. At 19 months, 62% of patients with progressive MS and BaFU data ( n = 13) had NEPAD. Of n = 13 patients whose CSF-NfL at baseline was elevated, 77% were normalised within 12 months. Conclusions: Litak® was well tolerated. Effectiveness in relapsing MS appeared similar to cladribine tablets and was encouraging in progressive MS. Our data suggest cladribine may be safe and effective in MS-patients irrespective of their disease stage.

Background: Vaccination against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first approved on the 8th of December 2020. Though safe and effective, very rare side effects continue to be identified as global vaccination advances. They do not necessarily leave “a signal” in public registries if the incidence remains below previously reported total incidence levels. Optic neuritis (ON) is a rare but recognised adverse event after immunisation. The risk of post-vaccination ON and visual outcome in the context of global vaccination efforts against SARS-CoV-2 are not known. Methods: A global report on 73 deep-phenotyped individuals with post-SARS-CoV-2 vaccination ON observed in 15 of 55 countries with designated experts between 14 February to 18 July 2021. Statistical analyses were performed on type of vaccine, number of jabs, time to onset of ON, demographics, clinical features and treatment. Paraclinical data included immunological testing for autoantibodies against myelin oligodendrocyte glycoprotein (MOG) and aquaporin-4, magnetic resonance imaging (MRI) of the brain and orbits, retinal optical coherence tomography (OCT). The primary outcome was the visual acuity (VA). Findings: The characteristics of the 69 individuals included, differed from pre-COVID whole population-based incidence studies in frequency of bilateral presentation, age distribution and radiological features more commonly found in immune-mediated ON. Most events (67%) occurred after vaccination with AstraZeneca, followed by Pfizer-BioNTech (26%) and Sinovac (7%). In 56 this was after the first and in 13 after the second jab with the same vaccine. Autoantibodies against MOG were present in 15 and not detected for aquaporin-4. The condition was steroid responsive in most (58/62), requiring plasma exchange in a few (5) with spontaneous recovery in the remainder (7). The incidence was highest in the UK (0.036 per 100,000 persons) where vaccination commenced earliest. Importantly, the pattern of presentation in time lagged about 1-5 weeks behind the pattern of national age group vaccination. The median VA at presentation was logMAR 1.0 and recovered to 0.0. Interpretation: Post-SARS-CoV-2 vaccination ON is an extremely rare adverse event with generally good outcome of visual function. The global incidence of post-vaccination ON (0.0017 per 100,000 persons) is lower than for ON (3.74 per 100,000 persons in the UK). A causal relationship is plausible, but the overall risk benefit balance is in favour of SARS-CoV-2 vaccination. Funding Information: None. Declaration of Interests: None. Ethics Approval Statement: Reporting of patients was approved by the Institutional Research Board at Moorfields Eye Hospital (study number CaRS_24).

Objective To investigate whether T2 lesion load and magnetisation transfer ratio (MTR) in the normal-appearing white matter (NAWM) and grey matter (GM) at study entry are independent predictors of progression and whether their changes correlate with the accrual of disability, over 5 years in early primary progressive multiple sclerosis (PPMS). Methods Forty-seven patients with early PPMS and 18 healthy controls were recruited at baseline and invited to attend clinical 6-monthly assessments for 3 years, and after 5 years. Patients were scored on the Expanded Disability Status Scale and multiple sclerosis functional composite subtests (25-foot timed walk test (TWT), nine-hole peg test and paced auditory serial addition test). At each time point, all subjects underwent brain MRI including T2-weighted, magnetisation transfer and volumetric sequences. T2 lesion load (T2LL), MTR histogram parameters and volumes for NAWM and GM were calculated. Statistical analyses identified predictors of progression and correlations between MRI changes and clinical changes over time. Results Baseline T2LL and GM peak location and peak height MTR were independent predictors of progression, as measured by TWT; a model including these three predictors explained 91% of the variance of the progression on TWT, a significantly higher percentage than that obtained when the predictors were modelled individually (80%, 74% and 68%, respectively). A greater progression rate correlated with a steeper increase in T2LL and a faster decline in GM mean and peak location MTR. Conclusions The combined assessment of both visible white matter damage and GM involvement is useful in predicting progression in PPMS.

Background: Cognitive impairment in primary progressive multiple sclerosis (PPMS) is common and correlates modestly with contemporary lesion burden and brain volume. Using a cohort/case control methodology, we explore the ability of MRI abnormalities, including those in the normal-appearing brain tissue, to predict future cognitive dysfunction in PPMS. Methods: Thirty-one patients recruited into a longitudinal study within 5 years of onset of PPMS were assessed neuropsychologically on average 5.5 years later along with 31 matched healthy controls. MRI data obtained at entry into the study (lesion metrics, brain volumes, magnetization transfer ratio histogram metrics, and magnetic resonance spectroscopy metabolite concentrations) were used to predict cognitive impairment at follow-up. Results: Twenty-nine percent of patients were categorized as cognitively impaired. T2 lesion volume was the best MRI predictor of overall cognitive function and performance on tests of verbal memory and attention/speed of information processing. Low gray matter magnetization transfer ratio was the best predictor of poor performance on a further test of attention/speed of information processing and an executive function test. Low gray and white matter volumes were independent predictors of poor performance on a second test of executive function. Conclusions: MRI abnormalities observed in early primary progressive multiple sclerosis can predict cognitive impairment 5 years later. While focal damage disrupting white matter tracts appears to be the most important predictor of subsequent cognitive dysfunction, gray matter pathology also plays a role.

The diagnostic criteria used in primary progressive (PP) and relapsing—remitting (RR) multiple sclerosis (MS) show substantial differences. This introduces complexity in the diagnosis of MS which could be resolved if these criteria could be unified in terms of the requirements for dissemination in space (DIS). The aim of this study was to assess whether a single algorithm may be used to demonstrate DIS in all forms of MS. Five sets of RRMS criteria for DIS were applied to a cohort of 145 patients with established PPMS (mean disease duration: 11 years — PPMS-1): C1: Barkhof—Tintoré (as in 2005 McDonald’s criteria); C2: Swanton et al. (as in JNNP 2006); C3: presence of oligoclonal bands plus two lesions (as in McDonald’s criteria); C4 and C5: a two-step approach was also followed (patients not fulfilling C1 or C2 were then assessed for C3). Two sets of PPMS criteria for DIS were applied: C6: Thompson et al. (as in 2001 McDonald’s criteria); C7: 2005 McDonald criteria. A second sample of 55 patients with less than 5 years of disease duration (PPMS-2) was also analysed using an identical approach. For PPMS-1/PPMS-2, fulfilment was: C1:73.8%/66.7%; C2:72.1%/59.3%; C3:89%/79.2%; C4:96%/92.3%; C5:96%/85.7%; C6:85.8%/78.7%; C7:91%/80.4%. Levels of fulfilment suggest that the use of a single set of criteria for DIS in RRMS and PPMS might be feasible, and reinforce the added value of cerebrospinal fluid (CSF) findings to increase fulfilment in PPMS. Unification of the DIS criteria for both RRMS and PPMS could be considered in further revisions of the MS diagnostic criteria.

We investigated the relationship between the damage occurring in the brain normal‐appearing white matter (NAWM) and in the gray matter (GM) in patients with early Primary Progressive multiple sclerosis (PPMS), using Tract‐Based Spatial Statistics (TBSS) and an optimized voxel‐based morphometry (VBM) approach. Thirty‐five patients with early PPMS underwent diffusion tensor and conventional imaging and were clinically assessed. TBSS and VBM were employed to localize regions of lower fractional anisotropy (FA) and lower GM volume in patients compared with controls. Areas of anatomical and quantitative correlation between NAWM and GM damage were detected. Multiple regression analyses were performed to investigate whether NAWM FA or GM volume of regions correlated with clinical scores independently from the other and from age and gender. In patients, we found 11 brain regions that showed an anatomical correspondence between reduced NAWM FA and GM atrophy; of these, four showed a quantitative correlation (i.e., the right sensory motor region with the adjacent corticospinal tract, the left and right thalamus with the corresponding thalamic radiations and the left insula with the adjacent WM). Either the NAWM FA or the GM volume in each of these regions correlated with disability. These results demonstrate a link between the pathological processes occurring in the NAWM and in the GM in PPMS in specific, clinically relevant brain areas. Longitudinal studies will determine whether the GM atrophy precedes or follows the NAWM damage. The methodology that we described may be useful to investigate other neurological disorders affecting both the WM and the GM. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.

Objective To determine whether in primary progressive multiple sclerosis (PPMS) combining scores of Expanded Disability Status Scale (EDSS) with data from Timed 25-Foot Walk (T25FW) and 9-Hole Peg Test (9HPT) would produce a clinical endpoint that has a higher event rate than EDSS alone. Methods In a group of 161 PPMS patients, EDSS, T25FW, and 9HPT were performed at three time points over 2 years. We calculated how many patients showed clinically meaningful deterioration (or improvement) on individual and combined scales. We defined improvements on one scale with deterioration on the other as “opposing changes.” We investigated the possible effect of baseline disability on the definition of our endpoint by dividing the population into two subsets of patients determined by baseline EDSS level. Results On individual scales, event rates were highest on T25FW: 34% and 46% 1 year and 2 years after baseline. On a combination of two scales, at 1 year the event rate was highest on T25FW/9HPT (46%; with a high rate of opposing changes) and at 2 years on T25FW/EDSS (57%; with a lower rate of opposing changes). In both subsets, event rates were highest on T25FW and (at 2 years) on the combination of T25FW/EDSS. Conclusions T25FW has the highest event rate as a single scale, independent of baseline disability level. A term of 2 years turned out to be more meaningful to observe than 1 year. “Worsening on either T25FW or EDSS” is the most appropriate composite endpoint in this patient group.

Although the mechanisms underlying the accumulation of disability in primary progressive (PP) multiple sclerosis (MS) are still unclear, a major role seems to be played by `occult' tissue damage. We investigated whether conventional and magnetization transfer (MT) MRI may provide complementary information for the assessment of PPMS severity. Conventional and MT MRI scans from 226 PPMS patients and 84 healthy controls were collected for centralized analysis. The expanded disability status scale (EDSS) score was rated at the time of MRI acquisition. T2 lesion volume, normalized brain volume (NBV) and cervical cord cross-sectional area (CSA) were measured. Magnetization transfer ratio (MTR) histograms from whole brain tissue, normal-appearing white matter and grey matter (NAGM) were also obtained. Mean NBV, CSA and MTR histogram-derived metrics showed significant inter-centre heterogeneity. After correcting for the acquisition centre, pooled average MTR and histogram peak height values were different between PPMS patients and controls for all tissue classes ( P-values between 0.03 and 0.0001). More severe brain and cord atrophy and MT MRI-detectable NAGM damage were found in patients who required walking aids than in those who did not ( P-values: 0.03, 0.001 and 0.016). A composite score of NBV, CSA, whole brain and NAGM MTR histogram peak height z-scores was correlated with patients' EDSS ( r = 0.37, P 0.001). Magnetization transfer MRI might provide information complementary to that given by conventional MRI when assessing PPMS severity. Sequence-related variability of measurements makes the standardization of MT MRI acquisition essential for the design of multicentre studies. Multiple Sclerosis 2008; 14: 455—464. http://msj.sagepub.com

Rates of progression vary widely in primary progressive multiple sclerosis. This multicenter study aimed to identify predictors of progression over 10 years. A total of 101 patients who had been imaged at baseline and 2 years were scored on the expanded disability status scale after 10 years. Ordinal logistic regression identified the following independent variables that predicted progression: male sex, shorter disease duration, and slower timed walk test at baseline (best overall predictor), and deterioration in expanded disability status scale score and reduction in brain volume over 2 years. These predictors of long-term disability provide some insight into disease progression.

Objectives: Prediction of long term clinical outcome in patients with primary progressive multiple sclerosis (PPMS) using imaging has important clinical implications, but remains challenging. We aimed to determine whether spatial location of T2 and T1 brain lesions predicts clinical progression during a 10-year follow-up in PPMS. Methods: Lesion probability maps of the T2 and T1 brain lesions were generated using the baseline scans of 80 patients with PPMS who were clinically assessed at baseline and then after 1, 2, 5 and 10 years. For each patient, the time (in years) taken before bilateral support was required to walk (time to event (TTE)) was used as a measure of progression rate. The probability of each voxel being ‘lesional’ was correlated with TTE, adjusting for age, gender, disease duration, centre and spinal cord cross sectional area, using a multiple linear regression model. To identify the best, independent predictor of progression, a Cox regression model was used. Results: A significant correlation between a shorter TTE and a higher probability of a voxel being lesional on T2 scans was found in the bilateral corticospinal tract and superior longitudinal fasciculus, and in the right inferior fronto-occipital fasciculus (p

Background: In multiple sclerosis (MS), demyelination and neuroaxonal damage are seen in the hippocampus, and MRI has revealed hippocampal atrophy. Objectives: To investigate and compare hippocampal volume loss in patients with relapsing—remitting MS (RRMS) and primary progressive MS (PPMS) using manual volumetry, and explore its association with memory dysfunction. Methods: Hippocampi were manually delineated on volumetric MRI of 34 patients with RRMS, 23 patients with PPMS and 18 controls. Patients underwent neuropsychological tests of verbal and visuospatial recall memory. Linear regression was used to compare hippocampal volumes between subject groups, and to assess the association with memory function. Results: Hippocampal volumes were smaller in MS patients compared with controls, and were similar in patients with RRMS and PPMS. The mean decrease in hippocampal volume in MS patients was 317 mm3 (9.4%; 95% CI 86 to 549; p = 0.008) on the right and 284 mm3 (8.9%; 95% CI 61 to 508; p = 0.013) on the left. A borderline association of hippocampal volume with memory performance was observed only in patients with PPMS. Conclusion: Hippocampal atrophy occurs in patients with RRMS and PPMS. Factors additional to hippocampal atrophy may impact on memory performance.

Fewer gadolinium-enhancing lesions are seen in established primary progressive multiple sclerosis (PPMS) compared with other subtypes. Previously, we found unexpectedly high enhancement levels in early PPMS (42%), suggesting an early inflammatory phase. The objective of this study was to investigate whether this level of enhancement was maintained, and whether it influenced clinical progression, over 5 years. Forty-five patients with PPMS, within 5 years of onset, were scored on the Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite (MSFC) and its subtests (including the timed walk test [TWT]) 6-monthly for 3 years, and at 5 years. T1-weighted brain and spinal cord images after triple dose gadolinium—DTPA, and T2-weighted brain sequences were also acquired. A mixed effect logistic model evaluated change in the percentage of patients with enhancing lesions. Ordinal logistic and multiple linear regression models identified predictors of progression, adjusted for T2 lesion load. The percentage of patients with enhancing lesions in the brain and spinal cord declined over 5 years ( p = 0.03). Among patients with enhancement, more enhancing lesions at baseline predicted greater decline in mobility on the TWT over 5 years ( p = 0.02). In conclusion, a proportion of patients with PPMS may undergo an early inflammatory phase, which has some impact on subsequent mobility.

For the Timed 25-Foot Walk (T25FW) and 9-Hole Peg Test (9HPT), components of the Multiple Sclerosis Functional Composite (MSFC), cut-off points of 20% change have previously been defined as meaningful endpoints of functional decline. Recently, however, a 15% change of MSFC components was introduced. The objective of this study was to determine optimal cut-offs for all MSFC components to indicate clinical disease progression in a primary progressive (PP) multiple sclerosis (MS) population. T25FW, 9HPT and the Paced Auditory Serial Addition Test (PASAT) were performed in 161 patients with PPMS with a 2-year interval. Absolute and relative differences in test scores were calculated. For each cut-off point of relative change, proportions of patients who progressed (deterioration beyond cut-off value) and improved (improvement beyond cut-off value) were calculated. Further, we calculated the ratio of ‘improved’ versus ‘progressed’ patients. Line graphs were created indicating: percentage progressed patients, percentage improved patients, and ratio of improved versus progressed patients. The optimal cut-off was determined by searching the cut-off point with the lowest ratio of improved versus progressed patients, while at the same time capturing a substantial amount of progression. For both T25FW and 9HPT, the ratio between patients that improved and worsened clearly decreased between the cut-offs of 15% and 20%. For the PASAT, the ratio between patients improved and worsened was persistently poor. In conclusion, a cut-off of 20% for both T25FW and 9HPT has a better signal-to-noise ratio than lower values (e.g. 15%) and is therefore preferable for the assessment of disease progression. No satisfactory cut-off point for the PASAT could be determined.

Primary progressive multiple sclerosis (MS) is a chronic demyelinating degenerative disorder of the central nervous system. The most common presentation is with a spastic paraparesis, which may be asymmetrical. In contrast to relapsing remitting MS, discrete attacks are not a characteristic feature and the temporal course is of gradual symptomatic deterioration. The current diagnostic criteria are based on this clinical phenotype, with supportive evidence from magnetic resonance imaging, and examination of cerebrospinal fluid and visual evoked potentials in some cases. At present, there is no effective disease modifying therapy, but a wide range of symptomatic treatments are available. These may be of great benefit to individual patients and include pharmacological measures, multidisciplinary therapist input and neurorehabilitation. New treatments which target neurodegeneration and promote brain repair are required, and research in these areas offers hope for the future.

Progression rates in primary progressive multiple sclerosis (PPMS) vary widely and brain magnetisation transfer imaging (MTI) has potential as an early prognostic indicator. We investigated the predictive value of MTI and the longitudinal changes developing over 1 year in early PPMS.To determine (1) whether baseline brain MTI parameters in early PPMS predict clinical changes over 1 year, independent of brain volume and (2) whether a change in magnetisation transfer (MT) parameters occurs over 1 year, independent of atrophy.30 patients with PPMS within 5 years of symptom onset and 15 controls underwent MT and volumetric imaging studies, at baseline and at 1 year. Patients underwent clinical assessment using the Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite (MSFC), including the timed walk subtest (TWT). Normalised MT histograms were generated for whole brain, normal appearing brain tissue (NABT) and normal appearing white and grey matter (NAWM and NAGM) segments. Multiple regression analyses were performed to investigate whether baseline MTR parameters predicted clinical change over 1 year, adjusting for baseline brain volume. MTR changes over 1 year were assessed using paired t tests.In patients, lower baseline NAWM MTR predicted greater deterioration in EDSS and MSFC, particularly in walking ability measured by the TWT, independent of NAWM baseline volume (p = 0.001). NAGM MTR mean (p0.001), and to a lesser extent NAWM mean (p = 0.011) and lesion MTR (p = 0.03), decreased over 1 year.NAWM MTR may provide information on short term clinical prognosis in early PPMS. MTI is sensitive to brain tissue changes over 1 year in early PPMS, which were primarily seen in the NAGM.

Disability in primary progressive multiple sclerosis (PPMS) has been correlated with damage to the normal appearing brain tissues. Magnetization transfer ratio (MTR) and volume changes indicate that much of this damage occurs in the normal appearing grey matter, but the clinical significance of this remains uncertain. We aimed to localize these changes to distinct grey matter regions, and investigate the clinical impact of the MTR changes. 46 patients with early PPMS and 23 controls underwent MT and high-resolution T1-weighted imaging. Patients were scored on the Expanded Disability Status Scale (EDSS), Multiple Sclerosis Functional Composite and subtests (Nine-Hole Peg Test, Timed Walk Test, Paced Auditory Serial Addition Test [PASAT]). Grey matter volume and MTR were compared between patients and controls, adjusting for age. Mean MTR for significant regions within the motor network and in areas relevant to PASAT performance were correlated with appropriate clinical scores, adjusting for grey matter volume. Patients showed reduced MTR and atrophy in the right pre- and left post-central gyri, right middle frontal gyrus, left insula, and thalamus bilaterally. Reduced MTR without significant atrophy occurred in the left pre-central gyrus, left superior frontal gyri, bilateral superior temporal gyri, right insula and visual cortex. Higher EDSS correlated with lower MTR in the right primary motor cortex (BA 4). In conclusion, localized grey matter damage occurs in early PPMS, and MTR change is more widespread than atrophy. Damage demonstrated by reduced MTR is clinically eloquent.

IntroductionIt is important that we attract high-calibre medics to neurology. There are few studies of what motivated neurologists to choose their speciality, when they chose, or what else they might have become.MethodsAll UK neurology trainees were invited to complete an online survey.Results160 trainees responded (53% female; 17% less-than-fulltime). 54% decided on neurology before graduating (6% before medical school), whilst 29% decided after foundation training. Common reasons to choose neurology included: academically interesting (72%); clinical exposure as a student or junior (67%); personality fit (53%); influential role-model (37%). Less common motivations included lifestyle, family friendliness, prestige, and family members with neurological conditions. Two trainees chose neurology because they personally have a neurological condition. When asked what their second choice of medical career would have been the answers were diverse and 31 different specialties were named, but only one might have been a neurosurgeon.ConclusionsCareers advice should begin early in medical school and continue through medical training with direct exposure to clinical neurology. Traditional neurology values such as the intellectual challenge should be emphasised. Neurologists have a broad interest in medical and psychiatric specialties underlining the importance of core medical training to developing neurologists of the future.

BACKGROUND Magnetization transfer imaging has the potential to provide a surrogate marker for progression in primary progressive multiple sclerosis (PPMS). OBJECTIVES To investigate whether brain magnetization transfer imaging, T2 lesion load, and atrophy changes over 3 years reflect concurrent clinical changes, and which baseline imaging measure best predicts progression over 3 years in early PPMS. DESIGN Prospective study. SETTING National Hospital for Neurology and Neurosurgery and the Institute of Neurology, London, England. PATIENTS Forty-seven patients with PPMS (of whom 43 completed the study) and 18 control subjects. INTERVENTIONS Brain magnetization transfer imaging (including T2-weighted images) and volume sequences every 6 months for 3 years. MAIN OUTCOME MEASURES Changes in Expanded Disability Status Scale (EDSS) score and associations with rate of change in imaging variables. RESULTS More rapid decline in gray matter mean and peak location magnetization transfer ratio and T2 lesion load increase were associated with greater rates of progression on the EDSS. Baseline gray matter peak height magnetization transfer ratio best predicted progression over 3 years. CONCLUSION Gray matter magnetization transfer ratio meets many of the criteria for a surrogate marker of progression in early PPMS.