Torben Fog - A Danish pioneer in a multi-faceted spectrum of multiple sclerosis research

Torben Fog was committed to multiple sclerosis (MS) research for more than four decades, starting before the defence of his thesis in 1948 and lasting until his death in 1987. His research was multi-facetted, making him one of the great pioneers in the study of essential parts of the pathology, immunology and treatment of MS. He has contributed with meticulous studies of the MS plaques, documenting the perivenous distribution of plaques in the spinal cord. He constructed a scoring system for the disability in MS and used a computer programme to calculate a total neurological deficit. Together with his co-workers, Fog in 1972 was the first to report the association between MS and the human leukocyte antigen system. Fog can be considered as the father of immunomodulatory therapy in MS, treating MS patients with the first transfer factor, and as early as 1980, he was the first to treat MS with intramuscular natural interferon.

Extended interval dosing with ocrelizumab in multiple sclerosis

BACKGROUND

This study investigates clinical and biomarker differences between standard interval dosing (SID) and extended interval dosing (EID) of ocrelizumab therapy in multiple sclerosis (MS).

METHODS

This is a prospective, double-arm, open-label, multi-center study in Denmark. Participants diagnosed with MS on ocrelizumab therapy >12 months were included (n = 184). Clinical, radiological, and blood-based biomarker outcomes were evaluated. MRI disease activity, relapses, worsening of neurostatus, and No Evidence of Disease Activity-3 (NEDA-3) were used as a combined endpoint.

RESULTS

Out of 184 participants, 107 participants received EID (58.2%), whereas 77 participants received SID (41.8%). The average extension was 9 weeks with a maximum of 78 weeks. When comparing EID to SID, we found higher levels of B-cells, lower serum concentrations of ocrelizumab, and similar levels of age-adjusted NFL and GFAP in the two groups. No difference in NEDA-3 between EID and SID was demonstrated (hazard ratio: 1.174, p = 0.69). Higher levels of NFL were identified in participants with disease activity. Body mass index correlated with levels of ocrelizumab and B-cells.

CONCLUSION

Extending one treatment interval of ocrelizumab on average 9 weeks and up to 78 weeks did not result in clinical, radiological, or biomarker evidence of worsening compared with SID.

Rebound of clinical disease activity after fingolimod discontinuation? A nationwide cohort study of patients in Denmark

OBJECTIVE

We investigated whether clinical rebound occurred after fingolimod discontinuation in a complete population of patients with relapsing-remitting multiple sclerosis (RRMS) in Denmark. We further identified clinical and demographical factors associated with disease reactivation after fingolimod discontinuation.

METHODS

The population comprised 992 RRMS patients treated with fingolimod for 6 months or more. We estimated annualised relapse rates (ARR) before, during and after treatment. We estimated overall ARRs and ARRs stratified by disease activity before discontinuation. We calculated the proportion of patients with a higher clinical disease activity after discontinuation than before treatment start. Finally, we analysed the association between variables at discontinuation and time to first relapse after discontinuation.

RESULTS

The ARR 3 months after discontinuation (ARR=0.56; 95% CI=0.47 to 0.66) was statistically significantly lower (p<0.01) than the ARR 1 year before treatment (ARR=0.74; 95% CI=0.69 to 0.80). Results were similar when repeating analyses in patients with and without disease activity before discontinuation. In total, 124 patients (12.5%) had clinical rebound. Of those, 36 had no disease breakthrough before discontinuation (3.6% of total population). On treatment disease activity (HR=1.98, p<0.01), lower age (HR=0.98, p=0.01) and female sex (HR=1.68, p=0.02) were associated with a higher relapse risk after discontinuation.

CONCLUSIONS

Based on average ARR levels, there was no evidence of clinical rebound after fingolimod discontinuation. In total, 12.5% of patients had clinical rebound. Only 3.6%, however, had clinical rebound without disease activity before discontinuation. Disease activity before discontinuation, female sex and younger age were statistically significantly associated with a higher relapse risk after discontinuation.

Impact of methodological choices in comparative effectiveness studies: application in natalizumab versus fingolimod comparison among patients with multiple sclerosis

Background

Natalizumab and fingolimod are used as high-efficacy treatments in relapsing–remitting multiple sclerosis. Several observational studies comparing these two drugs have shown variable results, using different methods to control treatment indication bias and manage censoring. The objective of this empirical study was to elucidate the impact of methods of causal inference on the results of comparative effectiveness studies.

Methods

Data from three observational multiple sclerosis registries (MSBase, the Danish MS Registry and French OFSEP registry) were combined. Four clinical outcomes were studied. Propensity scores were used to match or weigh the compared groups, allowing for estimating average treatment effect for treated or average treatment effect for the entire population. Analyses were conducted both in intention-to-treat and per-protocol frameworks. The impact of the positivity assumption was also assessed.

Results

Overall, 5,148 relapsing–remitting multiple sclerosis patients were included. In this well-powered sample, the 95% confidence intervals of the estimates overlapped widely. Propensity scores weighting and propensity scores matching procedures led to consistent results. Some differences were observed between average treatment effect for the entire population and average treatment effect for treated estimates. Intention-to-treat analyses were more conservative than per-protocol analyses. The most pronounced irregularities in outcomes and propensity scores were introduced by violation of the positivity assumption.

Conclusions

This applied study elucidates the influence of methodological decisions on the results of comparative effectiveness studies of treatments for multiple sclerosis. According to our results, there are no material differences between conclusions obtained with propensity scores matching or propensity scores weighting given that a study is sufficiently powered, models are correctly specified and positivity assumption is fulfilled.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01623-8.

Natalizumab Versus Fingolimod in Patients with Relapsing-Remitting Multiple Sclerosis: A Subgroup Analysis From Three International Cohorts

INTRODUCTION

Natalizumab has proved to be more effective than fingolimod in reducing disease activity in relapsing-remitting multiple sclerosis (RRMS). Whether this association is universal for all patient groups remains to be determined.

OBJECTIVE

The aim of this study was to compare the relative effectiveness of natalizumab and fingolimod in RRMS subgroups defined by the baseline demographic and clinical characteristics of interest.

METHODS

Patients with RRMS who were given natalizumab or fingolimod were identified in a merged cohort from three international registries. Efficacy outcomes were compared across subgroups based on patients' sex, age, disease duration, Expanded Disability Status Scale (EDSS) score, and disease and magnetic resonance imaging (MRI) activity 12 months prior to treatment initiation. Study endpoints were number of relapses (analyzed with weighted negative binomial generalized linear model) and 6-month confirmed disability worsening and improvement events (weighted Cox proportional hazards model), recorded during study therapy. Each patient was weighted using inverse probability of treatment weighting based on propensity score.

RESULTS

A total of 5148 patients (natalizumab 1989; fingolimod 3159) were included, with a mean ± standard deviation age at baseline of 38 ± 10 years, and the majority (72%) were women. The median on-treatment follow-up was 25 (quartiles 15-41) months. Natalizumab was associated with fewer relapses than fingolimod (incidence rate ratio [IRR]; 95% confidence interval [CI]) in women (0.76; 0.65-0.88); in those aged ≤ 38 years (0.64; 0.54-0.76); in those with disease duration ≤ 7 years (0.63; 0.53-0.76); in those with EDSS score < 4 (0.75; 0.64-0.88), < 6 (0.80; 0.70-0.91), and ≥ 6 (0.52; 0.31-0.86); and in patients with pre-baseline relapses (0.74; 0.64-0.86). A higher probability of confirmed disability improvement on natalizumab versus fingolimod (hazard ratio [HR]; 95% CI) was observed among women (1.36; 1.10-1.66); those aged > 38 years (1.34; 1.04-1.73); those with disease duration > 7 years (1.33; 1.01-1.74); those with EDSS score < 6 (1.21; 1.01-1.46) and ≥ 6 (1.93; 1.11-3.34); and patients with no new MRI lesion (1.73; 1.19-2.51).

CONCLUSIONS

Overall, in women, younger patients, those with shorter disease durations, and patients with pre-treatment relapses, natalizumab was associated with a lower frequency of multiple sclerosis relapses than fingolimod. It was also associated with an increased chance of recovery from disability among most patients, particularly women and those with no recent MRI activity.

Ocrelizumab treatment in multiple sclerosis: A Danish population-based cohort study

BACKGROUND AND PURPOSE

Real-world evidence regarding the effectiveness and safety of ocrelizumab for the treatment of multiple sclerosis (MS) is limited. The aim was to evaluate the effectiveness and safety of ocrelizumab treatment for MS in a real-world setting.

METHODS

A nationwide population-based cohort study was conducted where clinical and magnetic resonance imaging data of MS patients enrolled prospectively in the Danish Multiple Sclerosis Registry who initiated ocrelizumab treatment between January 2018 and November 2020 were analyzed.

RESULTS

A total of 1104 patients (85.7% relapsing-remitting MS [RRMS], 8.8% secondary progressive MS [SPMS], 5.5% primary progressive MS [PPMS]) were included, with a median follow-up period of 1.3 years. At baseline, the mean age was 41.4 years in the RRMS group, 44.5 years in the PPMS group and 50.3 years in the SPMS group. Median Expanded Disability Status Scale score was 2.5, 3.5 and 5.5, respectively. Most RRMS and SPMS patients had received previous disease-modifying therapies (87.5% and 91.8%, respectively), whereas PPMS patients were mostly treatment naïve (78.7%). After ocrelizumab initiation, 9.3% of the patients experienced a relapse and 8.7% a 24 weeks confirmed disability worsening. Conversely, 16.7% showed a 24 weeks confirmed disability improvement. After ~1 year of treatment, most patients (94.5%) were free of magnetic resonance imaging activity. Ocrelizumab was generally well tolerated, as side effects were only reported for 10% of patients, mostly consisting of infusion-related reactions and infections.

CONCLUSIONS

It is shown that most MS patients treated with ocrelizumab are clinically stabilized and with an adverse event profile consistent with the experience from the pivotal clinical trials.

Imaging cortical multiple sclerosis lesions with ultra-high field MRI

BACKGROUND

Cortical lesions are abundant in multiple sclerosis (MS), yet difficult to visualize in vivo. Ultra-high field (UHF) MRI at 7 T and above provides technological advances suited to optimize the detection of cortical lesions in MS.

PURPOSE

To provide a narrative and quantitative systematic review of the literature on UHF MRI of cortical lesions in MS.

METHODS

A systematic search of all literature on UHF MRI of cortical lesions in MS published before September 2020. Quantitative outcome measures included cortical lesion numbers reported using 3 T and 7 T MRI and between 7 T MRI sequences, along with sensitivity of UHF MRI towards cortical lesions verified by histopathology.

RESULTS

7 T MRI detected on average 52 ± 26% (mean ± 95% confidence interval) more cortical lesions than the best performing image contrast at 3 T, with the largest increase in type II-IV intracortical lesion detection. Across all studies, the mean cortical lesion number was 17 ± 6 per patient. In progressive MS cohorts, approximately four times more cortical lesions were reported than in CIS/early RRMS, and RRMS. Yet, there was no difference in lesion type ratio between these MS subtypes. Furthermore, superiority of one MRI sequence over another could not be established from available data. Post-mortem lesion detection with UHF MRI agreed only modestly with pathological examinations. Mean pro- and retrospective sensitivity was 33 ± 6% and 71 ± 10%, respectively, with the highest sensitivity towards type I and type IV lesions.

CONCLUSION

UHF MRI improves cortical lesion detection in MS considerably compared to 3 T MRI, particularly for type II-IV lesions. Despite modest sensitivity, 7 T MRI is still capable of visualizing all aspects of cortical lesion pathology and could potentially aid clinicians in diagnosing and monitoring MS, and progressive MS in particular. However, standardization of acquisition and segmentation protocols is needed.

Real-world outcomes for a complete nationwide cohort of more than 3200 teriflunomide-treated multiple sclerosis patients in The Danish Multiple Sclerosis Registry

Objective

Teriflunomide is a once-daily, oral disease-modifying therapy (DMT) for relapsing forms of multiple sclerosis (MS). We studied clinical outcomes in a real-world setting involving a population-based large cohort of unselected patients enrolled in The Danish Multiple Sclerosis Registry (DMSR) who started teriflunomide treatment between 2013–2019.

Methods

This was a complete nationwide population-based cohort study with prospectively enrolled unselected cases. Demographic and disease-specific patient parameters related to treatment history, efficacy outcomes, and discontinuation and switching rates among other clinical variables were assessed at baseline and during follow-up visits.

Results

A total of 3239 patients (65.4% female) started treatment with teriflunomide during the study period, 56% of whom were treatment-naïve. Compared to previously treated patients, treatment-naïve patients were older on average at disease onset, had a shorter disease duration, a lower Expanded Disability Status Scale score at teriflunomide treatment start and more frequently experienced a relapse in the 12 months prior to teriflunomide initiation. In the 3001 patients initiating teriflunomide treatment at least 12 months before the cut-off date, 72.7% were still on treatment one year after treatment start. Discontinuations in the first year were due mainly to adverse events (15.6%). Over the full follow-up period, 47.5% of patients discontinued teriflunomide treatment. Sixty-three percent of the patients treated with teriflunomide for 5 years were relapse-free, while significantly more treatment-naïve versus previously treated patients experienced a relapse during the follow-up (p<0.0001). Furthermore, 85% of the patients with available data were free of disability worsening at the end of follow-up.

Conclusions

Solid efficacy and treatment persistence data consistent with other real-world studies were obtained over the treatment period. Treatment outcomes in this real-world scenario of the population-based cohort support previous findings that teriflunomide is an effective and generally well-tolerated DMT for relapsing MS patients with mild to moderate disease activity.

The effectiveness of natalizumab vs fingolimod-A comparison of international registry studies

BACKGROUND

Natalizumab and fingolimod were the first preparations recommended for disease breakthrough in priorly treated relapsing-remitting multiple sclerosis. Of three published head-to-head studies two showed that natalizumab is the more effective to prevent relapses and EDSS worsening.

METHODS

By re-analyzing original published results from MSBase, France, and Denmark using uniform methodologies, we aimed at identifying the effects of differences in methodology, in the MS-populations, and at re-evaluating the differences in effectiveness between the two drugs. We gained access to copies of the individual amended databases and pooled all data. We used uniform inclusion/exclusion criteria and statistical methods with Inverse Probability Treatment Weighting.

RESULTS

The pooled analyses comprised 968 natalizumab- and 1479 fingolimod treated patients. The on-treatment natalizumab/fingolimod relapse rate ratio was 0.77 (p=0.004). The hazard ratio (HR) for a first relapse was 0.82 (p=0.030), and the HR for sustained EDSS improvement was 1.4 (p=0.009). There were modest differences between each of the original published studies and the replication study, but the conclusions of the three original studies remained unchanged: in two of them natalizumab was more effective, but in the third there was no difference between natalizumab and fingolimod.

CONCLUSION

The results were largely invariant to the epidemiological and statistical methods but differed between the MS populations. Generally, the advantage of natalizumab was confirmed.

Clinical and pathological insights into the dynamic nature of the white matter multiple sclerosis plaque

OBJECTIVE

An extensive analysis of white matter plaques in a large sample of multiple sclerosis (MS) autopsies provides insights into the dynamic nature of MS pathology.

METHODS

One hundred twenty MS cases (1,220 tissue blocks) were included. Plaque types were classified according to demyelinating activity based on stringent criteria. Early active, late active, smoldering, inactive, and shadow plaques were distinguished. A total of 2,476 MS white matter plaques were identified. Plaque type distribution was analyzed in relation to clinical data.

RESULTS

Active plaques were most often found in early disease, whereas at later stages, smoldering, inactive, and shadow plaques predominated. The presence of early active plaques rapidly declined with disease duration. Plaque type distribution differed significantly by clinical course. The majority of plaques in acute monophasic and relapsing-remitting MS (RRMS) were active. Among secondary progressive MS (SPMS) cases with attacks, all plaque types could be distinguished including active plaques, in contrast to SPMS without attacks, in which inactive plaques predominated. Smoldering plaques were frequently and almost exclusively found in progressive MS. At 47 years of age, an equilibrium was observed between active and inactive plaques, whereas smoldering plaques began to peak. Men displayed a higher proportion of smoldering plaques.

INTERPRETATION

Disease duration, clinical course, age, and gender contribute to the dynamic nature of white matter MS pathology. Active MS plaques predominate in acute and early RRMS and are the likely substrate of clinical attacks. Progressive MS transitions to an accumulation of smoldering plaques characterized by microglial activation and slow expansion of pre-existing plaques. Whether current MS therapeutics impact this pathological driver of disease progression remains uncertain.

Demyelination versus remyelination in progressive multiple sclerosis

The causes of incomplete remyelination in progressive multiple sclerosis are unknown, as are the pathological correlates of the different clinical characteristics of patients with primary and secondary progressive disease. We analysed brains and spinal cords from 51 patients with progressive multiple sclerosis by planimetry. Thirteen patients with primary progressive disease were compared with 34 with secondary progressive disease. In patients with secondary progressive multiple sclerosis, we found larger brain plaques, more demyelination in total and higher brain loads of active demyelination compared with patients with primary progressive disease. In addition, the brain density of plaques with high-grade inflammation and active demyelination was highest in secondary progressive multiple sclerosis and remained ~18% higher than in primary progressive multiple sclerosis after adjustments for other plaque types and plaque number (P<0.05). Conversely, the proportion of remyelinated shadow plaques (P<0.05) and the overall remyelination capacity (P<0.01) per brain were higher in primary, compared with secondary, progressive multiple sclerosis. By contrast, there were no group differences in the brain load or frequency of low-grade inflammatory plaques with slowly expanding demyelination. Spinal cord lesion loads and remyelination capacity were also comparable in the two patient groups. Remyelinated areas were more vulnerable than the normal-appearing white matter to new demyelination, including active demyelination in secondary progressive multiple sclerosis. 'Recurrent' slowly expanding demyelination, affecting remyelinated areas, and the load of slowly expanding demyelination correlated with incomplete remyelination in both groups. In turn, incomplete remyelination in the spinal cord correlated with higher disease-related disability (determined retrospectively; r = -0.53; P<0.05 for remyelination capacity versus disease severity). By contrast, such a correlation was not observed in the brain. We propose that regulatory and reparative properties could protect the white matter of the brain in patients with primary progressive multiple sclerosis. These patients may, thereby, be spared symptoms until the spinal cord is affected. By contrast, recurrent active demyelination of repaired myelin could explain why similar symptoms often develop in consecutive relapses in relapsing-remitting/secondary progressive multiple sclerosis. Our data also indicate that slowly expanding demyelination may irreparably destroy normal and repaired myelin, supporting the concept of slowly expanding demyelination as an important pathological correlate of clinical progression.

The relation between inflammation and neurodegeneration in multiple sclerosis brains

Some recent studies suggest that in progressive multiple sclerosis, neurodegeneration may occur independently from inflammation. The aim of our study was to analyse the interdependence of inflammation, neurodegeneration and disease progression in various multiple sclerosis stages in relation to lesional activity and clinical course, with a particular focus on progressive multiple sclerosis. The study is based on detailed quantification of different inflammatory cells in relation to axonal injury in 67 multiple sclerosis autopsies from different disease stages and 28 controls without neurological disease or brain lesions. We found that pronounced inflammation in the brain is not only present in acute and relapsing multiple sclerosis but also in the secondary and primary progressive disease. T- and B-cell infiltrates correlated with the activity of demyelinating lesions, while plasma cell infiltrates were most pronounced in patients with secondary progressive multiple sclerosis (SPMS) and primary progressive multiple sclerosis (PPMS) and even persisted, when T- and B-cell infiltrates declined to levels seen in age matched controls. A highly significant association between inflammation and axonal injury was seen in the global multiple sclerosis population as well as in progressive multiple sclerosis alone. In older patients (median 76 years) with long-disease duration (median 372 months), inflammatory infiltrates declined to levels similar to those found in age-matched controls and the extent of axonal injury, too, was comparable with that in age-matched controls. Ongoing neurodegeneration in these patients, which exceeded the extent found in normal controls, could be attributed to confounding pathologies such as Alzheimer's or vascular disease. Our study suggests a close association between inflammation and neurodegeneration in all lesions and disease stages of multiple sclerosis. It further indicates that the disease processes of multiple sclerosis may die out in aged patients with long-standing disease.

Fatal neurogenic pulmonary edema in a patient with progressive multiple sclerosis

We report a case of fatal neurogenic pulmonary edema in progressive multiple sclerosis (MS). The patient had one isolated relapse-like episode. Six years later progressive disease began, lasting 5 years until unexpected death during sleep. Medico-legal autopsy revealed pulmonary edema and neuropathological examination showed infiltrations with lymphocytes and microglia in the respiratory centers of the medulla. More classical demyelinated lesions were found in the white matter of spinal cord and in the gray matter of the brain along with disseminated perivascular lymphocytic infiltrates. Medullary inflammation in progressive MS may result in sudden fatal respiratory failure.

Cholestasis and regulation of genes related to drug metabolism and biliary transport in rat liver following treatment with cyclosporine A and sirolimus (Rapamycin)

Cyclosporine A and sirolimus are used alone or in combination as immunosuppressants in organ transplantation. To elucidate hepatic side effects, we examined hepatic mRNA of proteins involved in biliary and hepatocellular transport of drugs, formation of glutathione (GSH) and drug metabolising cytochrome P-450 enzymes (CYPs) in rats treated orally for 2 weeks with cyclosporine A (15 mg/kg/day), sirolimus (0.4 mg/kg/day), their combination (same doses), or vehicle. Liver function tests (alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and bilirubin) in blood were then analysed as were hepatic mRNA levels of canalicular transport proteins (Mrp2, Bsep, Mdr1b and Mdr2), sinusoidal transport proteins (Ntcp, Oatp1 and Oatp2), GSH related enzymes (gamma-glutamylcysteine synthetase light (GCSlc) and heavy (GCShc) chain subunits and glutathione-S-transferase) and CYPs (CYP3A9, CYP1A2, CYP2E1 and CYP2BI/II). Cyclosporine A caused moderate cholestatic changes in liver enzymes, which was synergistically exacerbated by sirolimus. The data suggest that the underlying mechanisms behind cholestasis were not totally identical in the different treatment regimens. Cholestasis secondary to cyclosporine A could be related to reduction in mRNA expression of GSH synthesising enzymes and Mrp2, leading to reduced protection against oxidative stress and reduced bile acid-independent bile flow. After sirolimus treatment, Mrp2 mRNA was also reduced together with reduced levels of most CYPs and increased Oatp2, possibly leading to accumulation of toxic metabolites in the hepatocytes. The enhanced cholestatic effect of the combination treatment could be related to reduced GSH synthesising enzymes and even more pronounced reduction in Mrp2 mRNA and increase of Oatp2 mRNA.