Effects of Ibudilast on Retinal Atrophy in Progressive Multiple Sclerosis Subtypes: Post Hoc Analyses of the SPRINT-MS Trial

Re-defining progression in multiple sclerosis

PURPOSE OF REVIEW

The purpose of this article is to provide an overview of progression in multiple sclerosis (MS), including definitions, pathological mechanisms, and evidence that progressive biology begins early in the disease course.

RECENT FINDINGS

Definitions of MS clinical course have been refined to acknowledge the presence of both relapse and progression biology throughout the disease. Progression independent of relapse activity represents a significant proportion of disability worsening in relapsing-remitting MS (RRMS) disease. Progression in MS appears to be caused by the complex interplay of multiple processes, including nonresolving inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, energetic failure, and neuro-axonal degeneration. These processes appear to begin in the earliest disease stages and their contribution to clinical phenotypes is dynamic over time. Promising results from clinical trials of tolebrutinib, in particular, underline the utility of targeting both innate and adaptive immune mechanisms to reduce disability accumulation.

SUMMARY

Pathological processes that underpin MS progression are detectable early in RRMS, evolve throughout the disease course and correlate with disability accumulation. Progression in MS should not be defined dichotomously - the focus instead should be on recognizing progressive components based on clinical measures and biomarkers early in the disease to better individualize treatment strategies.

Optical coherence tomography and angiography in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Anterior visual pathway involvement is common in multiple sclerosis (MS) and optical coherence tomography (OCT) can be utilized to examine the integrity of the ganglion cell axons (peri-papillary retinal nerve fiber layer; pRNFL) and cell bodies (ganglion cell & inner plexiform layer; GCIPL). OCT angiography (OCTA) can be used to investigate the retinal microvasculature. In this systematic review and meta-analysis, we synthesized OCT and OCTA findings in MS.

METHODS

We identified studies that performed OCT and OCTA in people with MS and included data permitting at least one of the following comparisons: 1) MS optic neuritis (MS-ON) vs healthy-control (HC) eyes; 2) MS non-ON (MS-NON) vs HC eyes; and 3) MS-ON vs MS-NON eyes.

RESULTS

The OCT meta-analysis included 170 studies and 8542 HC, 5529 MS-ON, and 14,822 MS-NON eyes. MS-ON and MS-NON eyes had lower pRNFL and GCIPL thickness compared to HC. There was no difference in inner nuclear layer (INL) thickness between HC and MS; INL was thicker in MS-ON compared to MS-NON eyes. The OCTA meta-analysis included 24 studies and 1344 HC, 505 MS-ON, and 1168 MS-NON eyes. MS-ON and MS-NON eyes had lower peripapillary vessel density and macular superficial vessel density compared to HC. We also summarized 12 studies evaluating the diagnostic yield of inter-eye differences in OCT measurements for detecting unilateral optic nerve involvement.

CONCLUSIONS

OCT allows for reliable quantification of retinal neuro-axonal damage in MS. In our review, we highlight studies demonstrating that OCT can establish robust thresholds for detecting unilateral optic nerve involvement.

The relationship between optical coherence tomography and magnetic resonance imaging measurements in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Several studies show that optical coherence tomography (OCT) metrics e with cognition, disability, and brain structure in people with multiple sclerosis (PwMS). This review the correlation between OCT parameters and magnetic resonance imaging (MRI) measurements in PwMS.

METHODS

A comprehensive search of PubMed/MEDLINE, Embase, Scopus, and Web of Science was performed, including studies published in English up to November 29, 2024 to identify studies reporting quantitative data on the correlation between baseline OCT parameters and MRI measurements in PwMS. The meta-analysis was performed using R software version 4.4.0.

RESULTS

From 4931 studies, 68 studies on 6168 PwMS (67.4 % female) were included. The most significant correlations were found between peripapillary retinal nerve fiber layer (pRNFL) thickness and lower T1 lesion volume r = -0.42 (95 % CI: -0.52 to -0.31, p-value <0.001, I2 = 24 %), greater thalamic volume r = 0.39 (95 % CI: 0.17 to 0.61, p-value <0.001, I2 = 81 %), and lower T2 lesion volume r = -0.37 (95 % CI: -0.54 to -0.21, p-value <0.001, I2 = 85 %), respectively. Additionally, lower macular ganglion cell-inner plexiform layer (mGCIPL) thickness showed the most significant correlations with positive and lower thalamic volume r = 0.37 (95 % CI: 0.1 to 0.64, p-value = 0.008, I2 = 88 %), and positive and lower grey matter volume (GMV) 0.33 (95 % CI: 0.15 to 0.52, p-value <0.001, I2 = 81 %), respectively.

CONCLUSION

pRNFL and mGCIPL thickness are correlated with MRI measurements, suggesting that OCT can serve as a non-invasive, cost-effective, and complementary tool to MRI for enhancing the exploring of brain structural changes in PwMS.

Ongoing phase 2 agents for multiple sclerosis: could we break the phase 3 trial deadlock?

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system. While disease-modifying therapies have significantly improved the management of relapsing MS, progressive MS remains a major clinical challenge.

AREAS COVERED

This review provides a general overview of recent and ongoing phase 2 clinical trials investigating treatments for MS, summarizing emerging results when available. The trials are categorized based on the desired therapeutic effect: immunomodulatory treatments, neuroprotection, and remyelination. A comprehensive literature search was conducted using databases such as PubMed and ClinicalTrials.gov to identify relevant studies, with a focus on promising therapies that address both inflammatory and neurodegenerative processes in MS.

EXPERT OPINION

Despite promising results from phase 2 trials, many phase 3 trials fail to demonstrate significant efficacy. This discrepancy is partly due to limitations in biomarkers, which often lack disease specificity and fail to predict long-term outcomes. Additionally, smaller, narrowly focused phase 2 trials may overestimate efficacy, leading to challenges when transitioning to larger, more inclusive phase 3 trials. Recruitment of patients with less aggressive disease further complicates phase 3 success. Addressing these challenges requires the refinement of biomarkers, adoption of unified definitions for outcomes like progression independent of relapse activity (PIRA), and trial designs that better capture the complexity of MS progression.

Effect of siponimod on retinal thickness, a marker of neurodegeneration, in participants with SPMS: Findings from the EXPAND OCT substudy

BACKGROUND

People with MS show abnormal thinning of the retinal layers, which is associated with clinical disability and brain atrophy, and is a potential surrogate marker of neurodegeneration and treatment effects.

OBJECTIVE

To evaluate the utility of retinal thickness as a surrogate marker of neurodegeneration and treatment effect in participants with secondary progressive MS (SPMS) from the optical coherence tomography (OCT) substudy of the EXPAND Phase 3 clinical trial (siponimod versus placebo).

METHODS

In the OCT substudy population (n = 159), treatment effects on change in the average thickness of the retinal layer, peripapillary retinal nerve fiber layer (pRNFL), and combined macular ganglion cell and inner plexiform layers (GCIPL) were analyzed by high-definition spectral domain OCT at months 3, 12, and 24.

RESULTS

Thinning from baseline was observed across all retinal layers and time points in the placebo group. Siponimod significantly reduced GCIPL thinning versus placebo at month 24 (adjusted mean [SE] [µm]: -0.47 [0.81] vs. -4.29 [1.23]; p = 0.01), and overall retinal thinning at months 12 (+0.66 [0.54] vs. -1.86 [0.75]; p = 0.006) and 24 (-0.05 [0.59] vs. -2.30 [0.88]; p = 0.033). Although not significant, results for pRNFL consistently followed the same trends.

CONCLUSION

This exploratory substudy supports further investigation of OCT measurement of retinal atrophy as a non-invasive potential biomarker of treatment effects on neurodegeneration in SPMS.

Primary Progressive Multiple Sclerosis-A Key to Understanding and Managing Disease Progression

Primary progressive multiple sclerosis (PPMS), the least frequent type of multiple sclerosis (MS), is characterized by a specific course and clinical symptoms, and it is associated with a poor prognosis. It requires extensive differential diagnosis and often a long-term follow-up before its correct recognition. Despite recent progress in research into and treatment for progressive MS, the diagnosis and management of this type of disease still poses a challenge. Considering the modern concept of progression "smoldering" throughout all the stages of disease, a thorough exploration of PPMS may provide a better insight into mechanisms of progression in MS, with potential clinical implications. The goal of this study was to review the current evidence from investigations of PPMS, including its background, clinical characteristics, potential biomarkers and therapeutic opportunities. Processes underlying CNS damage in PPMS are discussed, including chronic immune-mediated inflammation, neurodegeneration, and remyelination failure. A review of potential clinical, biochemical and radiological biomarkers is presented, which is useful in monitoring and predicting the progression of PPMS. Therapeutic options for PPMS are summarized, with approved therapies, ongoing clinical trials and future directions of investigations. The clinical implications of findings from PPMS research would be associated with reliable assessments of disease outcomes, improvements in individualized therapeutic approaches and, hopefully, novel therapeutic targets, relevant for the management of progression.

Retinal layer thinning for monitoring disease-modifying treatment in relapsing multiple sclerosis-Evidence for applying a rebaselining concept

BACKGROUND

Employing a rebaselining concept may reduce noise in retinal layer thinning measured by optical coherence tomography (OCT).

METHODS

From an ongoing prospective observational study, we included patients with relapsing multiple sclerosis (RMS), who had OCT scans at disease-modifying treatment (DMT) start (baseline), 6-12 months after baseline (rebaseline), and ⩾12 months after rebaseline. Mean annualized percent loss (aL) rates (%/year) were calculated both from baseline and rebaseline for peripapillary-retinal-nerve-fiber-layer (aLpRNFLbaseline/aLpRNFLrebaseline) and macular-ganglion-cell-plus-inner-plexiform-layer (aLGCIPLbaseline/aLGCIPLrebaseline) by mixed-effects linear regression models.

RESULTS

We included 173 RMS patients (mean age 31.7 years (SD 8.8), 72.8% female, median disease duration 15 months (12-94) median baseline-to-last-follow-up-interval 37 months (18-71); 56.6% moderately effective DMT (M-DMT), 43.4% highly effective DMT (HE-DMT)). Both mean aLpRNFLbaseline and aLGCIPLbaseline significantly increased in association with relapse (0.51% and 0.26% per relapse, p < 0.001, respectively) and disability worsening (1.10% and 0.48%, p < 0.001, respectively) before baseline, but not with DMT class. Contrarily, neither aLpRNFLrebaseline nor aLGCIPLrebaseline was dependent on relapse or disability worsening before baseline, while HE-DMT significantly lowered aLpRNFLrebaseline (by 0.31%, p < 0.001) and aLGCIPLrebaseline (0.25%, p < 0.001) compared with M-DMT.

CONCLUSIONS

Applying a rebaselining concept significantly improves differentiation of DMT effects on retinal layer thinning by avoiding carry-over confounding from previous disease activity.

Homonymous Hemiatrophy of Macular Ganglion Cell Layer as a Marker of Retrograde Neurodegeneration in Multiple Sclerosis-A Narrative Review

Retrograde axonal neurodegeneration along the visual pathway-either direct or trans-synaptic-has already been demonstrated in multiple sclerosis (MS), as well as in compressive, vascular, or posttraumatic lesions of the visual pathway. Optical coherence tomography (OCT) can noninvasively track macular and optic nerve changes occurring as a result of this phenomenon. Our paper aimed to review the existing literature regarding hemimacular atrophic changes in the ganglion cell layer identified using OCT examination in MS patients without prior history of optic neuritis. Homonymous hemimacular atrophy has been described in post-chiasmal MS lesions, even in patients with normal visual field results. Temporal and nasal macular OCT evaluation should be performed separately in all MS patients, in addition to an optic nerve OCT evaluation and a visual field exam.

Novel and Emerging Treatments to Target Pathophysiological Mechanisms in Various Phenotypes of Multiple Sclerosis

The objective is to comprehensively review novel pharmacotherapies used in multiple sclerosis (MS) and the possibilities they may carry for therapeutic improvement. Specifically, we discuss pathophysiological mechanisms worth targeting in MS, ranging from well known targets, such as autoinflammation and demyelination, to more novel and advanced targets, such as neuroaxonal damage and repair. To set the stage, a brief overview of clinical MS phenotypes is provided, followed by a comprehensive recapitulation of both clinical and paraclinical outcomes available to assess the effectiveness of treatments in achieving these targets. Finally, we discuss various promising novel and emerging treatments, including their respective hypothesized modes of action and currently available evidence from clinical trials. SIGNIFICANCE STATEMENT: This comprehensive review discusses pathophysiological mechanisms worth targeting in multiple sclerosis. Various promising novel and emerging treatments, including their respective hypothesized modes of action and currently available evidence from clinical trials, are reviewed.

Macular OCT's Proficiency in Identifying Retrochiasmal Visual Pathway Lesions in Multiple Sclerosis-A Pilot Study

Optical coherence tomography (OCT) is a non-invasive imaging technique based on the principle of low-coherence interferometry that captures detailed images of ocular structures. Multiple sclerosis (MS) is a neurodegenerative disease that can lead to damage of the optic nerve and retina, which can be depicted by OCT. The purpose of this pilot study is to determine whether macular OCT can be used as a biomarker in the detection of retrochiasmal lesions of the visual pathway in MS patients. We conducted a prospective study in which we included 52 MS patients and 27 healthy controls. All participants underwent brain MRI, visual field testing, and OCT evaluation of the thicknesses of the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer (GCL), and macular inner plexiform layer (IPL). OCT measurements were adjusted for optic neuritis (ON). VF demonstrated poor capability to depict a retrochiasmal lesion identified by brain MRI (PPV 0.50). In conclusion, the OCT analysis of the macula appears to excel in identifying retrochiasmal MS lesions compared to VF changes. The alterations in the GCL and IPL demonstrate the most accurate detection of retrochiasmal visual pathway changes in MS patients.

Serum macrophage migration inhibitory factor levels predict brain atrophy in people with primary progressive multiple sclerosis

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a cytokine linked to multiple sclerosis (MS) progression that is thought to be inhibited by ibudilast. SPRINT-MS was a phase 2 placebo-controlled trial of ibudilast in progressive multiple sclerosis (PMS).

OBJECTIVE

To determine whether baseline MIF levels predict imaging outcomes and assess the effects of ibudilast on serum and cerebrospinal fluid (CSF) MIF levels in people with PMS treated with ibudilast.

METHODS

Participants in the SPRINT-MS trial were treated with either ibudilast or placebo and underwent brain magnetic resonance imaging (MRI) every 24 weeks over a duration of 96 weeks. MIF was measured in serum and CSF.

RESULTS

MIF levels were compared with imaging outcomes in 223 participants from the SPRINT-MS study. In the primary progressive multiple sclerosis (PPMS) cohort, males had higher serum (p < 0.001) and CSF (p = 0.01) MIF levels, as compared with females. Higher baseline serum MIF levels in PPMS were associated with faster brain atrophy (beta = -0.113%, 95% confidence interval (CI): -0.204% to -0.021%; p = 0.016). These findings were not observed in secondary progressive multiple sclerosis (SPMS). Ibudilast did not affect either serum or CSF MIF levels.

CONCLUSIONS

Serum MIF levels were associated with male sex and predicted brain atrophy in PPMS, but not SPMS. Ibudilast did not demonstrate an effect on MIF levels, as compared with placebo, although we cannot exclude a functional effect.