Time to Change the Current Clinical Classification of Multiple Sclerosis?

Recent advances in the treatment of primary and secondary progressive Multiple Sclerosis

BACKGROUND

The article highlights upcoming potential treatments, which target different phases of inflammation and offer remyelinating strategies as well as direct and indirect neuroprotective and oligodendrocyte protective effects, providing a hopeful outlook for patients with primary and secondary progressive multiple sclerosis (PPMS and SPMS).

OBJECTIVES

The review aims to identify potential treatments and ongoing clinical trials for PPMS and SPMS, and compare their mechanisms of action, efficacy, and side effects with current treatments.

METHODS

We reviewed ongoing clinical trials for PPMS and SPMS on the NIH website, as well as articles from PubMed, Embase, and clinicaltrails.gov since 2010.

RESULTS

BTKIs like, tolebrutinib, and fenebrutinib are being explored as potential PMS treatments. Vidofludimus calcium, an orally available treatment, has shown a reduction of active and new MRI lesions. Other treatments like simvastatin, N-acetylcysteine (NAC), and alpha-lipoic acid are being explored for their antioxidant properties. AHSCT and mesenchymal stem cell therapy are experimental options for younger patients with high inflammatory activity.

CONCLUSIONS

SPMS and PPMS are being studied for new treatments and future trials should consider combination therapies targeting inflammation, demyelination, and neuronal death, as the pathogenesis of PMS involves complex factors.

A translational MRI approach to validate acute axonal damage detection as an early event in multiple sclerosis

Axonal degeneration is a central pathological feature of multiple sclerosis and is closely associated with irreversible clinical disability. Current noninvasive methods to detect axonal damage in vivo are limited in their specificity and clinical applicability, and by the lack of proper validation. We aimed to validate an MRI framework based on multicompartment modeling of the diffusion signal (AxCaliber) in rats in the presence of axonal pathology, achieved through injection of a neurotoxin damaging the neuronal terminal of axons. We then applied the same MRI protocol to map axonal integrity in the brain of multiple sclerosis relapsing-remitting patients and age-matched healthy controls. AxCaliber is sensitive to acute axonal damage in rats, as demonstrated by a significant increase in the mean axonal caliber along the targeted tract, which correlated with neurofilament staining. Electron microscopy confirmed that increased mean axonal diameter is associated with acute axonal pathology. In humans with multiple sclerosis, we uncovered a diffuse increase in mean axonal caliber in most areas of the normal-appearing white matter, preferentially affecting patients with short disease duration. Our results demonstrate that MRI-based axonal diameter mapping is a sensitive and specific imaging biomarker that links noninvasive imaging contrasts with the underlying biological substrate, uncovering generalized axonal damage in multiple sclerosis as an early event.

Harmonizing Definitions for Progression Independent of Relapse Activity in Multiple Sclerosis: A Systematic Review

Importance

Emerging evidence suggests that progression independent of relapse activity (PIRA) is a substantial contributor to long-term disability accumulation in relapsing-remitting multiple sclerosis (RRMS). To date, there is no uniform agreed-upon definition of PIRA, limiting the comparability of published studies.

Objective

To summarize the current evidence about PIRA based on a systematic review, to discuss the various terminologies used in the context of PIRA, and to propose a harmonized definition for PIRA for use in clinical practice and future trials.

Evidence Review

A literature search was conducted using the search terms multiple sclerosis, PIRA, progression independent of relapse activity, silent progression, and progression unrelated to relapses in PubMed, Embase, Cochrane, and Web of Science, published between January 1990 and December 2022.

Findings

Of 119 identified single records, 48 eligible studies were analyzed. PIRA was reported to occur in roughly 5% of all patients with RRMS per annum, causing at least 50% of all disability accrual events in typical RRMS. The proportion of PIRA vs relapse-associated worsening increased with age, longer disease duration, and, despite lower absolute event numbers, potent suppression of relapses by highly effective disease-modifying therapy. However, different studies used various definitions of PIRA, rendering the comparability of studies difficult.

Conclusion and Relevance

PIRA is the most frequent manifestation of disability accumulation across the full spectrum of traditional MS phenotypes, including clinically isolated syndrome and early RRMS. The harmonized definition suggested here may improve the comparability of results in current and future cohorts and data sets.

Do the current MS clinical course descriptors need to change and if so how? A survey of the MS community

BACKGROUND AND OBJECTIVES

The current clinical course descriptors of multiple sclerosis (MS) include a combination of clinical and magnetic resonance imaging (MRI) features. Recently there has been a growing call to base these descriptors more firmly on biological mechanisms. We investigated the implications of proposing a new mechanism-driven framework for describing MS.

METHODS

In a web-based survey, multiple stakeholders rated the need to change current MS clinical course descriptors, the definitions of disease course and their value in clinical practice and related topics.

RESULTS

We received 502 responses across 49 countries. In all, 77% of the survey respondents supported changing the current MS clinical course descriptors. They preferred a framework that informs treatment decisions, aids the design and conduct of clinical trials, allows patients to understand their disease, and links disease mechanisms and clinical expression of disease. Clinical validation before dissemination and ease of communication to patients were rated as the most important aspects to consider when developing any new framework for describing MS.

CONCLUSION

A majority of MS stakeholders agreed that the current MS clinical course descriptors need to change. Any change process will need to engage a wide range of affected stakeholders and be guided by foundational principles.

Does the Multiple Sclerosis Impact Scale-29 (MSIS-29) have the range to capture the experience of fully ambulatory multiple sclerosis patients? Learnings from the ASCLEPIOS studies

Background

Trials of disease-modifying therapies (DMTs) for multiple sclerosis (MS) often include patients with minimal disability. Patient-reported outcome instruments used in these trials have often not captured physical and psychological treatment effects concomitant with observed clinical benefits.

Objective

To examine whether the Multiple Sclerosis Impact Scale-29 (MSIS-29) captures changes in the impact of MS in a sample of patients enrolled in the Phase 3 ASCLEPIOS studies (ofatumumab vs. teriflunomide).

Methods

Measurement properties (i.e. item fit, reliability, and targeting) of the MSIS-29 were analyzed using Rasch measurement theory (RMT) in data from two phase 3 ofatumumab clinical trials including patients with relapsing-remitting or secondary progressive MS (N = 1882). Targeting of the MSIS-29 items to the patient population was explored within groups categorized by Expanded Disability Status Scale (EDSS) scores.

Results

Under RMT analyses, both the Physical and Psychological Impact scales of the MSIS-29 were not appropriately targeted to the overall sample of patients. In particular, 49% and 30% of patients with an EDSS score ≤ 2.5 had fewer physical and psychological impacts, respectively, than would typically be captured by these MSIS-29 items compared to patients with EDSS scores of ≥ 3.

Conclusion

The MSIS-29 is commonly used to evaluate the patient-reported physical and psychological impact of MS. However, it may be limited in evaluating changes associated with DMTs in patients with minimal disability.

Multiple sclerosis: role of meningeal lymphoid aggregates in progression independent of relapse activity

The emphasis on mechanisms driving multiple sclerosis (MS) symptomatic worsening suggests that we move beyond categorical clinical classifiers such as relapsing-remitting MS (RR-MS) and progressive MS (P-MS). Here, we focus on the clinical phenomenon progression independent of relapse activity (PIRA), which begins early in the disease course. PIRA occurs throughout MS, becoming more phenotypically evident as patients age. The underlying mechanisms for PIRA include chronic-active demyelinating lesions (CALs), subpial cortical demyelination, and nerve fiber injury following demyelination. We propose that much of the tissue injury associated with PIRA is driven by autonomous meningeal lymphoid aggregates, present before disease onset and unresponsive to current therapeutics. Recently, specialized magnetic resonance imaging (MRI) has identified and characterized CALs as paramagnetic rim lesions in humans, enabling novel radiographic-biomarker-clinical correlations to further understand and treat PIRA.