Retinal layer thinning predicts treatment failure in relapsing multiple sclerosis

Evolution of retinal degeneration and prediction of disease activity in relapsing and progressive multiple sclerosis

Retinal optical coherence tomography has been identified as biomarker for disease progression in relapsing-remitting multiple sclerosis (RRMS), while the dynamics of retinal atrophy in progressive MS are less clear. We investigated retinal layer thickness changes in RRMS, primary and secondary progressive MS (PPMS, SPMS), and their prognostic value for disease activity. Here, we analyzed 2651 OCT measurements of 195 RRMS, 87 SPMS, 125 PPMS patients, and 98 controls from five German MS centers after quality control. Peripapillary and macular retinal nerve fiber layer (pRNFL, mRNFL) thickness predicted future relapses in all MS and RRMS patients while mRNFL and ganglion cell-inner plexiform layer (GCIPL) thickness predicted future MRI activity in RRMS (mRNFL, GCIPL) and PPMS (GCIPL). mRNFL thickness predicted future disability progression in PPMS. However, thickness change rates were subject to considerable amounts of measurement variability. In conclusion, retinal degeneration, most pronounced of pRNFL and GCIPL, occurs in all subtypes. Using the current state of technology, longitudinal assessments of retinal thickness may not be suitable on a single patient level.

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.

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

BACKGROUND AND OBJECTIVES

Ganglion cell + inner plexiform layer (GCIPL) thinning, measured by optical coherence tomography (OCT), reflects global neurodegeneration in multiple sclerosis (MS). Atrophy of the inner (INL) and outer nuclear layer (ONL) may also be prominent in progressive MS (PMS). The phase 2, SPRINT-MS trial found reduced brain atrophy with ibudilast therapy in PMS. In this post hoc analysis of the SPRINT-MS trial, we investigate (1) retinal atrophy (2) differences in response by subtype and (3) associations between OCT and MRI measures of neurodegeneration.

METHODS

In the multicenter, double-blind SPRINT-MS trial, participants with secondary progressive MS (SPMS) or primary progressive MS (PPMS) were randomized to ibudilast or placebo. OCT and MRI data were collected every 24 weeks for 96 weeks. Extensive OCT quality control and algorithmic segmentation produced consistent results across Cirrus HD-OCT and Spectralis devices. Primary endpoints were GCIPL, INL, and ONL atrophy, assessed by linear mixed-effects regression. Secondary endpoints were associations of OCT measures, brain parenchymal fraction, and cortical thickness, assessed by partial Pearson correlations.

RESULTS

One hundred thirty-four PPMS and 121 SPMS participants were included. GCIPL atrophy was 79% slower in the ibudilast (-0.07 ± 0.23 µm/y) vs placebo group (-0.32 ± 0.20 µm/y, p = 0.003). This effect predominated in the PPMS cohort (ibudilast: -0.08 ± 0.29 µm/y vs placebo: -0.60 ± 0.29 µm/y, a decrease of 87%, p < 0.001) and was not detected in the SPMS cohort (ibudilast: -0.21 ± 0.28 µm/y vs placebo: -0.14 ± 0.27 µm/y, p = 0.55). GCIPL, INL, and ONL atrophy rates correlated with whole brain atrophy rates across the cohort (r = 0.27, r = 0.26, and r = 0.20, respectively; p < 0.001). Power calculations from these data show future trials of similar size and design have ≥80% power to detect GCIPL atrophy effect sizes of approximately 40%.

DISCUSSION

Ibudilast treatment decreased GCIPL atrophy in PMS, driven by the PPMS cohort, with no effect seen in SPMS. Modulated atrophy of retinal layers may be detectable in sample sizes smaller than the SPRINT-MS trial and correlate with whole brain atrophy in PMS, further highlighting their utility as outcomes in PMS.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that ibudilast reduces composite ganglion cell + inner plexiform layer atrophy, without reduction of inner or outer nuclear layer atrophy, in patients with primary progressive MS but not those with secondary progressive MS.

Emerging imaging and liquid biomarkers in multiple sclerosis

The advent of highly effective disease modifying therapy has transformed the landscape of multiple sclerosis (MS) care over the last two decades. However, there remains a critical, unmet need for sensitive and specific biomarkers to aid in diagnosis, prognosis, treatment monitoring, and the development of new interventions, particularly for people with progressive disease. This review evaluates the current data for several emerging imaging and liquid biomarkers in people with MS. MRI findings such as the central vein sign and paramagnetic rim lesions may improve MS diagnostic accuracy and evaluation of therapy efficacy in progressive disease. Serum and cerebrospinal fluid levels of several neuroglial proteins, such as neurofilament light chain and glial fibrillary acidic protein, show potential to be sensitive biomarkers of pathologic processes such as neuro-axonal injury or glial-inflammation. Additional promising biomarkers, including optical coherence tomography, cytokines and chemokines, microRNAs, and extracellular vesicles/exosomes, are also reviewed, among others. Beyond their potential integration into MS clinical care and interventional trials, several of these biomarkers may be informative of MS pathogenesis and help elucidate novel targets for treatment strategies.

Retinal ganglion cell loss is associated with future disability worsening in early relapsing-remitting multiple sclerosis

BACKGROUND AND PURPOSE

Thinning of the retinal combined ganglion cell and inner plexiform layer (GCIP) as measured by optical coherence tomography (OCT) is a common finding in patients with multiple sclerosis. This study aimed to investigate whether a single retinal OCT analysis allows prediction of future disease activity after a first demyelinating event.

METHODS

This observational cohort study included 201 patients with recently diagnosed clinically isolated syndrome or relapsing-remitting multiple sclerosis from two German tertiary referral centers. Individuals underwent neurological examination, magnetic resonance imaging, and OCT at baseline and at yearly follow-up visits.

RESULTS

Patients were included at a median disease duration of 2.0 months. During a median follow-up of 59 (interquartile range = 43-71) months, 82% of patients had ongoing disease activity as demonstrated by failing the no evidence of disease activity 3 (NEDA-3) criteria, and 19% presented with confirmed disability worsening. A GCIP threshold of ≤77 μm at baseline identified patients with a high risk for NEDA-3 failure (hazard ratio [HR] = 1.7, 95% confidence interval [CI] = 1.1-2.8, p = 0.04), and GCIP measures of ≤69 μm predicted disability worsening (HR = 2.2, 95% CI = 1.2-4.3, p = 0.01). Higher rates of annualized GCIP loss increased the risk for disability worsening (HR = 2.5 per 1 μm/year increase of GCIP loss, p = 0.03).

CONCLUSIONS

Ganglion cell thickness as measured by OCT after the initial manifestation of multiple sclerosis may allow early risk stratification as to future disease activity and progression.

Swept-Source Optical Coherence Tomography Thresholds in Differentiating Clinical Outcomes in a Real-World Cohort of Treatment-Naïve Multiple Sclerosis Patients

This study aimed to determine whether peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell–inner plexiform layer (GCIPL) thickness thresholds for single-time-point swept-source optical coherence tomography (SS-OCT) measures can differentiate the clinical outcomes of treatment-naïve people with multiple sclerosis (pwMS). A total of 275 patients with the clinically isolated syndrome (n = 23), benign MS (n = 8), relapsing–remitting MS (n = 185), secondary progressive MS (n = 28), primary progressive MS (n = 31), and with no history of optic neuritis were included. The mean Expanded Disability Status Scale (EDSS) score was 3.0 ± 1.6. The cut-off values of pRNFL (87 µm and 88 µm) and GCIPL (70 µm) thicknesses have been adopted from previous studies using spectral-domain OCT. PwMS with pRNFL ≤87 µm and ≤88 µm had a longer disease duration, more advanced disability, and more frequently progressive MS variants compared to those with greater pRNFL thicknesses. In distinguishing pwMS with disability greater than or equal to the mean EDSS score (EDSS ≥ 3) from those with less severe disability, GCIPL thickness <70 µm had the highest sensitivity, while pRNFL thickness ≤87 µm had the greatest specificity. The optimal cut-off values differentiating patients with EDSS ≥ 3 from those with less severe disability was 63 µm for GCIPL thickness and 93.5 µm for pRNFL thickness. In conclusion, pRNFL and GCIPL thickness thresholds for single-time-point SS-OCT measurements may be helpful in differentiating the disability status of treatment-naïve pwMS.

Optical coherence tomography (OCT) measurements and cognitive performance in multiple sclerosis: a systematic review and meta-analysis

BACKGROUND

Several studies report mixed associations between the retinal nerve fiber layer (RNFL) thickness with cognitive and physical disability in persons with multiple sclerosis (PwMS). Systematic synthesis of these findings is crucial in deriving credible conclusions.

METHODS

Five databases were searched from their inception to March 2022. The inclusion criteria for studies were MS-specific and required RNFL and cognitive performance data in order to be analyzed. The selection processes followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

The systematic review yielded 31 studies that investigated the association between RNFL thickness and cognitive performance. Twenty-two studies reported positive associations, and nine did not. The meta-analysis included 11 studies with a total of 782 PwMS with mean age of 40.5 years, mean Expanded Disability Status Scale (EDSS) of 2.7, and disease duration of 11.3 years. RNFL thickness was significantly associated Symbol Digit Modalities Test (pooled r = 0.306, p < 0.001), Paced Auditory Serial Addition Test (pooled r = 0.374, p < 0.001) and Word List Generation (WLG, pooled r = 0.177, p < 0.001). RNFL was also significantly correlated with visuospatial learning and memory tests (pooled r = 0.148, p = 0.042) and verbal learning and memory tests (pooled r = 0.245, p = 0.005). Within three eligible studies, no significant association between ganglion cell inner-plexiform layer and SDMT 0.083 (95% CI - 0.186, 0.352) was noted. The heterogeneity was high in all correlation studies (I² > 63% and p < 0.008) except for the WLG and visuospatial memory findings.

CONCLUSION

RNFL thickness is associated with cognitive processing speed, verbal learning and memory, visual learning and memory, as well as verbal fluency in PwMS. The number of studies included in the meta-analyses were limited due to non-standardized reporting.

Association of paramagnetic rim lesions and retinal layer thickness in patients with multiple sclerosis

BACKGROUND

Paramagnetic rim lesions (PRLs) are chronic active lesions associated with a more severe disease course in multiple sclerosis (MS). Retinal layer thinning measured by optical coherence tomography (OCT) is a biomarker of neuroaxonal damage associated with disability progression in MS.

OBJECTIVE

We aimed to determine a potential association between OCT parameters (peripapillary retinal nerve fiber layer (pRNFL) ganglion cell-inner plexiform layer (GCIPL), inner nuclear layer (INL) thickness), and PRLs in patients with MS (pwMS).

METHODS

In this cross-sectional retrospective study, we included pwMS with both 3T brain MRI and an OCT scan. Regression models were calculated with OCT parameters (pRNFL, GCIPL, INL) as dependent variables, and the number of PRLs as an independent variable adjusted for covariates.

RESULTS

We analyzed data from 107 pwMS (mean age 34.7 years (SD 10.9), 64.5% female, median disease duration 6 years (IQR 1-13), median EDSS 1.5 (range 0-6.5)). Higher number of PRLs was associated with lower pRNFL (β = -0.18; 95% CI -0.98, -0.03; p = 0.038) and GCIPL thickness (β = -0.21; 95% CI -0.58, -0.02; p = 0.039).

CONCLUSION

The association between higher number of PRLs and lower pRNFL and GCIPL thicknesses provides additional evidence that pwMS with PRLs are affected by a more pronounced neurodegenerative process.

Optical coherence tomography as a prognostic tool for disability progression in MS: a systematic review

Since multiple sclerosis (MS) is characterized by an unpredictable disease course, accurate prognosis and personalized treatment constitute an important challenge in clinical practice. We performed a qualitative systematic review to assess the predictive value of retinal layer measurement by spectral-domain optical coherence tomography (SD-OCT) in MS patients. Longitudinal MS cohort studies that determined the risk of clinical deterioration based on peripapillary retinal nerve fiber layer (pRNFL) and/or macular ganglion cell-inner plexiform layer (mGCIPL) atrophy were included. Our search strategy and selection process yielded eight articles in total. Of those, five studies only focused on patients with a relapsing-remitting disease pattern (RRMS). After correction for confounders such as disease duration, we found that (1) cross-sectional measurement of pRNFL thickness ≤ 88 µm; (2) cross-sectional measurement of mGCIPL thickness < 77 µm; (3) longitudinal measurement of pRNFL thinning > 1.5 µm/year; and (4) longitudinal measurement of mGCIPL thinning ≥ 1.0 µm/year is associated with an increased risk for disability progression in subsequent years. Longitudinal mGCIPL assessment consistently resulted in the highest risk estimates in our analysis. Within these studies, inclusion and exclusion criteria accounted for the retinal degeneration inherent to (acute) optic neuritis (ON). This small systematic review provides additional evidence that OCT-measured pRNFL and/or mGCIPL atrophy can predict disability progression in RRMS patients. We therefore recommend close clinical follow-up or initiation/change of treatment in RRMS patients with increased risk for clinical deterioration based on retinal layer thresholds, in particular when other poor prognostic signs co-occur.

Optical coherence tomography assessment of axonal and neuronal damage of the retina in patients with familial and sporadic multiple sclerosis

Objective

To assess axonal and neuronal damage of the retina in patients with familial (fMS) and sporadic multiple sclerosis (sMS).

Methods

87 relapsing-remitting MS patients (45 patients with sMS, 42 patients with fMS) and 30 healthy controls were included in the study. Optical coherence tomography (OCT) was performed with the spectral domain optical coherence tomography (SD-OCT, Heidelberg Engineering, Germany). The peripapillary retinal nerve fiber layer (pRNFL) thickness, ganglion cell-inner plexiform layer (GCIPL) thickness, total macular volume (TMV) and the inner nuclear layer (INL) thickness were measured.

Results

A significant reduction of the pRNFL thickness was detected in sMS and fMS compared to the control group (86.29 (+/- 16.13) μm in sMS, 84.78 (+/- 12.92) μm in fMS, 98.93 (+/- 6.71) μm in control group; p < 0.001). There was no significant difference in the pRNFL thickness between sMS and fMS (p = 0.5239). The GCIPL thickness was significantly decreased in sMS and fMS compared to the control group [66.0581 (+/- 11.2674) μm in sMS, 63.8386 (+/-10.004) μm in fMS, 76.5074 (+/- 5.0004) μm in control group; p < 0.001]. A significant reduction of the TMV was shown in sMS and fMS compared to the control group [8.4541(+/- 0.4727) mm3 in sMS, 8.3612 (+/- 0.4448) mm3 in fMS, 8.8387 (+/- 0.314) mm3 in control group; p < 0.0011]. No difference in the GCIPL thickness and TMV between sMS and fMS was found (p = 0.3689 and p = 0.3758, respectively). The INL thickness in sMS and fMS did not differ compared to the control group [34.2323 (+/- 2.7006) μm in sMS, 34.5159 (+/- 2.9780) μm in fMS, 33.6148 (+/- 2.0811) μm in control group; p = 0.5971 and p = 0.1870, respectively] and between the two forms (p = 0.4894).

Conclusion

We confirmed the presence of axonal and neuronal damage of the retina in sMS and fMS. Both forms of MS did not differ significantly from each other with respect to RFNL, GCIPL, MV and INL. ON induced significant reduction of the pRNFL, GCIPL and MV in both groups of pwMS.

Retinal layer thinning as a biomarker of long-term disability progression in multiple sclerosis

BACKGROUND

Peripapillary retinal nerve fibre layer and macular ganglion cell plus inner plexiform layer thinning are markers of neuroaxonal degeneration in multiple sclerosis.

OBJECTIVE

We aimed to investigate the value of peripapillary retinal nerve fibre layer and ganglion cell plus inner plexiform layer thinning for prediction of long-term disability.

METHODS

This is a 6-year prospective longitudinal study on 93 multiple sclerosis patients. Optical coherence tomography scans were performed at baseline, after 1, 2 and 6 years. Primary endpoint was disability progression after 6 years, defined as expanded disability status scale worsening and/or cognitive deterioration. Univariate and multivariate analysis was used to investigate the value of peripapillary retinal nerve fibre layer and ganglion cell plus inner plexiform layer to predict the primary endpoint.

RESULTS

A total of 57 (61.3%) patients had disability worsening, 40 (43.0%) expanded disability status scale worsening and 34 (36.6%) cognitive deterioration. Mean peripapillary retinal nerve fibre layer and ganglion cell plus inner plexiform layer baseline thickness were 93.0 and 75.2 µm, and mean annualised peripapillary retinal nerve fibre layer and ganglion cell plus inner plexiform layer thinning rates over 6 years were 1.3 and 1.6 µm, respectively. Univariate and multivariate analysis revealed lower peripapillary retinal nerve fibre layer and ganglion cell plus inner plexiform layer baseline thickness and higher annualised thinning rates in patients with disability progression after 6 years. Effects were more pronounced for ganglion cell plus inner plexiform layer and expanded disability status scale worsening than for peripapillary retinal nerve fibre layer models and cognitive deterioration.

CONCLUSION

Ganglion cell plus inner plexiform layer and peripapillary retinal nerve fibre layer measurements depict neurodegeneration and predict disability progression in multiple sclerosis.