Serum Neurofilament Light Trajectories and Their Relation to Subclinical Radiological Disease Activity in Relapsing Multiple Sclerosis Patients in the APLIOS Trial.

INTRODUCTION: Several studies have described prognostic value of serum neurofilament light chain (sNfL) at the group level in relapsing multiple sclerosis (RMS) patients. Here, we aimed to explore the temporal association between sNfL and development of subclinical disease activity as assessed by magnetic resonance imaging (MRI) at the group level and evaluate the potential of sNfL as a biomarker for capturing subclinical disease activity in individual RMS patients. METHODS: In the 12-week APLIOS study, patients (N = 284) received subcutaneous ofatumumab 20 mg. Frequent sNfL sampling (14 time points over 12 weeks) and monthly MRI scans enabled key analyses including assessment of the group-level temporal relationship of sNfL levels with on-study subclinical development of gadolinium-enhancing (Gd +)T1 lesions. Prognostic value of baseline sNfL ("high" vs. "low") level for subsequent on-study clinical relapse or Gd + T1 activity was assessed. Individual patient-level development of on-study Gd + T1 lesions was compared across three predictors: baseline Gd + T1 lesion number, baseline sNfL ("high" vs. "low"), and time-matched sNfL. RESULTS: In patients developing Gd + T1 lesions at week 4 (absent at baseline), sNfL levels increased during the month preceding the week-4 MRI scan and then gradually decreased back to baseline. High versus low baseline sNfL conferred increased risk of subsequent on-study clinical relapse or Gd + T1 activity (HR, 2.81; p < 0.0001) in the overall population and, notably, also in the patients without baseline Gd + T1 lesions (HR, 2.48; p = 0.0213). Individual patient trajectories revealed a marked difference in Gd + T1 lesions between patients with the ten highest vs. lowest baseline sNfL levels (119 vs. 19 lesions). Prognostic value of baseline or time-matched sNfL for on-study Gd + T1 lesions was comparable to that of the number of baseline MRI Gd + T1 lesions. CONCLUSIONS: sNfL measurement may have utility in capturing and monitoring subclinical disease activity in RMS patients. sNfL assessments could complement regular MRI scans and may provide an alternative when MRI assessment is not feasible. CLINICALTRIALS: GOV: NCT03560739. CLASSIFICATION OF EVIDENCE: This study provides class I evidence that serum neurofilament light may be used as a biomarker for monitoring subclinical disease activity in relapsing multiple sclerosis patients, as shown by its elevation in the weeks preceding the development of new gadolinium-enhancing T1 lesion activity.

Serum GFAP and NfL Levels Differentiate Subsequent Progression and Disease Activity in Patients With Progressive Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Neurodegeneration and astrocytic activation are pathologic hallmarks of progressive multiple sclerosis (MS) and can be quantified by serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP). We investigated sNfL and sGFAP as tools for stratifying patients with progressive MS based on progression and disease activity status. METHODS: We leveraged our Comprehensive Longitudinal Investigation of MS at the Brigham and Women's Hospital (CLIMB) natural history study, which includes clinical, MRI data and serum samples collected over more than 20 years. We included patients with MS with a confirmed Expanded Disability Status Scale (EDSS) score ≥3 that corresponds with our classifier for patients at high risk of underlying progressive pathology. We analyzed sNfL and sGFAP within 6 months from the confirmed EDSS score ≥3 corresponding with our baseline visit. Patients who further developed 6-month confirmed disability progression (6mCDP) were classified as progressors. We further stratified our patients into active/nonactive based on new brain/spinal cord lesions or relapses in the 2 years before baseline or during follow-up. Statistical analysis on log-transformed sGFAP/sNfL assessed the baseline association with demographic, clinical, and MRI features and associations with future disability. RESULTS: We included 257 patients with MS who had an average EDSS score of 4.0 and a median follow-up after baseline of 7.6 years. sNfL was higher in patients with disease activity in the 2 years before baseline (adjusted ß = 1.21; 95% CI 1.04-1.42; p = 0.016), during the first 2 years of follow-up (adjusted ß = 1.17; 95% CI = 1.01-1.36; p = 0.042). sGFAP was not increased in the presence of disease activity. Higher sGFAP levels, but not sNfL levels, were associated with higher risk of 6mCDP (adjusted hazard ratio [HR] = 1.71; 95% CI = 1.19-2.45; p = 0.004). The association was stronger in patients with low sNfL (adjusted HR = 2.44; 95% CI 1.32-4.52; p = 0.005) and patients who were nonactive in the 2 years prior or after the sample. DISCUSSION: Higher levels of sGFAP correlated with subsequent progression, particularly in nonactive patients, whereas sNfL reflected acute disease activity in patients with MS at high risk of underlying progressive pathology. Thus, sGFAP and sNfL levels may be used to stratify patients with progressive MS for clinical research studies and clinical trials and may inform clinical care.

Prognostic Value of Serum Neurofilament Light Chain for Disease Activity and Worsening in Patients With Relapsing Multiple Sclerosis: Results From the Phase 3 ASCLEPIOS I and II Trials.

Objective: This study aims to confirm the prognostic value of baseline serum neurofilament light chain (sNfL) for on-study disease activity and worsening in patients with relapsing MS (RMS). Background: Previous post-hoc studies suggested that sNfL could be a prognostic biomarker in RMS. In the phase 3 ASCLEPIOS I/II trials in which ofatumumab demonstrated better efficacy outcomes than teriflunomide, treatment with ofatumumab also led to significantly reduced sNfL levels compared to teriflunomide treatment. Design/Methods: In this study, we report protocol-planned analyses from the pooled ASCLEPIOS I/II trials (N=1882). Per protocol, patients were stratified by median baseline sNfL levels (9.3 pg/ml) into high (>median) and low (≤median) categories to prognosticate: annualized rate of new/enlarging T2 (neT2) lesions in year 1 and 2, annualized relapse rate, annual percentage change in whole brain (WB) and regional brain volume [thalamus, white matter (WM), cortical gray matter (cGM)], and disability outcomes. Similar analyses were performed for the recently diagnosed (within 3 years), treatment-naive patients (no prior disease-modifying therapy) subgroup. Results: High versus low sNfL at baseline was prognostic of increased on-study T2 lesion formation at year 1 (relative increase: ofatumumab +158%; teriflunomide +69%, both p<0.001), which persisted in year 2 (+65%, p=0.124; +46%, p=0.003); of higher annual percentage change of WB volume (ofatumumab, -0.32% vs. -0.24%, p=0.044, and teriflunomide, -0.43% vs. -0.29%, p=0.002), thalamic volume (-0.56% vs. -0.31%, p=0.047 and -0.94% vs. -0.49%, p<0.001), and WM volume (-0.30% vs. -0.19%, p=0.083 and -0.38% vs. -0.18%, p=0.003) but not of cGM volume (-0.39% vs. -0.32%, p=0.337 and -0.49% vs. -0.46%, p=0.563). A single sNfL assessment at baseline was not prognostic for on-study relapses or disability worsening. Results were similar in the subgroup of recently diagnosed, treatment-naive patients. Conclusion: This study confirms that baseline sNfL levels are prognostic of future on-study lesion formation and whole brain and regional atrophy in all RMS patients, including recently diagnosed, treatment-naive patients.

Blood Neurofilament Light in Progressive Multiple Sclerosis: Post Hoc Analysis of 2 Randomized Controlled Trials.

BACKGROUND AND OBJECTIVES: To investigate the potential of plasma neurofilament light (pNfL) as a biomarker of disease progression and treatment response in progressive multiple sclerosis (PMS) with and without acute disease activity. METHODS: A post hoc blinded analysis of pNfL levels in 2 placebo-controlled, phase 3 studies in secondary progressive multiple sclerosis (SPMS; EXPAND) and primary progressive multiple sclerosis (PPMS; INFORMS) using siponimod and fingolimod, respectively, as active compounds was performed. pNfL levels were quantified using a single molecule array (Homebrew Simoa) immunoassay from stored ethylenediaminetetraacetic acid (EDTA) plasma samples of all patients who consented for exploratory biomarker analysis in either study; pNfL levels were divided into high (≥30 pg/mL) and low (<30 pg/mL) at baseline. We investigated the association of pNfL levels with disability progression, cognitive decline, and brain atrophy and their sensitivity to indicate treatment response through clinical measures. RESULTS: We analyzed pNfL in 4,185 samples from 1,452 patients with SPMS and 1,172 samples from 378 patients with PPMS. Baseline pNfL levels were higher in SPMS (geomean 32.1 pg/mL) than in PPMS (22.0 pg/mL; p < 0.0001). In both studies, higher baseline pNfL levels were associated with older age, higher Expanded Disability Status Scale score, more Gd+ lesions, and higher T2 lesion load (all p < 0.05). Independent of treatment, high vs low baseline pNfL levels were associated with significantly higher risks of confirmed 3-month (SPMS [32%], hazard ratio [95% CI] 1.32 [1.09-1.61]; PPMS [49%], 1.49 [1.05-2.12]) and 6-month disability progression (SPMS [26%], 1.26 [1.01-1.57]; PPMS [48%], 1.48 [1.01-2.17]), earlier wheelchair dependence (SPMS [50%], 1.50 [0.96-2.34]; PPMS [197%], 2.97 [1.44-6.10]), cognitive decline (SPMS [41%], 1.41 [1.09-1.84]), and higher rates of brain atrophy (mean change at month 24: SPMS, -0.92; PPMS, -1.39). Baseline pNfL levels were associated with future disability progression and the degree of brain atrophy regardless of presence or absence of acute disease activity (gadolinium-enhancing lesions or recent occurrence of relapses before baseline). pNfL levels were lower in patients treated with siponimod or fingolimod vs placebo-treated patients and higher in those having experienced disability progression. DISCUSSION: pNfL was associated with future clinical and radiologic disability progression features at the group level. pNfL was reduced by treatment and may be a meaningful outcome measure in PMS studies. TRIAL REGISTRATION INFORMATION: EXPAND (ClinicalTrials.gov identifier: NCT01665144) and INFORMS (ClinicalTrials.gov identifier: NCT00731692).

Safety of Fingolimod in Patients with Multiple Sclerosis Switched from Natalizumab: Results from TRANSITION-A 2-Year, Multicenter, Observational, Cohort Study.

Multiple sclerosis (MS) patients receiving natalizumab and who are at risk of developing progressive multifocal leukoencephalopathy (PML) often switch to other high-efficacy disease-modifying therapies including fingolimod as a risk mitigation strategy, which could impact treatment safety and effectiveness. The TRANSITION study aimed to evaluate the safety of fingolimod over two years in patients with MS after switching from natalizumab in a real-world setting. The safety and effectiveness were assessed by monitoring serious and other adverse events (SAEs, AEs). We assessed effectiveness by recording relapses, Expanded Disability Status Scale (EDSS) scores, and MRI activity. Of 637 patients enrolled, 505 completed the study (mean age, 42 years). Overall, 72.8% and 12.7% experienced AEs and SAEs respectively. The most common AEs were fatigue, headache, and urinary tract infection; no cases of PML were observed. Fingolimod treatment resulted in low disease activity. Patients with ≤8 weeks washout period had a markedly lower risk of relapses (4.5%) than those with >8 weeks (51.4%). In patients switching from natalizumab to fingolimod, no new safety signals with overall low relapse activity were observed in patients with washout latencies of ≤8 weeks before fingolimod initiation. Fingolimod was found to be safe and effective in patients transitioning from natalizumab.

Serum NfL levels in the first five years predict 10-year thalamic fraction in patients with MS.

BACKGROUND: Serum neurofilament light chain (sNfL) levels are associated with relapses, MRI lesions, and brain volume in multiple sclerosis (MS). OBJECTIVE: To explore the value of early serum neurofilament light (sNfL) measures in prognosticating 10-year regional brain volumes in MS. METHODS: Patients with MS enrolled in the Comprehensive Longitudinal Investigations in MS at Brigham and Women's Hospital (CLIMB) study within five years of disease onset who had annual blood samples from years 1-10 (n = 91) were studied. sNfL was measured with a single molecule array (SIMOA) assay. We quantified global cortical thickness and normalized deep gray matter (DGM) volumes (fractions of the thalamus, caudate, putamen, and globus pallidus) from high-resolution 3 T MRI at 10 years. Correlations between yearly sNfL levels and 10-year MRI outcomes were assessed using linear regression models. RESULTS: sNfL levels from years 1 and 2 were associated with 10-year thalamus fraction. Early sNfL levels were not associated with 10-year putamen, globus pallidus or caudate fractions. At 10 years, cortical thickness was not associated with early sNfL levels, but was weakly correlated with total DGM fraction. CONCLUSIONS: Early sNfL levels correlate with 10-year thalamic volume, supporting its role as a prognostic biomarker in MS.

Long-term prognostic value of longitudinal measurements of blood neurofilament levels.

OBJECTIVE: To assess the long-term prognostic value of an integral of longitudinal measurements of plasma neurofilament light chain levels (NfLlong) over 12 and 24 months vs single neurofilament light chain (NfL) measurements in patients with relapsing-remitting MS (RRMS) and its additional value when combined with clinical and MRI measures. METHODS: This analysis included continuously fingolimod-treated patients with RRMS from the 24-month FTY720 Research Evaluating Effects of Daily Oral therapy in Multiple Sclerosis (FREEDOMS)/12-month Trial Assessing Injectable Interferon vs FTY720 Oral in Relapsing-Remitting Multiple Sclerosis (TRANSFORMS) phase 3 trials and their long-term extension, LONGTERMS. Patients were classified into high (≥30 pg/mL, n = 110) and low (<30 pg/mL, n = 164) NfL categories based on the baseline (BL) NfL value or the geometric mean NfLlong calculated over 12 and 24 months to predict disability-related outcomes and brain volume loss (BVL). The additional prognostic value of NfL was quantified using the area under the receiver operating characteristic (ROC) curve. RESULTS: A single high (vs low) NfL measure at BL was prognostic of a higher risk of reaching Expanded Disability Status Scale (EDSS) score ≥4 earlier (hazard ratio [HR] = 2.19; 95% CI = 1.21-3.97) and higher BVL over 120 months (difference: -1.12%; 95% CI = -2.07 to -0.17). When NfLlong was measured over 24 months, high NfL was associated with a higher risk of reaching EDSS score ≥4 (HR = 7.91; 95% CI = 2.99-20.92), accelerated 6-month confirmed disability worsening (HR = 3.14; 95% CI = 1.38-7.11), and 20% worsening in the Timed 25-Foot Walk Test (HR = 3.05; 95% CI = 1.38-6.70). Area under the ROC curve was consistently highest in models combining NfL with clinical and MRI measures. CONCLUSIONS: NfLlong had a higher prognostic value than single NfL assessments on long-term outcomes in RRMS. Combining it with clinical and MRI measures increased sensitivity and specificity to predict long-term disease outcomes. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that NfLlong was more strongly associated with long-term outcomes than single NfL assessments in patients with RRMS.

Serum neurofilament light chain and optical coherence tomography measures in MS: A longitudinal study.

OBJECTIVE: To study the association between serum neurofilament light chain (sNfL) and multiple optical coherence tomography (OCT) measures in patients with MS and healthy controls (HCs). METHODS: In this prospective study, 110 patients with MS were recruited, together with 52 age- and sex-matched HCs. Clinical evaluation and spectral domain OCT and sNfL were obtained at baseline and after 5.5 years of follow-up. Nested linear mixed models were used to assess differences between MS vs HC and associations between sNfL and OCT measures. Partial correlation coefficients are reported, and p values were adjusted for the false discovery rate. RESULTS: At baseline, peripapillary retinal nerve fiber layer thickness (pRNFLT) and macular ganglion cell and inner plexiform layer thickness (mGCIP) were significantly lower in MS than HC both in MS-associated optic neuritis (MSON) (p = 0.007, p = 0.001) and nonaffected MSON (n-MSON) eyes (p = 0.003, p = 0.018), along with total macular volume (TMV) in n-MSON eyes (p = 0.011). At follow-up, MS showed significantly lower pRNFLT, mGCIP, and TMV both in MSON and n-MSON eyes (p < 0.001) compared with HC. In MS n-MSON eyes, sNfL was significantly associated with baseline pRNFLT and mGCIP (q = 0.019). No significant associations were found in MSON eyes. CONCLUSIONS: This study confirms the ability of sNfL to detect neurodegeneration in MS and advocates for the inclusion of sNfL and OCT measures in clinical trials. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that sNfL levels were associated with MS neurodegeneration measured by OCT.

Serum neurofilament light chain is a useful biomarker in pediatric multiple sclerosis.

OBJECTIVE: To investigate serum neurofilament light chain (sNfL) as a potential biomarker for disease activity and treatment response in pediatric patients with multiple sclerosis (MS). METHODS: In this retrospective cohort study, sNfL levels were measured in a pediatric MS cohort (n = 55, follow-up 12-105 months) and in a non-neurologic pediatric control cohort (n = 301) using a high-sensitivity single-molecule array assay. Association of sNfL levels and treatment and clinical and MRI parameters were calculated. RESULTS: Untreated patients had higher sNfL levels than controls (median 19.0 vs 4.6 pg/mL; CI [4.732, 6.911]), p < 0.001). sNfL levels were significantly associated with MRI activity (+9.1% per contrast-enhancing lesion, CI [1.045, 1.138], p < 0.001; +0.6% per T2-weighted lesion, CI [1.001, 1.010], p = 0.015). Higher values were associated with a relapse <90 days ago (+51.1%; CI [1.184, 1.929], p < 0.001) and a higher Expanded Disability Status Scale score (CI [1.001, 1.240], p = 0.048). In patients treated with interferon beta-1a/b (n = 27), sNfL levels declined from 14.7 to 7.9 pg/mL after 6 ± 2 months (CI [0.339, 0.603], p < 0.001). Patients with insufficient control of clinical or MRI disease activity under treatment with interferon beta-1a/b or glatiramer acetate who switched to fingolimod (n = 18) showed a reduction of sNfL levels from 16.5 to 10.0 pg/mL 6 ± 2 months after switch (CI [0.481, 0.701], p < 0.001). CONCLUSIONS: sNfL is a useful biomarker for monitoring disease activity and treatment response in pediatric MS. It is most likely helpful to predict disease severity and to guide treatment decisions in patients with pediatric MS. This study provides Class III evidence that sNfL levels are associated with disease activity in pediatric MS.

Serum neurofilament light chain level associations with clinical and cognitive performance in multiple sclerosis: A longitudinal retrospective 5-year study.

BACKGROUND: A limited number of studies investigated associations between serum neurofilament light chain (sNfL) and cognition in persons with multiple sclerosis (PwMS). OBJECTIVE: To assess cross-sectional and longitudinal associations between sNfL levels, clinical, and cognitive performance in PwMS and age-matched healthy controls (HCs). MATERIALS: One hundred twenty-seven PwMS (85 relapsing-remitting MS/42 progressive MS), 20 clinically isolated syndrome patients, and 52 HCs were followed for 5 years. sNfL levels were measured using the single-molecule array (Simoa) assay and quantified in picograms per milliliter. Expanded Disability Status Scale (EDSS), walking, and manual dexterity tests were obtained. At follow-up, Brief International Cognitive Assessment for MS (BICAMS) was utilized. Cognitively impaired (CI) status was derived using HC-based z-scores. Age-, sex-, and education-adjusted analysis of covariance (ANCOVA) and regression models were used. Multiple comparison-adjusted values of q < 0.05 were considered significant. RESULTS: In PwMS, sNfL levels were cross-sectionally associated with walking speed (r = 0.235, q = 0.036), manual dexterity (r = 0.337, q = 0.002), and cognitive processing speed (CPS; r =-0.265, q = 0.012). Baseline sNfL levels predicted 5-year EDSS scores (r = 0.25, q = 0.012), dexterity (r = 0.224, q = 0.033), and CPS (r =-0.205, q = 0.049). CI patients had higher sNfL levels (27.2 vs. 20.6, p = 0.016) and greater absolute longitudinal sNfL increase when compared with non-CI patients (4.8 vs. 0.7, p = 0.04). CONCLUSION: Higher sNfL levels are associated with poorer current and future clinical and cognitive performance.

A multimodal approach to assess the validity of atrophied T2-lesion volume as an MRI marker of disease progression in multiple sclerosis.

BACKGROUND: Atrophied T2-lesion volume (LV) is a novel MRI marker representing brain-lesion loss due to atrophy, able to predict long-term disability progression and conversion to secondary-progressive multiple sclerosis (MS). OBJECTIVE: To better characterize atrophied T2-LV via comparison with other multidisciplinary markers of MS progression. METHODS: We studied 127 MS patients (85 relapsing-remitting, RRMS and 42 progressive, PMS) and 20 clinically isolated syndrome (CIS) utilizing MRI, optical coherence tomography, and serum neurofilament light chain (sNfL) at baseline and at 5-year follow-up. Symbol Digit Modalities Test (SDMT) was obtained at follow-up. Atrophied T2-LV was calculated by combining baseline lesion masks with follow-up CSF partial-volume maps. Measures were compared between MS patients who developed or not disease progression (DP). Partial correlations between atrophied T2-LV and other biomarkers were performed, and corrected for multiple comparisons. RESULTS: Atrophied T2-LV was the only biomarker that significantly differentiated DP from non-DP patients over the follow-up (p = 0.007). In both DP and non-DP groups, atrophied T2-LV was associated with baseline T2-LV and T1-LV (both p = 0.003), absolute change of T1-LV (DP p = 0.038; non-DP p = 0.003) and percentage of brain volume change (both p = 0.003). Furthermore, in the DP group, atrophied T2-LV was related to baseline brain parenchymal (p = 0.017) and thalamic (p = 0.003) volumes, thalamic volume change and follow-up SDMT (both p = 0.003). In non-DP patients, atrophied T2-LV was significantly related to baseline sNfL (p = 0.008), contrast-enhancing LV (p = 0.02) and percentage ventricular volume change (p = 0.003). CONCLUSION: Atrophied T2-LV is associated with disability accrual in MS, and to several multimodal markers of disease evolution.

Serum neurofilament light chain levels associations with gray matter pathology: a 5-year longitudinal study.

BACKGROUND: Gray matter (GM) pathology is closely associated with physical and cognitive impairment in persons with multiple sclerosis (PwMS). Similarly, serum neurofilament light chain (sNfL) levels are related to MS disease activity and progression. OBJECTIVES: To assess the cross-sectional and longitudinal associations between sNfL and MRI-derived lesion and brain volume outcomes in PwMS and age-matched healthy controls (HCs). MATERIALS AND METHODS: Forty-seven HCs and 120 PwMS were followed over 5 years. All subjects underwent baseline and follow-up 3T MRI and sNfL examinations. Lesion volumes (LV) and global, tissue-specific and regional brain volumes were assessed. sNfL levels were analyzed using single molecule array (Simoa) assay and quantified in pg/mL. The associations between sNfL levels and MRI outcomes were investigated using regression analyses adjusted for age, sex, baseline disease modifying treatment (DMT) use and change in DMT over the follow-up. False discovery rate (FDR)-adjusted q-values <0.05 were considered significant. RESULTS: In PwMS, baseline sNfL was associated with baseline T1 -, T2 - and gadolinium-LV (q = 0.002, q = 0.001 and q < 0.001, respectively), but not with their longitudinal changes. Higher baseline sNfL levels were associated with lower baseline deep GM (ß = -0.257, q = 0.017), thalamus (ß = -0.216, q = 0.0017), caudate (ß = -0.263, q = 0.014) and hippocampus (ß = -0.267, q = 0.015) volumes. Baseline sNfL was associated with longitudinal decline of deep GM (ß = -0.386, q < 0.001), putamen (ß = -0.395, q < 0.001), whole brain (ß = -0.356, q = 0.002), thalamus (ß = -0.272, q = 0.049), globus pallidus (ß = -0.284, q = 0.017), and GM (ß = -0.264, q = 0.042) volumes. No associations between sNfL and MRI-derived measures were seen in the HCs. CONCLUSION: Higher sNfL levels were associated with baseline LVs and greater development of GM atrophy in PwMS.

Blood neurofilament light as a potential endpoint in Phase 2 studies in MS.

OBJECTIVES: To assess whether neurofilament light chain (NfL) could serve as an informative endpoint in Phase 2 studies in patients with relapsing-remitting multiple sclerosis (RRMS) and estimate the sample size requirements with NfL as the primary endpoint. METHODS: Using data from the Phase 3 FREEDOMS study, we evaluated correlation of NfL at Month 6 with 2-year outcomes: relapses, confirmed disability worsening (CDW), new or enlarging T2 lesions (active lesions), and brain volume loss (BVL). We compared the proportion of treatment effect (PTE) on 2-year relapses and BVL explained by 6-month log-transformed NfL levels with the PTE explained by the number of active lesions over 6 months. We estimated sample size requirements for different treatment effects. RESULTS: At Month 6, blood NfL levels (pg/mL, median [range]) were lower in the fingolimod arm (fingolimod (n = 132) 18 [8-247]; placebo (n = 114) 26 [8-159], P < 0.001). NfL at 6 months correlated with number of relapses (r = 0.25, P < 0.001), 6-month CDW (hazard ratio 1.83, P = 0.012), active lesions (r = 0.46, P < 0.001), and BVL (r = -0.41, P < 0.001) at Month-24. The PTE (95% CI) on 24-month relapses and BVL explained by 6-month NfL was 25% (8-60%) and 60% (32-132%), and by 6-month active lesions was 28% (11-66%) and 45% (18-115%), respectively. Assuming a 20-40% treatment-related reduction in NfL levels, 143-28 patients per arm will be required. CONCLUSIONS: Blood NfL may qualify as an informative and easy-to-measure endpoint for future Phase 2 clinical studies that captures both inflammatory- and noninflammatory-driven neuroaxonal injury in RRMS.

Blood neurofilament light chain as a biomarker of MS disease activity and treatment response.

OBJECTIVE: To assess the value of blood neurofilament light chain (NfL) as a biomarker of recent, ongoing, and future disease activity and tissue damage and its utility to monitor treatment response in relapsing-remitting multiple sclerosis. METHODS: We measured NfL in blood samples from 589 patients with relapsing-remitting multiple sclerosis (from phase 3 studies of fingolimod vs placebo, FREEDOMS and interferon [IFN]-ß-1a, TRANSFORMS) and 35 healthy controls and compared NfL levels with clinical and MRI-related outcomes. RESULTS: At baseline, NfL levels (pg/mL) were higher in patients than in healthy controls (30.5 and 27.0 vs 16.9, p = 0.0001) and correlated with T2 lesion load and number of gadolinium-enhancing T1 lesions (p < 0.0001, both). Baseline NfL levels, treatment, and number of new or enlarging T2 lesions during the studies predicted NfL levels at the end of study (all p < 0.01). High vs low baseline NfL levels were associated (estimate [95% confidence interval]) with an increased number of new or enlarging T2 lesions (ratio of mean: 2.64 [1.51-4.60]; p = 0.0006), relapses (rate ratio: 2.53 [1.67-3.83]; p < 0.0001), brain volume loss (difference in means: -0.78% [-1.02 to -0.54]; p < 0.0001), and risk of confirmed disability worsening (hazard ratio: 1.94 [0.97-3.87]; p = 0.0605). Fingolimod significantly reduced NfL levels already at 6 months (vs placebo 0.73 [0.656-0.813] and IFN 0.789 [0.704-0.884]), which was sustained until the end of the studies (vs placebo 0.628 [0.552-0.714] and IFN 0.794 [0.705-0.894]; p < 0.001, both studies at all assessments). CONCLUSIONS: Blood NfL levels are associated with clinical and MRI-related measures of disease activity and neuroaxonal damage and have prognostic value. Our results support the utility of blood NfL as an easily accessible biomarker of disease evolution and treatment response.

Neurofilament light chain serum levels correlate with 10-year MRI outcomes in multiple sclerosis.

OBJECTIVE: To assess the value of annual serum neurofilament light (NfL) measures in predicting 10-year clinical and MRI outcomes in multiple sclerosis (MS). METHODS: We identified patients in our center's Comprehensive Longitudinal Investigations in MS at Brigham and Women's Hospital (CLIMB) study enrolled within 5 years of disease onset, and with annual blood samples up to 10 years (n = 122). Serum NfL was measured using a single molecule array (SIMOA) assay. An automated pipeline quantified brain T2 hyperintense lesion volume (T2LV) and brain parenchymal fraction (BPF) from year 10 high-resolution 3T MRI scans. Correlations between averaged annual NfL and 10-year clinical/MRI outcomes were assessed using Spearman's correlation, univariate, and multivariate linear regression models. RESULTS: Averaged annual NfL values were negatively associated with year 10 BPF, which included averaged year 1-5 NfL values (unadjusted P < 0.01; adjusted analysis P < 0.01), and averaged values through year 10. Linear regression analyses of averaged annual NfL values showed multiple associations with T2LV, specifically averaged year 1-5 NfL (unadjusted P < 0.01; adjusted analysis P < 0.01). Approximately 15-20% of the BPF variance and T2LV could be predicted from early averaged annual NfL levels. Also, averaged annual NfL levels with fatigue score worsening between years 1 and 10 showed statistically significant associations. However, averaged NfL measurements were not associated with year 10 EDSS, SDMT or T25FW in this cohort. INTERPRETATION: Serum NfL measured during the first few years after the clinical onset of MS contributed to the prediction of 10-year MRI brain lesion load and atrophy.

Perspectives on Subcutaneous Route of Administration as an Immunogenicity Risk Factor for Therapeutic Proteins.

An increasing number of therapeutic proteins are being developed for delivery through the subcutaneous (SC) route of administration. Relative to intravenous (IV) administration, the SC route offers more convenience to patients, flexibility in dosing, and potential to reduce health care costs. There is a perception that SC administration can pose a higher immunogenicity risk than IV administration for a given protein. To evaluate whether there is a difference in therapeutic protein immunogenicity associated with administration routes, a more detailed understanding of the interactions with the immune system by each route is needed. Few approved therapeutic proteins have available clinical immunogenicity data sets in the public domain that represent both IV and SC administration routes. This has prevented a direct comparison of the 2 routes of administration across a large sample size. Of the 6 marketed products where SC and IV route-related incidences of anti-drug antibody (ADA) were available, 4 were associated with higher immunogenicity incidence with SC. In other cases, there was no apparent difference between the SC and IV routes. Overall, the ADA incidence was low (<15%) with no impact on safety or efficacy. The challenges associated with identifying specific risk factors unique to SC administration are discussed.

The effects of intrathecal rituximab on biomarkers in multiple sclerosis.

OBJECTIVES: Clinical trials of IV-rituximab have proved successful. It is unclear whether intrathecal (IT)-rituximab is more efficacious at lower doses. We examine its effects on B-cell biomarkers. METHODS: MS patients received IT-rituximab at 3 time-points. CSF and serum samples were obtained at up to 5 time-points (days 0, 7, 14, 56 and 112). Serum and CSF BAFF and CXCL13, and CSF kappa and lambda free light chains (FLC) were measured. Flow cytometry was performed, examining effects on lymphocytes, CD3-19+ and CD3-20+ cells. RESULTS: CSF BAFF fell following rituximab (p=0.0091 absolute values, p=0.0284 change from baseline) whilst serum BAFF increased across time-points 1-4 (p=0.0005 absolute values, p=0.0017 change from baseline). There were significant reductions in CD20+ and CD19+ cells in blood from baseline (p<0.0001) but not in CSF. CSF kappa FLC levels significantly increased (p=0.0480). CONCLUSIONS: BAFF levels fall in CSF but increase in serum following IT-rituximab. Rituximab appears to act peripherally with dramatic decreases in peripheral CD20+ and CD19+ cells. It is likely that CSF B-cell counts were too low to enable differences to be seen. The rapid reduction in B-cells suggests rituximab has immediate effects. The profound depletion of B-cells, despite low doses of rituximab, underlines rituximab's efficacy.

T-cell dependent immunogenicity of protein therapeutics: Preclinical assessment and mitigation.

Protein therapeutics hold a prominent and rapidly expanding place among medicinal products. Purified blood products, recombinant cytokines, growth factors, enzyme replacement factors, monoclonal antibodies, fusion proteins, and chimeric fusion proteins are all examples of therapeutic proteins that have been developed in the past few decades and approved for use in the treatment of human disease. Despite early belief that the fully human nature of these proteins would represent a significant advantage, adverse effects associated with immune responses to some biologic therapies have become a topic of some concern. As a result, drug developers are devising strategies to assess immune responses to protein therapeutics during both the preclinical and the clinical phases of development. While there are many factors that contribute to protein immunogenicity, T cell- (thymus-) dependent (Td) responses appear to play a critical role in the development of antibody responses to biologic therapeutics. A range of methodologies to predict and measure Td immune responses to protein drugs has been developed. This review will focus on the Td contribution to immunogenicity, summarizing current approaches for the prediction and measurement of T cell-dependent immune responses to protein biologics, discussing the advantages and limitations of these technologies, and suggesting a practical approach for assessing and mitigating Td immunogenicity.