Extended interval dosing of natalizumab: a two-center, 7-year experience

Low natalizumab trough concentrations are associated with reduced seroconversion of the John Cunningham virus in natalizumab-treated patients with multiple sclerosis

BACKGROUND

Natalizumab is a highly effective drug for patients with relapsing-remitting multiple sclerosis (MS). A disadvantage of this treatment is the risk of progressive multifocal leukoencephalopathy in patients who are seropositive for the John Cunningham virus (JCV). JCV seroconversion rates increase under natalizumab treatment compared with non-natalizumab using controls. The aim of this study was to assess whether lower natalizumab trough concentrations are associated with reduced JCV seroconversion compared with higher natalizumab trough concentrations.

METHODS

Two overlapping cohorts of patients treated with intravenous natalizumab in the Netherlands were combined for this study. JCV seroconversion was assessed during periods of high (≥15 µg/mL) and low (<15 µg/mL) natalizumab trough concentrations. Low trough concentrations were mainly the result of trough concentration guided personalised extended interval dosing (EID). The seroconversion rates during high and low trough concentrations were compared using a generalised linear mixed model with a Poisson link function.

RESULTS

A total of 357 patients from 21 hospitals in the Netherlands were included. The annual seroconversion rate of 8.4% observed in patients during periods of high trough concentrations (n=226) was 2.32 times higher than the seroconversion rate of 4.8% in patients during periods of low trough concentrations (n=252) (95% CI=1.32 to 4.08, p=0.0035).

CONCLUSIONS

The seroconversion rate observed in patients with MS with low trough concentrations was substantially lower compared with those with high trough concentrations during natalizumab treatment. This emphasises the importance of personalised EID, where intervals between infusions are prolonged to achieve lower natalizumab trough concentrations, to increase drug safety.

Pharmacokinetic Model-Informed Precision Dosing of Natalizumab in Multiple Sclerosis

Intravenous natalizumab is an effective treatment for relapsing-remitting multiple sclerosis. However, the standard treatment interval of 4 weeks may be excessive for many patients. Personalized interval extension using therapeutic drug monitoring (TDM) can result in adequate drug exposure while reducing hospital visits and healthcare costs. Here, we investigate to which extent TDM-guided personalized dosing can benefit from model-informed precision dosing (MIPD). Individual posterior PK estimates were derived using patient weight and two trough concentrations at the standard dose interval by Bayesian estimation using a newly developed population PK model. MIPD was compared to a previously deployed TDM-guided stratified personalized dosing protocol (SPD) using a decision tree to personalize dosing intervals. Accuracy (mean prediction error) of the predicted dosing intervals was 4.8% versus 24% for model-informed estimates versus decision tree, respectively, when aiming for a 10 μg/mL trough concentration, and 4.8% versus 86% when aiming for 5 μg/mL. Corresponding precision (root mean square error) was 2.3 versus 4.0, and 1.5 versus 5 μg/mL. Finally, we evaluated the feasibility of a MIPD approach to attain a therapeutic trough of 2 μg/mL. Simulating MIPD showed a reduction in the average infusions versus the standard interval by 40%, with an average dose interval of 7 weeks, while maintaining adequate drug exposure. MIPD was concluded to be superior to the conventional TDM-guided personalized dosing approach in terms of enhanced precision in individual dose interval selection, enabling more efficient interval extensions. Simulations supported the clinical deployment of natalizumab MIPD.

Effectiveness of 6-week dosing of Natalizumab versus continued 4-week treatment for Multiple Sclerosis: An observational registry-based study

BACKGROUND

Multiple sclerosis (MS) impacts quality of life. Every-4-week (Q4W) regimen of natalizumab (NTZ) is approved for relapsing-remitting multiple sclerosis (RRMS) but increases progressive multifocal leukoencephalopathy (PML) risk. This study aimed to assess the impact of switching to an every-6-week (Q6W) dosing of NTZ in RRMS patients previously treated with Q4W dosing for ≥12 months.

METHODS

This observational, registry-based, two-armed, retrospective comparative study included 243 patients (69 males and 174 females; mean age=35.7 ± 8.8 years) from the Kuwait National Registry between January 2018 and June 2023. All patients initially received NTZ Q4W. After one-year, 202 patients were switched to Q6W, while 41 remained on Q4W. Outcome parameters included patients free from clinical relapse, annualized relapse rate (ARR), expanded disability status scale (EDSS), confirmed disability worsening (CDW), no evidence of disease activity (NEDA), magnetic resonance imaging findings, and adverse events (AE). Kaplan-Meier survival curves depicted clinical endpoints for both groups.

RESULTS

Relapse proportion, ARR, EDSS, and new/enlarged T2 and gadolinium lesions significantly reduced after initiating NTZ (p < 0.05). CDW occurred in 7.4 % of patients and NEDA in 86.2 %. No significant difference (p > 0.05) was observed between the Q4W and Q6W groups for any parameters. AEs were reported in 13 patients (p = 0.88). Kaplan-Meier analysis demonstrated no significant difference (p > 0.05) in the mean survival times without relapse, AEs, new T2 lesions, and without disability progression between groups.

CONCLUSION

Both Q4W and Q6W NTZ regimens provided comparable safety and effectiveness in RRMS patients, effectively preventing relapses, AEs, disability progression, and occurrence of enlarged/new T2 lesions. In addition, no patient developed PML.

Analysis of serum natalizumab concentrations obtained during routine clinical care in patients with multiple sclerosis: A cross-sectional study

BACKGROUND

Natalizumab is a humanized monoclonal antibody administered at a fixed dose of 300 mg intravenously or subcutaneously every 4-6 weeks to treat relapsing-remitting multiple sclerosis. In this prospective cross-sectional study, natalizumab serum concentrations obtained during routine healthcare were measured, and the relationships between different routes of administration, sampling times, body characteristics, changes in blood count, and presence of anti-natalizumab antibodies were evaluated.

METHODS

Ninety-two patients were included in this study. Blood samples were collected 0-48 days after administration, and natalizumab serum and anti-natalizumab antibody concentrations, as well as blood counts were measured. Subsequently, patients were divided into three groups according to the collection time after natalizumab administration.

RESULTS

During the entire monitored period, serum natalizumab concentrations ranged from 1.8 to 193.3 µg/mL and 1.8 to 100.3 µg/mL after intravenous and subcutaneous administrations, respectively. A significant inverse correlation was found between serum natalizumab concentrations and differential and absolute peripheral blood neutrophil counts, erythrocyte counts, and hemoglobin concentrations.

CONCLUSION

Although all patients were treated with the same dose, a 30-fold difference in serum natalizumab concentrations was observed. This wide inter-individual variability can potentially lead to an increased risk of natalizumab adverse events or, conversely, suboptimal therapeutic concentrations with the risk of further worsening of multiple sclerosis.

Improvement of fatigue, depression, and processing speed two weeks post Natalizumab infusion in Multiple Sclerosis: No difference between standard and extended interval dosing schedules

BACKGROUND

Fatigue, depression and slow processing speed are debilitating symptoms in people with Relapsing-Remitting Multiple Sclerosis (RRMS) that significantly impacts on the quality of life. Natalizumab, a disease-modifying treatment, improves clinical symptoms but questions remain about the comparative efficacy between its standard interval dosing (SID) and extended interval dosing (EID) schedules.

OBJECTIVE

To examine the impact of short term natalizumab dosing schedules-SID versus EID-on the so called "invisible symptoms", specifically focusing on symptom exacerbation during the 'wearing-off' phase before infusion and the subsequent relief post-infusion.

METHODS

Forty-two RRMS patients were assessed one week before (T0) and two weeks after pre-and post-natalizumab infusion (T1) for fatigue symptoms using the Fatigue Scale for Motor and Cognitive Functions (FSMC), the Modified Fatigue Impact Scale (MFIS), and the Fatigue Symptoms and Impacts Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS). Processing speed and depression were measured by the symbol digit modality test (SDMT), and the Beck Depression Inventory-II (BDI-II). Participants were categorized into either the SID or EID dosing schedules of natalizumab, and their outcomes were compared.

RESULTS

Forty-two patients (21 SID; 21 EID) completed the study. Fatigue severity scales, SDMT, and BDI-II scores improved from T0 to T1. No significant differences in fatigue symptoms were found between the SID and EID groups, whether during the "wearing-off" period (T0) or post-infusion (T1).

CONCLUSIONS

Both SID and EID dosing regimens of natalizumab are similarly effective in reducing fatigue symptoms, depression and improving processing speed in individuals with RRMS, with no observed differences during the "wearing-off" periods or after re-infusion.

Pharmacokinetics and Pharmacodynamics of Natalizumab 6-Week Dosing vs Continued 4-Week Dosing for Relapsing-Remitting Multiple Sclerosis

BACKGROUND AND OBJECTIVES

Exposure to natalizumab, an efficacious treatment for relapsing-remitting multiple sclerosis (RRMS), is associated with increased risk of progressive multifocal leukoencephalopathy (PML). Compared with every-4-week (Q4W) dosing, extended-interval dosing of natalizumab is associated with decreased risk of PML. Clinical efficacy was maintained in the majority of patients switched to every-6-week (Q6W) dosing in the phase 3b NOVA clinical trial. In this article, we report pharmacokinetics (PK) and pharmacodynamics (PD) of Q6W vs Q4W dosing in NOVA.

METHODS

In NOVA study Part 1, participants with RRMS (aged 18-60 years) and Expanded Disability Status Scale score <5.5, who were stable on IV natalizumab Q4W dosing for ≥12 months, were randomized to continue IV Q4W dosing or switched to IV Q6W dosing of natalizumab and followed for 72 weeks. Exploratory outcomes were measurements of trough serum natalizumab concentration, α4-integrin saturation, and soluble vascular cell adhesion molecule-1 (sVCAM-1) concentration. A mixed model of repeated measures was used to estimate mean treatment differences between groups. Patient-level PK and PD data were examined in those with relapse or radiologic disease activity.

RESULTS

In NOVA, 486 (Q6W, n = 245; Q4W, n = 241) and 487 (Q6W, n = 246; Q4W, n = 241) participants were included in the PK and PD populations, respectively. Mean trough natalizumab concentrations ranged from 10 to 21 μg/mL (Q6W) and 33-38 μg/mL (Q4W), and mean α4-integrin saturation remained above 65.5% (Q6W) and above 77.9% (Q4W). In the Q6W group, mean sVCAM-1 levels increased 23.6% by week 24 and remained elevated throughout the study, while mean sVCAM-1 levels remained generally stable in the Q4W group. Most participants with T2 lesion activity or relapse activity, in either treatment arm, maintained trough natalizumab levels >10 μg/mL and trough α4-integrin saturation >50%.

DISCUSSION

Compared with Q4W dosing, Q6W dosing was associated with a 60%-70% decrease in mean trough natalizumab levels and a 9%-16% decrease in mean α4-integrin saturation. At the patient level, neither natalizumab concentration nor α4-integrin saturation was consistently predictive of lesion or relapse activity, suggesting that trough natalizumab and α4-integrin saturation measurements should be interpreted with caution in clinical practice.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov, NCT03689972; EudraCT, 2018-002145-11. Submitted 2018-09-27. First patient enrolled: 2018-12-26. https://clinicaltrials.gov/study/NCT03689972.

MS treatment de-escalation: review and commentary

Almost all currently licensed disease-modifying therapies (DMTs) for MS treatment require prolonged if not lifelong administration. Yet, as people age, the immune system has increasingly reduced responsiveness, known as immunosenescence. Many MS DMTs reduce the responsiveness of the immune system, increasing the risks for infections and possibly cancers. As people with MS (pwMS) age, it is recognized that inflammatory MS activity declines. Several studies have addressed de-escalation of DMTs for relapsing MS under special circumstances. Here, we review evidence for de-escalating DMTs as a strategy that is particularly relevant to pwMS of older age. Treatment de-escalation can involve various strategies, such as extended or reduced dosing, switching from high-efficacy DMTs having higher risks to moderately effective DMTs with lesser risks, or treatment discontinuation. Studies have suggested that for natalizumab extended dosing maintained clinical efficacy while reducing the risk of PML. Extended interval dosing of ocrelizumab mitigated the decline of Ig levels. Retrospective and observational discontinuation studies demonstrate that age is an essential modifier of drug efficacy. Discontinuation of MS treatment in older patients has been associated with a stable disease course, while younger patients who discontinued treatment were more likely to experience new clinical activity. A recently completed 2-year randomized-controlled discontinuation study in 260 stable pwMS > 55 years found stable clinical multiple sclerosis with only a small increased risk of new MRI activity upon discontinuation. DMT de-escalation or discontinuation in MS patients older than 55 years may be non-inferior to continued treatment with immunosuppressive agents having higher health risks. However, despite several small studies, a definite conclusion about treatment de-escalation in older pwMS will require larger and longer studies. Ideally, comparison of de-escalation versus continuation versus discontinuation of DMTs should be done by prospective randomized-controlled trials enrolling sufficient numbers of subjects to allow comparisons for MS patients of both sexes within age groups, such as 55-59, 60-65, 66-69, etc. Optimally, such studies should be 3 years or longer and should incorporate testing for specific markers of immunosenescence (such as T-cell receptor excision circles) to account for differential aging of individuals.

Prospective trial of natalizumab personalised extended interval dosing by therapeutic drug monitoring in relapsing-remitting multiple sclerosis (NEXT-MS)

BACKGROUND

Extended interval dosing (EID) of natalizumab is a promising strategy to optimise treatment in multiple sclerosis (MS). Personalised EID by therapeutic drug monitoring can enable further extension of treatment intervals.

METHODS

The NEXT-MS trial is an investigator-initiated prospective phase IV non-randomised study. Adults with a diagnosis of relapsing-remitting MS who received ≥6 natalizumab infusions were included in three groups: personalised EID with a target drug trough concentration of 10 µg/mL (EID10), an exploratory group of personalised EID with a target of 5 µg/mL (EID5) and standard interval dosing (SID) of 4 weeks. The primary outcome is radiological disease activity (new/newly enlarged T2 lesions) comparing the EID10 group to a historical cohort of SID (HSID).

RESULTS

Results of the first phase of the NEXT-MS trial are reported here (n=376) as the study will continue with an amended protocol. In the EID10 group (n=251), incidence rate of radiological activity was 10.0 per 1000 person-years, which was non-inferior to the HSID cohort (24.7 per 1000 person-years (n=87), incidence rate difference 14.7, 90% CI -4.5 to 34.0). Incidence rate of radiological activity was 10.0 per 1000 person-years in the EID5 group (n=65), and 47.0 per 1000 person-years in the SID group (n=60). Serum neurofilament light levels did not increase over time within the EID groups. There were no cases of progressive multifocal leukoencephalopathy.

CONCLUSIONS

MS disease activity is adequately controlled with personalised natalizumab EID. Interval extension to a drug trough concentration of 5 µg/mL is likely a safe target to extend natalizumab treatment intervals >6 weeks.

TRIAL REGISTRATION NUMBER

NCT04225312.

Safety and efficacy of extended versus standard interval dosing of natalizumab in multiple sclerosis patients: a systematic review and meta-analysis

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory, immune-mediated disease affecting the central nervous system. Natalizumab, an FDA-approved monoclonal antibody for MS, has been explored for its off-label extended interval dosing (EID), suggesting a potential reduction in the risk of progressive multifocal leukoencephalopathy (PML) compared to standard interval dosing (SID). Our objective was to assess the efficacy and safety of EID in comparison to SID for natalizumab treatment in patients with MS.

METHODS

We searched PubMed, Embase, WOS, Scopus, Ovid, Science Direct, Clinical trials.gov, and Cochrane Library. Our assessed outcomes were clinical relapses, MRI activity, change in expanded disability status scale [EDSS], and the risk of PML. The EID group was defined as 5 to 8 weeks [EID (Q5-8W)]. The analysis was conducted using RevMan ver. 5.4. The effect estimates were presented as a risk ratio [RR] or mean difference with 95% confidence intervals [CI] using SID group as the reference for comparisons.

RESULTS

Fourteen studies met our inclusion criteria: 2 RCTs, 1 switched single-arm trial, and 12 observational studies. No significant differences were found in all efficacy outcomes of interest. Risk of clinical relapses [RR = 0.90, (95%CI 0.80, 1.02)], risk of new or newly enlarging T2 hyperintense MRI lesions [RR = 0.78, (95%CI 0.59, 1.04)], risk gadolinium enhancing lesions [RR = 1.30, (95%CI 0.98, 1.72)], change in EDSS [MD = 0.09 (95%CI - 0.57, 0.76)], risk of PML [RR = 1.09, 95%CI (0.24, 4.94)].

CONCLUSION

In summary, our meta-analysis indicates that natalizumab maintains its effectiveness under extended interval dosing [up to 8 weeks], presenting comparable risks for clinical relapses, MRI lesions, EDSS, and PML. Caution is advised given study limitations and heterogeneity. Robust conclusions necessitate well-designed high-quality prospective studies.

Treatment modifiers across different regimens of natalizumab treatment in MS: An Italian real-world experience

Despite its widespread use in clinical practice, the effectiveness of natalizumab extended interval dosing (EID) adopted from treatment start across different treatment intervals and individual modifiers (body mass index - BMI) is still under-investigated. Here, seven-hundred and forty-five multiple sclerosis (MS) patients, exposed to natalizumab for 3.30 ​± ​1.34 years, were retrospectively enrolled in an observational multicenter study. After stratifying patients in EID or standard interval dosing (SID), we assessed differences in time to relapse, MRI activity and Expanded Disability Status Scale (EDSS) progression. The primary analysis was conducted on patients exposed to EID interval from 5 weeks and 1 day to 7 weeks, while a secondary analysis included also EID periods up to 8 weeks. An additional analysis explored the impact of BMI. No differences in time to first relapse, time to radiological activity, time to EDSS progression or time to EDA (evidence of disease activity) were detected between SID and EID group (EID interval from 5 weeks to 1 day to 7 weeks). When including EID periods from 7 weeks and 1 day to 8 weeks, the EID group showed a trend towards higher risk of experience clinical relapses than the SID group. A higher EDA risk was also identified in EID patients with BMI above median. In conclusion, a higher risk of relapses seems to occur for EID above 7 weeks. Independently from the EID scheme adopted, higher BMI increases the risk of EDA in these patients.

Lessons learned after 20 years of real-world experience with natalizumab

BACKGROUND

While natalizumab (NTZ) is an effective therapy for multiple sclerosis (MS), it is associated with an increased risk of progressive multifocal leukoencephalopathy (PML). After 20 years (2002-2022) of experience with NTZ at our center, we observed no cases of PML.

OBJECTIVES

We evaluated the likelihood of experiencing PML in a subset of our treatment cohort, as well as reviewed treatment practices at our center that may mitigate PML risk.

METHODS

For this retrospective study, we reviewed patient characteristics, treatment practices, and clinical and MRI findings in patients receiving NTZ from 2006 to 2020. Observation of no PML cases was compared to the global and US PML incidences, and to the expected incidence based on published risk estimates.

RESULTS

766 patients were evaluated. The number of NTZ infusions received ranged from 1 to 126, with a mean of 28. Patients received neurological examination prior to each infusion, which sometimes resulted in a pause in therapy to rule out PML if clinical worsening occurred. Extended interval dosing (EID) was the overall dosing schedule for 31% of patients. EID did not result in higher rates of radiological disease worsening than standard interval dosing (SID) patients. Depending on the analysis conducted, the finding of 0 PML cases in our cohort ranged from slightly unexpected to slightly expected.

CONCLUSIONS

The utilization of EID as well as regular clinical monitoring of patients may have lowered PML risk while still maintaining NTZ efficacy.

Progressive multifocal leukoencephalopathy with natalizumab extended or standard interval dosing in the United States and the rest of the world

BACKGROUND

Progressive multifocal leukoencephalopathy (PML), an important identified risk for natalizumab, has been described for standard interval dosing (SID; dosing interval every-4-weeks). Information on PML with natalizumab extended interval dosing (EID; dosing interval >every-4-weeks) in the US and the rest of the world (ROW) is limited.

RESEARCH DESIGN AND METHODS

A retrospective analysis of patient demographics, risk factors, clinical characteristics, and clinical outcomes was conducted on confirmed natalizumab EID and SID PML cases evaluated from Biogen pharmacovigilance systems.

RESULTS

Of 857 confirmed natalizumab PML cases, EID and SID accounted for 7.5% and 92.5%, respectively (US: 12.9% and 87.1%; ROW: 5.4% and 94.6%). PML risk factors included anti-JCV index > 1.5 (US: EID, 56.7% and SID, 12.8%; ROW: EID, 44.1% and SID, 21.0%), mean duration of natalizumab treatment (US: 90.0 and 70.2 months; ROW: 54.1 and 49.8 months), and prior immunosuppressive therapy (US: 20.0% and 21.7%; ROW:11.8% and 18.0%). In the EID and SID groups, 68.8% and 76.0% of patients, respectively, were alive at up to 2 years after diagnosis.

CONCLUSIONS

This analysis provides insights on PML in patients receiving natalizumab that extend current knowledge, particularly regarding PML in patients receiving natalizumab EID, which can be built upon in the future.

High levels of endothelial ICAM-1 prohibit natalizumab mediated abrogation of CD4+ T cell arrest on the inflamed BBB under flow in vitro

INTRODUCTION

The humanized anti-α4 integrin blocking antibody natalizumab (NTZ) is an effective treatment for relapsing-remitting multiple sclerosis (RRMS) that is associated with the risk of progressive multifocal leukoencephalopathy (PML). While extended interval dosing (EID) of NTZ reduces the risk for PML, the minimal dose of NTZ required to maintain its therapeutic efficacy remains unknown.

OBJECTIVE

Here we aimed to identify the minimal NTZ concentration required to inhibit the arrest of human effector/memory CD4+ T cell subsets or of PBMCs to the blood-brain barrier (BBB) under physiological flow in vitro.

RESULTS

Making use of three different human in vitro BBB models and in vitro live-cell imaging we observed that NTZ mediated inhibition of α4-integrins failed to abrogate T cell arrest to the inflamed BBB under physiological flow. Complete inhibition of shear resistant T cell arrest required additional inhibition of β2-integrins, which correlated with a strong upregulation of endothelial intercellular adhesion molecule (ICAM)-1 on the respective BBB models investigated. Indeed, NTZ mediated inhibition of shear resistant T cell arrest to combinations of immobilized recombinant vascular cell adhesion molecule (VCAM)-1 and ICAM-1 was abrogated in the presence of tenfold higher molar concentrations of ICAM-1 over VCAM-1. Also, monovalent NTZ was less potent than bivalent NTZ in inhibiting T cell arrest to VCAM-1 under physiological flow. In accordance with our previous observations ICAM-1 but not VCAM-1 mediated T cell crawling against the direction of flow.

CONCLUSION

Taken together, our in vitro observations show that high levels of endothelial ICAM-1 abrogate NTZ mediated inhibition of T cell interaction with the BBB. EID of NTZ in MS patients may thus require consideration of the inflammatory status of the BBB as high levels of ICAM-1 may provide an alternative molecular cue allowing for pathogenic T cell entry into the CNS in the presence of NTZ.

Real-World Effectiveness of Natalizumab Extended Interval Dosing in a French Cohort

INTRODUCTION

Natalizumab, a therapy for relapsing-remitting multiple sclerosis (RRMS), is associated with a risk of progressive multifocal leukoencephalopathy (PML). Over the last several years, practitioners have used off-label extended interval dosing (EID) of natalizumab to reduce PML risk, despite the absence of a large-scale efficacy evaluation.

METHODS

We conducted a retrospective, multicenter cohort study among adults with RRMS receiving stable standard interval dosing (SID), defined as a ≥ 12-month consecutive period of ≥ 11 natalizumab infusions/year in France. We compared the 12-month risk difference of remaining relapse-free (primary endpoint) between patients who switched to EID (≤ 9 natalizumab infusions) and those who remained on SID, with a noninferiority margin of - 11%. We used propensity score methods such as inverse probability treatment weighting (IPTW) and 1:1 propensity score matching (PSM). Secondary endpoints were annualized relapse rate, disease progression, and safety.

RESULTS

Baseline characteristics were similar between patients receiving EID (n = 147) and SID (n = 156). The proportion of relapse-free patients 12 months postbaseline was 142/147 in the EID (96.6%) and 144/156 in the SID group (92.3%); risk difference (95% CI) 4.3% (- 1.3 to 9.8%); p < 0.001 for non-inferiority. There were no significant differences between relapse rates (0.043 vs. 0.083 per year, respectively; p = 0.14) or Expanded Disability Status Scale mean scores (2.43 vs. 2.72, respectively; p = 0.18); anti-JC virus index values were similar (p = 0.23); and no instances of PML were reported. The comparisons using IPTW (n = 306) and PSM (n = 204) were consistent.

CONCLUSION

These results support the pertinence of using an EID strategy for RRMS patients treated with natalizumab.

CLINICAL TRIALS

gov identifier (NCT04580381).

Switch to ocrelizumab in MS patients treated with natalizumab in extended interval dosing at high risk of PML: A 96-week follow-up pilot study

We aimed to assess the long-term safety and effectiveness of ocrelizumab in a cohort of patients with multiple sclerosis (MS) at high risk of progressive multifocal leukoencephalopathy (PML), previously treated with natalizumab in extending interval dosing (EID), who switched to ocrelizumab and to compare them with patients who continued EID-natalizumab. Thirty MS patients previously treated with natalizumab in EID (every 8 weeks) were included in this observational retrospective cohort study. Among them, 17 patients were switched to ocrelizumab and 13 continued with EID-natalizumab. Except for the John Cunningham virus (JCV) index, no significant differences were detected between both groups. Main outcome measures included: annualized relapse rate (ARR), radiological activity, disability progression, and the NEDA-3 index. Patients were followed for 96 weeks. The median washout period in ocrelizumab-switchers was 6 weeks. Among them, AAR and radiological activity during follow-up were 0.03, without significant differences in comparison with the previous period on natalizumab-EID. The comparison between ocrelizumab-switchers and patients continuing on EID-natalizumab showed no significant differences in AAR, radiological activity, or disability progression. However, the proportion of patients maintaining a NEDA-3 status in week 96 was slightly superior among ocrelizumab-switchers (94 vs 69%). No serious adverse events were observed in any group. In conclusion, switching from EID-natalizumab to ocrelizumab can be considered as a therapeutic option, particularly in patients with MS at high risk of PML, to mitigate the risks of both PML and disease reactivation.

Serum neurofilament light levels in natalizumab-treated patients with multiple sclerosis who switch to extended interval dosing from every-4-week dosing in real-world clinical practice

BACKGROUND

Serum levels of neurofilament light chain (sNfL) are a potentially useful biomarker for assessing the efficacy of multiple sclerosis (MS) treatments.

OBJECTIVE

To compare levels of sNfL in patients with MS who switched from natalizumab every 4 weeks (Q4W) to extended interval dosing (EID) and patients who remained on Q4W dosing in real-world clinical practice.

METHODS

This was a retrospective analysis of samples from patients treated with natalizumab from 2010 to 2015 at a single center in the United States. Levels of sNfL were compared in patients who stayed on Q4W dosing or who switched to EID (parallel-arm analyses) and during Q4W and EID periods in patients who switched to EID (pre- and post-switch analyses).

RESULTS

The analysis included 139 patients (Q4W: n = 79; EID: n = 60). After adjustment, levels of sNfL did not significantly differ between patients who remained on Q4W dosing and those who switched to EID in parallel-arm analyses (adjusted Q4W-EID difference = 0.51 pg/mL; p = 0.60) or pre- and post-switch analyses (adjusted difference = 0.96 pg/mL; p = 0.10).

CONCLUSION

These sNfL biomarker results suggest that the effectiveness of natalizumab is maintained in patients who switch from Q4W dosing to EID.

Decrease of natalizumab drug levels after switching from intravenous to subcutaneous administration in patients with multiple sclerosis

BACKGROUND

Natalizumab is effective in the treatment of multiple sclerosis (MS). In 2021, the European Medicines Agency approved the subcutaneous (SC) variant of natalizumab which can be used instead of intravenous administration. However, the course of drug levels varies between administration routes, and the Food and Drug Administration rejected the request for approval of natalizumab SC for reasons that were not disclosed. Our objective was to evaluate the course of natalizumab trough drug levels in patients who switched from natalizumab intravenous to SC on various treatment intervals.

METHODS

The NEXT-MS trial (N=382) investigates personalised treatment of natalizumab, in which infusion intervals are prolonged based on individual natalizumab trough drug levels. In 2021, an amendment was approved allowing participants to switch from intravenous to SC administration with frequent measurements of natalizumab drug levels and antidrug antibodies (ADAs). Results were compared with linear mixed model analyses.

RESULTS

Until December 2022, 15 participants switched to SC natalizumab. Natalizumab drug levels with SC administration were on average 55% lower compared with intravenous administration (Exp (estimate) 0.45, 95% CI 0.39 to 0.53, p<0.001), leading to very low trough drug levels in three patients on extended treatment intervals. No natalizumab ADAs were detected during intravenous or SC treatment. None of the participants on natalizumab SC showed evidence of MS disease activity.

CONCLUSIONS

Natalizumab trough drug levels can decrease after switching from natalizumab intravenous to SC administration. We advise to monitor trough drug levels in patients with low natalizumab drug levels during intravenous treatment, patients with higher body mass index or patients on extended treatment intervals who switch to SC administration of natalizumab.

Current advances in the pharmacological prevention and management of cognitive dysfunction in multiple sclerosis

INTRODUCTION

Cognitive impairment (CI) is a core feature of Multiple Sclerosis (MS), being detectable in up to 65% of subjects. Treatment of CI can be considered of paramount importance. However, no standardized strategies are available to date to define the best treatment approach, especially for the pharmacological management.

AREAS COVERED

In this narrative review, the authors outline the latest advances in pharmacological management of CI in MS, including Disease Modifying Treatments (DMTs) which indirectly may or may not influence CI and symptomatic drugs. Selected publications were restricted to those written in English, reporting on an adult relapsing-remitting MS or progressive MS sample, assessing the effects of (at least) 1 DMT or treatment in a longitudinal design, reporting data on (at least) one standardized cognitive test performed at baseline and follow-up, and published between January 2018 and May 2022.

EXPERT OPINION

Recent data can be considered encouraging and inspiring for future studies. Overall, there is preliminary evidence of a beneficial effect of DMTs on cognition, particularly for high-efficacy DMTs. As for symptomatic treatments, dalfampridine appears to be the only medication with robust evidence of a positive effect on cognition. However, the definition of clinically meaningful change/improvement in cognitive functions remains an unmet need. Future studies should assess the role of other patient-related factors that can be associated with a better cognitive response to treatments and investigate the possible positive effect of multimodal interventions on cognition.

Controversies in neuroimmunology: multiple sclerosis, vaccination, SARS-CoV-2 and other dilemas

Neuroimmunology is a discipline that increasingly broadens its horizons in the understanding of neurological diseases. At the same time, and in front of the pathophysiological links of neurological diseases and immunology, specific diagnostic and therapeutic approaches have been proposed. Despite the important advances in this discipline, there are multiple dilemmas that concern and filter into clinical practice. This article presents 15 controversies and a discussion about them, which are built with the most up-to-date evidence available. The topics included in this review are: steroid decline in relapses of multiple sclerosis; therapeutic recommendations in MS in light of the SARS-CoV-2 pandemic; evidence of vaccination in multiple sclerosis and other demyelinating diseases; overview current situation of isolated clinical and radiological syndrome; therapeutic failure in multiple sclerosis, as well as criteria for suspension of disease-modifying therapies; evidence of the management of mild relapses in multiple sclerosis; recommendations for prophylaxis against Strongyloides stercolaris; usefulness of a second course of immunoglobulin in the Guillain-Barré syndrome; criteria to differentiate an acute-onset inflammatory demyelinating chronic polyneuropathy versus Guillain-Barré syndrome; and, the utility of angiotensin-converting enzyme in neurosarcoidosis. In each of the controversies, the general problem is presented, and specific recommendations are offered that can be adopted in daily clinical practice.

Natalizumab extended-interval dosing in multiple sclerosis to mitigate progressive multifocal leukoencephalopathy risk: initial study evidence and real-world experience

The high efficacy of natalizumab in the treatment of relapsing-remitting multiple sclerosis (MS) is without controversy. Indeed, effective disease control was not only demonstrated in the pivotal trials but has been corroborated impressively in real-world observations. This monoclonal IgG4 antibody blocks the α4β1 integrin-mediated leukocyte-endothelial interaction and thereby inhibits the migration of immune cells to the brain parenchyma. However, treatment with natalizumab carries the risk of progressive multifocal leukoencephalopathy (PML). This potentially lethal side effect is a significant limitation for treatment initiation and long-term therapy. Natalizumab is given intravenously or subcutaneously in the standard dose of 300 mg every 4 weeks, allowing drug concentrations at levels that ensure continuous α4β1 integrin receptor saturation on the surface of immune cells. Extended-interval dosing (EID) is an emerging treatment approach that aims to mitigate the natalizumab-related PML risk by prolonging the standard infusion intervals to 6 weeks or even more. This treatment approach may abrogate the PML risk due to improved immune surveillance within the central nervous system while maintaining clinical efficacy. Moreover, even an individual interval dosing can be envisioned based on the availability of a biomarker that is capable of monitoring both safety and efficacy aspects. This review summarizes the early and encouraging evidence for EID from observational and randomized-controlled trials and discusses current limitations and upcoming challenges for introducing a tailored treatment approach.

No increase of serum neurofilament light in relapsing-remitting multiple sclerosis patients switching from standard to extended-interval dosing of natalizumab

Background:

Accumulating evidence supports the efficacy of administering natalizumab (NZ) with extended-interval dosing (EID) in patients with relapsing-remitting multiple sclerosis (RRMS).

Objectives:

We switched NZ dosing from 4-week to 6-week intervals in patients with RRMS, and investigated the effect on serum neurofilament light chain (sNfL) concentrations.

Methods:

We included two cohorts of patients with RRMS treated with NZ: one received the standard-interval dosing (4 weeks) at baseline, and were switched to 6-week intervals (EID4–6, N = 45). The other cohort received EID (5- or 6-week intervals) both at baseline and during follow-up (EID5/6, N = 25). Serum samples were collected in the EID4–6 cohort at every NZ infusion, for 12 months. The primary outcome was the change in sNfL concentrations after switching to EID.

Results:

The baseline mean sNfL concentration in the EID4–6 cohort was 10.5 ng/L (standard deviation (SD) = 6.1), and it remained unchanged at 12 months. Moreover, individual sNfL concentrations did not change significantly after extending the NZ dosing intervals. In addition, the EID4–6 and EID5/6 cohorts had similar baseline sNfL concentrations.

Conclusion:

We concluded that extending the NZ dosing interval did not increase axonal damage, as determined with sNfL, in patients with RRMS.

Comparison of switching to 6-week dosing of natalizumab versus continuing with 4-week dosing in patients with relapsing-remitting multiple sclerosis (NOVA): a randomised, controlled, open-label, phase 3b trial

BACKGROUND

Treatment with natalizumab once every 4 weeks is approved for patients with relapsing-remitting multiple sclerosis, but is associated with a risk of progressive multifocal leukoencephalopathy. Switching to extended-interval dosing is associated with lower progressive multifocal leukoencephalopathy risk, but the efficacy of this approach is unclear. We aimed to assess the safety and efficacy of natalizumab once every 6 weeks compared with once every 4 weeks in patients with relapsing-remitting multiple sclerosis.

METHODS

We did a randomised, controlled, open-label, phase 3b trial (NOVA) at 89 multiple sclerosis centres across 11 countries in the Americas, Europe, and Western Pacific. Included participants were aged 18-60 years with relapsing-remitting multiple sclerosis and had been treated with intravenous natalizumab 300 mg once every 4 weeks with no relapses for at least 12 months before randomisation, with no missed doses in the previous 3 months. Participants were randomly assigned (1:1), using a randomisation sequence generated by the study funder and contract personnel with interactive response technology, to switch to natalizumab once every 6 weeks or continue with once every 4 weeks. The centralised MRI reader, independent neurology evaluation committee, site examining neurologists, site backup examining neurologists, and site examining technicians were masked to study group assignments. The primary endpoint was the number of new or newly enlarging T2 hyperintense lesions at week 72, assessed in all participants who received at least one dose of assigned treatment and had at least one postbaseline MRI, relapse, or neurological examination or efficacy assessment. Missing primary endpoint data were handled under prespecified primary and secondary estimands: the primary estimand included all data, regardless of whether participants remained on the assigned treatment; the secondary estimand classed all data obtained after treatment discontinuation or study withdrawal as missing. Safety was assessed in all participants who received at least one dose of study treatment. Study enrolment is closed and an open-label extension study is ongoing. This study is registered with EudraCT, 2018-002145-11, and ClinicalTrials.gov, NCT03689972.

FINDINGS

Between Dec 26, 2018, and Aug 30, 2019, 605 patients were assessed for eligibility and 499 were enrolled and assigned to receive natalizumab once every 6 weeks (n=251) or once every 4 weeks (n=248). After prespecified adjustments for missing data, mean numbers of new or newly enlarging T2 hyperintense lesions at week 72 were 0·20 (95% CI 0·07-0·63) in the once every 6 weeks group and 0·05 (0·01-0·22) in the once every 4 weeks group (mean lesion ratio 4·24 [95% CI 0·86-20·85]; p=0·076) under the primary estimand, and 0·31 (95% CI 0·12-0·82) and 0·06 (0·01-0·31; mean lesion ratio 4·93 [95% CI 1·05-23·20]; p=0·044) under the secondary estimand. Two participants in the once every 6 weeks group with extreme new or newly enlarging T2 hyperintense lesion numbers (≥25) contributed most of the excess lesions. Adverse events occurred in 194 (78%) of 250 participants in the once every 6 weeks group and 190 (77%) of 247 in the once every 4 weeks group, and serious adverse events occurred in 17 (7%) and 17 (7%), respectively. No deaths were reported. There was one case of asymptomatic progressive multifocal leukoencephalopathy (without clinical signs) in the once every 6 weeks group, and no cases in the once every 4 weeks group; 6 months after diagnosis, the participant was without increased disability and remained classified as asymptomatic.

INTERPRETATION

We found a numerical difference in the mean number of new or newly enlarging T2 hyperintense lesions at week 72 between the once every 6 weeks and once every 4 weeks groups, which reached significance under the secondary estimand, but interpretation of statistical differences (or absence thereof) is limited because disease activity in the once every 4 weeks group was lower than expected. The safety profiles of natalizumab once every 6 weeks and once every 4 weeks were similar. Although this trial was not powered to assess differences in risk of progressive multifocal leukoencephalopathy, the occurrence of the (asymptomatic) case underscores the importance of monitoring and risk factor consideration in all patients receiving natalizumab.

FUNDING

Biogen.

Healthcare resource utilization and costs for extended interval dosing of natalizumab in multiple sclerosis

Aims: Natalizumab is approved as an infusion every 4 weeks (standard-interval dosing [SID]) in relapsing-remitting multiple sclerosis (MS). Extended-interval dosing (EID) reduces risk of progressive multifocal leukoencephalopathy (PML) compared with SID, but the impact on healthcare resources and costs remains unknown. Methods: In this population-based study, we included 208 natalizumab-treated MS patients who were classified into EID (≤15 infusions in the previous 18 months; n = 51; age = 33.7 ± 11.1 years; female = 72.5%) and SID (>15 infusions in the previous 18 months; n = 157; age = 36.5 ± 10.8 years; female = 68.1%) groups. Results: Natalizumab EID had fewer MS outpatient visits (p = 0.01) and related costs (p = 0.03), and lower natalizumab costs (p < 0.01) compared with SID, without changes in other healthcare resources and costs. Conclusion: Natalizumab EID is associated with reduced direct treatment costs, apparently without additional healthcare burden.

[Clinical and radiological effectiveness of natalizumab extended dosage interval in patients with relapsing multiple sclerosis]

INTRODUCTION

Natalizumab (NTZ) is a very effective treatment approved for highly active multiple sclerosis. The main risk of treatment with NTZ is the possibility of developing progressive multifocal leukoencephalopathy, which is related to JC virus positivity and the number of NTZ infusions. This risk decreases with the extended dosage interval (EDI), which involves 9 or fewer infusions/year. However, it is a matter of controversy as to whether EDI remains effective in reducing recurrences and the presence of new lesions in magnetic resonance imaging (MRI).

PATIENTS AND METHODS

A prospective observational study was conducted from 1 April 2019 to 30 June 2021, following up patients on NTZ treatment who switched to EDI. Patients should have at least one MRI six months after the start of EDI. The presence of attacks or MRI activity (new lesions in T2) during the EDI was recorded.

RESULTS

Twenty-three patients with a mean age of 43.5 ± 9.4 years were included. The median number of NTZ infusions was 68 (minimum, 25; maximum, 127). The median interval between the start of the EDI and the last MRI was 14 months (minimum, 6; maximum, 25), and 23 months from the last medical follow-up visit (minimum, 7; maximum, 28). Two patients (8.7%) presented with attacks and two others (8.7%) showed MRI activity.

CONCLUSIONS

EDI with NTZ maintains high clinical and activity effectiveness in MRI.

Extended Interval Dosing Natalizumab and impact on neuropsychological deficits in Relapsing-Remitting Multiple Sclerosis

Background: Cognitive impairment and neuropsychiatric symptoms are frequently reported in Relapsing-Remitting Multiple Sclerosis (RRMS). Natalizumab (NTZ) is usually administered on a 4-weekly Standard Interval Dosing (SID) schedule. However, Extended Interval Dosing (EID) at 6–8 weekly intervals has been proven non-inferior regarding relapse risk, with a lower risk of Progressive Multifocal Leukoencephalopathy (PML). The impact of EID NTZ on neuropsychological deficits in RRMS has not been studied. Objective: To determine if EID NTZ demonstrates an improvement in neuropsychological parameters in RRMS patients. Method: We performed a retrospective, observational analysis of 34 RRMS patients treated between August 2015–2017. Patients underwent baseline neuropsychological testing before commencing EID NTZ. A second evaluation was performed, on average 28 months after commencing treatment. Results: Z scores at the initial assessment showed baseline cognitive impairment in multiple domains. 14/20 Z-scores showed an improvement post-NTZ and 5/14 reached statistical significance; namely Trails A (visual attention/processing speed), Line-orientation (visual-spatial), Picture-naming (word finding), Digital-Span (attention, executive function and memory) and Story-recall (memory). The Hospital Anxiety and Depression Scale (HADS) data remained unchanged. Correlation matrix showed no association between HADS scores, the time between assessments and the changes in Z scores. Conclusion: This data suggests the efficacy of EID NTZ in improving cognitive impairment in RRMS. A prospective observational study is warranted.

Updated Perspectives on the Challenges of Managing Multiple Sclerosis During Pregnancy

Multiple sclerosis (MS) is a chronic immune-mediated, inflammatory, and degenerative disease that is up to three times more frequent in young women. MS does not alter fertility and has no impact on fetal development, the course of pregnancy, or childbirth. The Pregnancy in Multiple Sclerosis Study in 1998 showed that pregnancy, mostly in untreated women, did not adversely affect MS, as disease activity decreased during pregnancy (although it significantly increased in the first trimester postpartum). These findings, together with the limited information available on the potential risks of fetal exposure to disease modifying treatments (DMTs), meant that women were advised to delay the onset of DMTs, stop them prior to conception, or, in case of unplanned pregnancy, discontinue them when pregnancy was confirmed. Now, many women with MS receive DMTs before pregnancy and, despite being considered a period of MS stability, up to 30% of patients could relapse in the first trimester postpartum. Factors associated with an increased risk of relapse and disability during pregnancy and postpartum include relapses before and during pregnancy, a greater disability at the time of conception, the occurrence of relapses after DMT cessation before conception, and the use of high-efficacy DMTs before conception, especially natalizumab or fingolimod. Strategies to prevent postpartum activity are needed in some patients, but consensus is lacking regarding the therapeutic strategies for women with MS of a fertile age. This, along with the increasing number of DMTs, means that the decision-making processes in aspects related to family planning and therapeutic strategies before, during, and after pregnancy are increasingly more complex. The purpose of this review is to provide an update on pregnancy-related issues in women with MS, including recommendations for counseling, general management, use of DMTs in pre-pregnancy, pregnancy, and postpartum periods, and breastfeeding-related aspects of DMTs.

No difference in radiologic outcomes for natalizumab patients treated with extended interval dosing compared with standard interval dosing: Real-world evidence from MS PATHS

BACKGROUND

Extended interval dosing (EID; average dosing interval approximately every 6 weeks) of natalizumab is associated with significantly lower risk of progressive multifocal leukoencephalopathy than standard interval dosing (SID; every 4 weeks) in patients with relapsing-remitting multiple sclerosis (MS). Real-world studies, though limited, suggest that natalizumab effectiveness is generally maintained in patients who switch to EID after initiation of stable treatment with SID. MS PATHS (Multiple Sclerosis Partners Advancing Technology and Health Solutions) is a collaborative, multicenter learning health system that generates real-world clinical and MRI data using highly standardized acquisition protocols. We compared MRI outcomes in MS PATHS patients treated with natalizumab EID versus SID. We also compared MRI outcomes in patients treated with natalizumab (EID and/or SID) versus injectable MS platform therapy.

METHODS

Natalizumab infusion data from the TOUCH Prescribing Program database and MS PATHS MRI assessment data from seven US sites as of July 23, 2020, were used to identify patients with relapsing-remitting MS who had received natalizumab EID or SID in the interval between two MRI scans (an MRI segment). Patients who received injectable platform MS therapy between two MRI scans were also identified. MRI data were used to determine the incidence rate and odds of developing new or enlarging T2 lesions, annualized percentage change in T2 lesion volume (T2LV), and annualized percentage change in brain parenchymal fraction (BPF). MRI outcomes were compared for 1) natalizumab EID treatment versus natalizumab SID treatment, 2) natalizumab treatment (EID + SID) versus platform therapy, and 3) natalizumab EID versus platform therapy. Propensity score-based weighting or matching were used to balance covariates at the start of MRI segments for all comparisons.

RESULTS

The MRI outcomes observed with natalizumab EID treatment did not differ significantly from those observed with natalizumab SID treatment. The odds ratio for any new or enlarging T2 lesion was 1.07 (95% confidence interval [CI]: 0.93, 1.24; p = 0.355), and the rate ratio (95% CI) for new or enlarging T2 lesions was 1.62 (0.93, 2.82; p = 0.090). Differences (95% CI) between EID and SID patients in mean annualized percentage change in T2LV and BPF were 1.56% (-3.77%, 6.90%; p = 0.566) and -0.11% (-0.25%, -0.10%; p = 0.096), respectively. Conversely, when MRI outcomes in natalizumab and platform therapy patients were compared, there were significant differences favoring natalizumab in all assessments: the odds of any new or enlarging T2 lesion (odds ratio: 0.69 [95% CI: 0.64, 0.75]; p<0.001), the incidence rate of new or enlarging T2 lesions (rate ratio: 0.47 [95% CI: 0.37, 0.61]; p<0.001), annualized percentage change (decrease) in T2LV (difference: -3.68% [95% CI: -7.06%, -0.30%]; p = 0.033), and annualized percentage change (increase) in BPF (difference: 0.22% [95% CI: 0.16%, 0.29%]; p<0.001). Results of the subgroup comparison of natalizumab EID patients with platform therapy patients were similar to those of the overall-natalizumab-group-versus-platform-therapy comparison.

CONCLUSIONS

The results indicate that natalizumab EID and SID provide comparable real-world effectiveness on quantitative MRI metrics. These data further demonstrate that natalizumab EID can provide superior real-world effectiveness to injectable platform therapy on quantitative MRI metrics.

Extended dosing of monoclonal antibodies in multiple sclerosis

Over the past two decades, treatment options for patients with multiple sclerosis (MS) have increased exponentially. In the current therapeutic landscape, "no evidence of MS disease activity" is within reach in many of our patients. Minimizing risks of complications, improving treatment convenience, and decreasing health care costs are goals that are yet to be reached. One way to optimize MS therapy is to implement personalized or extended interval dosing. Monoclonal antibodies are suitable candidates for personalized dosing (by therapeutic drug monitoring) or extended interval dosing. An increasing number of studies are performed and underway reporting on altered dosing intervals of anti-α₄β₁-integrin treatment (natalizumab) and anti-CD20 treatment (ocrelizumab, rituximab, and ofatumumab) in MS. In this review, current available evidence regarding personalized and extended interval dosing of monoclonal antibodies in MS is discussed with recommendations for future research and clinical practice.

Evaluation of Natalizumab Pharmacokinetics and Pharmacodynamics: Toward Individualized Doses

Background: Plasma concentration of natalizumab falls above the therapeutic threshold in many patients who, therefore, receive more natalizumab than necessary and have higher risk of progressive multifocal leukoencephalopathy.

Objective: To assess in a single study the individual and treatment characteristics that influence the pharmacokinetics and pharmacodynamics of natalizumab in multiple sclerosis (MS) patients in the real-world practice.

Methods: Prospective observational study to analyse the impact of body weight, height, body surface area, body mass index, gender, age, treatment duration, and dosage scheme on natalizumab concentrations and the occupancy of α4-integrin receptor (RO) by natalizumab.

Results: Natalizumab concentrations ranged from 0.72 to 67 μg/ml, and RO from 26 to 100%. Body mass index inversely associated with natalizumab concentration (beta = −1.78; p ≤ 0.001), as it did body weight (beta = −0.34; p = 0.001), but not height, body surface area, age or gender Extended vs. standard dose scheme, but not treatment duration, was inversely associated with natalizumab concentration (beta = −7.92; p = 0.016). Similar to natalizumab concentration, body mass index (beta = −1.39; p = 0.001) and weight (beta = −0.31; p = 0.001) inversely impacted RO. Finally, there was a strong direct linear correlation between serum concentrations and RO until 9 μg/ml (rho = 0.71; p = 0.003). Nevertheless, most patients had higher concentrations of natalizumab resulting in the saturation of the integrin.

Conclusions: Body mass index and dosing interval are the main variables found to influence the pharmacology of natalizumab. Plasma concentration of natalizumab and/or RO are wide variable among patients and should be routinely measured to personalize treatment and, therefore, avoid either over and underdosing.

No evidence for loss of natalizumab effectiveness with every-6-week dosing: a propensity score-matched comparison with every-4-week dosing in patients enrolled in the Tysabri Observational Program (TOP)

Background:

Extended interval dosing of natalizumab is associated with significantly lower progressive multifocal leukoencephalopathy risk compared with every-4-week (Q4W) dosing in patients with relapsing-remitting multiple sclerosis. Previous studies have suggested that natalizumab effectiveness is maintained in patients who switch from Q4W to extended interval dosing but have been limited by a lack of well-matched patient cohorts.

Methods:

Tysabri Observational Program (TOP) data as of November 2019 were used to identify patients with relapsing-remitting multiple sclerosis treated with natalizumab Q4W and those with a single physician-indicated dosing change from Q4W to every-6-week (Q6W) dosing after ⩾1 year of Q4W treatment. Patients were propensity score matched at the time of the switch from Q4W to Q6W dosing. Clinical outcomes (annualized relapse rate and probability of remaining relapse free or free of 24-week confirmed disability worsening) and safety outcomes were assessed for the two cohorts.

Results:

This study included 219 pairs of propensity score–matched Q6W and Q4W patients. Annualized relapse rates were similar for Q6W (0.150) and Q4W (0.157) patients. The probability of remaining relapse free [hazard ratio = 1.243 (95% confidence interval = 0.819–1.888); p = 0.307] and of remaining free of 24-week confirmed disability worsening [hazard ratio = 0.786 (95% confidence interval = 0.284–2.176); p = 0.644] did not differ significantly between Q6W and Q4W patients. Summarized safety results for the matched Q6W and Q4W patients are also presented.

Conclusion:

These real-world findings in well-matched patient cohorts from TOP demonstrate that natalizumab effectiveness is maintained in patients who switch to Q6W dosing after ⩾1 year of Q4W dosing.

ClinicalTrials.gov identifier:

NCT00493298

Home infusions of natalizumab for people with multiple sclerosis: a pilot randomised crossover trial

OBJECTIVE

The delivery of healthcare at home has expanded to intravenous infusions of monoclonal antibodies. A recently developed model of care for home infusions of natalizumab for people with relapsing-remitting multiple sclerosis was evaluated. This pilot study of home infusions of natalizumab and usual care (attendance in a hospital out-patients' clinic) compared safety, feasibility, patient satisfaction, effectiveness and costs.

METHODS

In this randomised AB/BA crossover trial, 37 adults were randomised to usual care (n = 19) or home infusions (n = 18). After three infusions, patients crossed over to the alternate treatment for another three infusions. Patient safety outcomes and adherence, satisfaction, quality of life, disability and costs were compared.

RESULTS

No adverse events were recorded from 207 infusions from 35 patients across both home and clinic infusions. There was no difference in adherence (p = 0.71) and infection rates (p = 0.84) between home and clinic settings. Satisfaction with "convenience" of home infusions was significantly greater (p = 0.008) but there were no differences in quality of life measures. Excluding pharmacy, costs were A$74 lower per infusion at home, including A$16 of patients" out-of-pocket costs.

INTERPRETATION

There were no differences in safety and effectiveness between clinic and home infusions of natalizumab. The home infusions were shown to be feasible, more convenient and less expensive than usual care. Larger scale studies are required to verify these preliminary findings, particularly around safety and management of hypersensitivity adverse events in the home setting and for equivalence of clinical outcomes.

Natalizumab Pharmacokinetics and -Dynamics and Serum Neurofilament in Patients With Multiple Sclerosis

Background: Natalizumab (NAT) is a high-efficacy treatment for relapsing remitting multiple sclerosis (RRMS). However, it is associated with an increased risk of progressive multifocal leukoencephalopathy that sometimes requires treatment cessation with a risk of returning disease activity. The aim of this study was to characterize the pharmacokinetics and -dynamics as well as neurodestruction marker serum neurofilament light chain (sNfL) in patients with RRMS and secondary progressive MS (SPMS) stopping NAT in correlation to clinical data. Methods: In this study, 50 RRMS and 9 SPMS patients after NAT cessation were included. Five RRMS patients on NAT treatment holiday were evaluated. Clinical and radiological disease activity were systemically assessed by frequent exams after NAT stop. Free NAT concentration, cell bound NAT, α4-integrin expression and α4-integrin-receptor saturation as well as immune cell frequencies were measured for up to 4 months after NAT withdrawal. Additionally, sNfL levels were observed up to 12 months in RRMS and up to 4 months in SPMS patients. Results: NAT cessation was associated with a return of disease activity in 38% of the RRMS and 33% of the SPMS patients within 12 and 7 months, respectively. Concentration of free and cell bound NAT as well as α4-integrin-receptor saturation decreased in the RRMS and SPMS patients whereas α4-integrin expression increased over time. NAT induced increase of lymphocytes and its subsets normalized and a non-significant drop of NK and Th17 T-cells counts could be detected. All RRMS patients showed physiological sNfL levels <8pg/ml 1 month after last NAT infusion. During follow-up period sNfL levels peaked up to 16-fold and were linked to return of disease activity in 19 of the 37 RRMS patients. Treatment holiday was also associated with a return of disease activity in 4 of 5 patients and with an increase of sNfL at an individual level. Conclusions: We demonstrate the reversibility of NAT pharmacodynamic and -kinetic markers. sNfL levels are associated with the recurrence of disease activity and can also serve as an early marker to predict present before onset of clinical or radiological disease activity on the individual level.

Highly effective disease-modifying treatment as initial MS therapy

PURPOSE OF REVIEW

Using highly effective (HE) compounds right from the beginning of disease-modifying immunotherapy (DMT) in people with multiple sclerosis (pwMS) has gained popularity among clinicians and pwMS alike. We discuss the most recent evidence supporting this approach, and whether any of the associated risks should stop us adopting it as a default strategy.

RECENT FINDINGS

With the addition of injectable ofatumumab, and the two oral sphingosine one phosphate modulators siponimod and ozanimod, ten HE DMTs are now available for pwMS, though variation in licensing status and cost may limit their use in some healthcare environments. Real World evidence based on large MS registry data suggests the superiority of early HE DMT over a slow treatment escalation approach; delaying HE DMT leads to more rapid and often irreversible disability accrual. Mechanistically, B-cell depletion, particularly memory B-cell suppression, is a common denominator closely associated with DMT efficacy.

SUMMARY

The concept that HE DMTs are necessarily associated with a high risk of adverse effects, is no longer supported by the evidence. The rather predictable and manageable risk profile of most HE DMTs should lower the threshold for clinicians to discuss such treatment with pwMS as a first line approach.

Does Extended Interval Dosing Natalizumab Preserve Effectiveness in Multiple Sclerosis? A 7 Year-Retrospective Observational Study

The extended interval dosing (EID) of natalizumab has been suggested to be associated with a reduced risk of progressive multifocal leukoencephalopathy (PML) and short-term preservation of efficacy but its long-term effectiveness remain unknown. We aimed to determine the long-term effectiveness and safety of natalizumab in an EID setting in a cohort of patients with multiple sclerosis (MS) treated for more than 7 years. We conducted an observational retrospective cohort study, including 39 (34 female, 5 male) patients with clinically definite relapsing-MS, initially treated with standard interval dosing (SID) of natalizumab (mean time 54 months [SD29]) who were then switched to EID, every 8 weeks (mean time 76 months [SD13]). The main outcome measures included the following: i) annualized relapse rate (ARR), ii) radiological activity, iii) disability progression, and iv) NEDA-3 no evidence of disease activity index. EID preserved ARR, radiological activity, and prevented disability worsening during follow-up. The proportion of patients maintaining their NEDA-3 status after 24, 48, and 72 months of natalizumab administration in EID was 94%, 73%, and 70%, respectively. Stratified analysis according to history of drug therapy showed that the EID of natalizumab was slightly more effective in naïve patients than in those previously treated with other immunosuppressive drugs. No cases of PML or other severe adverse reactions were reported. In conclusion, long-term therapy with natalizumab in an EID setting following an SID regimen maintained its disease-modifying activity, and was safe and well tolerated for over 7 years. These encouraging observational results need to be confirmed in controlled clinical trials.

MRI activity and extended interval of Natalizumab dosing regimen: a multicentre Italian study

BACKGROUND

To minimize the risk of Progressive Multifocal Leukoencephalopathy and rebound in JCV-positive multiple sclerosis (MS) patients after 24 natalizumab doses, it has been proposed to extend the administrations interval. The objective is to evaluate the EID efficacy on MRI activity compared with the standard interval dosing (SID).

METHODS

Observational, multicentre, retrospective cohort study, starting from the 24th natalizumab infusion to the loss of follow-up or 2 years after baseline. Three hundred and sixteen patients were enrolled. The median dose interval (MDI) following the 24th infusion was 5 weeks, with a bimodal distribution (modes at 4 and 6 weeks). Patients were grouped into 2 categories according to the mean number of weeks between doses: <5 weeks, SID; ≥5 weeks, EID.

RESULTS

One hundred and eighty-seven patients were in the SID group (MDI = 4.5 weeks) and 129 in the EID group (MDI 6.1 weeks). The risk to develop active lesions on MRI is similar in SID and EID groups during the 6 and 12 months after the 24th natalizumab infusion, respectively 4.27% (95% CI:0.84-7.70) vs 4.71% (95% CI:0.16-9.25%) [p = 0.89] and 8.50% (95% CI:4.05-12.95) vs 6.55% (95% CI:2.11-11.00%) [p = 0.56]. The EID regimen does not appear to increase the occurrence of MRI activity during follow-up.

CONCLUSION

There is no evidence of the reduced efficacy of natalizumab in an EID setting regarding the MRI activity. This observation supports the need for a bigger randomized study to assess the need to change the standard of the natalizumab dosing schedule, to better manage JCV-positive patients.

Multidisciplinary Approach to the Diagnosis and In-Hospital Management of COVID-19 Infection: A Narrative Review

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2 or COVID-19 disease) was declared a pandemic on 11th March 2020 by the World Health Organization. This unprecedented circumstance has challenged hospitals' response capacity, requiring significant structural and organizational changes to cope with the surge in healthcare demand and to minimize in-hospital risk of transmission. As our knowledge advances, we now understand that COVID-19 is a multi-systemic disease rather than a mere respiratory tract infection, therefore requiring holistic care and expertise from various medical specialties. In fact, the clinical spectrum of presentation ranges from respiratory complaints to gastrointestinal, cardiac or neurological symptoms. In addition, COVID-19 pandemic has created a global burden of mental illness that affects the general population as well as healthcare practitioners. The aim of this manuscript is to provide a comprehensive and multidisciplinary insight into the complexity of this disease, reviewing current scientific evidence on COVID-19 management and treatment across several medical specialties involved in the in-hospital care of these patients.

Clinical effectiveness of different natalizumab interval dosing schedules in a large Italian population of patients with multiple sclerosis

INTRODUCTION

Natalizumab (NTZ) is one of the most effective treatment options for multiple sclerosis (MS) treatment. Our study aimed to evaluate the effectiveness of NTZ when administered according to the extended dosing strategy compared with standard 4-weekly administration in a large Italian MS population.

MATERIALS AND METHODS

This retrospective multicentre study included patients with relapsing-remitting MS (RR-MS) who received NTZ administrations between the 1 June 2012 and the 15 May 2018 and were followed by the 'Italian MS Register'. All patients with MS were stratified into two groups based on NTZ administration schedule: standard interval dosing (SID) patients who received infusions on average from 28 to 32 days (median 30) and extended interval dosing (EID) including patients who have been infused with interval between 33 and 49 days (median 43). Clinical data were assessed at baseline (before starting NTZ), after 12 (T1) and 24 months (T2) of treatment.

RESULTS

Out of 5231 patients with RR-MS screened, 2092 (mean age 43.2±12.0, 60.6% women) were enrolled. A total of 1254 (59.9%) received NTZ according to SID, and 838 (40.1%) according to EID. At 12 and 24 months, no differences in terms of annualised relapse rate and disability status were found between the two groups. Progression index and confirmed disability worsening were similar between the two groups.

DISCUSSION

The use of NTZ with an extended interval schedule showed similar effectiveness compared with SID. Unchanged clinical efficacy of EID schedule may raise the question of a possible advantage in terms of tolerability and safety.

Second-generation immunotherapeutics in multiple sclerosis: can we discard their precursors?

Options for disease-modifying therapies in multiple sclerosis have increased over the past two decades. Among these innovations are interferon-β, glatiramer acetate, fumaric acid and dihydroorotate dehydrogenase inhibitors, an antibody targeting the migration of immune cells, a compound that traps immune cells in lymphoid organs by sphingosine 1-phosphate receptor (S1PR) modulation and immune-reconstitution therapies. Second-generation drugs such as pegylated interferon-β, advanced CD20 depleting antibodies, more-specific S1PR modulators and new formulations have been developed to achieve higher efficacy while exhibiting fewer side effects. In this review, we address the shortcomings of the parent drugs, present the pros and cons of the second-generation therapies and summarize upcoming developments in the field of immunotherapy for multiple sclerosis.

Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.

Modeling the Efficacy of Natalizumab in Multiple Sclerosis Patients Who Switch From Every-4-Week Dosing to Extended-Interval Dosing

Natalizumab is approved for multiple sclerosis treatment at a dose of 300 mg every 4 weeks. Extended‐interval dosing of natalizumab has been proposed as a strategy to mitigate the risk of progressive multifocal leukoencephalopathy, but the efficacy of extended‐interval dosing is not established. Previous models suggesting lower efficacy when initiating natalizumab treatment with extended‐interval dosing rather than every‐4‐week dosing are inconsistent with reports from clinical observations and real‐world studies conducted in patient populations switching to extended‐interval dosing after a period of receiving natalizumab every 4 weeks. Here, the efficacy of natalizumab extended‐interval dosing was modeled specifically in patients switching from every‐4‐week dosing to extended‐interval dosing. Published population pharmacokinetic/pharmacodynamic models were used to simulate the distribution of alpha‐4 integrin saturations for different body weight categories and dosing intervals (every 5, 6, 7, 8, 10, or 12 weeks). Generalized estimating equations relating alpha‐4 integrin saturation to probability of multiple sclerosis lesion or relapse were derived from RESTORE trial data, which included patients (n = 175) who discontinued natalizumab after being treated every 4 weeks for ≥1 year and had no relapses in the year before discontinuation. The model‐based simulations described indicate that every‐5‐week or every‐6‐week dosing is likely to maintain the efficacy of natalizumab, particularly at body weights <80 kg, in patients who switch after a period of stability on every‐4‐week dosing. The efficacy of natalizumab decreases as dosing intervals and body weight increase. Partial model validation was achieved in that observed outcomes in an independent clinical study were similar to those predicted by the models.

Personalized extended interval dosing of natalizumab in MS: A prospective multicenter trial

OBJECTIVE

To determine whether natalizumab efficacy is maintained when switching to personalized extended interval dosing based on individual natalizumab trough concentrations in patients with relapsing-remitting multiple sclerosis (RRMS).

METHODS

This was a prospective multicenter single-arm trial with 1 year follow-up and a 1-year extension phase. Participants were adult persons with RRMS treated with natalizumab without disease activity in the year prior to enrollment. The natalizumab treatment interval was based on longitudinal natalizumab trough concentrations. Patients received 3 monthly MRI scans, relapse assessments, and disability scoring during follow-up. The primary endpoint was the occurrence of gadolinium-enhancing lesions on MRI. Secondary endpoints were new/enlarging T2 lesions on MRI and relapses and progression on the Expanded Disability Status Scale (EDSS) during follow-up and extension phase.

RESULTS

Sixty-one patients were included. Eighty-four percent extended the interval from a 4-week interval to a 5- to 7-week interval. No patient developed gadolinium-enhancing lesions (95% confidence interval [CI] 0%-7.4%) during follow-up. No new/enlarging T2 lesions (95% CI 0%-7.4%) or relapses (95% CI 0%-7.4%) were reported during follow-up and in the extension phase. Median EDSS was comparable at baseline (3.0, interquartile range [IQR] 2.0-5.0) and after follow-up (3.0, IQR 2.0-5.0).

CONCLUSION

Personalized extended interval dosing did not induce recurrence of MS disease activity. Natalizumab efficacy was maintained in stable patients with RRMS receiving personalized extended interval dosing based on individual natalizumab concentrations.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that personalized extended interval dosing of natalizumab does not result in recurrence of disease activity in stable patients with RRMS.

Wearing-off at the end of natalizumab dosing intervals is associated with low receptor occupancy

Objective

We aimed to investigate whether wearing-off symptoms at the end of the natalizumab dosing interval were associated with clinical and demographic patient characteristics or natalizumab receptor occupancy (RO) on leukocytes.

Methods

In this cross-sectional study of 40 patients with relapsing-remitting MS (RRMS) receiving natalizumab at the Department of Neurology, Haukeland University Hospital, we recorded clinical and demographic data including age, body mass index (BMI), working status, smoking habits, disease characteristics, treatment duration, vitamin D levels, and wearing-off symptoms. We quantified neurofilament light chain in serum and measured natalizumab RO in leukocyte subtypes by high-parameter mass cytometry. Associations with wearing-off symptoms were analyzed.

Results

Eight (20.0%) patients who reported regular occurrence of wearing-off symptoms, 9 (22.5%) who sometimes had wearing-off symptoms, and 23 (57.5%) who did not have wearing-off symptoms were evaluated. Patients who regularly had wearing-off symptoms had lower natalizumab RO than patients who reported having such symptoms sometimes or never. The former group also had higher BMI and higher frequency of sick leave. High BMI was associated with low RO. No other demographic or disease characteristics were associated with the phenomenon.

Conclusions

Low RO may explain the wearing-off phenomenon observed in some patients with RRMS treated with natalizumab, and high BMI may be the underlying cause.

Pregnancy outcomes amongst multiple sclerosis females with third trimester natalizumab use

BACKGROUND

Natalizumab, a monoclonal antibody directed against alpha-4-integrin, is an efficacious treatment used in Multiple Sclerosis (MS). Use in early pregnancy is safe but information in the third trimester is limited. Ceasing natalizumab is often associated with an increased risk in MS relapse and in some instances natalizumab continuation during pregnancy may be required. However natalizumab crosses the placenta in late pregnancy and has been associated with hematological abnormalities. We present clinical and hematological outcome data of newborns from a series of MS patients who received natalizumab during their second and third pregnancy trimesters. We describe possible methods to mitigate risks to the fetus.

METHODS

Retrospective chart review of 15 births from mothers receiving natalizumab throughout pregnancy.

RESULTS

Thirteen mothers with third-trimester exposure to natalizumab were identified. Median age at conception was 34 years (26-40) and median disease duration was 53.5 months (11-204). The 13 mothers gave birth to 15 newborns (2 mothers each with 2 individual births), median (SD) birth weight was 2778 gs (2100 - 3790). Congenital or laboratory abnormalities were identified in 5 which included anemia (n = 2) and thrombocytopenia (n = 3).

CONCLUSIONS

Complications following natalizumab administration during the second and third trimester of pregnancy occurred in 33% of newborns. However, did not result in mortality or morbidity. Dose alterations during the third trimester, pre-delivery umbilical cord sampling and IVIG administration may reduce hematological effects on newborns. Prospective studies with larger numbers of patients are required to provide further evidence regarding the safety of Natalizumab use in pregnancy.

Pregnancy-related issues in women with multiple sclerosis: an evidence-based review with practical recommendations

Objective: To review the current evidence regarding pregnancy-related issues in multiple sclerosis (MS) and to provide recommendations specific for each of them. Research design and methods: A systematic review was performed based on a comprehensive literature search. Results: MS has no effect on fertility, pregnancy or fetal outcomes, and pregnancies do not affect the long-term disease course and accumulation of disability. There is a potential risk for relapse after use of gonadotropin-releasing hormone agonists during assisted reproduction techniques. At short-term, pregnancy leads to a reduction of relapses during the third trimester, followed by an increased risk of relapses during the first three months postpartum. Pregnancies in MS are not per se high risk pregnancies, and MS does not influence the mode of delivery or anesthesia unless in the presence of significant disability. MRI is not contraindicated during pregnancy; however, gadolinium contrast media should be avoided whenever possible. It is safe to use pulse dose methylprednisolone infusions to manage acute disabling relapses during pregnancy and breastfeeding. However, its use during the first trimester of pregnancy is still controversial. Women with MS should be encouraged to breastfeed with a possible favorable effect of exclusive breastfeeding. Disease-modifying drugs can be classified according to their potential for pregnancy-associated risk and impact on fetal outcome. Interferon beta (IFNβ) and glatiramer acetate (GA) may be continued until pregnancy is confirmed and, after consideration of the individual risk-benefit if continued, during pregnancy. The benefit of continuing natalizumab during the entire pregnancy may outweigh the risk of recurring disease activity, particularly in women with highly active MS. GA and IFNβ are considered safe during breastfeeding. The use of natalizumab during pregnancy or lactation requires monitoring of the newborn. Conclusions: This review provides current evidence and recommendations for counseling and management of women with MS preconception, during pregnancy and postpartum.

Extending the Interval of Natalizumab Dosing: Is Efficacy Preserved?

Extending the natalizumab interval after the 24th administration could reduce the risk of progressive multifocal leukoencephalopathy (PML). The objective is to evaluate the noninferiority of the efficacy of an extended interval dosing (EID) compared with the standard interval dosing (SID) of natalizumab. It is an observational, multicenter (14 Italian centers), retrospective cohort study, starting from the 24th natalizumab infusion to the loss of follow-up or 2 years after baseline. Patients were grouped in 2 categories according to the mean number of weeks between doses: < 5 weeks, SID; ≥ 5 weeks, EID. Three hundred and sixty patients were enrolled. Median dose interval (MDI) following 24th infusion was 4.7 weeks, with a bimodal distribution (modes at 4 and 6 weeks). Two hundred and sixteen patients were in the SID group (MDI = 4.3 weeks) and 144 in the EID group (MDI 6.2 weeks). Annualized relapse rate was 0.060 (95% CI = 0.033-0.087) in the SID group and 0.039 (95% CI = 0.017-0.063) in the EID group. The non-inferiority of EID versus SID was satisfied. In conclusion, there is no evidence of a reduced efficacy of natalizumab in an EID setting. This observation confirms previous results and together with the emerging evidence of a reduced risk of PML associated to an EID, supports the need of a randomized study to assess the need to change the standard of the natalizumab dosing schedule.

Therapy with cladribine is efficient and safe in patients previously treated with natalizumab

Background:

The humanized anti-α4 integrin monoclonal antibody natalizumab has proven to be very effective in patients with highly active relapsing-remitting multiple sclerosis (MS), but harbors the risk of progressive multifocal leukoencephalopathy (PML). Recently, new therapeutic options have become available for patients with high risk of developing PML while on natalizumab treatment. One of these new therapeutics is the oral synthetic purine analogue cladribine. In order to determine whether therapy with cladribine is effective and safe in patients with MS who previously had been treated with natalizumab, we analyzed clinical, radiological, and laboratory data of 17 patients whose disease modifying treatment (DMT) was switched from natalizumab to cladribine.

Methods:

A total of 17 patients with prior natalizumab treatment were switched to a DMT with cladribine because of a John Cunningham virus (JCV) antibody index above 1.5 (N = 13), ongoing disease activity (N = 6), magnetic resonance imaging (MRI) disease activity (N = 4), or patients preference (N = 2). A chart review and follow up of those patients was performed. In addition to MRI and laboratory data, clinical data regarding MS relapses and disease progression or possible adverse events were analyzed.

Results:

The median duration of cladribine treatment between February 2018 and April 2019 amounted to 9.7 months (range: 1.5–15 months). None of our 17 patients presented with a clinical relapse. Only two patients showed a new T2 lesion on brain MRI, but without any signs of PML. As expected, reduction of lymphocyte count was frequent in cladribine-treated patients, but only four patients exhibited lymphopenia grade 2 (500–800/µl).

Conclusions:

In our cohort the switch from natalizumab to cladribine treatment was effective and safe. So far, no serious adverse events other than lymphopenia have been observed, especially no cases of PML.

Risk of natalizumab-associated PML in patients with MS is reduced with extended interval dosing

OBJECTIVE

To use the large dataset from the Tysabri Outreach: Unified Commitment to Health (TOUCH) program to compare progressive multifocal leukoencephalopathy (PML) risk with natalizumab extended interval dosing (EID) vs standard interval dosing (SID) in patients with multiple sclerosis (MS).

METHODS

This retrospective cohort study included anti-JC virus antibody-positive patients (n = 35,521) in the TOUCH database as of June 1, 2017. The effect of EID on PML risk was evaluated with 3 planned analyses using Kaplan-Meier methods stratified by prior immunosuppressant use. Risk of PML was analyzed by Cox regression adjusted for age, sex, prior immunosuppressants, time since natalizumab initiation, and cumulative number of infusions.

RESULTS

This study included 35,521 patients (primary analysis: 1,988 EID, 13,132 SID; secondary analysis: 3,331 EID, 15,424 SID; tertiary analysis: 815 EID, 23,168 SID). Mean average dosing intervals were 35.0 to 43.0 and 29.8 to 30.5 days for the EID and SID cohorts, respectively. Hazard ratios (95% confidence intervals) of PML risk for EID vs SID were 0.06 (0.01-0.22, p < 0.001) and 0.12 (0.05-0.29, p < 0.001) for the primary and secondary analyses, respectively. Relative risk reductions were 94% and 88% in favor of EID for the primary and secondary analyses, respectively. The tertiary analysis included no cases of PML with EID.

CONCLUSION

Natalizumab EID is associated with clinically and statistically significantly lower PML risk than SID.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for patients with MS, natalizumab EID is associated with a lower PML risk than SID.

Pharmacodynamic assessment of cell-bound natalizumab on PBMC samples stored in liquid nitrogen

Natalizumab is a monoclonal IgG4 antibody used for treatment of relapsing remitting MS. Natalizumab interferes with lymphocyte migration by blocking alpha-4 integrin (CD49d). Saturation levels of alpha-4 integrin on circulating T cells by natalizumab have been associated with clinical effectiveness of therapy. However, in most cases, measurements have been carried out using freshly isolated PBMCs. The aim of this study was to set up and evaluate a method to measure relative levels of cell-bound natalizumab using frozen PBMC samples. A new method was set up to measure cell-bound natalizumab by flow cytometry on T cell subsets using fully saturated cells as a 100% reference. A comparison was made between spike samples and samples of natalizumab-treated MS patients freshly isolated and stored in liquid nitrogen. Cell-bound natalizumab could be measured (using an anti-IgG4 antibody) on cells stored in liquid nitrogen. Natalizumab was found to slowly dissociate from the cells during isolation and subsequent sample work-up. This dissociation was more pronounced for monovalent natalizumab resulting from Fab arm exchange (the predominant isoform in patients) than bivalent natalizumab straight from the vial. We established a correction factor to account for this phenomenon. The resulting method has good accuracy compared to assessing fresh cells. The inter-assay precision (%CV) is ca. 12% using frozen cells. In conclusion, we established a method to assess relative levels of cell-bound natalizumab on cells obtained from frozen PBMC samples.