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.

Statistical methodology for highly variable compounds: A novel design approach for the ofatumumab Phase 2 bioequivalence study.

This article describes a novel mixed-scaling testing strategy, in combination with an adaptive parallel-groups bioequivalence trial, to test pharmacokinetic equivalence of two formulations of a drug with highly variable pharmacokinetics. The methodology was applied to the Phase 2 APLIOS study in relapsing multiple sclerosis patients, where the bioequivalence of subcutaneous ofatumumab 20 mg administered via an autoinjector pen (test formulation) versus prefilled syringe (reference formulation) in the abdomen has been studied. Due to a high coefficient of variation (CV) of the relevant pharmacokinetic metrics (AUCtau and Cmax ) for the reference formulation (>30%), a reference-Scaled bioequivalence (RSABE) approach was applied but modified for a parallel-groups design. In the absence of regulatory guidance for applying RSABE in parallel-group designs, and in contrast to the available regulatory guidance for RSABE in cross-over trials, the suggested testing strategy uses the between-subject variability of the reference drug instead of the corresponding within-subject variability that would be available if a standard cross-over bioequivalence trial had been possible. Moreover, due to high uncertainty in the initial CV estimate for the sample size determination, a two-stage adaptive design was used, allowing for a sample size adjustment based on the pharmacokinetic variability observed at an interim analysis. The interim analysis timing was pre-specified based on simulations which included re-estimation of the final sample size at the end of the first stage to ensure sufficient power of the RSABE test at the end of the second stage. Using this approach, bioequivalence was shown between the test and reference formulations. The APLIOS trial is registered at ClinicalTrials.gov: NCT03560739.

Rapid and sustained B-cell depletion with subcutaneous ofatumumab in relapsing multiple sclerosis: APLIOS, a randomized phase-2 study.

BACKGROUND: Ofatumumab, the first fully human anti-CD20 monoclonal antibody, is approved in several countries for relapsing multiple sclerosis (RMS). OBJECTIVE: To demonstrate the bioequivalence of ofatumumab administered by an autoinjector versus a pre-filled syringe (PFS) and to explore the effect of ofatumumab on B-cell depletion. METHODS: APLIOS (NCT03560739) is a 12-week, open-label, parallel-group, phase-2 study in patients with RMS receiving subcutaneous ofatumumab 20 mg every 4 weeks (q4w) (from Week 4, after initial doses on Days 1, 7, and 14). Patients were randomized 10:10:1:1 to autoinjector or PFS in the abdomen, or autoinjector or PFS in the thigh, respectively. Bioequivalence was determined by area under the curve (AUCτ) and maximum plasma concentration (Cmax) for Weeks 8-12. B-cell depletion and safety/tolerability were assessed. RESULTS: A total of 256 patients contributed to the bioequivalence analyses (autoinjector-abdomen, n = 128; PFS-abdomen, n = 128). Abdominal ofatumumab pharmacokinetic exposure was bioequivalent for autoinjector and PFS (geometric mean AUCτ, 487.7 vs 474.1 h × µg/mL (ratio 1.03); Cmax, 1.409 vs 1.409 µg/mL (ratio 1.00)). B-cell counts (median cells/µL) depleted rapidly in all groups from 214.0 (baseline) to 2.0 (Day 14). Ofatumumab was well tolerated. CONCLUSION: Ofatumumab 20 mg q4w self-administered subcutaneously via autoinjector is bioequivalent to PFS administration and provides rapid B-cell depletion.

A framework to guide dose & regimen strategy for clinical drug development.

Optimizing new drug therapies remains a challenge for clinical development, despite the use of ever more sophisticated quantitative methodologies. Although conceptually simple, the idea of finding the right treatment at the right dose for the right patient to ensure an appropriate balance of risks and benefits is challenging and requires a multidisciplinary approach. In this paper, we present a framework developed as a tool for organizing knowledge and facilitating collaboration in development teams.