Targeting B cells in multiple sclerosis

Pharmacokinetics, Pharmacodynamics, Bioavailability, and Immunogenicity of Obexelimab Following Subcutaneous Administration in Healthy Japanese and Non-Japanese Volunteers

INTRODUCTION

Obexelimab is an investigational, bifunctional, non-depleting, humanized monoclonal antibody that binds CD19 and FcγRIIb to inhibit B cells, plasmablasts, and CD19-expressing plasma cells. In clinical trials, intravenous (IV) administration of obexelimab has been well-tolerated, and demonstrated clinical activity in patients with rheumatoid arthritis, systemic lupus erythematosus, and immunoglobulin G4-related disease. This study was performed to evaluate the pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of obexelimab following subcutaneous (SC) administration, and compare PK/PD profiles between healthy Japanese and non-Japanese volunteers.

METHODS

This was a Phase I, open-label, parallel group, multiple-dose study. Participants were randomized to five cohorts to receive three doses of obexelimab as 125 mg SC every 14 days (q14d), 250 mg SC q14d, 375 mg SC q14d, 250 mg IV q14d, and 125 mg SC every 7 days, then monitored during a 28-day safety follow-up period. PK/PD assessments were performed after the first and third doses.

RESULTS

A total of 50 healthy volunteers (25 Japanese and 25 non-Japanese) were enrolled and distributed evenly between dose cohorts. All SC dosing regimens were well-tolerated. Dose-proportional PK was observed following SC doses with a bioavailability of approximately 60%. No clinically meaningful differences in PK parameters were found between healthy Japanese and non-Japanese participants. Antidrug antibodies (ADA) were detected in 6/50 (12%) participants after dosing. ADA had no or minimal impact on PK in all six ADA positive participants. Near-complete CD19 receptor occupancy and an absolute B-cell count nadir of approximately 50% baseline levels were maintained for the duration of the study in both populations.

CONCLUSION

Obexelimab SC administration demonstrated favorable bioavailability, was well-tolerated, and showed no clinically meaningful ethnic differences in PK/PD. These results support further clinical development of SC obexelimab to treat B-cell mediated autoimmune diseases.

TRIAL REGISTRATION

NCT02867098.

Leptomeningeal enhancement in multiple sclerosis and other neurological diseases: A systematic review and Meta-Analysis

BACKGROUND

The lack of systematic evidence on leptomeningeal enhancement (LME) on MRI in neurological diseases, including multiple sclerosis (MS), hampers its interpretation in clinical routine and research settings.

PURPOSE

To perform a systematic review and meta-analysis of MRI LME in MS and other neurological diseases.

MATERIALS AND METHODS

In a comprehensive literature search in Medline, Scopus, and Embase, out of 2292 publications, 459 records assessing LME in neurological diseases were eligible for qualitative synthesis. Of these, 135 were included in a random-effects model meta-analysis with subgroup analyses for MS.

RESULTS

Of eligible publications, 161 investigated LME in neoplastic neurological (n = 2392), 91 in neuroinfectious (n = 1890), and 75 in primary neuroinflammatory diseases (n = 4038). The LME-proportions for these disease classes were 0.47 [95%-CI: 0.37-0.57], 0.59 [95%-CI: 0.47-0.69], and 0.26 [95%-CI: 0.20-0.35], respectively. In a subgroup analysis comprising 1605 MS cases, LME proportion was 0.30 [95%-CI 0.21-0.42] with lower proportions in relapsing-remitting (0.19 [95%-CI 0.13-0.27]) compared to progressive MS (0.39 [95%-CI 0.30-0.49], p = 0.002) and higher proportions in studies imaging at 7 T (0.79 [95%-CI 0.64-0.89]) compared to lower field strengths (0.21 [95%-CI 0.15-0.29], p < 0.001). LME in MS was associated with longer disease duration (mean difference 2.2 years [95%-CI 0.2-4.2], p = 0.03), higher Expanded Disability Status Scale (mean difference 0.6 points [95%-CI 0.2-1.0], p = 0.006), higher T1 (mean difference 1.6 ml [95%-CI 0.1-3.0], p = 0.04) and T2 lesion load (mean difference 5.9 ml [95%-CI 3.2-8.6], p < 0.001), and lower cortical volume (mean difference -21.3 ml [95%-CI -34.7--7.9], p = 0.002).

CONCLUSIONS

Our study provides high-grade evidence for the substantial presence of LME in MS and a comprehensive panel of other neurological diseases. Our data could facilitate differential diagnosis of LME in clinical settings. Additionally, our meta-analysis corroborates that LME is associated with key clinical and imaging features of MS. PROSPERO No: CRD42021235026.

Radiosynthesis of [11C]Ibrutinib via Pd-Mediated [11C]CO Carbonylation: Preliminary PET Imaging in Experimental Autoimmune Encephalomyelitis Mice

Ibrutinib is a first-generation Bruton's tyrosine kinase (BTK) inhibitor that has shown efficacy in autoimmune diseases and has consequently been developed as a positron emission tomography (PET) radiotracer. Herein, we report the automated radiosynthesis of [11C]ibrutinib through 11C-carbonylation of the acrylamide functional group, by reaction of the secondary amine precursor with [11C]CO, iodoethylene, and palladium-NiXantphos. [11C]Ibrutinib was reliably formulated in radiochemical yields of 5.4% ± 2.5% (non-decay corrected; n = 9, relative to starting [11C]CO2), radiochemical purity >99%, and molar activity of 58.8 ± 30.8 GBq/μmol (1.55 ± 0.83 Ci/μmol). Preliminary PET/magnetic resonance imaging with [11C]ibrutinib in experimental autoimmune encephalomyelitis (EAE) mice showed a 49% higher radioactivity accumulation in the spinal cord of mice with EAE scores of 2.5 vs. sham mice.