Tocilizumab is safe and tolerable and reduces C-reactive protein concentrations in the plasma and cerebrospinal fluid of ALS patients

Document Type

Article

Abstract

Introduction/Aims: We tested safety, tolerability, and target engagement of tocilizumab in amyotrophic lateral sclerosis (ALS) patients. Methods: Twenty-two participants, whose peripheral blood mononuclear cell (PBMC) gene expression profile reflected high messenger ribonucleic acid (mRNA) expression of inflammatory markers, were randomized 2:1 to three tocilizumab or placebo treatments (weeks 0, 4, and 8; 8 mg/kg intravenous). Participants were followed every 4 wk in a double-blind fashion for 16 wk and assessed for safety, tolerability, plasma inflammatory markers, and clinical measures. Cerebrospinal fluid (CSF) was collected at baseline and after the third treatment. Participants were genotyped for Asp358Ala polymorphism of the interleukin 6 receptor (IL-6R) gene. Results: Baseline characteristics, safety, and tolerability were similar between treatment groups. One serious adverse event was reported in the placebo group; no deaths occurred. Mean plasma C-reactive protein (CRP) level decreased by 88% in the tocilizumab group and increased by 4% in the placebo group (−3.0-fold relative change, P <.001). CSF CRP reduction (−1.8-fold relative change, P =.01) was associated with IL-6R C allele count. No differences in PBMC gene expression or clinical measures were observed between groups. Discussion: Tocilizumab treatment was safe and well tolerated. PBMC gene expression profile was inadequate as a predictive or pharmacodynamic biomarker. Treatment reduced CRP levels in plasma and CSF, with CSF effects potentially dependent on IL-6R Asp358Ala genotype. IL-6 trans-signaling may mediate a distinct central nervous system response in individuals inheriting the IL-6R C allele. These results warrant further study in ALS patients where IL-6R genotype and CRP levels may be useful enrichment biomarkers.

Keywords

amyotrophic lateral sclerosis, C-reactive protein, interleukin-6, microglia, tocilizumab

Publication Date

9-1-2021

Publication Title

Muscle and Nerve

ISSN

0148639X

E-ISSN

10974598

Volume

64

Issue

3

First Page

309

Last Page

320

PubMed ID

34075589

Digital Object Identifier (DOI)

10.1002/mus.27339

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