Soluble serum VCAM-1, whole blood mRNA expression and treatment response in natalizumab-treated multiple sclerosis

Soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1) and Natalizumab Serum Concentration as Potential Biomarkers for Pharmacodynamics and Treatment Response of Patients with Multiple Sclerosis Receiving Natalizumab

BACKGROUND

Natalizumab (NTZ) is an established treatment for highly active, relapsing-remitting multiple sclerosis. In the context of rare progressive multifocal leukoencephalopathy and extended interval dosing as a treatment option, biomarkers for treatment monitoring are required. Natalizumab serum concentration (NTZ SC) and soluble vascular cell adhesion molecule 1 (sVCAM-1) concentration were shown to change on treatment with NTZ. We aimed to investigate whether NTZ SC and sVCAM-1 could be suitable pharmacodynamic markers and whether they could predict disease activity on NTZ, improving the concept of personalized multiple sclerosis treatment.

METHODS

In a retrospective study at the Medical University of Innsbruck, Austria, we identified patients treated with NTZ and chose samples longitudinally collected during routine follow-ups for the measurement of NTZ SC and sVCAM-1 by an enzyme-linked immunosorbent assay. We correlated these with clinical and demographic variables and clinical outcomes. Furthermore, we analyzed the stability of NTZ SC and sVCAM-1 during treatment.

RESULTS

One hundred and thirty-seven patients were included. We found a strong negative correlation between NTZ SC and sVCAM-1. Both showed significant associations with body mass index, infusion interval, sample age, and anti-drug-antibodies. Natalizumab serum concentration was reduced in extended interval dosing, but not sVCAM-1. Only sVCAM-1 showed a weak association with relapses during treatment, while there was no association with disease progression. Both NTZ SC and sVCAM-1 showed a wide inter-individual distribution while levels in single patients were stable on treatment.

CONCLUSIONS

Soluble vascular cell adhesion molecule 1 is a suitable pharmacodynamic marker during treatment with NTZ, which is significantly reduced already after the first dose, remains stable in individual patients even on extended interval dosing, and strongly correlates with NTZ SC. Because of the high inter-individual range, absolute levels of sVCAM-1 and NTZ SC are difficult to introduce as treatment monitoring biomarkers in order to predict disease activity in single patients.

Alterations of the miR-126-3p/POU2AF1/Spi-B Axis and JCPyV Reactivation in Multiple Sclerosis Patients Receiving Natalizumab

Natalizumab (NTZ) can reactivate human polyomavirus John Cunningham polyomavirus (JCPyV) latent infection and lead to progressive multifocal leukoencephalopathy (PML). NTZ modulates the expression of microRNA-126-3p (miR-126-3p) and its target genes, Spi-B, POU2AF1, and vascular cell adhesion molecule-1 (VCAM-1); Spi-B protein binds the JCPyV regulatory region, initiating early gene transcription. This paper is aimed to evaluate the miR-126-3p and soluble (s)VCAM-1 concentration, Spi-B/POU2AF1 gene expression, and JCPyV activity in patients with multiple sclerosis (MS) before and during 2-years NTZ. Serum miR-126-3p and sVCAM-1 concentration was measured before NTZ and after 1, 12, and 24 months of treatment in 22 MS subjects, 1 patient who developed PML, and 29 healthy controls (HCs). The Spi-B and POU2AF1 expression in blood was analyzed at baseline and at month 24 in 13 patients with MS; results were clusterized based on JCPyV activity. miR-126-3p was significantly downregulated in MS before and during NTZ but was greatly increased in the PML patient. sVCAM-1 concentration was comparable in MS and HCs, and was reduced by NTZ in MS and PML. Spi-B/POU2AF1 expression was significantly increased in MS at baseline and was upregulated by NTZ, particularly in JCPyV-infected patients in whom JCPyV reactivation was detected. Taken together, the results suggest that the modulation of the miR-126-3p/POU2AF1/Spi-B axis associates with JCPyV activity in NTZ-treated patients with MS.

Assessing Blood-Based Biomarkers to Define a Therapeutic Window for Natalizumab

Natalizumab is a monoclonal antibody that binds CD49d. Although it is one of the most effective treatments for Relapsing-Remitting Multiple Sclerosis (RRMS), a dosing regimen has not been optimized for safety and efficacy in individual patients. We aimed to identify biomarkers to monitor Natalizumab treatment and to establish a personalized dose utilizing an ongoing longitudinal study in 29 RRMS patients under Natalizumab with standard interval dose (SD) of 300 mg/4wks or extended interval dose (EID) of 300 mg/6wks. Blood samples were analyzed by flow cytometry to determine CD49d saturation and expression in several T and B lymphocytes subpopulations. Each patient was analyzed at two different timepoints separated by 3 Natalizumab administrations. Natalizumab and sVCAM-1 levels in serum were also analyzed using ELISA. To determine the reproducibility of various markers, two different timepoints were compared and no significant differences were observed for CD49d expression nor for saturation; SD patients had higher saturation levels (~80%) than EID patients (~60%). A positive correlation exists between CD49d saturation and Natalizumab serum levels. CD49d expression and saturation are stable parameters that could be used as biomarkers in the immunomonitoring of Natalizumab treatment. Moreover, Natalizumab and sVCAM-1 serum levels could be used to optimize an individual's dosing schedule.