Multiple Sclerosis, Dimethyl Fumarate, Diffusion Tensor Imaging Magnetic Resonance Imaging Clinical Trial
Official title:
An Open-label, Observational, Single-blinded, Longitudinal Study to Evaluate the Effect of Dimethyl Fumarate on Gray and White Matter Pathology in Subjects With Relapsing Multiple Sclerosis
The primary aim of this study is to explore the effect of dimethyl fumarate on gray matter (GM) pathology, as measured by changes in diffusion-tensor imaging (DTI) of the thalamus in patients with relapsing multiple sclerosis (MS). The secondary objective of this study is to investigate the effect of dimethyl fumarate on evolution of microstructural changes in normal appearing white matter (NAWM), as measured by DTI.
Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune disorder characterized
by chronic inflammation, axonal demyelination, and neuronal degeneration. The complex
pathophysiology of MS is mediated by autoreactive T cells that ultimately invade and attack
the CNS by traversing the blood-brain barrier (BBB), resulting in persistent irreversible
axonal damage and physical disability. Magnetic resonance imaging (MRI) metrics contribute
substantially to the diagnosis and management of MS, providing critical information
regarding disease activity in addition to serving as secondary endpoint measures for
clinical trials evaluating MS therapies. Traditional MRI techniques (e.g., contrast enhanced
[CE] T1-weighted imaging, spin-echo [SE] T2-weighted imaging [T2-WI]) have proven effective
for detecting the presence of macroscopic white matter (WM) MS lesions but are limited by
the inability to effectively delineate microscopic tissue damage occurring in
normal-appearing white matter (NAWM) and microscopic and macroscopic tissue damage in
normal-appearing gray matter (NAGM). Furthermore, the brain-lesion burden on traditional MRI
scans correlates only modestly with clinical disease progression. Thus, a need exists to use
alternative non-conventional MRI techniques and approaches that more accurately monitor
clinical disease activity and efficacy of disease-modifying therapies.
Dimethyl fumarate (Biogen Idec, Inc, Cambridge, MA, USA) is an FDA approved oral treatment
for relapsing MS. One phase II and 2 phase III randomized, placebo-controlled and
double-blinded clinical trials established that dimethyl fumarate significantly reduces
relapse rates and improves disability along with neuroradiologic outcomes relative to
placebo.
There is growing evidence to suggest that oxidative stress has a significant role in the
pathogenesis of MS. Therapies that reduce oxidative stress, as well as inflammation, are of
increasing interest. Fumaric acid esters are known to activate anti-oxidative pathways, as
well as modulate the inflammatory cascade. Several in vivo studies have shown that nuclear
factor E2-related factor 2 (Nrf2) has a role in attenuating proinflammatory stimuli through
the modulation of cytokine signaling and through its involvement in glutathione homeostasis.
For example, in one animal study, Nrf2-deficient mice were found to have increased
expression of proinflammatory mediators, including cyclooxygenase-2, interleukin (IL)-1b,
IL-6 and tumour necrosis factor-a, compared with wild-type mice. Nrf2 is also established as
the guardian of redox homeostasis and has been shown to be critical for attenuating
oxidative stress. Under oxidative conditions, Nrf2 enters into and accumulates within the
nucleus of cells and activates the expression of a battery of cytoprotective and
detoxification genes. A number of in vitro and in vivo studies have consistently
demonstrated the key role of the Nrf2 signaling pathway in protecting the CNS from oxidative
stress-related damage. Currently, oral dimethyl fumarate is the only agent that appears to
directly target Nrf2, which it does by inducing the cleavage of kelch-like erythroid
cell-derived protein with "cap'n'collar" homology-associated protein 1 (Keap1) from Nrf2 in
the cell cytoplasm. By cleaving this Keap1-Nrf2 complex, Nrf2 is free to cross the nuclear
membrane and interact with other nuclear transcription factors to upregulate the antioxidant
response element. Via this mechanism, dimethyl fumarate appears to have a distinct dual
mechanism of action in attenuating oxidative stress as well as in reducing inflammatory
response.
Dimethyl fumarate showed robust effect in suppressing the appearance of new CE, T2
hyperintense and T1 hypointense lesions along with their volumes. In a recent study,
dimethyl fumarate also exerted potential for cytoprotection and remyelination, as evidenced
by changes in magnetization transfer ratio. However, the dimethyl fumarate effect on
non-conventional MRI metrics, such as diffusion-tensor imaging (DTI) has not been explored.
;
Observational Model: Case Control