Author Of 1 Presentation
LB01.02 - Phase 2 clinical trial evidence that a retinoid-X receptor agonist promotes remyelination in people with relapsing-remitting multiple sclerosis
Abstract
Background
Retinoid acid X receptor [RXR] gamma agonists promote oligodendrocyte progenitor cell differentiation and remyelination following experimental demyelination.
Objectives
To assess the safety and efficacy of bexarotene, a non-specific RXR agonist licensed for cutaneous T-cell lymphoma, as a remyelinating therapy in people with relapsing remitting multiple sclerosis.
Methods
In a double-blind, placebo-controlled, phase 2a trial (Cambridge Centre for Myelin Repair: CCMR-One), participants aged 18-50 years with relapsing remitting multiple sclerosis, stable on dimethyl fumarate for at least 6 months, were randomised to bexarotene 300mg/m2 or placebo for 6 months. The primary efficacy outcome was change in mean lesional magnetisation transfer ratio (MTR) for lesions whose baseline MTR was below the median lesional MTR for that patient. The secondary efficacy outcome was change in full-field visual evoked potential (VEP) latency in eyes with electrophysiological evidence of optic neuropathy (baseline latency >118ms). We analysed by intention to treat.
Results
52 patients were randomised 1:1 to receive six months of bexarotene or placebo. Two placebo patients withdrew before receiving study drug and one bexarotene patient withdrew consent during the trial. All bexarotene patients experienced adverse effects, notably central hypothyroidism (26 [100%]) and hypertriglyceridaemia (24 [92%, mean maximum of 6.79 mmol/L ,SD 4.4]; as well as rash (13 [50%]) and neutropenia (10 [38%]). Two discontinued placebo because of adverse events and five discontinued bexarotene because of rash [2], neutropenia, triglyceridaemia and mood disturbance. The primary efficacy outcome was negative (mean submedian lesion MTR change was 0.25pu in the bexarotene group versus 0.09pu in the placebo group, p=0.54), but in an exploratory, lesion-level analysis, though treatment difference in submedian lesions was too small to achieve significance, it was statistically significantly greater than in supermedian lesions (p=0·007). This suggests that bexarotene has a biological effect on MTR and that this effect is dependent on baseline lesional MTR. This interpretation is supported by the finding that bexarotene treatment reduced full field visual evoked potential latency compared to placebo in the 52 eyes with delayed VEPS at baseline, by 4·66 ms/eye (95% CI -8·38 -0·93; p=0·014) and in all eyes, by a per-protocol analysis, by 4.02ms/eye (P=0.015).
Conclusions
Despite a negative primary efficacy outcome, evidence from both magnetisation transfer ratio imaging and visual evoked potentials suggest that a retinoic X receptor agonist, bexarotene, promotes remyelination in people with multiple sclerosis. We have also a heterogeneous response of MS lesions to a drug promoting remyelination. Although bexarotene’s safety profile precludes its widespread use, these data support efforts to develop a selective RXR-gamma agonist.
Author Of 1 Presentation
P0671 - Exploring the gut microbiome in multiple sclerosis via the international MS Microbiome Study (iMSMS) (ID 1532)
- S. Singh
- M. Mendoza
- R. Baumann
- J. Landefeld
- P. Casaccia
- I. Katz Sand
- Z. Xia
- H. Weiner
- T. Chitnis
- S. Chandran
- P. Connick
- D. Oteagui
- T. Castillo-Trivino
- S. Caillier
- A. Santaniello
- G. Ackermann
- G. Humphrey
- L. Negrotto
- M. Farez
- R. Hohlfeld
- A. Pröbstel
- X. Jia
- J. Graves
- A. Bar-Or
- H. Wekerle
- J. Oksenberg
- T. West
- J. Correale
- B. Cree
- S. Hauser
- R. Knight
- S. Baranzini
Abstract
Background
The gut microbiota is emerging as a critical regulator of immune responses and appears to play an important role in MS. The International Multiple Sclerosis Microbiome study (iMSMS) is a global collaboration aimed at elucidating the role of commensal gut bacteria in MS by acquiring and analyzing samples from 2000 patients and 2000 household healthy controls.
Objectives
The iMSMS focuses on identifying the microbes, genes and pathways that are involved in MS pathogenesis and on investigating how the microbiome changes response to treatment.
Methods
A total of 576 case and household healthy control pairs were recruited from 7 centers located in the US (West and East coasts), Europe and South America. Stool samples were collected and evaluated by both 16S and shallow whole metagenome shotgun sequencing. Univariate and multivariate linear regression analyses were conducted to understand patterns of variation on gut microbiome.
Results
This is the largest MS microbiome study reported to date. Our results showed a statistically significant difference of beta diversity between MS and healthy controls for the first time in MS. Intriguingly, multiple species of Akkermansia, including the known mucin-degrading bacterium Akkermansia muciniphila, were significantly enriched in untreated MS patients after adjusting for confounding factors, but the difference was not detected in treated MS group versus control. Ruminococcus torques and Eisenbergiella tayi were also among the top significantly enriched bacteria in MS. Inversely, a main butyrate producer, Faecalibacterium prausnitzii, was significantly decreased in the untreated MS group. Functional pathways of L-tryptophan biosynthesis and L-threonine biosynthesis were slightly increased in untreated MS patients, while 5-aminoimidazole ribonucleotide biosynthesis I was increased in the treated group.
Conclusions
Our large household-controlled study allowed us to identify modest but statistically robust MS-associated changes in bacterial composition and functions. It provides the foundation for all future studies of the gut microbiota in MS. The strain-level genomic variation and microbiome-derived molecules need to be further explored for understanding microbial adaptation and pathogenicity.