Lancet neurology
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Oral treatment options for disease-modifying therapy in relapsing multiple sclerosis have substantially increased over the past decade with four approved oral compounds now available: fingolimod, dimethyl fumarate, teriflunomide, and cladribine. Although these immunomodulating therapies are all orally administered, and thus convenient for patients, they have different modes of action. These distinct mechanisms of action allow better adaption of treatments according to individual comorbidities and offer different mechanisms of treatment such as inhibition of immune cell trafficking versus immune cell depletion, thereby substantially expanding the available treatment options. ⋯ New sphingosine-1-phosphate receptor (S1PR) modulators with more specific S1PR target profiles and potentially better safety profiles compared with fingolimod were tested in patients with relapsing multiple sclerosis. For example, siponimod, which targets S1PR1 and S1PR5, was approved in March, 2019, by the US Food and Drug Administration for the treatment of relapsing multiple sclerosis including active secondary progressive multiple sclerosis. Ozanimod, another S1P receptor modulator in the approval stage that also targets S1PR1 and S1PR5, reduced relapse rates and MRI activity in two phase 3 trials of patients with relapsing multiple sclerosis. Blocking of matrix metalloproteinases or tyrosine kinases are novel modes of action in the treatment of relapsing multiple sclerosis, which are exhibited by minocycline and evobrutinib, respectively. Minocycline reduced conversion to multiple sclerosis in patients with a clinically isolated syndrome. Evobrutinib reduced MRI activity in a phase 2 trial, and a phase 3 trial is underway, in patients with relapsing multiple sclerosis. Diroximel fumarate is metabolised to monomethyl fumarate, the active metabolite of dimethyl fumarate, reduces circulating lymphocytes and modifies the activation profile of monocytes, and is being tested in this disease with the aim to improve gastrointestinal tolerability. The oral immunomodulator laquinimod did not reach the primary endpoint of reduction in confirmed disability progression in a phase 3 trial of patients with relapsing multiple sclerosis. In a phase 2 trial of patients with primary progressive multiple sclerosis, laquinimod also did not reach the primary endpoint of a reduction in brain volume loss, as a consequence the development of this drug will probably not be continued in multiple sclerosis. WHERE NEXT?: Several new oral compounds are in late-stage clinical development. With new modes of action introduced to the treatment of multiple sclerosis, the question of how to select and sequence different treatments in individual patients arises. Balancing risks with the expected efficacy of disease-modifying therapies will still be key for treatment selection. However, risks as well as efficacy can change when moving from the controlled clinical trial setting to clinical practice. Because some oral treatments, such as cladribine, have long-lasting effects on the immune system, the cumulative effects of sequential monotherapies can resemble the effects of a concurrent combination therapy. This treatment scheme might lead to higher efficacy but also to new safety concerns. These sequential treatments were largely excluded in phase 2 and 3 trials; therefore, monitoring both short-term and long-term effects of sequential disease-modifying therapies in phase 4 studies, cohort studies, and registries will be necessary.
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Prion disease is a rare, fatal, and exceptionally rapid neurodegenerative disease. Although incurable, prion disease follows a clear pathogenic mechanism, in which a single gene gives rise to a single prion protein (PrP) capable of converting into the sole causal disease agent, the misfolded prion. As efforts progress to leverage this mechanistic knowledge toward rational therapies, a principal challenge will be the design of clinical trials. ⋯ About 15% of prion disease cases are genetic, creating an opportunity for early therapeutic intervention to delay or prevent disease. Highly variable age of onset and absence of established prodromal biomarkers might render infeasible existing models for testing drugs before disease onset. Advancement of near-term targeted therapeutics could crucially depend on thoughtful design of rigorous presymptomatic trials.
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Stroke remains a leading cause of adult disability and the demand for stroke rehabilitation services is growing. Substantial advances are yet to be made in stroke rehabilitation practice to meet this demand and improve patient outcomes relative to current care. ⋯ Strategies for improving trial quality include new approaches to the selection of patients, control interventions, and endpoint measures. Although stroke rehabilitation research strives for better trials, interventions, and outcomes, rehabilitation practices continue to help patients regain independence after stroke.
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Alzheimer's disease is a debilitating and highly heritable neurological condition. As such, genetic studies have sought to understand the genetic architecture of Alzheimer's disease since the 1990s, with successively larger genome-wide association studies (GWAS) and meta-analyses. These studies started with a small sample size of 1086 individuals in 2007, which was able to identify only the APOE locus. In 2013, the International Genomics of Alzheimer's Project (IGAP) did a meta-analysis of all existing GWAS using data from 74 046 individuals, which stood as the largest Alzheimer's disease GWAS until 2018. This meta-analysis discovered 19 susceptibility loci for Alzheimer's disease in populations of European ancestry. ⋯ Three new Alzheimer's disease GWAS published in 2018 and 2019, which used larger sample sizes and proxy phenotypes from biobanks, have substantially increased the number of known susceptibility loci in Alzheimer's disease to 40. The first, an updated GWAS from IGAP, included 94 437 individuals and discovered 24 susceptibility loci. Although IGAP sought to increase sample size by recruiting additional clinical cases and controls, the two other studies used parental family history of Alzheimer's disease to define proxy cases and controls in the UK Biobank for a genome-wide association by proxy, which was meta-analysed with data from GWAS of clinical Alzheimer's disease to attain sample sizes of 388 324 and 534 403 individuals. These two studies identified 27 and 29 susceptibility loci, respectively. However, the three studies were not independent because of the large overlap in their participants, and interpretation can be challenging because different variants and genes were highlighted by each study, even in the same locus. Furthermore, neither the variant with the strongest Alzheimer's disease association nor the nearest gene are necessarily causal. This situation presents difficulties for experimental studies, drug development, and other future research. WHERE NEXT?: The ultimate goal of understanding the genetic architecture of Alzheimer's disease is to characterise novel biological pathways that underly Alzheimer's disease pathogenesis and to identify novel drug targets. GWAS have successfully contributed to the characterisation of the genetic architecture of Alzheimer's disease, with the identification of 40 susceptibility loci; however, this does not equate to the discovery of 40 Alzheimer's disease genes. To identify Alzheimer's disease genes, these loci need to be mapped to variants and genes through functional genomics studies that combine annotation of variants, gene expression, and gene-based or pathway-based analyses. Such studies are ongoing and have validated several genes at Alzheimer's disease loci, but greater sample sizes and cell-type specific data are needed to map all GWAS loci.