ECTRIMS/ACTRIMS 2017: Closing in on neurorepair in progressive multiple sclerosis

Failed, Interrupted, or Inconclusive Trials on Immunomodulatory Treatment Strategies in Multiple Sclerosis: Update 2015-2020

In the past decades, multiple sclerosis (MS) treatment has experienced vast changes resulting from major advances in disease-modifying therapies (DMT). Looking at the overall number of studies, investigations with therapeutic advantages and encouraging results are exceeded by studies of promising compounds that failed due to either negative or inconclusive results or have been interrupted for other reasons. Importantly, these failed clinical trials are informative experiments that can help us to understand the pathophysiological mechanisms underlying MS. In several trials, concepts taken from experimental models were not translatable to humans, although they did not lack a well-considered pathophysiological rationale. The lessons learned from these discrepancies may benefit future studies and reduce the risks for patients. This review summarizes trials on MS since 2015 that have either failed or have been interrupted for various reasons. We identify potential causes of failure or inconclusiveness, looking at the path from basic animal experiments to clinical trials, and discuss the implications for our current view on MS pathogenesis, clinical practice, and future study designs. We focus on anti-inflammatory treatment strategies, without including studies on already approved and effective DMT. Clinical trials addressing neuroprotective and alternative treatment strategies are presented in a separate article.

The monoclonal antibody GNbAC1: targeting human endogenous retroviruses in multiple sclerosis

Background:

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS). Despite improvements of immunomodulatory therapies in relapsing–remitting MS, the pathomechanisms of progressive disease are poorly understood and therapeutically addressed to date. A pathophysiological role for proteins encoded by human endogenous retroviruses (HERVs) has been proposed. GNbAC1 is a monoclonal antibody directed against the envelope protein of a HERV with postulated involvement in MS.

Methods:

This review addresses the treatment concept of GNbAC1, the design, preclinical and clinical development of the antibody, as published by November 2018. All four in-human trials (of which two addressed MS) are discussed.

Conclusion:

The treatment concept of GNbAC1 is appealing but remains controversial due to conflicting results regarding the hypothesized underlying pathomechanism. Anticipated immunomodulatory effects were not observed in clinical or pharmacodynamic analyses of the currently available data. However, a magnetic resonance imaging sign compatible with the remyelinating potential of GNbAC1 encouraged further development of this antibody in progressive MS. No relevant issues with tolerability or safety have been described to date.