Effect of Ezogabine on Cortical and Spinal Motor Neuron Excitability in Amyotrophic Lateral Sclerosis: A Randomized Clinical Trial.

Importance: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of the motor nervous system. Clinical studies have demonstrated cortical and spinal motor neuron hyperexcitability using transcranial magnetic stimulation and threshold tracking nerve conduction studies, respectively, although metrics of excitability have not been used as pharmacodynamic biomarkers in multi-site clinical trials. Objective: To ascertain whether ezogabine decreases cortical and spinal motor neuron excitability in ALS. Design, Setting, and Participants: This double-blind, placebo-controlled phase 2 randomized clinical trial sought consent from eligible participants from November 3, 2015, to November 9, 2017, and was conducted at 12 US sites within the Northeast ALS Consortium. Participants were randomized in equal numbers to a higher or lower dose of ezogabine or to an identical matched placebo, and they completed in-person visits at screening, baseline, week 6, and week 8 for clinical assessment and neurophysiological measurements. Interventions: Participants were randomized to receive 600 mg/d or 900 mg/d of ezogabine or a matched placebo for 10 weeks. Main Outcomes and Measures: The primary outcome was change in short-interval intracortical inhibition (SICI; SICI-1 was used in analysis to reflect stronger inhibition from an increase in amplitude) from pretreatment mean at screening and baseline to the full-dose treatment mean at weeks 6 and 8. The secondary outcomes included levels of cortical motor neuron excitability (including resting motor threshold) measured by transcranial magnetic stimulation and spinal motor neuron excitability (including strength-duration time constant) measured by threshold tracking nerve conduction studies. Results: A total of 65 participants were randomized to placebo (23), 600 mg/d of ezogabine (23), and 900 mg/d of ezogabine (19 participants); 45 were men (69.2%) and the mean (SD) age was 58.3 (8.8) years. The SICI-1 increased by 53% (mean ratio, 1.53; 95% CI, 1.12-2.09; P = .009) in the 900-mg/d ezogabine group vs placebo group. The SICI-1 did not change in the 600-mg/d ezogabine group vs placebo group (mean ratio, 1.15; 95% CI, 0.87-1.52; P = .31). The resting motor threshold increased in the 600-mg/d ezogabine group vs placebo group (mean ratio, 4.61; 95% CI, 0.21-9.01; P = .04) but not in the 900-mg/d ezogabine group vs placebo group (mean ratio, 1.95; 95% CI, -2.64 to 6.54; P = .40). Ezogabine caused a dose-dependent decrease in excitability by several other metrics, including strength-duration time constant in the 900-mg/d ezogabine group vs placebo group (mean ratio, 0.73; 95% CI, 0.60 to 0.87; P < .001). Conclusions and Relevance: Ezogabine decreased cortical and spinal motor neuron excitability in participants with ALS, suggesting that such neurophysiological metrics may be used as pharmacodynamic biomarkers in multisite clinical trials. Trial Registration: ClinicalTrials.gov Identifier: NCT02450552.

Pharmacological Profiling of Purified Human Stem Cell-Derived and Primary Mouse Motor Neurons.

Directed differentiation of human pluripotent stem cells (hPSCs) has enabled the generation of specific neuronal subtypes that approximate the intended primary mammalian cells on both the RNA and protein levels. These cells offer unique opportunities, including insights into mechanistic understanding of the early driving events in neurodegenerative disease, replacement of degenerating cell populations, and compound identification and evaluation in the context of precision medicine. However, whether the derived neurons indeed recapitulate the physiological features of the desired bona fide neuronal subgroups remains an unanswered question and one important for validating stem cell models as accurate functional representations of the primary cell types. Here, we purified both hPSC-derived and primary mouse spinal motor neurons in parallel and used extracellular multi-electrode array (MEA) recording to compare the pharmacological sensitivity of neuronal excitability and network function. We observed similar effects for most receptor and channel agonists and antagonists, supporting the consistency between human PSC-derived and mouse primary spinal motor neuron models from a physiological perspective.

A Tongue Lesion as a Sign of a Systemic Disease.

Amyloidosis is the extracellular fibril deposition of a variety of proteins, many of which circulate as plasma ingredients. It is a disease difficult to identify due to its nonspecific symptoms and manifestations. Amyloidosis of the tongue, either isolated or part of the systemic disease, is rare and its features resemble those of a tumor. We report the case of a patient with amyloidosis who presented with a tongue lesion, weakness, nonspecific arthritis, and dyspnea on exertion that resulted in multiorgan system failure.