Stride Velocity 95th Centile Detects Decline in Ambulatory Function Over Shorter Intervals than the 6-Minute Walk Test or North Star Ambulatory Assessment in Duchenne Muscular Dystrophy.

Background: Stride Velocity 95th Centile (SV95C) is the first wearable device-derived clinical outcome assessment (COA) to receive European Medicines Agency (EMA) qualification as a primary endpoint in ambulant patients with Duchenne muscular dystrophy (DMD) aged ≥4 years. Objective: To compare SV95C-in its first-ever clinical trial application as a secondary endpoint-with established motor function COAs used in the trial (Four-Stair Climb [4SC] velocity, North Star Ambulatory Assessment [NSAA], and Six-Minute Walk Distance [6MWD]). Methods: SV95C was a secondary endpoint in a subset (n = 47) of participants in the SPITFIRE/WN40227 trial of taldefgrobep alfa, which was discontinued due to lack of clinical benefit. Participants in the ≤48-week SV95C sub-study were 6-11 years old and received corticosteroids for ≥6 months pre-treatment. Pearson correlations were used to compare SV95C with the other COAs. Responsiveness and changes over time were respectively assessed via standardized response means (SRMs) based on absolute changes and mixed models for repeated measures. Results: SV95C change at Week 24 was -0.07 m/s, with limited variability (standard deviation: 0.16, n = 27). The SRM for SV95C indicated moderate responsiveness to clinical change at the earliest timepoint (Week 12, n = 46), while those of the other COAs did not indicate moderate responsiveness until Week 36 (6MWD, n = 33) or Week 48 (4SC velocity, n = 20; NSAA total score, n = 20). Baseline correlations between SV95C and other COAs were strong (r = 0.611-0.695). Correlations between SV95C change from baseline to Week 48 and changes in other COAs were moderate to strong (r = 0.443-0.678).∥. Conclusions: Overall, SV95C demonstrated sensitivity to ambulatory decline over short intervals, low variability, and correlation with established COAs. Although the negative trial precluded demonstration of SV95C's sensitivity to drug effect, these findings support the continued use of SV95C in DMD clinical trials.

Evolving regulatory perspectives on digital health technologies for medicinal product development.

Digital health technology tools (DHTTs) present real opportunities for accelerating innovation, improving patient care, reducing clinical trial duration and minimising risk in medicines development. This review is comprised of four case studies of DHTTs used throughout the lifecycle of medicinal products, starting from their development. These cases illustrate how the regulatory requirements of DHTTs used in medicines development are based on two European regulatory frameworks (medical device and the medicinal product regulations) and highlight the need for increased collaboration between various stakeholders, including regulators (medicines regulators and device bodies), pharmaceutical sponsors, manufacturers of devices and software, and academia. As illustrated in the examples, the complexity of the interactions is further increased by unique challenges related to DHTTs. These case studies are the main examples of DHTTs with a regulatory assessment thus far, providing an insight into the applicable current regulatory approach; they were selected by a group of authors, including regulatory specialists from pharmaceutical sponsors, technology experts, academic researchers and employees of the European Medicines Agency. For each case study, the challenges faced by sponsors and proposed potential solutions are discussed, and the benefit of a structured interaction among the different stakeholders is also highlighted.

Stride Velocity 95th Centile: Insights into Gaining Regulatory Qualification of the First Wearable-Derived Digital Endpoint for use in Duchenne Muscular Dystrophy Trials.

In 2019, stride velocity 95th centile (SV95C) became the first wearable-derived digital clinical outcome assessment (COA) qualified by the European Medicines Agency (EMA) for use as a secondary endpoint in trials for Duchenne muscular dystrophy. SV95C was approved via the EMA's qualification pathway for novel methodologies for medicine development, which is a voluntary procedure for assessing the regulatory acceptability of innovative methods used in pharmaceutical research and development. SV95C is an objective, real-world digital ambulation measure of peak performance, representing the speed of the fastest strides taken by the wearer over a recording period of 180 hours. SV95C is correlated with traditional clinic-based assessments of motor function and has greater sensitivity to clinical change over 6 months than other wearable-derived stride variables, for example, median stride length or velocity. SV95C overcomes many limitations of episodic, clinic-based motor function testing, allowing the assessment of ambulation ability between clinic visits and under free-living conditions. Here we highlight considerations and challenges in developing SV95C using evidence generated by a high-performance wearable sensor. We also provide a commentary of the device's technical capabilities, which were a determining factor in the regulatory approval of SV95C. This article aims to provide insights into the methods employed, and the challenges faced, during the regulatory approval process for researchers developing new digital tools for patients with diseases that affect motor function.

First Regulatory Qualification of a Novel Digital Endpoint in Duchenne Muscular Dystrophy: A Multi-Stakeholder Perspective on the Impact for Patients and for Drug Development in Neuromuscular Diseases.

BACKGROUND: Functional outcome measures used to assess efficacy in clinical trials of investigational treatments for rare neuromuscular diseases like Duchenne muscular dystrophy (DMD) are performance-based tasks completed by the patient during hospital visits. These are prone to bias and may not reflect motor abilities in real-world settings. Digital tools, such as wearable devices and other remote sensors, provide the opportunity for continuous, objective, and sensitive measurements of functional ability during daily life. Maintaining ambulation is of key importance to individuals with DMD. Stride velocity 95th centile (SV95C) is the first wearable acquired digital endpoint to receive qualification from the European Medicines Agency (EMA) to quantify the ambulation ability of ambulant DMD patients aged ≥5 years in drug therapeutic studies; it is also currently under review for the US Food and Drug Administration (FDA) qualification. SUMMARY: Focusing on SV95C as a key example, we describe perspectives of multiple stakeholders on the promise of novel digital endpoints in neuromuscular disease drug development.

Functional characterization of hyperpolarization-activated cyclic nucleotide-gated channels in rat pancreatic beta cells.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate pacemaker activity in some cardiac cells and neurons. In the present study, we have identified the presence of HCN channels in pancreatic beta-cells. We then examined the functional characterization of these channels in beta-cells via modulating HCN channel activity genetically and pharmacologically. Voltage-clamp experiments showed that over-expression of HCN2 in rat beta-cells significantly increased HCN current (I(h)), whereas expression of dominant-negative HCN2 (HCN2-AYA) completely suppressed endogenous I(h). Compared to control beta-cells, over-expression of I(h) increased insulin secretion at 2.8 mmol/l glucose. However, suppression of I(h) did not affect insulin secretion at both 2.8 and 11.1 mmol/l glucose. Current-clamp measurements revealed that HCN2 over-expression significantly reduced beta-cell membrane input resistance (R(in)), and resulted in a less-hyperpolarizing membrane response to the currents injected into the cell. Conversely, dominant negative HCN2-AYA expression led to a substantial increase of R(in), which was associated with a more hyperpolarizing membrane response to the currents injected. Remarkably, under low extracellular potassium conditions (2.5 mmol/l K(+)), suppression of I(h) resulted in increased membrane hyperpolarization and decreased insulin secretion. We conclude that I(h) in beta-cells possess the potential to modulate beta-cell membrane potential and insulin secretion under hypokalemic conditions.

Effects of pan- and subtype-selective N-methyl-D-aspartate receptor antagonists on cortical spreading depression in the rat: therapeutic potential for migraine.

Spreading depression (SD) has long been associated with the underlying pathophysiology of migraine. Evidence that the N-methyl-D-aspartate (NMDA) glutamate receptor (NMDA-R) is implicated in the generation and propagation of SD has itself been available for more than 15 years. However, to date, there are no reports of NMDA-R antagonists being developed for migraine therapy. In this study, an uncompetitive, pan-NMDA-R blocker, memantine, approved for clinical use, and two antagonists with selectivity for NMDA-R containing the NR2B subunit, (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606) and (+/-)-(R*,S*)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propanol (Ro 25-6981), were investigated to assess their protective effects against SD in the rat. Under isoflurane anesthesia, d.c. potential and the related cortical blood flow and partial pressure of O2 (pO2) were recorded simultaneously at separate cortical sites. Drugs (1, 3, and 10 mg/kg i.p.) were given 1 h or 30 min before KCl application to the brain surface. Core temperature and arterial pCO2,pO2, and pH measurements confirmed physiological stability. KCl induced 7.7+/-1.8 (mean+/-S.D.) SD events with d.c. amplitude of 14.9+/-2.8 mV. Memantine and CP-101,606 dose-dependently decreased SD event number (to 2.0+/-1.8 and 2.3+/-2.9, respectively) and SD amplitude at doses relevant for therapeutic use. Ro 25-6981 also decreased SD events significantly, but less effectively (to 4.5+/-1.6), without affecting amplitude. These results indicate that NR2B-containing NMDA receptors are key mediators of SD, and as such, memantine- and NR2B-selective antagonists may be useful new therapeutic agents for the treatment of migraine and other SD-related disorders (e.g., stroke and brain injury). Whether chronic, rather than acute, treatment may improve their efficacy remains to be determined.

Characterization of the human HCN1 channel and its inhibition by capsazepine.

The human hyperpolarization-activated cyclic nucleotide-gated 1 (hHCN1) subunit was heterologously expressed in mammalian cell lines (CV-1 and CHO) and its properties investigated using whole-cell patch-clamp recordings. Activation of this recombinant channel, by membrane hyperpolarization, generated a slowly activating, noninactivating inward current. The pharmacological properties of hHCN1-mediated currents resembled those of native hyperpolarization-activated currents (I(h)), that is, blockade by Cs(+) (99% at 5 mm), ZD 7288 (98% at 100 microm) and zatebradine (92% at 10 microm). Inhibition of the hHCN1-mediated current by ZD 7288 was apparently independent of prior channel activation (i.e. non-use-dependent), whereas that induced by zatebradine was use-dependent. The VR1 receptor antagonist capsazepine inhibited hHCN1-mediated currents in a concentration-dependent (IC(50)=8 microm), reversible and apparently non-use-dependent manner. This inhibitory effect of capsazepine was voltage-independent and associated with a leftward shift in the hHCN1 activation curve as well as a dramatic slowing of the kinetics of current activation. Elevation of intracellular cAMP or extracellular K(+) significantly enhanced aspects of hHCN1 currents. However, these manipulations did not significantly affect the capsazepine-induced inhibition of hHCN1. The development of structural analogues of capsazepine may yield compounds that could selectively inhibit HCN channels and prove useful for the treatment of neurological disorders where a role for HCN channels has been described.

Regulation of calcitonin gene-related peptide release from rat trigeminal nucleus caudalis slices in vitro.

Calcitonin gene-related peptide (CGRP) released from trigeminal primary afferents has been implicated in the pathophysiology of migraine. Here, we have used an in vitro slice preparation to investigate its release from nerve terminals in the rat trigeminal nucleus caudalis. Extracellular-calcium dependent CGRP release was stimulated by both capsaicin and neuronal depolarization with KCl. The capsaicin (1 microM)-evoked CGRP release was blocked by capsazepine and was also attenuated in the presence of the cyclooxygenase inhibitor, indomethacin, an effect that was reversed when slices were stimulated with capsaicin in the presence of the cyclooxygenase metabolite, prostaglandin E(2). Taken together, these data further highlight the importance of prostaglandins as enhancers of neuropeptide release and suggest that CGRP released from the central terminals of trigeminal neurones has the potential to be involved in the transmission of nociceptive information of relevance to migraine headache.

Mitogen and stress response kinase-1 (MSK1) mediates excitotoxic induced death of hippocampal neurones.

Activation of the mitogen-activated protein kinase (MAPK/ERK) signal transduction pathway may mediate excitotoxic neuronal cell death in vitro and during ischemic brain injury in vivo. However, little is known, of the upstream regulation or downstream consequences of ERK activation under these conditions. Magnesium removal has been described to induce hyperexcitability and degeneration in cultured hippocampal neurones. Here, we show that neurotoxicity evoked by Mg2+ removal in primary hippocampal neurones stimulates ERK, but not p38, phosphorylation. Removal of Mg2+ also resulted in induction of the MAPK/ERK substrate mitogen- and stress-response kinase 1 (MSK1) and induced phosphorylation of the MSK1 substrate, the transcription factor cAMP response element binding protein (CREB). Neuronal death and phosphorylation of components in this cascade were inhibited by the Raf inhibitor SB-386023, by the MEK inhibitor U0126, or by the MSK1 inhibitors H89 and Ro318220. Importantly, this form of cell death was inhibited in hippocampal neurones cultured from MSK1-/- mice and inhibitors of Raf or MEK had no additive neuroprotective effect. Together, these data indicate that MSK1 is a physiological kinase for CREB and that this activity is an essential component of activity-dependent neuronal cell death.

The neuronal versus vascular hypothesis of migraine and cortical spreading depression.

Our understanding of the pathophysiological mechanisms of migraine remains poor despite the availability of clinically effective drugs and many years of research. Historically, two independent theories regarding the aetiology of headache were suggested: vascular and neuronal. However, recent data demonstrate that neuronal excitation modulates both the pial and meningeal circulation through a critical interaction with the trigeminal nerve, supporting the concept that the integration of neuronal and vascular information in the trigeminovascular network represents a key event in the aetiology of migraine.

Eletriptan Pfizer.

Pfizer has developed and launched eletriptan, a 5-HT1B/1D agonist, for the potential treatment of migraine with and without aura. Eletriptan has 6-fold greater affinity for the 5-HT1D receptor than sumatriptan, and a 3-fold greater affinity for the 5-HT1B receptor [249570]. Eletriptan pharmacology has also been evaluated in vitro in comparison with zolmitriptan (AstraZeneca plc) and naratriptan (GlaxoSmithKline plc) [290116].

The selective p38 inhibitor SB-239063 protects primary neurons from mild to moderate excitotoxic injury.

Inhibition of the p38 mitogen-activated protein kinase (MAP Kinase) pathway reduces acute ischemic injury in vivo, suggesting a direct role for this signaling pathway in a number of neurodegenerative processes. The present study was designed to evaluate further the role of p38 MAP Kinase in acute excitotoxic neuronal injury using the selective p38 inhibitor SB-239063 (trans-1-(4hydroxycyclohexyl)-4-(fluorophenyl)-5-(2-methoxy-pyrimidin-4-yl) imidazole). Unlike the widely used p38 inhibitor, SB-203580 (4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole), this second generation p38 inhibitor more selectively inhibits p38 MAP Kinase without affecting the activity of other MAP Kinase signaling pathways and provides a more accurate means to selectively assess the role of p38 in excitotoxicity that has not been previously possible. SB-239063 provided substantial protection against cell death induced by either oxygen glucose deprivation (OGD) or magnesium deprivation in cultured neurons. The ability of this compound to block excitotoxicity was not due to direct inhibition of N-methyl-D-aspartate (NMDA) receptor-mediated currents as SB-239063 did not alter NMDA electrophysiological responses. SB-239063 did not protect against a severe excitotoxic insult induced by 60-min exposure to NMDA. However, when tested against a less severe, brief (5 min) NMDA exposure, p38 inhibition provided substantial protection. These data demonstrate that inhibition of p38 MAP Kinase can confer neuroprotection in vitro against mild but not severe excitotoxic exposure, and suggests that other additional pathways/mechanism(s) may be involved in severe excitotoxic cell death.