Safety, pharmacokinetics, and target engagement of a brain penetrant RIPK1 inhibitor, SAR443820 (DNL788), in healthy adult participants.

SAR443820 (DNL788) is a selective, orally bioavailable, brain penetrant inhibitor of receptor-interacting serine/threonine protein kinase 1 (RIPK1). This phase I first-in-human healthy participant study (NCT05795907) was comprised of three parts: randomized, double-blind, placebo-controlled single ascending dose (SAD; part 1a); 14-day multiple ascending dose (MAD; part 2) parts that evaluated safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of SAR443820; and a separate open-label, single-dose part 1b (PK-cerebrospinal fluid [CSF]) to assess SAR443820 levels in CSF. SAR443820 was well-tolerated in healthy participants, and no treatment discontinuation related to an adverse event (AE) occurred. Most common AEs were dizziness and headache. No clinically meaningful changes were noted in laboratory values, vital signs, or electrocardiogram parameters. SAR443820 had a favorable PK profile, with plasma half-lives (geometric mean) ranged between 5.7-8.0 h and 7.2-8.9 h after single and repeated doses, respectively. There were no major deviations from dose proportionality for maximum concentration and area under the curve across SAR443820 doses. Mean CSF-to-unbound plasma concentration ratio ranged from 0.8 to 1.3 over time (assessed up to 10 h postdose), indicating high brain penetrance. High levels of inhibition of activated RIPK1, as measured by decrease in pS166-RIPK1, were achieved in both SAD and MAD parts, with a maximum median inhibition from baseline close to 90% at predose (Ctrough ) after multiple dosing in MAD, reflecting a marked RIPK1 target engagement at the peripheral level. These results support further development of SAR443820 in phase II trials in amyotrophic lateral sclerosis (NCT05237284) and multiple sclerosis (NCT05630547).

An innovative phase 2 proof-of-concept trial design to evaluate SAR445088, a monoclonal antibody targeting complement C1s in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND AND AIMS: Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare immune-mediated disease of the peripheral nerves, with significant unmet treatment needs. Clinical trials in CIDP are challenging; thus, new trial designs are needed. We present design of an open-label phase 2 study (NCT04658472) evaluating efficacy and safety of SAR445088, a monoclonal antibody targeting complement C1s, in CIDP. METHODS: This phase 2, proof-of-concept, multicenter, open-label trial will evaluate the efficacy, and safety of SAR445088 in 90 patients with CIDP across three groups: (1) currently treated with standard-of-care (SOC) therapies, including immunoglobulin or corticosteroids (SOC-Treated); (2) refractory to SOC (SOC-Refractory); and (3) naïve to SOC (SOC-Naïve). Enrolled participants undergo a 24-week treatment period (part A), followed by an optional treatment extension for up to an additional 52 weeks (part B). In part A, the primary endpoint for the SOC-Treated group is the percentage of participants with a relapse after switching from SOC to SAR445088. The primary endpoint for the SOC-Refractory and SOC-Naïve groups is the percentage of participants with a response, compared to baseline. Secondary endpoints include safety, tolerability, immunogenicity, and efficacy of SAR445088 during 12-week overlapping period (SOC-Treated). Part B evaluates long-term safety and durability of efficacy. Data analysis will be performed using Bayesian statistics (predefined efficacy thresholds) and historical data-based placebo assumptions to support program decision-making. INTERPRETATION: This innovative trial design based on patient groups and Bayesian statistics provides an efficient paradigm to evaluate new treatment candidates across the CIDP spectrum and can help accelerate development of new therapies.

Classical Complement Pathway Inhibition in a "Human-On-A-Chip" Model of Autoimmune Demyelinating Neuropathies.

Chronic autoimmune demyelinating neuropathies are a group of rare neuromuscular disorders with complex, poorly characterized etiology. Here we describe a phenotypic, human-on-a-chip (HoaC) electrical conduction model of two rare autoimmune demyelinating neuropathies, chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN), and explore the efficacy of TNT005, a monoclonal antibody inhibitor of the classical complement pathway. Patient sera was shown to contain anti-GM1 IgM and IgG antibodies capable of binding to human primary Schwann cells and induced pluripotent stem cell derived motoneurons. Patient autoantibody binding was sufficient to activate the classical complement pathway resulting in detection of C3b and C5b-9 deposits. A HoaC model, using a microelectrode array with directed axonal outgrowth over the electrodes treated with patient sera, exhibited reductions in motoneuron action potential frequency and conduction velocity. TNT005 rescued the serum-induced complement deposition and functional deficits while treatment with an isotype control antibody had no rescue effect. These data indicate that complement activation by CIDP and MMN patient serum is sufficient to mimic neurophysiological features of each disease and that complement inhibition with TNT005 was sufficient to rescue these pathological effects and provide efficacy data included in an investigational new drug application, demonstrating the model's translational potential.

Selective atrophy of the cervical enlargement in whole spinal cord MRI of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a deadly neurodegenerative disorder affecting motor neurons in the spinal cord and brain. Studies have reported on atrophy within segments of the cervical cord, but we are not aware of previous investigations of the whole spinal cord. Herein we present our findings from a 3T MRI study involving 32 subjects (15 ALS participants and 17 healthy controls) characterizing cross-sectional area along the entire cord. We report atrophy of the cervical enlargement in ALS participants, but no evidence of atrophy of the thoracolumbar enlargement. These results suggest that MR-based analyses of the cervical cord may be sufficient for in vivo investigations of spinal cord atrophy in ALS, and that atrophy of the cervical enlargement (C4-C7) is a potential imaging marker for quantifying lower motor neuron degradation.

Safety, pharmacokinetics and target engagement of novel RIPK1 inhibitor SAR443060 (DNL747) for neurodegenerative disorders: Randomized, placebo-controlled, double-blind phase I/Ib studies in healthy subjects and patients.

RIPK1 is a master regulator of inflammatory signaling and cell death and increased RIPK1 activity is observed in human diseases, including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). RIPK1 inhibition has been shown to protect against cell death in a range of preclinical cellular and animal models of diseases. SAR443060 (previously DNL747) is a selective, orally bioavailable, central nervous system (CNS)-penetrant, small-molecule, reversible inhibitor of RIPK1. In three early-stage clinical trials in healthy subjects and patients with AD or ALS (NCT03757325 and NCT03757351), SAR443060 distributed into the cerebrospinal fluid (CSF) after oral administration and demonstrated robust peripheral target engagement as measured by a reduction in phosphorylation of RIPK1 at serine 166 (pRIPK1) in human peripheral blood mononuclear cells compared to baseline. RIPK1 inhibition was generally safe and well-tolerated in healthy volunteers and patients with AD or ALS. Taken together, the distribution into the CSF after oral administration, the peripheral proof-of-mechanism, and the safety profile of RIPK1 inhibition to date, suggest that therapeutic modulation of RIPK1 in the CNS is possible, conferring potential therapeutic promise for AD and ALS, as well as other neurodegenerative conditions. However, SAR443060 development was discontinued due to long-term nonclinical toxicology findings, although these nonclinical toxicology signals were not observed in the short duration dosing in any of the three early-stage clinical trials. The dose-limiting toxicities observed for SAR443060 preclinically have not been reported for other RIPK1-inhibitors, suggesting that these toxicities are compound-specific (related to SAR443060) rather than RIPK1 pathway-specific.

The Role of the Complement System in Chronic Inflammatory Demyelinating Polyneuropathy: Implications for Complement-Targeted Therapies.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common, heterogeneous, immune-mediated neuropathy, characterized by predominant demyelination of motor and sensory nerves. CIDP follows a relapsing-remitting or a progressive course and causes substantial disability. The pathogenesis of CIDP involves a complex interplay of multiple aberrant immune responses, creating a pro-inflammatory environment, subsequently inflicting damage on the myelin sheath. Though the exact triggers are unclear, diverse immune mechanisms encompassing cellular and humoral pathways are implicated. The complement system appears to play a role in promoting macrophage-mediated demyelination. Complement deposition in sural nerve biopsies, as well as signs of increased complement activation in serum and CSF of patients with CIDP, suggest complement involvement in CIDP pathogenesis. Here, we present a comprehensive overview of the preclinical and clinical evidence supporting the potential role of the complement system in CIDP. This understanding furnishes a strong rationale for targeting the complement system to develop new therapies that could serve the unmet needs of patients affected by CIDP, particularly in those refractory to standard therapies.

Tocilizumab is safe and tolerable and reduces C-reactive protein concentrations in the plasma and cerebrospinal fluid of ALS patients.

INTRODUCTION/AIMS: We tested safety, tolerability, and target engagement of tocilizumab in amyotrophic lateral sclerosis (ALS) patients. METHODS: Twenty-two participants, whose peripheral blood mononuclear cell (PBMC) gene expression profile reflected high messenger ribonucleic acid (mRNA) expression of inflammatory markers, were randomized 2:1 to three tocilizumab or placebo treatments (weeks 0, 4, and 8; 8 mg/kg intravenous). Participants were followed every 4 wk in a double-blind fashion for 16 wk and assessed for safety, tolerability, plasma inflammatory markers, and clinical measures. Cerebrospinal fluid (CSF) was collected at baseline and after the third treatment. Participants were genotyped for Asp358 Ala polymorphism of the interleukin 6 receptor (IL-6R) gene. RESULTS: Baseline characteristics, safety, and tolerability were similar between treatment groups. One serious adverse event was reported in the placebo group; no deaths occurred. Mean plasma C-reactive protein (CRP) level decreased by 88% in the tocilizumab group and increased by 4% in the placebo group (-3.0-fold relative change, P < .001). CSF CRP reduction (-1.8-fold relative change, P = .01) was associated with IL-6R C allele count. No differences in PBMC gene expression or clinical measures were observed between groups. DISCUSSION: Tocilizumab treatment was safe and well tolerated. PBMC gene expression profile was inadequate as a predictive or pharmacodynamic biomarker. Treatment reduced CRP levels in plasma and CSF, with CSF effects potentially dependent on IL-6R Asp358 Ala genotype. IL-6 trans-signaling may mediate a distinct central nervous system response in individuals inheriting the IL-6R C allele. These results warrant further study in ALS patients where IL-6R genotype and CRP levels may be useful enrichment biomarkers.

Ibudilast (MN-166) in amyotrophic lateral sclerosis- an open label, safety and pharmacodynamic trial.

Ibudilast (MN-166) is an inhibitor of macrophage migration inhibitory factor (MIF) and phosphodiesterases 3,4,10 and 11 (Gibson et al., 2006; Cho et al., 2010). Ibudilast attenuates CNS microglial activation and secretion of pro-inflammatory cytokines (Fujimoto et al., 1999; Cho et al., 2010). In vitro evidence suggests that ibudilast is neuroprotective by suppressing neuronal cell death induced by microglial activation. People with ALS have increased microglial activation measured by [11C]PBR28-PET in the motor cortices. The primary objective is to determine the impact of ibudilast on reducing glial activation and neuroaxonal loss in ALS, measured by PBR28-PET and serum Neurofilament light (NfL). The secondary objectives included determining safety and tolerability of ibudilast high dosage (up to 100 mg/day) over 36 weeks. In this open label trial, 35 eligible ALS participants underwent ibudilast treatment up to 100 mg/day for 36 weeks. Of these, 30 participants were enrolled in the main study cohort and were included in biomarker, safety and tolerability analyses. Five additional participants were enrolled in the expanded access arm, who did not meet imaging eligibility criteria and were included in the safety and tolerability analyses. The primary endpoints were median change from baseline in (a) PBR28-PET uptake in primary motor cortices, measured by standard uptake value ratio (SUVR) over 12-24 weeks and (b) serum NfL over 36-40 weeks. The secondary safety and tolerability endpoints were collected through Week 40. The baseline median (range) of PBR28-PET SUVR was 1.033 (0.847, 1.170) and NfL was 60.3 (33.1, 219.3) pg/ml. Participants who completed both pre and post-treatment scans had PBR28-PET SUVR median(range) change from baseline of 0.002 (-0.184, 0.156) , P = 0.5 (n = 22). The median(range) NfL change from baseline was 0.4 pg/ml (-1.8, 17.5), P = 0.2 (n = 10 participants). 30(86%) participants experienced at least one, possibly study drug related adverse event. 13(37%) participants could not tolerate 100 mg/day and underwent dose reduction to 60-80 mg/day and 11(31%) participants discontinued study drug early due to drug related adverse events. The study concludes that following treatment with ibudilast up to 100 mg/day in ALS participants, there were no significant reductions in (a) motor cortical glial activation measured by PBR28-PET SUVR over 12-24 weeks or (b) CNS neuroaxonal loss, measured by serum NfL over 36-40 weeks. Dose reductions and discontinuations due to treatment emergent adverse events were common at this dosage in ALS participants. Future pharmacokinetic and dose-finding studies of ibudilast would help better understand tolerability and target engagement in ALS.

Ultra-high field (7T) functional magnetic resonance imaging in amyotrophic lateral sclerosis: a pilot study.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the central nervous system that results in a progressive loss of motor function and ultimately death. It is critical, yet also challenging, to develop non-invasive biomarkers to identify, localize, measure and/or track biological mechanisms implicated in ALS. Such biomarkers may also provide clues to identify potential molecular targets for future therapeutic trials. Herein we report on a pilot study involving twelve participants with ALS and nine age-matched healthy controls who underwent high-resolution resting state functional magnetic resonance imaging at an ultra-high field of 7 Tesla. A group-level whole-brain analysis revealed a disruption in long-range functional connectivity between the superior sensorimotor cortex (in the precentral gyrus) and bilateral cerebellar lobule VI. Post hoc analyses using atlas-derived left and right cerebellar lobule VI revealed decreased functional connectivity in ALS participants that predominantly mapped to bilateral postcentral and precentral gyri. Cerebellar lobule VI is a transition zone between anterior motor networks and posterior non-motor networks in the cerebellum, and is associated with a wide range of key functions including complex motor and cognitive processing tasks. Our observation of the involvement of cerebellar lobule VI adds to the growing number of studies implicating the cerebellum in ALS. Future avenues of scientific investigation should consider how high-resolution imaging at 7T may be leveraged to visualize differences in functional connectivity disturbances in various genotypes and phenotypes of ALS along the ALS-frontotemporal dementia spectrum.

Comparison of Two Clinical Upper Motor Neuron Burden Rating Scales in ALS Using Quantitative Brain Imaging.

Several clinical upper motor neuron burden scales (UMNSs) variably measure brain dysfunction in amyotrophic lateral sclerosis (ALS). Here, we compare relationship of two widely used clinical UMNSs in ALS (Penn and MGH UMNSs) with (a) neuroimaging markers of brain dysfunction and (b) neurological impairment status using the gold-standard functional measure, the revised ALS Functional Rating Scale (ALSFRS-R). MGH UMNS measures hyperreflexia alone, and Penn UMNS measures hyperreflexia, spasticity, and pseudobulbar affect. Twenty-eight ALS participants underwent both Penn and MGH UMNSs, at a matching time-point as a simultaneous [11C]PBR28 positron emission tomography (PBR28-PET)/Magnetic Resonance scan and ALSFRS-R. The two UMNSs were compared for localization and strength of association with neuroimaging markers of: (a) neuroinflammation, PBR28-PET and MR Spectroscopy metabolites (myo-inositol and choline) and (b) corticospinal axonal loss, fractional anisotropy (FA), and MR Spectroscopy metabolite (N-acetylaspartate). Among clinical UMN manifestations, segmental hyperreflexia, spasticity, and pseudobulbar affect occurred in 100, 43, and 18% ALS participants, respectively. Pseudobulbar affect did not map to any specific brain regional dysfunction, while hyperreflexia and spasticity subdomains significantly correlated and colocalized neurobiological changes to corticospinal pathways on whole brain voxel-wise analyses. Both UMNS total scores showed significant and similar strength of association with (a) neuroimaging changes (PBR28-PET, FA, MR Spectroscopy metabolites) in primary motor cortices and (b) severity of functional decline (ALSFRS-R). Hyperreflexia is the most frequent clinical UMN manifestation and correlates best with UMN molecular imaging changes in ALS. Among Penn UMNS's subdomains, hyperreflexia carries the weight of association with neuroimaging markers of biological changes in ALS. A clinical UMN scale comprising hyperreflexia items alone is clinically relevant and sufficient to predict the highest yield of molecular neuroimaging abnormalities in ALS.

Effects of mexiletine on hyperexcitability in sporadic amyotrophic lateral sclerosis: Preliminary findings from a small phase II randomized controlled trial.

BACKGROUND: To collect preliminary data on the effects of mexiletine on cortical and axonal hyperexcitability in sporadic amyotrophic lateral sclerosis (ALS) in a phase 2 double-blind randomized controlled trial. METHODS: Twenty ALS subjects were randomized to placebo and mexiletine 300 or 600 mg daily for 4 wk and assessed by transcranial magnetic stimulation and axonal excitability studies. The primary endpoint was change in resting motor threshold (RMT). RESULTS: RMT was unchanged with 4 wk of mexiletine (combined active therapies) as compared to placebo, which showed a significant increase (P = .039). Reductions of motor evoked potential (MEP) amplitude (P = .013) and accommodation half-time (P = .002), secondary outcome measures of cortical and axonal excitability, respectively, were also evident at 4 wk on mexiletine. CONCLUSIONS: The relative stabilization of RMT in the treated subjects was unexpected and could be attributed to unaccounted sources of error or chance. However, a possible alternative cause is neuromodulation preventing an increase. The change in MEP amplitude and accommodation half-time supports the reduction of cortical and axonal hyperexcitability with mexiletine.

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.

The NEALS primary lateral sclerosis registry.

BACKGROUND AND OBJECTIVE: Primary lateral sclerosis (PLS) is a neurodegenerative disease characterized by progressive upper motor neuron dysfunction. Because PLS patients represent only 1 to 4% of patients with adult motor neuron diseases, there is limited information about the disease's natural history. The objective of this study was to establish a large multicenter retrospective longitudinal registry of PLS patients seen at Northeast ALS Consortium (NEALS) sites to better characterize the natural progression of PLS. Methods: Clinical characteristics, electrophysiological findings, laboratory values, disease-related symptoms, and medications for symptom management were collected from PLS patients seen between 2000 and 2015. Results: The NEALS registry included data from 250 PLS patients. Median follow-up time was 3 years. The mean rate of functional decline measured by ALSFRS-R total score was -1.6 points/year (SE:0.24, n = 124); the mean annual decline in vital capacity was -3%/year (SE:0.55, n = 126). During the observational period, 18 patients died, 17 patients had a feeding tube placed and 7 required permanent assistive ventilation. Conclusions: The NEALS PLS Registry represents the largest available aggregation of longitudinal clinical data from PLS patients and provides a description of expected natural disease progression. Data from the registry will be available to the PLS community and can be leveraged to plan future clinical trials in this rare disease.

Phase 1-2 Trial of Antisense Oligonucleotide Tofersen for SOD1 ALS.

BACKGROUND: Tofersen is an antisense oligonucleotide that mediates the degradation of superoxide dismutase 1 (SOD1) messenger RNA to reduce SOD1 protein synthesis. Intrathecal administration of tofersen is being studied for the treatment of amyotrophic lateral sclerosis (ALS) due to SOD1 mutations. METHODS: We conducted a phase 1-2 ascending-dose trial evaluating tofersen in adults with ALS due to SOD1 mutations. In each dose cohort (20, 40, 60, or 100 mg), participants were randomly assigned in a 3:1 ratio to receive five doses of tofersen or placebo, administered intrathecally for 12 weeks. The primary outcomes were safety and pharmacokinetics. The secondary outcome was the change from baseline in the cerebrospinal fluid (CSF) SOD1 concentration at day 85. Clinical function and vital capacity were measured. RESULTS: A total of 50 participants underwent randomization and were included in the analyses; 48 participants received all five planned doses. Lumbar puncture-related adverse events were observed in most participants. Elevations in CSF white-cell count and protein were reported as adverse events in 4 and 5 participants, respectively, who received tofersen. Among participants who received tofersen, one died from pulmonary embolus on day 137, and one from respiratory failure on day 152; one participant in the placebo group died from respiratory failure on day 52. The difference at day 85 in the change from baseline in the CSF SOD1 concentration between the tofersen groups and the placebo group was 2 percentage points (95% confidence interval [CI], -18 to 27) for the 20-mg dose, -25 percentage points (95% CI, -40 to -5) for the 40-mg dose, -19 percentage points (95% CI, -35 to 2) for the 60-mg dose, and -33 percentage points (95% CI, -47 to -16) for the 100-mg dose. CONCLUSIONS: In adults with ALS due to SOD1 mutations, CSF SOD1 concentrations decreased at the highest concentration of tofersen administered intrathecally over a period of 12 weeks. CSF pleocytosis occurred in some participants receiving tofersen. Lumbar puncture-related adverse events were observed in most participants. (Funded by Biogen; ClinicalTrials.gov number, NCT02623699; EudraCT number, 2015-004098-33.).

Moving Toward Multicenter Therapeutic Trials in Amyotrophic Lateral Sclerosis: Feasibility of Data Pooling Using Different Translocator Protein PET Radioligands.

Neuroinflammation has been implicated in amyotrophic lateral sclerosis (ALS) and can be visualized using translocator protein (TSPO) radioligands. To become a reliable pharmacodynamic biomarker for ALS multicenter trials, TSPO radioligands have some challenges to overcome. We aimed to investigate whether multicenter data pooling of different TSPO tracers (11C-PBR28 and 18F-DPA714) is feasible, after validation of an established 11C-PBR28 PET pseudo reference analysis technique for 18F-DPA714. Methods: Seven ALS patients from Belgium (58.9 ± 6.7 y old, 5 men and 2 women), 8 healthy volunteers from Belgium (52.1 ± 15.2 y old, 3 men and 5 women), 7 ALS patients from the United States (53.4 ± 9.8 y old, 5 men and 2 women), and 7 healthy volunteers from the United States (54.6 ± 9.6 y old, 4 men and 3 women) from a previously published study underwent dynamic 18F-DPA714 (Leuven, Belgium) or 11C-PBR28 (Boston, Massachusetts) PET/MRI. For 18F-DPA714, maps of total volume of distribution (VT) were compared with SUV ratio (SUVR) images from 40 to 60 min after injection (SUVR40-60) calculated using the pseudo reference regions cerebellum, occipital cortex, and whole brain (WB) without ventricles. For 11C-PBR28, SUVR images from 60 to 90 min after injection using the WB without ventricles were calculated. Results: In line with previous studies, increased 18F-DPA714 uptake (17.0% ± 5.6%) in primary motor cortices was observed in ALS subjects, as measured by both VT and SUVR40-60 approaches. The highest sensitivity was found for SUVR calculated using the WB without ventricles (average cluster, 21.6% ± 0.1%). 18F-DPA714 VT ratio was highly correlated with the SUVR40-60 (r > 0.8, P < 0.001). A similar pattern of increased uptake (average cluster, 20.5% ± 0.5%) in the primary motor cortices was observed in ALS subjects for 11C-PBR28 SUVR calculated using the WB without ventricles. Analysis of the 18F-DPA714 and 11C-PBR28 data together resulted in a more extensive pattern of significantly increased glial activation bilaterally in the primary motor cortices. Conclusion: The same pseudo reference region analysis technique for 11C-PBR28 PET can be extended toward 18F-DPA714 PET. Therefore, in ALS, standardized analysis across these 2 tracers enables pooling of TSPO PET data across multiple centers and increases the power of TSPO as a biomarker for future therapeutic trials.

Selection design phase II trial of high dosages of tamoxifen and creatine in amyotrophic lateral sclerosis.

Objective: To conduct a phase-II trial using a ranking and selection paradigm where multiple treatments are compared with limited sample size and the best is chosen for a subsequent efficacy trial versus placebo. This strategy can find an effective treatment faster than traditional strategy of conducting larger trials against placebo. Methods: Sixty amyotrophic lateral sclerosis (ALS) participants were randomized 1:1:1 to creatine 30 g/day (CRE), tamoxifen 40 mg/day (T40), or tamoxifen 80 mg/day (T80), with matching placebo. The primary outcome was 38-week change in ALS Functional Rating Scale-Revised (ALSFRS-R), analyzed in a repeated-measures ANOVA. Secondary outcomes included slow vital capacity (SVC), quantitative muscle strength, early drug discontinuation (EDD), adverse events (AEs), and survival. Results: CRE participants experienced higher rates of drug-related AEs (82% vs. 43% T40, 47% T80) and EDD (50% vs. 24% T40, 29% T80). T80 participants experienced slower adjusted mean decline in ALSFRS-R in points/month (-0.80 vs. -0.84 T40, -0.85 CRE) and quantitative muscle strength but not in SVC and higher rates of mortality. Conclusion: Efficacy of T80 ranked numerically superior to CRE and T40 with respect to ALSFRS-R decline. Following the selection paradigm, T80 would be chosen to test against placebo. The approach was not designed to distinguish among treatments that are nearly equally effective or ineffective. If treatments are equivalent, then under the paradigm, it does not matter which treatment is selected. Newer approaches for increasing trial efficiency, including an adaptive platform trial design, may mitigate limitations of the selection design.

Prospective natural history study of C9orf72 ALS clinical characteristics and biomarkers.

OBJECTIVE: To define the natural history of the C9orf72 amyotrophic lateral sclerosis (C9ALS) patient population, develop disease biomarkers, and characterize patient pathologies. METHODS: We prospectively collected clinical and demographic data from 116 symptomatic C9ALS and 12 non-amyotrophic lateral sclerosis (ALS) full expansion carriers across 7 institutions in the United States and the Netherlands. In addition, we collected blood samples for DNA repeat size assessment, CSF samples for biomarker identification, and autopsy samples for dipeptide repeat protein (DPR) size determination. Finally, we collected retrospective clinical data via chart review from 208 individuals with C9ALS and 450 individuals with singleton ALS. RESULTS: The mean age at onset in the symptomatic prospective cohort was 57.9 ± 8.3 years, and median duration of survival after onset was 36.9 months. The monthly change was -1.8 ± 1.7 for ALS Functional Rating Scale-Revised and -1.4% ± 3.24% of predicted for slow vital capacity. In blood DNA, we found that G4C2 repeat size correlates positively with age. In CSF, we observed that concentrations of poly(GP) negatively correlate with DNA expansion size but do not correlate with measures of disease progression. Finally, we found that size of poly(GP) dipeptides in the brain can reach large sizes similar to that of their DNA repeat derivatives. CONCLUSIONS: We present a thorough investigation of C9ALS natural history, providing the basis for C9ALS clinical trial design. We found that clinical features of this genetic subset are less variant than in singleton ALS. In addition, we identified important correlations of C9ALS patient pathologies with clinical and demographic data.

ALS/SURV: a modification of the CAFS statistic.

We present a composite endpoint that can be used in amyotrophic lateral sclerosis (ALS) trials, which combines functional status (via the ALS functional rating scale) and survival, denoted ALS/SURV. ALS/SURV modifies and extends the combined assessment of function and survival (CAFS) score and assigns rankings to participants that withdraw or are lost to follow up in a way that does not disproportionately lower and skew ranks for those participants that reach study endpoint (either death or study completion). ALS/SURV has properties of: (1) ordering participants that completed the study from the shortest surviving participant to the last observed death followed by worst function to best function; (2) ordering participants withdrawing at time of withdrawal by their decline in functional status relative to all the participants still in the study; and (3) then maintaining this ordering at time of withdrawal relative to participants still in the study. These properties allow ALS/SURV to better account for participant drop out compared to CAFS. We derive and compare the rankings of participants from the ceftriaxone treatment trial for ALS/SURV and CAFS and demonstrate that ALS/SURV does not modify the ordering of participants that complete a study by the results of participants who withdraw. Additionally, ALS/SURV can be summarized as either median functional status or median survival along with interquartile range, thereby adding clinical meaning to the statistic. Finally, by applying normal deviates, confidence intervals can be computed and used to estimate power for future studies. In summary, the above properties support the role for ALS/SURV as a new ALS composite statistic.

Design and analysis of a clinical trial using previous trials as historical control.

BACKGROUND/AIMS: For single arm trials, a treatment is evaluated by comparing an outcome estimate to historically reported outcome estimates. Such a historically controlled trial is often analyzed as if the estimates from previous trials were known without variation and there is no trial-to-trial variation in their estimands. We develop a test of treatment efficacy and sample size calculation for historically controlled trials that considers these sources of variation. METHODS: We fit a Bayesian hierarchical model, providing a sample from the posterior predictive distribution of the outcome estimand of a new trial, which, along with the standard error of the estimate, can be used to calculate the probability that the estimate exceeds a threshold. We then calculate criteria for statistical significance as a function of the standard error of the new trial and calculate sample size as a function of difference to be detected. We apply these methods to clinical trials for amyotrophic lateral sclerosis using data from the placebo groups of 16 trials. RESULTS: We find that when attempting to detect the small to moderate effect sizes usually assumed in amyotrophic lateral sclerosis clinical trials, historically controlled trials would require a greater total number of patients than concurrently controlled trials, and only when an effect size is extraordinarily large is a historically controlled trial a reasonable alternative. We also show that utilizing patient level data for the prognostic covariates can reduce the sample size required for a historically controlled trial. CONCLUSION: This article quantifies when historically controlled trials would not provide any sample size advantage, despite dispensing with a control group.

Class I and II histone deacetylase expression is not altered in human amyotrophic lateral sclerosis: Neuropathological and positron emission tomography molecular neuroimaging evidence.

INTRODUCTION: There is an unmet need for mechanism-based biomarkers and effective disease modifying treatments in amyotrophic lateral sclerosis (ALS). Previous findings have provided evidence that histone deacetylases (HDAC) are altered in ALS, providing a rationale for testing HDAC inhibitors as a therapeutic option. METHODS: We measured class I and II HDAC protein and transcript levels together with acetylation levels of downstream substrates by using Western blotting in postmortem tissue of ALS and controls. [11 C]Martinostat, a novel HDAC positron emission tomography ligand, was also used to assess in vivo brain HDAC alterations in patients with ALS and healthy controls (HC). RESULTS: There was no significant difference in HDAC levels between patients with ALS and controls as measured by Western blotting and reverse-transcription quantitative polymerase chain reaction. Similarly, no differences were detected in [11 C]Martinostat-positron emission tomography uptake in ALS participants compared with HCs. DISCUSSION: These findings provide evidence that alterations in HDAC isoforms are not a dominant pathological feature at the bulk tissue level in ALS.