A Phase 1 study of GDC-0134, a dual leucine zipper kinase inhibitor, in ALS

Safety and efficacy of arimoclomol in patients with early amyotrophic lateral sclerosis (ORARIALS-01): a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial

BACKGROUND

Amyotrophic lateral sclerosis is a progressive neurodegenerative disorder leading to muscle weakness and respiratory failure. Arimoclomol, a heat-shock protein-70 (HSP70) co-inducer, is neuroprotective in animal models of amyotrophic lateral sclerosis, with multiple mechanisms of action, including clearance of protein aggregates, a pathological hallmark of sporadic and familial amyotrophic lateral sclerosis. We aimed to evaluate the safety and efficacy of arimoclomol in patients with amyotrophic lateral sclerosis.

METHODS

ORARIALS-01 was a multinational, randomised, double-blind, placebo-controlled, parallel-group trial done at 29 centres in 12 countries in Europe and North America. Patients were eligible if they were aged 18 years or older and met El Escorial criteria for clinically possible, probable, probable laboratory-supported, definite, or familial amyotrophic lateral sclerosis; had an ALS Functional Rating Scale-Revised score of 35 or more; and had slow vital capacity at 70% or more of the value predicted on the basis of the participant's age, height, and sex. Patients were randomly assigned (2:1) in blocks of 6, stratified by use of a stable dose of riluzole or no riluzole use, to receive oral arimoclomol citrate 1200 mg/day (400 mg three times per day) or placebo. The Randomisation sequence was computer generated centrally. Investigators, study personnel, and study participants were masked to treatment allocation. The primary outcome was the Combined Assessment of Function and Survival (CAFS) rank score over 76 weeks of treatment. The primary outcome and safety were analysed in the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT03491462, and is completed.

FINDINGS

Between July 31, 2018, and July 17, 2019, 287 patients were screened, 245 of whom were enrolled in the trial and randomly assigned. The modified intention-to-treat population comprised 239 patients (160 in the arimoclomol group and 79 in the placebo group): 151 (63%) were male and 88 (37%) were female; mean age was 57·6 years (SD 10·9). CAFS score over 76 weeks did not differ between groups (mean 0·51 [SD 0·29] in the arimoclomol group vs 0·49 [0·28] in the placebo group; p=0·62). Cliff's delta comparing the two groups was 0·039 (95% CI -0·116 to 0·194). Proportions of participants who died were similar between the treatment groups: 29 (18%) of 160 patients in the arimoclomol group and 18 (23%) of 79 patients in the placebo group. Most deaths were due to disease progression. The most common adverse events were gastrointestinal. Adverse events were more often deemed treatment-related in the arimoclomol group (104 [65%]) than in the placebo group (41 [52%]) and more often led to treatment discontinuation in the arimoclomol group (26 [16%]) than in the placebo group (four [5%]).

INTERPRETATION

Arimoclomol did not improve efficacy outcomes compared with placebo. Although available biomarker data are insufficient to preclude future strategies that target the HSP response, safety data suggest that a higher dose of arimoclomol would not have been tolerated.

FUNDING

Orphazyme.

Novel inhibitors of acute, axonal DLK palmitoylation are neuroprotective and avoid the deleterious side effects of cell-wide DLK inhibition

Dual leucine-zipper kinase (DLK) drives acute and chronic forms of neurodegeneration, suggesting that inhibiting DLK signaling could ameliorate diverse neuropathological conditions. However, direct inhibition of DLK's kinase domain in human patients and conditional knockout of DLK in mice both cause unintended side effects, including elevated plasma neurofilament levels, indicative of neuronal cytoskeletal disruption. Indeed, we found that a DLK kinase domain inhibitor acutely disrupted the axonal cytoskeleton and caused vesicle aggregation in cultured dorsal root ganglion (DRG) neurons, further cautioning against this therapeutic strategy. In seeking a more precise intervention, we found that retrograde (axon-to-soma) pro-degenerative signaling requires acute, axonal palmitoylation of DLK and hypothesized that modulating this post-translational modification might be more specifically neuroprotective than cell-wide DLK inhibition. To address this possibility, we screened >28,000 compounds using a high-content imaging assay that quantitatively evaluates DLK's palmitoylation-dependent subcellular localization. Of the 33 hits that significantly altered DLK localization in non-neuronal cells, several reduced DLK retrograde signaling and protected cultured DRG neurons from DLK-dependent neurodegeneration. Mechanistically, the two most neuroprotective compounds selectively prevent stimulus-dependent palmitoylation of axonal pools of DLK, a process crucial for DLK's recruitment to axonal vesicles. In contrast, these compounds minimally impact DLK localization and signaling in healthy neurons and avoid the cytoskeletal disruption associated with direct DLK inhibition. Importantly, our hit compounds also reduce pro-degenerative retrograde signaling in vivo, suggesting that modulating DLK's palmitoylation-dependent localization could be a novel neuroprotective strategy.

Development of novel treatments for amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease that causes paralysis whose etiology and pathogenesis have not been fully elucidated. Presently it is incurable and rapidly progressive with a survival of 2-5 years from onset, and no treatments could cure it. Therefore, it is urgent to identify which therapeutic target(s) are more promising to develop treatments that could effectively treat ALS. So far, more than 90 novel treatments for ALS patients have been registered on ClinicalTrials.gov, of which 23 are in clinical trials, 12 have been terminated and the rest suspended. This review will systematically summarize the possible targets of these novel treatments under development or failing based on published literature and information released by sponsors, so as to provide basis and support for subsequent drug research and development.

Regulation of the Activity of the Dual Leucine Zipper Kinase by Distinct Mechanisms

The dual leucine zipper kinase (DLK) alias mitogen-activated protein 3 kinase 12 (MAP3K12) has gained much attention in recent years. DLK belongs to the mixed lineage kinases, characterized by homology to serine/threonine and tyrosine kinase, but exerts serine/threonine kinase activity. DLK has been implicated in many diseases, including several neurodegenerative diseases, glaucoma, and diabetes mellitus. As a MAP3K, it is generally assumed that DLK becomes phosphorylated and activated by upstream signals and phosphorylates and activates itself, the downstream serine/threonine MAP2K, and, ultimately, MAPK. In addition, other mechanisms such as protein-protein interactions, proteasomal degradation, dephosphorylation by various phosphatases, palmitoylation, and subcellular localization have been shown to be involved in the regulation of DLK activity or its fine-tuning. In the present review, the diverse mechanisms regulating DLK activity will be summarized to provide better insights into DLK action and, possibly, new targets to modulate DLK function.

Biomarker Qualification for Neurofilament Light Chain in Amyotrophic Lateral Sclerosis: Theory and Practice

OBJECTIVE

To explore whether the utility of neurofilament light chain (NfL), as a biomarker to aid amyotrophic lateral sclerosis (ALS) therapy development, would be enhanced by obtaining formal qualification from the US Food and Drug Administration for a defined context-of-use.

METHODS

Consensus discussion among academic, industry, and patient advocacy group representatives.

RESULTS

A wealth of scientific evidence supports the use of NfL as a prognostic, response, and potential safety biomarker in the broad ALS population, and as a risk/susceptibility biomarker among the subset of SOD1 pathogenic variant carriers. Although NfL has not yet been formally qualified for any of these contexts-of-use, the US Food and Drug Administration has provided accelerated approval for an SOD1-lowering antisense oligonucleotide, based partially on the recognition that a reduction in NfL is reasonably likely to predict a clinical benefit.

INTERPRETATION

The increasing incorporation of NfL into ALS therapy development plans provides evidence that its utility-as a prognostic, response, risk/susceptibility, and/or safety biomarker-is already widely accepted by the community. The willingness of the US Food and Drug Administration to base regulatory decisions on rigorous peer-reviewed data-absent formal qualification, leads us to conclude that formal qualification, despite some benefits, is not essential for ongoing and future use of NfL as a tool to aid ALS therapy development. Although the balance of considerations for and against seeking NfL biomarker qualification will undoubtedly vary across different diseases and contexts-of-use, the robustness of the published data and careful deliberations of the ALS community may offer valuable insights for other disease communities grappling with the same issues. ANN NEUROL 2024;95:211-216.

Targeting synapse function and loss for treatment of neurodegenerative diseases

Synapse dysfunction and loss are hallmarks of neurodegenerative diseases that correlate with cognitive decline. However, the mechanisms and therapeutic strategies to prevent or reverse synaptic damage remain elusive. In this Review, we discuss recent advances in understanding the molecular and cellular pathways that impair synapses in neurodegenerative diseases, including the effects of protein aggregation and neuroinflammation. We also highlight emerging therapeutic approaches that aim to restore synaptic function and integrity, such as enhancing synaptic plasticity, preventing synaptotoxicity, modulating neuronal network activity and targeting immune signalling. We discuss the preclinical and clinical evidence for each strategy, as well as the challenges and opportunities for developing effective synapse-targeting therapeutics for neurodegenerative diseases.

Remyelination protects neurons from DLK-mediated neurodegeneration

Chronic demyelination is theorized to contribute to neurodegeneration and drive progressive disability in demyelinating diseases like multiple sclerosis. Here, we describe two genetic mouse models of inducible demyelination, one distinguished by effective remyelination, and the other by remyelination failure and persistent demyelination. By comparing these two models, we find that remyelination protects neurons from apoptosis, improves conduction, and promotes functional recovery. Chronic demyelination of neurons leads to activation of the mitogen-associated protein kinase (MAPK) stress pathway downstream of dual leucine zipper kinase (DLK), which ultimately induces the phosphorylation of c-Jun in the nucleus. Both pharmacological inhibition and CRISPR/Cas9-mediated disruption of DLK block c-Jun phosphorylation and the apoptosis of demyelinated neurons. These findings provide direct experimental evidence that remyelination is neuroprotective and identify DLK inhibition as a potential therapeutic strategy to protect chronically demyelinated neurons.

Plant derived active compounds of ayurvedic neurological formulation, Saraswatharishta as a potential dual leucine zipper kinase inhibitor: an in-silico study

Recent findings have highlighted the essential role of dual leucine zipper kinase (DLK) in neuronal degeneration. Saraswatharishta (SWRT), an ayurvedic formulation utilized in traditional Indian medicine, has demonstrated effectiveness in addressing neurodegenerative diseases. Herein, we aim to delve into the atomistic details of the mode of action of phytochemicals present in SWRT against DLK. Our screening process encompassed over 500 distinct phytochemicals derived from the main ingredients of the SWRT formulation. Through a comparative analysis of docking scores and relative poses, we successfully identified four novel compounds, which underwent further investigation via 2 × 500 ns long molecular dynamics (MD) simulations. Among the top four compounds, CID16066851 sourced from the Acorus calamus displayed the most stable complex with DLK. The molecular mechanics Poisson - Boltzmann surface area (MM-PBSA) calculations highlighted the significance of electrostatic and van der Waals interactions in the binding recognition process. Additionally, we identified key residues, namely Phe192, Leu243, Val139, and Leu141, as hotspots that predominantly govern the DLK-inhibitor interaction. Notably, the leading compounds are sourced from the Acorus calamus, Syzygium aromaticum, Zingiber officinale, and Anethum sowa plants present in the SWRT formulation. Overall, the findings of our study hold promise for future drug development endeavors combating neurodegenerative conditions.Communicated by Ramaswamy H. Sarma.

Mono- and Difluorinated Saturated Heterocyclic Amines for Drug Discovery: Systematic Study of Their Physicochemical Properties

A comprehensive study of physicochemical properties (pKa , LogP, and intrinsic microsomal clearance) within the series of mono- and difluorinated azetidine, pyrrolidine, and piperidine derivatives was performed. While the number of fluorine atoms and their distance to the protonation center were the major factors defining the compound's basicity, both pKa and LogP values were affected considerably by the conformational preferences of the corresponding derivatives. For example, features of "Janus face" (facially polarized) cyclic compounds (i. e., unusually high hydrophilicity) were identified for cis-3,5-difluoropiperidine, preferring a diaxial conformation. Intrinsic microsomal clearance measurements demonstrated high metabolic stability of the compounds studied (with a single exception of the 3,3-difluoroazetidine derivative). According to pKa - LogP plots, the title compounds provide a valuable extension of the fluorine-containing (e. g., fluoroalkyl-substituted) saturated heterocyclic amine series as building blocks for rational optimization studies in early drug discovery.

Shared learning from a physiologically based pharmacokinetic modeling strategy for human pharmacokinetics prediction through retrospective analysis of Genentech compounds

The quantitative prediction of human pharmacokinetics (PK) including the PK profile and key PK parameters are critical for early drug development decisions, successful phase I clinical trials, and the establishment of a range of doses to enable phase II clinical dose selection. Here, we describe an approach employing physiologically based pharmacokinetic (PBPK) modeling (Simcyp) to predict human PK and to validate its performance through retrospective analysis of 18 Genentech compounds for which clinical data are available. In short, physicochemical parameters and in vitro data for preclinical species were integrated using PBPK modeling to predict the in vivo PK observed in mouse, rat, dog, and cynomolgus monkey. Through this process, the in vitro to in vivo extrapolation (IVIVE) was determined and then incorporated into PBPK modeling in order to predict human PK. Overall, the prediction obtained using this PBPK-IVIVE approach captured the observed human PK profiles of the compounds from the dataset well. The predicted Cmax was within 2-fold of the observed Cmax for 94% of the compounds while the predicted area under the curve (AUC) was within 2-fold of the observed AUC for 72% of the compounds. Additionally, important IVIVE trends were revealed through this investigation, including application of scaling factors determined from preclinical IVIVE to human PK prediction for each molecule. Based upon the analysis, this PBPK-based approach now serves as a practical strategy for human PK prediction at the candidate selection stage at Genentech.

Discovery of IACS-52825, a Potent and Selective DLK Inhibitor for Treatment of Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a major unmet medical need with limited treatment options. Despite different mechanisms of action, diverse chemotherapeutics can cause CIPN through a converged pathway─an active axon degeneration program that engages the dual leucine zipper kinase (DLK). DLK is a neuronally enriched kinase upstream in the MAPK-JNK cascade, and while it is dormant under physiological conditions, DLK mediates a core mechanism for neuronal injury response under stress conditions, making it an attractive target for treatment of neuronal injury and neurodegenerative diseases. We have developed potent, selective, brain penetrant DLK inhibitors with excellent PK and activity in mouse models of CIPN. Lead compound IACS-52825 (22) showed strongly effective reversal of mechanical allodynia in a mouse model of CIPN and was advanced into preclinical development.

Promoting regeneration while blocking cell death preserves motor neuron function in a model of ALS

Amyotrophic lateral sclerosis (ALS) is a devastating and fatal neurodegenerative disease of motor neurons with very few treatment options. We had previously found that motor neuron degeneration in a mouse model of ALS can be delayed by deleting the axon damage sensor MAP3K12 or dual leucine zipper kinase (DLK). However, DLK is also involved in axon regeneration, prompting us to ask whether combining DLK deletion with a way to promote axon regeneration would result in greater motor neuron protection. To achieve this, we used a mouse line that constitutively expresses ATF3, a master regulator of regeneration in neurons. Although there is precedence for each individual strategy in the SOD1G93A mouse model of ALS, these have not previously been combined. By several lines of evidence including motor neuron electrophysiology, histology and behaviour, we observed a powerful synergy when combining DLK deletion with ATF3 expression. The combinatorial strategy resulted in significant protection of motor neurons with fewer undergoing cell death, reduced axon degeneration and preservation of motor function and connectivity to muscle. This study provides a demonstration of the power of combinatorial therapy to treat neurodegenerative disease.

Deciphering the multifunctional role of dual leucine zipper kinase (DLK) and its therapeutic potential in disease

Dual leucine zipper kinase (DLK, MAP3K12), a serine/threonine protein kinase, plays a key role in neuronal development, as it regulates axon regeneration and degeneration through its downstream kinase. Importantly, DLK is closely related to the pathogenesis of numerous neurodegenerative diseases and the induction of β-cell apoptosis that leads to diabetes. In this review, we summarize the current understanding of DLK function, and then discuss the role of DLK signaling in human diseases. Furthermore, various types of small molecule inhibitors of DLK that have been published so far are described in detail in this paper, providing some strategies for the design of DLK small molecule inhibitors in the future.

DLK-dependent mitochondrial fission drives axon degeneration and neuronal cell death

Currently there are no effective treatments for an array of neurodegenerative disorders to a large part because cell-based models fail to recapitulate disease. Here we developed a robust human iPSCbased model where laser axotomy causes retrograde axon degeneration leading to neuronal cell death. Time-lapse confocal imaging revealed that damage triggers a wave of mitochondrial fission proceeding from the site of injury to the soma. We demonstrated that mitochondrial fission and resultant cell death is entirely dependent on phosphorylation of dynamin related protein 1 (DRP1) by dual leucine zipper kinase (DLK). Importantly, we show that CRISPR mediated Drp1 depletion protected mouse retinal ganglion neurons from mitochondrial fission and degeneration after optic nerve crush. Our results provide a powerful platform for studying degeneration of human neurons, pinpoint key early events in damage related neural death and new focus for therapeutic intervention.

Discovery of Potent and Selective Dual Leucine Zipper Kinase/Leucine Zipper-Bearing Kinase Inhibitors with Neuroprotective Properties in In Vitro and In Vivo Models of Amyotrophic Lateral Sclerosis

Dual leucine zipper kinase (DLK) and leucine zipper-bearing kinase (LZK) are regulators of neuronal degeneration and axon growth. Therefore, there is a considerable interest in developing DLK/LZK inhibitors for neurodegenerative diseases. Herein, we use ligand- and structure-based drug design approaches for identifying novel amino-pyrazine inhibitors of DLK/LZK. DN-1289 (14), a potent and selective dual DLK/LZK inhibitor, demonstrated excellent in vivo plasma half-life across species and is anticipated to freely penetrate the central nervous system with no brain impairment based on in vivo rodent pharmacokinetic studies and human in vitro transporter data. Proximal target engagement and disease relevant pathway biomarkers were also favorably regulated in an in vivo model of amyotrophic lateral sclerosis.

New developments and opportunities in drugs being trialed for amyotrophic lateral sclerosis from 2020 to 2022

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that primarily affects motor neurons in the brain and spinal cord. In the recent past, there have been just two drugs approved for treatment, riluzole and edaravone, which only prolong survival by a few months. However, there are many novel experimental drugs in development. In this review, we summarize 53 new drugs that have been evaluated in clinical trials from 2020 to 2022, which we have classified into eight mechanistic groups (anti-apoptotic, anti-inflammatory, anti-excitotoxicity, regulated integrated stress response, neurotrophic factors and neuroprotection, anti-aggregation, gene therapy and other). Six were tested in phase 1 studies, 31 were in phase 2 studies, three failed in phase 3 studies and stopped further development, and the remaining 13 drugs were being tested in phase 3 studies, including methylcobalamin, masitinib, MN-166, verdiperstat, memantine, AMX0035, trazodone, CNM-Au8, pridopidine, SLS-005, IONN363, tofersen, and reldesemtiv. Among them, five drugs, including methylcobalamin, masitinib, AMX0035, CNM-Au8, and tofersen, have shown potent therapeutic effects in clinical trials. Recently, AMX0035 has been the third medicine approved by the FDA for the treatment of ALS after riluzole and edaravone.

Clinical studies in amyotrophic lateral sclerosis

PURPOSE OF REVIEW

The purpose of this review is to discuss the most important recent clinical studies in amyotrophic lateral sclerosis (ALS), including their impact on clinical practice, their methodology, and open questions to be addressed in the future.

RECENT FINDINGS

This article focuses on studies, which provided either a positive primary endpoint or positive post hoc analysis, including edaravone, sodium phenylbutyrate-taurursodiol, rasagiline, tofersen, and high-caloric, fat-rich nutrition. It also covers recent developments in the design of clinical ALS studies with regard to inclusion criteria, stratification factors, and outcome parameters.

SUMMARY

Recent clinical studies have indicated various substances to be considered for treatment of ALS. Edaravone has been approved by the US Food and Drug Association (FDA) but not by the European Medicines Agency (EMA), and further studies testing oral formulations are currently conducted. A follow-up study with sodium phenylbutyrate-taurursodiol is ongoing, while follow-up studies for rasagiline and high-caloric, fat-rich nutrition are planned. A phase III study with tofersen was negative but nevertheless yielded promising results. Important developments regarding the design of clinical ALS studies include the implementation of neurofilament light chain (NfL) levels as a standard outcome parameter and the consideration of progression rate for therapeutic response and stratification.

Emerging Therapies and Novel Targets for TDP-43 Proteinopathy in ALS/FTD

Nuclear clearance and cytoplasmic mislocalization of the essential RNA binding protein, TDP-43, is a pathologic hallmark of amyotrophic lateral sclerosis, frontotemporal dementia, and related neurodegenerative disorders collectively termed "TDP-43 proteinopathies." TDP-43 mislocalization causes neurodegeneration through both loss and gain of function mechanisms. Loss of TDP-43 nuclear RNA processing function destabilizes the transcriptome by multiple mechanisms including disruption of pre-mRNA splicing, the failure of repression of cryptic exons, and retrotransposon activation. The accumulation of cytoplasmic TDP-43, which is prone to aberrant liquid-liquid phase separation and aggregation, traps TDP-43 in the cytoplasm and disrupts a host of downstream processes including the trafficking of RNA granules, local translation within axons, and mitochondrial function. In this review, we will discuss the TDP-43 therapy development pipeline, beginning with therapies in current and upcoming clinical trials, which are primarily focused on accelerating the clearance of TDP-43 aggregates. Then, we will look ahead to emerging strategies from preclinical studies, first from high-throughput genetic and pharmacologic screens, and finally from mechanistic studies focused on the upstream cause(s) of TDP-43 disruption in ALS/FTD. These include modulation of stress granule dynamics, TDP-43 nucleocytoplasmic shuttling, RNA metabolism, and correction of aberrant splicing events.

Loss of Stathmin-2, a hallmark of TDP-43-associated ALS, causes motor neuropathy

TDP-43 mediates proper Stathmin-2 (STMN2) mRNA splicing, and STMN2 protein is reduced in the spinal cord of most patients with amyotrophic lateral sclerosis (ALS). To test the hypothesis that STMN2 loss contributes to ALS pathogenesis, we generated constitutive and conditional STMN2 knockout mice. Constitutive STMN2 loss results in early-onset sensory and motor neuropathy featuring impaired motor behavior and dramatic distal neuromuscular junction (NMJ) denervation of fast-fatigable motor units, which are selectively vulnerable in ALS, without axon or motoneuron degeneration. Selective excision of STMN2 in motoneurons leads to similar NMJ pathology. STMN2 knockout heterozygous mice, which better model the partial loss of STMN2 protein found in patients with ALS, display a slowly progressive, motor-selective neuropathy with functional deficits and NMJ denervation. Thus, our findings strongly support the hypothesis that STMN2 reduction owing to TDP-43 pathology contributes to ALS pathogenesis.