The use of immune checkpoint inhibitors (ICIs) for the treatment of various advanced and aggressive types of malignancy has significantly increased both survival and long-term remission rates. ICIs block crucial inhibitory pathways of the immune system, in order to trigger an aggravated immune response against the tumor. However, this enhanced immune activation leads to the development of numerous immune-related adverse events (irAEs), which may affect any system. Although severe neurological irAEs are relatively rare, they carry a high disability burden, and they can be potentially life-threatening. Therefore, clinicians must be alert and act promptly when individuals receiving ICIs present with new-onset neurological symptoms. In this narrative review, we have collected all the currently available data regarding the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of post-ICI neurological irAEs. This review aims to raise physicians’ awareness, enrich their knowledge regarding disease pathogenesis, and guide them through the diagnosis and management of post-ICI neurological irAEs.

Choroid plexus (CP) can be seen as a watchtower of the central nervous system (CNS) that actively regulates CNS homeostasis. A growing body of literature suggests that CP alterations are involved in the pathogenesis of multiple sclerosis (MS) but the underlying mechanisms remain elusive. CPs are enlarged and inflamed in relapsing-remitting (RRMS) but also in clinically isolated syndrome (CIS) and radiologically isolated syndrome (RIS) stages, far beyond MS diagnosis. Increases in the choroid plexus/total intracranial volume (CP/TIV) ratio have been robustly associated with increased lesion load, higher translocator protein (TSPO) uptake in normal-appearing white matter (NAWM) and thalami, as well as with higher annual relapse rate and disability progression in highly active RRMS individuals, but not in progressive MS. The CP/TIV ratio has only slightly been correlated with magnetic resonance imaging (MRI) findings (cortical or whole brain atrophy) and clinical outcomes (EDSS score) in progressive MS. Therefore, we suggest that plexus volumetric assessments should be mainly applied to the early disease stages of MS, whereas it should be taken into consideration with caution in progressive MS. In this review, we attempt to clarify the pathological significance of the temporal CP volume (CPV) changes in MS and highlight the pitfalls and limitations of CP volumetric analysis.

The exact etiologies of most neurodegenerative disorders remain poorly understood, therefore hampering the identification of molecular targets with clinical therapeutic potential. Recent clinical and experimental evidence supports the notion that amino acid metabolism could be implicated in the pathophysiology and disease progression of neurodegenerative diseases. This review aims to present the most common neurological diseases that lead to axonal degeneration and to examine the potential role of amino acid metabolism, with a particular focus on multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. The primary objective of this study is to identify potential amino acid biomarkers through metabolomics research and to propose therapeutic approaches by modulating amino acid-sensing signaling pathways to effectively monitor disease progression in neurodegenerative disorders. In this context, two distinct cellular signaling pathways are examined: the mechanistic target of rapamycin signaling pathway and the general control non-derepressible protein-integrated stress response pathway. These signaling cascades are analyzed in relation to each of the aforementioned neurological disorders to identify their potential regulatory roles in disease progression and pathophysiology. The review concludes by considering emerging amino acid biomarkers with potential clinical and diagnostic value, exploring signaling cascades for therapeutic manipulation to improve clinical outcomes in neurodegeneration, and providing insights for future research in the biomedical field.

Argininemia or arginase-1 deficiency constitutes a rare, genetic, metabolic disorder caused by mutations in arginase 1—the last enzyme of the urea cycle—that hydrolyses L-arginine to ornithine and urea. The disease is associated with progressive development of spasticity and other symptoms, including seizures, developmental delay, cognitive impairment, and hepatic pathology. The present review attempts to summarize the current knowledge on the pathophysiology of the disease and highlight novel methods for its evaluation. Different factors, such as the accumulation of arginine, ammonia, and guanidino compounds, act as neurotoxins and may account for the neurological sequelae observed in the disease. New markers, such as arginine/ornithine ratio along with metabolomics, machine learning algorithms, and genetic methods, can be useful in the early diagnosis of argininemia, while mobile phone apps can assist argininemic patients in adhering to the strict diet required. Neurophysiology, multi-modal imaging, and new modelling methods, such as induced pluripotent stem cells, hold promise for providing new insights into the pathophysiology of the disease. There are still many uncertainties regarding the underlying mechanisms of argininemia, but the use of novel modelling methods and new technology can lead to the decipherment of its pathophysiology, improvement of diagnostic accuracy, and better disease management.

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease, marked by progressive degeneration of upper and lower motor neurons. Clinically, genetically, and pathologically heterogeneous, ALS poses a major challenge for disease modeling and therapeutic translation. Over the past two decades, induced pluripotent stem cells (iPSCs) have reshaped our understanding of ALS pathogenesis and emerged as a promising translational platform for therapy development. ALS modeling has further expanded with the advent of three-dimensional systems, including ALS-on-chip platforms and organoid models, which better capture cell–cell interactions and tissue-level phenotypes. Despite these advances, effective disease-modifying therapies remain elusive. Recent clinical trial setbacks highlight the need for improved trial design alongside robust, translational iPSC models that can better predict therapeutic response. Nonetheless, the outlook is promising as large iPSC patient cohorts, quantitative phenotyping combined with genetically informed patient stratification, and reverse translational research are beginning to close the gap between in vitro discovery and clinical testing. In this review, we summarize the major advances in iPSC technology and highlight key iPSC-based studies of sporadic ALS. We further discuss emerging examples of iPSC-informed therapeutic strategies and outline the challenges associated with translating iPSC-derived mechanistic insights and pharmacological findings into successful clinical therapies.

Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease, characterized by progressive degeneration of upper and lower motor neurons. Clinically heterogeneous, ALS presents with varying patterns of muscle weakness, spasticity, and atrophy, ultimately impairing mobility, communication, swallowing, and respiration. The pathogenesis of ALS involves a complex interplay of genetic and environmental factors. Despite extensive research, ALS remains incurable, with only modestly effective disease-modifying therapies currently available. This review summarizes current understanding of ALS pathophysiology, clinical phenotypes, diagnosis, and ongoing therapeutic developments.