Sigma-1 Research Articles

BS148 Reduces the Aggressiveness of Metastatic Melanoma via Sigma-2 Receptor Targeting.

The management of advanced-stage melanoma is clinically challenging, mainly because of its resistance to the currently available therapies. Therefore, it is important to develop alternative therapeutic strategies. The sigma-2 receptor (S2R) is overexpressed in proliferating tumor cells and represents a promising vulnerability to target. Indeed, we have recently identified a potent S2R modulator (BS148) that is effective in melanoma. To elucidate its mechanism of action, we designed and synthesized a BS148 fluorescent probe that enters SK-MEL-2 melanoma cells as assessed using confocal microscopy analysis. We show that S2R knockdown significantly reduces the anti-proliferative effect induced by BS148 administration, indicating the engagement of S2R in BS148-mediated cytotoxicity. Interestingly, BS148 treatment showed similar molecular effects to S2R RNA interference-mediated knockdown. We demonstrate that BS148 administration activates the endoplasmic reticulum stress response through the upregulation of protein kinase R-like ER kinase (PERK), activating transcription factor 4 (ATF4) genes, and C/EBP homologous protein (CHOP). Furthermore, we show that BS148 treatment downregulates genes related to the cholesterol pathway and activates the MAPK signaling pathway. Finally, we translate our results into patient-derived xenograft (PDX) cells, proving that BS148 treatment reduces melanoma cell viability and migration. These results demonstrate that BS148 is able to inhibit metastatic melanoma cell proliferation and migration through its interaction with the S2R and confirm its role as a promising target to treat cancer.

Lenalidomide Promotes Melarsoprol-Activated cGAS-STING-Mediated Immunotherapy for Hepatocellular Carcinoma via Attenuating TNF-α Activity

Current immunotherapy has limited efficacy in hepatocellular carcinoma (HCC) due to the immunosuppressive tumor microenvironment (TME). The activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of the interferon genes (STING) pathway demonstrates great potential to unleash the immunosuppressive TME. The capacity of melarsoprol (MEL; an arsenic-containing drug) on activating the cGAS-STING pathway in HCC cells for antitumor immunotherapy was confirmed for the first time in this study. When MEL (particularly at high doses) activated the cGAS-STING pathway, however, HCC growth was not fully inhibited, mainly due to the hyperactivation of tumor necrosis factor α (TNF-α; a cytokine associated with the cGAS-STING pathway). Accordingly, lenalidomide (LEN; a clinically approved TNF-α inhibitor) was used to alleviate pro-tumorigenic effects of the MEL-activated cGAS-STING pathway while maintaining immunotherapeutic effects. To modulate the cGAS-STING pathway in vivo, a poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticle (NP) was used for co-delivery of MEL and LEN, and the co-loaded NP was coated with aminoethyl anisamide (AEAA, a ligand for Sigma-1 receptor)-modified erythrocyte membrane, forming a co-formulation. In this study, co-formulation was able to modulate the cGAS-STING-mediated efficacy and reverse the immunosuppressive TME in allograft and carcinogen-induced orthotopic HCC mouse models, respectively. Our study reveals an intrinsic hurdle to DNA damaging drug-mediated cGAS-STING monotherapy and provides a promising combination strategy to tackle immunosuppression in HCC.

Targeting Sigma-1 Receptor: A Promising Strategy in the Treatment of Parkinson's Disease.

Parkinson's disease is a neurodegenerative disease affecting mainly the elderly population. It is characterized by the loss of dopaminergic neurons of the substantia nigra pars compacta region. Parkinson's disease patients exhibit motor symptoms like tremors, rigidity, bradykinesia/hypokinesia, and non-motor symptoms like depression, cognitive decline, delusion, and pain. Major pathophysiological factors which contribute to neuron loss include excess/misfolded alpha-synuclein aggregates, microglial cell-mediated neuroinflammation, excitotoxicity, oxidative stress, and defective mitochondrial function. Sigma-1 receptors are molecular chaperones located at mitochondria-associated ER membrane. Their activation (by endogenous ligands or agonists) has shown neuroprotective and neurorestorative effects in various diseases. This review discusses the roles of activated Sig-1 receptors in modulating various pathophysiological features of Parkinson's disease like alpha-synuclein aggregates, neuroinflammation, excitotoxicity, and oxidative stress.

Effect of fluvoxamine on plasma interleukin-6 in patients with major depressive disorder: a prospective follow-up study.

Major depressive disorder (MDD) is associated with low-grade inflammation, and anti-inflammatory treatment can help improve depressive symptoms. A recent study found that fluvoxamine (FLV) can reduce Interleukin-6 (IL-6) production via sigma-1 receptor in inflammation models. However, the anti- IL-6 effect of FLV in treating patients with MDD and whether it can contribute to antidepressant effects remain unclear. A total of 65 patients with MDD and 34 healthy controls were recruited at baseline, and 50 patients completed the FLV treatment for 2 months. We assessed depression and anhedonia and collected plasma IL-6 levels at baseline, 1 month, and 2 months after baseline. This study evaluated the changes in clinical measures and IL-6 during treatment and analyzed their association. Further subgroup analyses were conducted in patients with MDD with high, medium, or low IL-6. Depression and anhedonia were significantly improved in patients with MDD, while the IL-6 did not significantly change after the FLV treatment. However, IL-6 significantly declined after the FLV treatment among patients with MDD with higher baseline IL-6. No significant associations were found between the changes in depressive symptoms and IL-6. Our study provided preliminary evidence suggesting that the anti-IL-6 effect of FLV might not play a vital role in its antidepressant treatment, at least in patients with MDD with low inflammation. However, for patients with MDD with higher IL-6, FLV can help reduce IL-6 significantly in the antidepressant treatment, which may help guide the individual treatment of MDD with higher IL-6 levels. https://clinicaltrials.gov/ct2/show/NCT04160377, identifier NCT04160377.

Fenfluramine: a plethora of mechanisms?

Developmental and epileptic encephalopathies are rare, treatment-resistant epilepsies with high seizure burden and non-seizure comorbidities. The antiseizure medication (ASM) fenfluramine is an effective treatment for reducing seizure frequency, ameliorating comorbidities, and potentially reducing risk of sudden unexpected death in epilepsy (SUDEP) in patients with Dravet syndrome and Lennox-Gastaut syndrome, among other rare epilepsies. Fenfluramine has a unique mechanism of action (MOA) among ASMs. Its primary MOA is currently described as dual-action sigma-1 receptor and serotonergic activity; however, other mechanisms may be involved. Here, we conduct an extensive review of the literature to identify all previously described mechanisms for fenfluramine. We also consider how these mechanisms may play a role in the reports of clinical benefit in non-seizure outcomes, including SUDEP and everyday executive function. Our review highlights the importance of serotonin and sigma-1 receptor mechanisms in maintaining a balance between excitatory (glutamatergic) and inhibitory (γ-aminobutyric acid [GABA]-ergic) neural networks, and suggests that these mechanisms may represent primary pharmacological MOAs in seizures, non-seizure comorbidities, and SUDEP. We also describe ancillary roles for GABA neurotransmission, noradrenergic neurotransmission, and the endocrine system (especially such progesterone derivatives as neuroactive steroids). Dopaminergic activity underlies appetite reduction, a common side effect with fenfluramine treatment, but any involvement in seizure reduction remains speculative. Further research is underway to evaluate promising new biological pathways for fenfluramine. A better understanding of the pharmacological mechanisms for fenfluramine in reducing seizure burden and non-seizure comorbidities may allow for rational drug design and/or improved clinical decision-making when prescribing multi-ASM regimens.

Synthesis, Computational Insights, and Evaluation of Novel Sigma Receptors Ligands.

The development of diazabicyclo[4.3.0]nonane and 2,7-diazaspiro[3.5]nonane derivatives as sigma receptors (SRs) ligands is reported. The compounds were evaluated in S1R and S2R binding assays, and modeling studies were carried out to analyze the binding mode. The most notable compounds, 4b (AD186, KiS1R = 2.7 nM, KiS2R = 27 nM), 5b (AB21, KiS1R = 13 nM, KiS2R = 102 nM), and 8f (AB10, KiS1R = 10 nM, KiS2R = 165 nM), have been screened for analgesic effects in vivo, and their functional profile was determined through in vivo and in vitro models. Compounds 5b and 8f reached the maximum antiallodynic effect at 20 mg/kg. The selective S1R agonist PRE-084 completely reversed their action, indicating that the effects are entirely dependent on the S1R antagonism. Conversely, compound 4b sharing the 2,7-diazaspiro[3.5]nonane core as 5b was completely devoid of antiallodynic effect. Interestingly, compound 4b fully reversed the antiallodynic effect of BD-1063, indicating that 4b induces an S1R agonistic in vivo effect. The functional profiles were confirmed by the phenytoin assay. Our study might establish the importance of 2,7-diazaspiro[3.5]nonane core for the development of S1R compounds with specific agonist or antagonist profile and the role of the diazabicyclo[4.3.0]nonane in the development of novel SR ligands.

Effect of Sigma-1 Receptor Activation on Renal Injury and Hypertension in Female Mice with Lupus

Systemic lupus erythematosus (SLE) is a female dominant autoimmune disease that presents with prominent renal injury and hypertension contributing to the morbidity and mortality. While the causality and association of the renal injury and hypertension is not completely understood, novel therapies to reduce these detrimental outcomes could be beneficial to SLE patients. The sigma-1 receptor is a cytoprotective ligand-regulated chaperone protein that acts by decreasing protein aggregation, cellular stress and cell death, thus preventing tissue injury. Activation of the sigma-1 receptor with pharmacological ligands enhances cytoprotection in autoimmune diseases like multiple sclerosis and Huntington’s disease; however, the efficacy of sigma-1 receptor agonists in SLE is not known. We hypothesize that sigma-1 receptor activation with the agonist, LS-1-127, will reduce renal injury and halt the progression of hypertension in SLE mice.Female SLE ( NZBWF1) mice and control ( NZW) mice were weighed and urine collected via metabolic cages weekly starting at 30 weeks of age. Urinary albumin was measured via dipsticks. At 33 weeks of age, SLE and control mice were treated with the sigma-1 receptor ligand (LS-1-127; 10 mg/kg IP) or equal volume of vehicle (10% DMSO; IP) three times a week for two weeks. At 35 weeks, mean arterial pressure (MAP) was measured in conscious mice using indwelling carotid catheters for two consecutive days and then mice were euthanized. Markers of renal injury, including urinary neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and creatinine were measured by ELISA.Body weight (g) was not different in SLE vs. control mice (39.2 ± 2.9 vs. 35.4 ± 0.9; p=0.44) and LS-1-127 did not alter body weight in SLE mice (39.1 ± 2.2; p=0.97) or controls (34.1 ± 0.6; p=0.84). Albuminuria was present in 44.4% (4 out of 9) of SLE/Veh mice and none of the controls. LS-1-127 did not improve albuminuria in SLE mice (50%; 3 out of 6). MAP (mmHg) was higher in SLE mice compared to control mice (146 ± 4 vs. 123 ± 3; n=9-10, p <0.0001). LS-1-127 did not significantly alter MAP in SLE mice (150± 8; n=6) or controls (124 ± 2; n=10). The NGAL-to-creatinine ratio (ng/mg) was higher in the SLE mice compared to controls (327.3±119.8 vs 63.2±4.3, n=9-12, p<0.0007). LS-1-127 treatment did not significantly alter the NGAL-to-creatinine ratio in SLE mice (484.3±209.0, n= 6) or control mice (71.7 ± 5.2, n=10). The KIM1-to-creatinine ratio (ng/mg) was not significantly different between any of the groups.In conclusion, two weeks of sigma-1 receptor activation with LS-1-127 did not significantly alter blood pressure or renal injury in female SLE mice with advanced disease. Further inquiry into the effect of LS-1-127 on the expression of various cellular stress markers in the kidney will be conducted. Also sigma-1 receptor activation at different stages of SLE disease progression warrants investigation. NIH (R01HL153703, K01HL139859) and Department of Defense (LR210096) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders.

The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.

Long-term effects of Roluperidone on negative symptoms of schizophrenia.

Roluperidone has antagonist properties for 5-HT2A, sigma2, α1A- and α1B-adrenergic receptors, but no dopaminergic binding affinities. In 2 randomized controlled trials (RCT), treatment improved negative symptoms of schizophrenia and social functioning among patients with moderate to severe negative symptoms. We report results of the protocol specified analysis of 2 open-label extension studies of 24 and 40weeks investigating whether improvement of negative symptoms was sustained without significant adverse effects or worsening of psychosis. Following 12-week double-blind phase of both RCTs, patients were eligible to receive monotherapy roluperidone 32mg/day or 64mg/day for 24weeks (trial 1) or 40weeks (trial 2) in open-label extension study. Trial 1 included 244 patients of whom 142 entered 24-week open-label extension and trial 2 included 513 patients of whom 341 entered 40-week open-label extension. Trial 1 had PANSS negative factor score of Pentagonal Structure Model as primary outcome. Trial 2 had Marder Negative Symptoms Factor Score as primary outcome measure and Personal and Social Performance (PSP) Total score as secondary outcome. During open-label extensions, continued improvements in negative symptoms and on PSP were observed. Overall rate of symptomatic worsening requiring discontinuation of roluperidone and treatment with an antipsychotic was <10%. Roluperidone was well tolerated with no meaningful changes in vital signs, laboratory values, weight gain, metabolic indices, or extrapyramidal symptoms. Results of 2 open-label extension trials support roluperidone as a treatment of negative symptoms and social functioning deficits in patients with moderate to severe negative symptoms of schizophrenia.

SIGMAR1 Confers Innate Resilience against Neurodegeneration.

The sigma-1 receptor (SIGMAR1) is one of a kind: a receptor chaperone protein. This 223 amino acid-long protein is enriched at the mitochondria-associated endoplasmic reticulum membrane (MAM), a specialized microdomain of the endoplasmic reticulum that is structurally and functionally connected to the mitochondria. As a receptor, SIGMAR1 binds a wide spectrum of ligands. Numerous molecules targeting SIGMAR1 are currently in pre-clinical or clinical development. Interestingly, the range of pathologies covered by these studies is broad, especially with regard to neurodegenerative disorders. Upon activation, SIGMAR1 can translocate and interact with other proteins, mostly at the MAM but also in other organelles, which allows SIGMAR1 to affect many cellular functions. During these interactions, SIGMAR1 exhibits chaperone protein behavior by participating in the folding and stabilization of its partner. In this short communication, we will shed light on how SIGMAR1 confers protection against neurodegeneration to the cells of the nervous system and why this ability makes SIGMAR1 a multifunctional therapeutic prospect.

Evaluation of Some Safety Parameters of Dual Histamine H3 and Sigma-2 Receptor Ligands with Anti-Obesity Potential.

Many studies have shown the high efficacy of histamine H3 receptor ligands in preventing weight gain. In addition to evaluating the efficacy of future drug candidates, it is very important to assess their safety profile, which is established through numerous tests and preclinical studies. The purpose of the present study was to evaluate the safety of histamine H3/sigma-2 receptor ligands by assessing their effects on locomotor activity and motor coordination, as well as on the cardiac function, blood pressure, and plasma activity of certain cellular enzymes. The ligands tested at a dose of 10 mg/kg b.w. did not cause changes in locomotor activity (except for KSK-74) and did not affect motor coordination. Significant reductions in blood pressure were observed after the administration of compounds KSK-63, KSK-73, and KSK-74, which seems logically related to the increased effect of histamine. Although the results of in vitro studies suggest that the tested ligands can block the human ether-a-go-go-related gene (hERG) potassium channels, they did not affect cardiac parameters in vivo. It should be noted that repeated administration of the tested compounds prevented an increase in the activity of alanine aminotransferase (AlaT) and gamma-glutamyl transpeptidases (gGT) observed in the control animals fed a palatable diet. The obtained results show that the ligands selected for this research are not only effective in preventing weight gain but also demonstrate safety in relation to the evaluated parameters, allowing the compounds to proceed to the next stages of research.

Cytotoxicity Profiles and Neuroprotective Properties of the Novel Ifenprodil Analogues as Sigma Ligands.

Neurodegeneration is a slow and progressive loss of neuronal cells or their function in specific regions of the brain or in the peripheral system. Among several causes responsible for the most common neurodegenerative diseases (NDDs), cholinergic/dopaminergic pathways, but also some endogenous receptors, are often involved. In this context, sigma 1 receptor (S1R) modulators can be used as neuroprotective and antiamnesic agents. Herein, we describe the identification of novel S1R ligands endowed with antioxidant properties, potentially useful as neuroprotective agents. We also computationally assessed how the most promising compounds might interact with the S1R protein's binding sites. The in silico predicted ADME properties suggested that they could be able to cross the brain-blood-barrier (BBB), and to reach the targets. Finally, the observation that at least two novel ifenprodil analogues (5d and 5i) induce an increase of the mRNA levels of the antioxidant NRF2 and SOD1 genes in SH-SY5Y cells suggests that they might be effective agents for protecting neurons against oxidative damage.

Gut microbiota from sigma-1 receptor knockout mice induces depression-like behaviors and modulates the cAMP/CREB/BDNF signaling pathway.

Depression is a common mental disorder that affects approximately 350 million people worldwide. Much remains unknown about the molecular mechanisms underlying this complex disorder. Sigma-1 receptor (Sig-1R) is expressed at high levels in the central nervous system. Increasing evidence has demonstrated a close association between the Sig-1R and depression. Recently, research has suggested that the gut microbiota may play a crucial role in the development of depression. Male Sig-1R knockout (Sig-1R KO) and wild-type (WT) mice were used for this study. All transgenic mice were of a pure C57BL/6J background. Mice received a daily gavage of vancomycin (100 mg/kg), neomycin sulfate (200 mg/kg), metronidazole (200 mg/kg), and ampicillin (200 mg/kg) for one week to deplete gut microbiota. Fecal microbiota transplantation (FMT) was conducted to assess the effects of gut microbiota. Depression-like behaviors was evaluated by tail suspension test (TST), forced swimming test (FST) and sucrose preference test (SPT). Gut microbiota was analyzed by 16s rRNA and hippocampal transcriptome changes were assessed by RNA-seq. We found that Sig-1R knockout induced depression-like behaviors in mice, including a significant reduction in immobility time and an increase in latency to immobility in the FST and TST, which was reversed upon clearance of gut microbiota with antibiotic treatment. Sig-1R knockout significantly altered the composition of the gut microbiota. At the genus level, the abundance of Alistipes, Alloprevotella, and Lleibacterium decreased significantly. Gut microbiota dysfunction and depression-like phenotypes in Sig-1R knockout mice could be reproduced through FMT experiments. Additionally, hippocampal RNA sequencing identified multiple KEGG pathways that are associated with depression. We also discovered that the cAMP/CREB/BDNF signaling pathway is inhibited in the Sig-1R KO group along with lower expression of neurotrophic factors including CTNF, TGF-α and NGF. Fecal bacteria transplantation from Sig-1R KO mice also inhibited cAMP/CREB/BDNF signaling pathway. In our study, we found that the gut-brain axis may be a potential mechanism through which Sig-1R regulates depression-like behaviors. Our study provides new insights into the mechanisms by which Sig-1R regulates depression and further supports the concept of the gut-brain axis.

Early Alterations of RNA Binding Protein (RBP) Homeostasis and ER Stress-Mediated Autophagy Contributes to Progressive Retinal Degeneration in the rd10 Mouse Model of Retinitis Pigmentosa (RP).

The retinal degeneration 10 (rd10) mouse model is widely used to study retinitis pigmentosa (RP) pathomechanisms. It offers a rather unique opportunity to study trans-neuronal degeneration because the cell populations in question are separated anatomically and the mutated Pde6b gene is selectively expressed in rod photoreceptors. We hypothesized that RNA binding protein (RBP) aggregation and abnormal autophagy might serve as early pathogenic events, damaging non-photoreceptor retinal cell types that are not primarily targeted by the Pde6b gene defect. We used a combination of immunohistochemistry (DAB, immunofluorescence), electron microscopy (EM), subcellular fractionation, and Western blot analysis on the retinal preparations obtained from both rd10 and wild-type mice. We found early, robust increases in levels of the protective endoplasmic reticulum (ER) calcium (Ca2+) buffering chaperone Sigma receptor 1 (SigR1) together with other ER-Ca2+ buffering proteins in both photoreceptors and non-photoreceptor neuronal cells before any noticeable photoreceptor degeneration. In line with this, we found markedly altered expression of the autophagy proteins p62 and LC3, together with abnormal ER widening and large autophagic vacuoles as detected by EM. Interestingly, these changes were accompanied by early, prominent cytoplasmic and nuclear aggregation of the key RBPs including pTDP-43 and FET family RBPs and stress granule formation. We conclude that progressive neurodegeneration in the rd10 mouse retina is associated with early disturbances of proteostasis and autophagy, along with abnormal cytoplasmic RBP aggregation.

Candidate 3-benzazepine-1-ol type GluN2B receptor radioligands (11C-NR2B-Me enantiomers) have high binding in cerebellum but not to σ1 receptors

IntroductionWe recently reported 11C-NR2B-SMe ([S-methyl-11C](R,S)-7-thiomethoxy-3-(4-(4-methyl-phenyl)butyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepin-1-ol) and its enantiomers as candidate radioligands for imaging the GluN2B subunit within rat N-methyl-D-aspartate receptors. However, these radioligands gave unexpectedly high and displaceable binding in rat cerebellum, possibly due to cross-reactivity with sigma-1 (σ1) receptors. This study investigated 11C-labeled enantiomers of a close analogue (7-methoxy-3-(4-(p-tolyl)butyl)-2,3,4,5-tetrahydro-1H-benzo[d]azepin-1-ol; NR2B-Me) of 11C-NR2B-SMe as new candidate GluN2B radioligands. PET was used to evaluate these radioligands in rats and to assess potential cross-reactivity to σ1 receptors.MethodsNR2B-Me was assayed for binding affinity and selectivity to GluN2B in vitro. 11C-NR2B-Me and its enantiomers were prepared by Pd-mediated treatment of boronic ester precursors with 11C-iodomethane. Brain PET scans were conducted after radioligand intravenous injection into rats. Various ligands for GluN2B receptors or σ1 receptors were administered at set doses in pre-blocking or displacement experiments to assess their impact on imaging data. 18F-FTC146 and enantiomers of 11C-NR2B-SMe were used for comparison. Radiometabolites from brain and plasma were measured ex vivo and in vitro.ResultsNR2B-Me enantiomers showed high GluN2B affinity and selectivity in vitro. 11C-NR2B-Me enantiomers gave high early whole rat brain uptake of radioactivity, including high uptake in cerebellum, followed by slower decline. Radioactivity in brain at 30 min ex vivo was virtually all unchanged radioligand. Only less lipophilic radiometabolites appeared in plasma. When 11C-(R)-NR2B-Me was used, three high-affinity GluN2B ligands—NR2B-SMe, Ro25-6981, and CO101,244—showed increasing pre-block of whole brain radioactivity retention with increasing dose. Two σ1 receptor antagonists, FTC146 and BD1407, were ineffective pre-blocking agents. Together, these results strongly resemble those obtained with 11C-NR2B-SMe enantiomers, except that 11C-NR2B-Me enantiomers showed faster reversibility of binding. When 18F-FTC146 was used as a radioligand, FTC146 and BD1407 showed strong pre-blocking effects whereas GluN2B ligands showed only weak blocking effects.Conclusion11C-NR2B-Me enantiomers showed specific binding to GluN2B receptors in rat brain in vivo. High unexpected specific binding in cerebellum was not due to σ1 receptors. Additional investigation is needed to identify the source of the high specific binding.Graphical

446 Accurate Localization of Back Pain by Radiomic Assessment of Sigma-1 Receptor Expression

INTRODUCTION: The current diagnostic tools that we have for back pain have low sensitivity and poor accuracy which leads to ineffective and unnecessary treatments, resulting in high health care costs and unwanted outcomes. Sigma-1 receptor (s1R) is broadly implicated in nociceptive signaling and peripheral pain sensation. METHODS: Specific patient selection for full body ([18F]FTC-146) PET/MRI scan was done after clinical and radiological review by a neurosurgeon specializing in spinal surgery. Six patients with various etiologies of back pain were included. For all the study participants, we recorded all relevant clinical details and reviewed prior diagnostic tests. All PET/MRI scans were completed at our institution’s facilities and images were reviewed and correlated by a musculoskeletal radiologist to identify lesions that may be causing patient’s symptoms. RESULTS: Our study results strongly support the likelihood of achieving enhanced diagnostic sensitivity to sources of back pain with the proposed s1r imaging approach. PET/MRI imaging matched the clinical diagnosis in all cases, including disc herniation, nerve compression, stenosis, and arthropathy. Additionally, it offered benefit over traditional MRI by identifying additional “functional” findings both within and outside the spine. This additional functional detail, was useful for patients with either no or multiple structural abnormalities on MRI to pinpoint the true cause of pain demonstrating the synergistic utility of this imaging modality. Such functional detail guided successful interventions including surgery, therapy, and injections in our patient cohort that successfully addressed the pain. CONCLUSIONS: Early results show promise for improved confidence and sensitivity in detecting sources of pain using full body ([18F]FTC-146) PET/MRI scan which can potentially improve patient management and outcomes.

125I-labeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (125I-OI5V) imaging visualized augmented sigma-1 receptor expression according to the severity of myocardial ischemia

BackgroundWe aimed to explore how the severity of myocardial ischemia affects myocardial sigma-1 receptor (Sig-1R) expression using 125I-labeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (125I-OI5V) imaging. Methods and resultsThe left coronary artery was occluded for 30, 20, and 10 minute, to vary the severity of myocardial ischemia, followed by reperfusion. Dual-tracer autoradiography of the left ventricular short-axis slices was performed 3 and 7 days after reperfusion. 125I-OI5V was injected 30 minute before sacrifice and the area at risk (AAR) was evaluated by 99mTc-MIBI. Intense 125I-OI5V uptake was observed in the AAR and was significantly increased with increasing ischemia duration. To evaluate salvaged and nonsalvaged areas (preserved and decreased perfusion areas), triple-tracer autoradiography was performed 3 days after reperfusion. After dual-tracer autoradiography, 201Tl was injected 20 minute post 125I-OI5V injection. On triple-tracer autoradiography, the AAR/normally perfused area 125I-OI5V uptake ratio was positively correlated with the nonsalvaged area/whole left ventricular (LV) area ratio (P < .05). The AAR/normally perfused area 125I-OI5V uptake ratio was negatively correlated with the 201Tl uptake ratio of the AAR to normally perfused areas (P < .05). The comparison of the immunostaining distribution of 125I-OI5V and the macrophage marker CD68 revealed that 125I-OI5V was present mainly in, and immediately adjacent to the macrophage infiltration area. ConclusionsSignificant 125I-OI5V uptake in the AAR depends on the duration of ischemia and reduced 201Tl uptake; furthermore, 125I-OI5V was found in and around the macrophage infiltrate area. These results indicate that iodine-labeled OI5V is a promising tool for visualizing Sig-1R expression according to the ischemic burden.

Improvement in Anxiety Symptoms in Depressed Patients Treated With AXS-05 (DEXTROMETHORPHAN-BUPROPION): Results From the Evolve Open-Label, Long-Term Study

AbstractBackgroundInnovative therapies to treat individuals with MDD, especially those with comorbid anxiety, are urgently needed.AXS-05 (dextromethorphan HBr 45 mg-bupropion HCl 105 mg) is a novel, oral, investigational NMDA receptor antagonist with multimodal activity. The dextromethorphan component of AXS-05 is an NMDA receptor antagonist and a sigma-1 receptor agonist. The bupropion component of AXS-05 serves primarily to increase the bioavailability of dextromethorphan.ObjectiveTo evaluate the effects of AXS-05 on anxiety in MDD.MethodsEVOLVE was an open-label study, in which patients were treated with AXS-05 twice daily for up to 15 months. Subjects had either rolled in after a prior AXS-05 study or were directly enrolled and had a DSM-5 diagnosis of MDD, a MADRS score of ≥25, and had been treated with ≥ 1 antidepressant in the current major depressive episode. A total of 186 patients were enrolled. Efficacy endpoints included MADRS and HAM-A. Here we present the results for the directly enrolled patients (n =146).ResultsMean baseline HAM-A scores were 15.6. Reductions from baseline to Weeks 1, 2, and 6 were 3.4±5.34 (p&lt; 0.001), 5.5±5.81 (p&lt; 0.001), and 8.6±5.75 (p&lt; 0.001), respectively. Improvements on the HAM-A were durable through Month 12 (-10.2±6.33; p&lt; 0.001). Remission (HAM-A ≤7) rates on the HAM-A at Weeks 1, 2, and 6 were 19.9%, 36.0%, and 58.1%, respectively. Remission at Month 12 was 78.3%.Long-term treatment with AXS-05 was generally well tolerated. The most commonly reported adverse events were COVID-19 infection (8.9%), nausea (8.9%), headache (7.5%), dry mouth (6.2%), insomnia (5.5%), and dizziness (5.5%).ConclusionsThese data support the use of AXS-05 in patients with comorbid depression and anxiety.FundingAxsome Therapeutics

Rapid Antidepressant Effects and MADRS Item Improvements With AXS-05 (DEXTROMETHORPHAN-BUPROPION), an Oral NMDA Receptor Antagonist in Major Depressive Disorder: Results From Two Randomized Double-Blind, Controlled Trials

AbstractBackgroundAXS-05 (dextromethorphan-bupropion) is a novel, oral, investigational, NMDA receptor antagonist with multimodal activity being developed for MDD. The dextromethorphan component of AXS-05 is an NMDA receptor antagonist and a sigma-1 receptor agonist. The bupropion component of AXS-05 serves primarily to increase the bioavailability of dextromethorphan.MethodsAXS-05 was evaluated in two double-blind, randomized, controlled, 6-week trials. The GEMINI trial (N=327) was placebo-controlled and the ASCEND trial (N=80) used bupropion as the control. Here we focus on efficacy in the first 2 weeks of treatment and present a pooled analysis of the individual items of the MADRS for AXS-05 as compared to control.ResultsIn GEMINI, starting at Week 1, AXS 05 was superior (p &lt; 0.05) to placebo on: mean MADRS improvement (7.3 vs. 4.9), MADRS response (15% vs. 7%), CGI-I (22% vs. 13%), CGI-S (0.7 vs. 0.4) and Q-LES-Q-SF (9.0% vs. 5.8%). At Week 2, AXS-05 was also statistically superior to placebo on MADRS remission (17% vs.8%) and on the SDS (6.8 vs. 4.5).In ASCEND, from Week 2, AXS-05 was superior (p&lt; 0.05) to bupropion on: mean MADRS improvement (12.5vs. 7.8), MADRS remission (26% vs. 3%), and CGI-S (1.41 vs. 0.9).At Week 1, treatment with AXS-05 resulted in greater improvements (p&lt; 0.05) in reported sadness, inner tension, inability to feel, pessimistic thoughts, and suicidal thoughts, as compared to control. At Week 6, AXS-05 demonstrated significant improvements over control on seven of the ten MADRS items.In the GEMINI trial, the most commonly reported adverse events were dizziness, nausea, headache, diarrhea, somnolence, and dry mouth.ConclusionsTreatment with AXS-05 resulted in rapid and broad antidepressant efficacy.FundingAxsome Therapeutics

Impact of AXS-05 (DEXTROMETHORPHAN-BUPROPION), an Oral NMDA Receptor Antagonist, on Anhedonic Symptoms in Major Depressive Disorder

AbstractBackgroundTreatments for MDD that can improve both overall depressive and anhedonic symptoms are urgently needed.AXS-05 (dextromethorphan-bupropion) is a novel, oral, investigational NMDA receptor antagonist with multimodal activity being developed for MDD. The dextromethorphan component of AXS-05 is an NMDA receptor antagonist and a sigma-1 receptor agonist. The bupropion component of AXS-05 serves primarily to increase the bioavailability of dextromethorphan.ObjectiveTo evaluate the effect of AXS-05 in improving anhedonic symptoms in MDD.MethodsGEMINI (N=327) was a randomized, double-blind, placebo-controlled, 6-week study, which randomized adults with MDD to AXS-05 (dextromethorphan HBr 45 mg- bupropion HCl 105 mg) or placebo, twice daily. The primary endpoint was change from baseline in the MADRS total score at Week 6. A post-hoc analysis was conducted to determine the impact of AXS-05 versus placebo on the 5-item MADRS anhedonia subscale (MAS).ResultsBaseline MAS scores were 19.8 and 19.6 in the AXS-05 and placebo group, respectively. At Week 1, AXS-05 treatment resulted in a significant mean reduction from baseline in the MAS score of 4.44 versus 2.69 points for placebo (p&lt; 0.001). At Week 6, the mean reduction from baseline in the MAS was 9.70 for AXS-05 compared to 7.22 for placebo (p=0.001). Response rates (≥ 50% MAS improvement) were significantly greater for AXS-05 compared to placebo at Week 1 (p&lt; 0.001) and at every time point thereafter.Treatment with AXS-05 was generally safe and well tolerated. The most common adverse events being dizziness, nausea, headache, diarrhea, somnolence, and dry mouth.ConclusionsTreatment with AXS-05 rapidly and significantly reduced anhedonic symptoms as well as overall depressive symptoms.FundingAxsome Therapeutics