AMPA receptors play an important role in the biological consequences of spinal cord injury: Implications for AMPA receptor modulators for therapeutic benefit.

Spinal cord injury (SCI) afflicts millions of individuals globally. There are few therapies available to patients. Ascending and descending excitatory glutamatergic neural circuits in the central nervous system are disrupted by SCI, making α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) a potential therapeutic drug target. Emerging research in preclinical models highlights the involvement of AMPARs in vital processes following SCI including breathing, pain, inflammation, bladder control, and motor function. However, there are no clinical trial data reported in this patient population to date. No work on the role of AMPA receptors in sexual dysfunction after SCI has been disclosed. Compounds with selective antagonist and potentiating effects on AMPA receptors have benefit in animal models of SCI, with antagonists generally showing protective effects early after injury and potentiators (ampakines) producing improved breathing and bladder function. The role of AMPARs in pathophysiology and recovery after SCI depends upon the time post injury, and the timing of AMPAR augmentation or antagonism. The roles of inflammation, synaptic plasticity, sensitization, neurotrophic factors, and neuroprotection are considered in this context. The data summarized and discussed in this paper document proof of principle and strongly encourage additional studies on AMPARs as novel gateways to therapeutic benefit for patients suffering from SCI. The availability of both AMPAR antagonists such as perampanel and AMPAR allosteric modulators (i.e., ampakines) such as CX1739, that have been safely administered to humans, provides an expedited means of clinical inquiry for possible therapeutic advances.

KRM-II-81 suppresses epileptifom activity across the neural network of cortical tissue from a patient with pharmacoresistant epilepsy.

A clinical case of a 19-year-old male patient with pharmacoresistant seizures occurring following parieto-occipital tumor-resection at age 6 is described. Seizure surgery work-up included prolonged video EEG monitoring and head CT without contrast. Seizure focus was localized to the left temporal lobe, and we felt that the patient was an excellent candidate for seizure surgery. The patient underwent a left frontotemporal craniotomy for removal of the seizure focus with intraoperative electrocorticography (ECoG) conducted pre and post resection. ECoG recordings pre- and post-resection confirmed resolution of seizure generation. Imaging obtained immediately postoperatively showed complete resection of the residual tumor with no evidence of recurrence in follow-ups. A year after the surgery the patient is seizure-free but remains on seizure medication. With the patient's consent the excised epileptogenic tissue was used for ex-vivo research studies. The microelectrode recordings confirmed epileptiform activity in the excised tissue incubated in excitatory artificial cerebrospinal fluid. The epileptiform activity in the epileptogenic tissue was suppressed by addition of KRM-II-81, a novel α2/3 subtype preferring GABAA receptor (GABAAR) potentiator with previously demonstrated antiepileptic efficacy in multiple animal models of epilepsy and with reduced potential for CNS side-effects compared to classical benzodiazepine GABAAR potentiators. These findings support the proposition that KRM-II-81 might reduce seizure burden in pharmacoresistant patients.

New Imidazodiazepine Analogue, 5-(8-Bromo-6-(pyridin-2-yl)-4H-benzo[f]imidazo[1,5-a][1,4]diazepin-3-yl)oxazole, Provides a Simplified Synthetic Scheme, High Oral Plasma and Brain Exposures, and Produces Antiseizure Efficacy in Mice, and Antiepileptogenic Activity in Neural Networks in Brain Slices from a Patient with Mesial Temporal Lobe Epilepsy.

KRM-II-81 (1) is an imidazodiazepine GABAA receptor (GABAAR) potentiator with broad antiseizure efficacy and a low sedative burden. A brominated analogue, DS-II-73 (5), was synthesized and pharmacologically characterized as a potential backup compound as KRM-II-81 moves forward into development. The synthesis from 2-amino-5-bromophenyl)(pyridin-2yl)methanone (6) was processed in five steps with an overall yield of 38% and without the need for a palladium catalyst. GABAAR binding occurred with a Ki of 150 nM, and only 3 of 41 screened binding sites produced inhibition ≥50% at 10 µM, and the potency to induce cytotoxicity was ≥240 mM. DS-II-73 was selective for α2/3/5- over that of α1-containing GABAARs. Oral exposure of plasma and brain of rats was more than sufficient to functionally impact GABAARs. Tonic convulsions in mice and lethality induced by pentylenetetrazol were suppressed by DS-II-73 after oral administration and latencies to clonic and tonic seizures were prolonged. Cortical slice preparations from a patient with pharmacoresistant epilepsy (mesial temporal lobe) showed decreases in the frequency of local field potentials by DS-II-73. As with KRM-II-81, the motor-impairing effects of DS-II-73 were low compared to diazepam. Molecular docking studies of DS-II-73 with the α1ß3γ2L-configured GABAAR showed low interaction with α1His102 that is suggested as a potential molecular mechanism for its low sedative side effects. These findings support the viability of DS-II-73 as a backup molecule for its ethynyl analogue, KRM-II-81, with the human tissue data providing translational credibility.

Structural Analogs of the GABAkine KRM-II-81 Are Orally Bioavailable Anticonvulsants without Sedation.

To provide back-up compounds to support the development of the GABAA receptor (GABAAR) potentiator KRM-II-81, three novel analogs were designed: replacing the pyridinyl with 2'-Cl-phenyl (FR-II-60), changing the positions of the N and O atoms in the oxazole ring with addition of an ethyl group (KPP-III-34 and KPP-III-51), or substituting a Br atom for the ethynyl of KRM-II-81 (KPP-III-34). The compounds bound to brain GABAARs. Intraperitoneal administration of FR-II-60 and KPP-III-34 produced anticonvulsant activity in mice [maximal electroshock (MES)-induced seizures or 6 Hz-induced seizures], whereas KPP-III-51 did not. Although all compounds were orally bioavailable, structural changes reduced the plasma and brain (FR-II-60 and KPP-III-51) exposures relative to KRM-II-81. Oral administration of each compound produced dose-dependent increases in the latency for both clonic and tonic seizures and the lethality induced by pentylenetetrazol (PTZ) in mice. Since KPP-III-34 produced the highest brain area under the curve (AUC) exposures, it was selected for further profiling. Oral administration of KPP-III-34 suppressed seizures in corneal-kindled mice, hippocampal paroxysmal discharges in mesial temporal lobe epileptic mice, and PTZ-induced convulsions in rats. Only transient sensorimotor impairment was observed in mice, and doses of KPP-III-34 up to 500 mg/kg did not produce impairment in rats. Molecular docking studies demonstrated that all compounds displayed a reduced propensity for binding to α1His102 compared with the sedating compound alprazolam; the bromine-substituted KPP-III-34 achieved the least interaction. Overall, these findings document the oral bioavailability and anticonvulsant efficacy of three novel analogs of KRM-II-81 with reduced sedative effects. SIGNIFICANCE STATEMENT: A new non-sedating compound, KRM-II-81, with reduced propensity for tolerance is moving into clinical development. Three new analogs were orally bioavailable, produced anticonvulsant effects in rodents, and displayed low sensorimotor impairment. KPP-III-34 demonstrated efficacy in models of pharmacoresistant epilepsy. Docking studies demonstrated a low propensity for compound binding to the α1His102 residue implicated in sedation. Thus, three additional structures have been added to the list of non-sedating imidazodiazepine anticonvulsants that could serve as backups in the clinical development of KRM-II-81.

Comparative anticonvulsant activity of the GABAkine KRM-II-81 and a deuterated analog.

A series of imidazodiazepines has been developed that possess reduced sedative liabilities but retain efficacy in anticonvulsant screening models. The latest of these compounds, (5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazole[1,5-α][1,4]diazepin-3-yl) oxazole known as KRM-II-81) is currently awaiting advancement into the clinic. A deuterated structural analog (D5-KRM-II-81) was made as a potential backup compound and studied here in comparison to KRM-II-81. In the present study, both compounds significantly prevented seizures in mice induced by 6 Hz (44 mA) electrical stimulation without significantly altering motoric function on a rotarod after intraperitoneal administration. Both compounds also significantly prevented clonic seizures, tonic seizures, and lethality induced by pentylenetetrazol in mice when given orally. D5-KRM-II-81 had a slightly longer duration of action against clonic and tonic seizures than KRM-II-81. Oral administration of 100 mg/kg of either KRM-II-81 or D5-KRM-II-81 was significantly less disruptive of sensorimotor function in mice than diazepam (5 mg/kg, p.o.). The present report documents that D5-KRM-II-81 represents another in this series of imidazodiazepines with anticonvulsant activity at doses that do not impair sensorimotor function.

Hydrochloride Salt of the GABAkine KRM-II-81.

Imidazodiazepine (5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo[f]imidazole[1,5-α][1,4]diazepin-3-yl) oxazole or KRM-II-81) is a potentiator of GABAA receptors (a GABAkine) undergoing preparation for clinical development. KRM-II-81 is active against many seizure and pain models in rodents, where it exhibits improved pharmacological properties over standard-of-care agents. Since salts can be utilized to create opportunities for increased solubility, enhanced absorption, and distribution, as well as for efficient methods of bulk synthesis, a hydrochloride salt of KRM-II-81 was prepared. KRM-II-81·HCl was produced from the free base with anhydrous hydrochloric acid. The formation of the monohydrochloride salt was confirmed by X-ray crystallography, as well as 1H NMR and 13C NMR analyses. High water solubility and a lower partition coefficient (octanol/water) were exhibited by KRM-II-81·HCl as compared to the free base. Oral administration of either KRM-II-81·HCl or the free base resulted in high concentrations in the brain and plasma of rats. Oral dosing in mice significantly increased the latency to both clonic and tonic convulsions and decreased pentylenetetrazol-induced lethality. The increased water solubility of the HCl salt enables intravenous dosing and the potential for higher concentration formulations compared with the free base without impacting anticonvulsant potency. Thus, KRM-II-81·HCl adds an important new compound to facilitate the development of these imidazodiazepines for clinical evaluation.

Can GABAkines quiet the noise? The GABAA receptor neurobiology and pharmacology of tinnitus.

Tinnitus is a highly prevalent and disabling disorder in which sound is perceived in the absence of an external auditory energy source. The disorder is complex and can arise from multiple etiologies. Co-morbid symptoms of anxiety, depression, and sleep loss are prevalent. There are no approved medications and the treatments that have been studied produce marginal improvements in symptoms. A major hypothesis of the etiology and maintenance of tinnitus is that inhibitory input mechanisms become compromised where impaired γ-aminobutyric acid (GABA) synaptic transmission has been implicated. This general idea lends support to the potential for enhanced inhibition by drugs that enhance GABA function (GABAkines) to dampen symptoms of tinnitus. Convergent evidence from neurochemical, anatomical, physiological, and pharmacological studies support the GABAA hypothesis. Although there is surprising a relatively sparse data set, examples of therapeutic efficacy have been reported with GABAkines. These studies have relied primarily on classical benzodiazepine anxiolytics like alprazolam and clonazepam. However, the possibility that novel GABAkines with unique activities might be effective have yet to be intensively explored. For example, data implicating extrasynaptic GABAAreceptors in the control of tinnitus suggests the potential for extrasynaptic GABAA receptor modulators. The large medical need, a basis for further testing of the GABAA hypothesis, and the recent reinvigoration of the drug development pipeline of new GABAkines, combine to give impetus and promise for further inquiry.

Metabolism, pharmacokinetics, and anticonvulsant activity of a deuterated analog of the α2/3-selective GABAkine KRM-II-81.

The imidazodiazepine, (5-(8-ethynyl-6-(pyridin-2-yl)-4H-benzo [f]imidazole[1,5-α][1,4]diazepin-3-yl) oxazole or KRM-II-81) is a new α2/3-selective GABAkine (gamma aminobutyric acid A receptor potentiator) with anticonvulsant, anxiolytic, and antinociceptive activity in preclinical models. Reducing metabolism was utilized as a means of potentially extending the half-life of KRM-II-81. In vitro and in vivo studies were conducted to evaluate metabolic liabilities. Incubation of KRM-II-81 in hepatocytes revealed sites of potential metabolism on the oxazole and the diazepine rings. These sites were targeted in the design of a deuterated analog (D5-KRM-II-81) that could be evaluated as a potentially longer-acting analog. In contrast to computer predictions, peak plasma concentrations of D5-KRM-II-81 in rats were not significantly greater than those produced by KRM-II-81 after oral administration. Furthermore, brain disposition of KRM-II-81 was higher than that of D5-KRM-II-81. The half-life of the two compounds in either plasma or brain did not statistically differ from one another but the tmax for D5-KRM-II-81 occurred slightly earlier than for KRM-II-81. Non-metabolic considerations might be relevant to the lack of increases in exposure by D5-KRM-II-81. Alternative sites of metabolism on KRM-II-81, not targeted by the current deuteration process, are also possible. Despite its lack of augmented exposure, D5-KRM-II-81, like KRM-II-81, significantly prevented seizures induced by pentylenetetrazol when given orally. The present findings introduce a new orally active anticonvulsant GABAkine, D5-KRM-II-81.

The imidazodiazepine, KRM-II-81: An example of a newly emerging generation of GABAkines for neurological and psychiatric disorders.

GABAkines, or positive allosteric modulators of γ-aminobutyric acid-A (GABAA) receptors, are used for the treatment of anxiety, epilepsy, sleep, and other disorders. The search for improved GABAkines, with reduced safety liabilities (e.g., dependence) or side-effect profiles (e.g., sedation) constituted multiple discovery and development campaigns that involved a multitude of strategies over the past century. Due to the general lack of success in the development of new GABAkines, there had been a decades-long draught in bringing new GABAkines to market. Recently, however, there has been a resurgence of efforts to bring GABAkines to patients, the FDA approval of the neuroactive steroid brexanolone for post-partum depression in 2019 being the first. Other neuroactive steroids are in various stages of clinical development (ganaxolone, zuranolone, LYT-300, Sage-324, PRAX 114, and ETX-155). These GABAkines and non-steroid compounds (GRX-917, a TSPO binding site ligand), darigabat (CVL-865), an α2/3/5-preferring GABAkine, SAN711, an α3-preferring GABAkine, and the α2/3-preferring GABAkine, KRM-II-81, bring new therapeutic promise to this highly utilized medicinal target in neurology and psychiatry. Herein, we also discuss possible conditions that have enabled the transition to a new age of GABAkines. We highlight the pharmacology of KRM-II-81 that has the most preclinical data reported. KRM-II-81 is the lead compound in a new series of orally bioavailable imidazodiazepines entering IND-enabling safety studies. KRM-II-81 has a preclinical profile predicting efficacy against pharmacoresistant epilepsies, traumatic brain injury, and neuropathic pain. KRM-II-81 also produces anxiolytic- and antidepressant-like effects in rodent models. Other key features of the pharmacology of this compound are its low sedation rate, lack of tolerance development, and the ability to prevent the development of seizure sensitization.

GABAkines - Advances in the discovery, development, and commercialization of positive allosteric modulators of GABAA receptors.

Positive allosteric modulators of γ-aminobutyric acid-A (GABAA) receptors or GABAkines have been widely used medicines for over 70 years for anxiety, epilepsy, sleep, and other disorders. Traditional GABAkines like diazepam have safety and tolerability concerns that include sedation, motor-impairment, respiratory depression, tolerance and dependence. Multiple GABAkines have entered clinical development but the issue of side-effects has not been fully solved. The compounds that are presently being developed and commercialized include several neuroactive steroids (an allopregnanolone formulation (brexanolone), an allopregnanolone prodrug (LYT-300), Sage-324, zuranolone, and ganaxolone), the α2/3-preferring GABAkine, KRM-II-81, and the α2/3/5-preferring GABAkine PF-06372865 (darigabat). The neuroactive steroids are in clinical development for post-partum depression, intractable epilepsy, tremor, status epilepticus, and genetic epilepsy disorders. Darigabat is in development for epilepsy and anxiety. The imidazodiazepine, KRM-II-81 is efficacious in animal models for the treatment of epilepsy and post-traumatic epilepsy, acute and chronic pain, as well as anxiety and depression. The efficacy of KRM-II-81 in models of pharmacoresistant epilepsy, preventing the development of seizure sensitization, and in brain tissue of intractable epileptic patients bodes well for improved therapeutics. Medicinal chemistry efforts are also ongoing to identify novel and improved GABAkines. The data document gaps in our understanding of the molecular pharmacology of GABAkines that drive differential pharmacological profiles, but emphasize advancements in the ability to successfully utilize GABAA receptor potentiation for therapeutic gain in neurology and psychiatry.

Effects of chronic systemic low-impact ampakine treatment on neurotrophin expression in rat brain.

Neurotrophin dysregulation has been implicated in a large number of neurodegenerative and neuropsychiatric diseases. Unfortunately, neurotrophins cannot cross the blood brain barrier thus, novel means of up regulating their expression are greatly needed. It has been demonstrated previously that neurotrophins are up regulated in response to increases in brain activity. Therefore, molecules that act as cognitive enhancers may provide a clinical means of up regulating neurotrophin expression. Ampakines are a class of molecules that act as positive allosteric modulators of AMPA-type glutamate receptors. Currently, they are being developed to prevent opioid-induced respiratory depression without sacrificing the analgesic properties of the opioids. In addition, these molecules increase neuronal activity and have been shown to restore age-related deficits in LTP in aged rats. In the current study, we examined whether two different ampakines could increase levels of BDNF and NGF at doses that are active in behavioral measures of cognition. Results demonstrate that ampakines CX516 and CX691 induce differential increases in neurotrophins across several brain regions. Notable increases in NGF were observed in the dentate gyrus and piriform cortex while notable BDNF increases were observed in basolateral and lateral nuclei of the amygdala. Taken together, our data demonstrates that chronic administration of clinically relevant doses of ampakines have the ability to elevate neurotrophin expression in different brain regions, and may have therapeutic benefit in multiple neurodegenerative and/or neuropsychiatric disorders.

Tarps differentially affect the pharmacology of ampakines.

Transmembrane AMPA receptor regulatory proteins (TARPs) govern AMPA receptor cell surface expression and distinct physiological properties including agonist affinity, desensitization and deactivation kinetics. The prototypical TARP, STG or γ2 and TARPs γ3, γ4, γ7 and γ8 are all expressed to varying degrees in the mammalian brain and differentially regulate AMPAR gating parameters. Positive allosteric AMPA receptor modulators or ampakines alter receptor rates of agonist binding/unbinding, channel opening and can offset receptor desensitization and deactivation. The effects of the two ampakines, CX614 and cyclothiazide (CTZ) were evaluated on homomeric GluR1-flip receptors and GluR2-flop receptors expressed on HEK293 cells by transient transfection with or without different TARPs γ2, γ3, γ4 or γ8 genes. γ4 was the most robust TARP in increasing the affinities of CX614 and CTZ on GluR1-flip receptors, but had no such effect on GluR2-flop receptors. However, γ8 gave the most significant increases in affinities of CX614 and CTZ on GluR2-flop. These data show that TARPs differentially affect the surface expression and kinetics of the AMPA receptor, as well as the pharmacology of ampakines for the AMPA receptor. The modulatory effects of TARPs on ampakine pharmacology are complex, being dependent on both the TARP subtype and the AMPA receptor subtypes/isoforms.

Ampakines Attenuate Staurosporine-induced Cell Death in Primary Cortical Neurons: Implications in the 'Chemo-Brain' Phenomenon.

BACKGROUND/AIM: Mounting evidence suggests that trophic cell signaling can be mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) activation. It has been demonstrated that exogenous application of brain-derived neurotrophic factor (BDNF) is highly neuroprotective in vitro against neurotoxic insults such as standard chemotherapies. MATERIALS AND METHODS: Because positive allosteric modulation of AMPARs with ampakines can increase both BDNF mRNA and protein in vitro and in vivo, we examined whether application of the ampakines CX614 and CX729 promoted neuroprotection against staurosporine-induced cell death in rat primary cortical neurons using propidium iodide to stain for dead cells. RESULTS: A transient 2-h pretreatment with CX614 or CX729 performed 24 h prior to staurosporine produced significant, time-dependent neuroprotection that was resistant to the AMPAR antagonists NBQX or GYKI 52466, suggesting that this effect may be independent of ion flow. Furthermore, the pretreatment time requirements of CX729 matched the time course for increased BDNF expression previously reported to occur in hippocampal slices, suggesting that increased neurotrophin expression might be associated with the neuroprotective effects conferred by ampakines. CONCLUSION: Our data demonstrate that ampakines may be able to perturb neuronal toxicity and peripheral neuropathy of front-line chemotherapies.

Stargazin differentially modulates ampakine gating kinetics and pharmacology.

It was previously reported that Stargazin (STG) enhances the surface expression of AMPA receptors, controls receptor gating and slows channel desensitization as an auxiliary subunit of the receptors. Ampakines are a class of AMPA receptor positive allosteric modulators that modify rates of transmitter binding, channel activity and desensitization parameters. As such, they have shown efficacy in animal models of neurodegenerative diseases, where excitatory synaptic transmission is compromised. Given the functional similarities between STG and ampakines, the current study sought to probe interactions between STG and ampakine gating properties. The effects of the high impact ampakines, CX614 and cyclothiazide (CTZ), were compared with homomeric GluR1-flip (Glur1i) and GluR2-flop (Glur2o) receptors expressed in HEK293 cells by transient transfection with or without STG gene. STG dramatically enhanced the surface expression of AMPA receptors and increased glutamate-induced steady-state currents during desensitization. STG also increased ratios of 500 µM kainate and 500 µM glutamate activated steady-state currents. STG reduced association rates of ampakines and differentially affected the dissociation rates for both CX614 and CTZ on desensitized receptors. The estimated Kd value for CX614 was lowered from 340 µM to 70 µM, whereas that for CTZ was lowered from 170 µM to 6 µM by STG. The data suggest that Stargazin can dramatically alter the conformation of the receptor dimer interface where CX614 and CTZ are known to bind. This work also demonstrates the importance of considering STG interactions when developing ampakines to treat neurodegenerative diseases in which AMPAergic signaling is compromised.

Brain Vacuolation Resulting From Administration of the Type II Ampakine CX717 Is An Artifact Related to Molecular Structure and Chemical Reaction With Tissue Fixative Agents.

Ampakines are small molecule positive allosteric modulators of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). One class II ("low impact") ampakine, CX717, has been implicated to have a neurotoxic effect based on findings in nonclinical, long-term toxicity studies. The neurotoxicity concerns, which halted the clinical development of the molecule, arose due to a finding of extensive white matter vacuolation in multiple brain regions of animals that were administered high doses of CX717 in several test species (unpublished data). This work characterized the features and a potential mechanism by which ampakines induce vacuoles in brain tissue. Brain sections from adult rats given CX717 (750 mg/kg BID by oral gavage) exhibited no vacuoles with acute or short-term dosing. However, after 14 or more days of treatment, vacuoles were prominent in cerebellum, globus pallidus, and hippocampus. Vacuole margins were lined by glial fibrillary acidic protein (GFAP), and by transmission electron microscopy were shown to be astrocyte processes. CX717-associated vacuoles occurred in formaldehyde-fixed specimens but not flash-frozen samples. Time-course experiments showed that brain tissue slices from CX717-treated animals exhibit no vacuoles until immersed in formaldehyde fixative, whereupon vacuoles form and expand in a time-dependent manner. Chemical interactions in test tube experiments have demonstrated that the combination of CX717 and formalin in an aqueous solution produces an exothermic reaction. Taken together, the data indicate that CX717 does not induce vacuoles in vivo, but rather is associated with astrocyte vacuolation post mortem, likely as the ampakine reacts with formalin to produce gas pockets in brain parenchyma.

Oncolytic Properties of Ampakines In Vitro.

BACKGROUND/AIM: The 5-year survival rate of glioblastoma (GBM) is ~10%, demonstrating that a new therapeutic modality for this cancer is desperately needed. Complicating the search for such a modality is that most large molecules cannot pass through the blood brain barrier, so molecules demonstrating efficacy in vitro may not be useful in vivo because they never reach the brain. Recently, the selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLX) was identified as an effective agent in targeting GBM in vitro and in vivo by agonizing AMPA-glutamate receptors (AMPARs), eliciting massive calcium influx and mitochondrial calcium overload and apoptosis. MATERIALS AND METHODS: In the current study, we used a colorimetric cell viability assay to determine if we could enhance the oncolytic effect of FLX in vitro by pre-treating cells with an AMPAR-positive allosteric modulator (Ampakine). RESULTS: Our results demonstrated for the first time that concentrations of the Class I ampakine CX614, which increase AMPAR agonist binding affinity, possess oncolytic activity as a sole agent and synergistically reduce GBM viability when paired with FLX. FLX also demonstrates a dose-dependent induction of apoptosis in cancer cells originating outside the CNS that overexpress calcium-permeable AMPARs. Likewise, CX614 inhibits cancer cell viability in a dose-dependent fashion and its combination with FLX synergistically reduces cell viability. These effects of CX614 were not seen with the Class II ampakines, CX717 and CX1739. CONCLUSION: CX614 inhibits the growth of multiple cancers in vitro and bolsters the oncolytic activity of FLX in several cancers.

Acute ampakine treatment ameliorates age-related deficits in long-term potentiation.

Memory loss observed as a consequence of aging is paralleled by a down-regulation of AMPA-type glutamate receptors (AMPARs) that mediate fast excitatory synaptic transmission. Activation of these receptors enhances long-term potentiation (LTP), a neuronal process demonstrated to be crucial for memory storage and thought to be a cellular substrate of learning and memory. In the present studies, we determined that LTP was reduced in aged rats when compared to young rats and that acute treatment with CX1846, a novel AMPAR positive allosteric modulator, fifteen minutes prior to tetanic stimulation completely reversed the significant deficit in LTP observed in aged rats. These results suggest that CX1846 might be useful for the treatment of age-related memory impairments.

Lifeguard inhibition of Fas-mediated apoptosis: A possible mechanism for explaining the cisplatin resistance of triple-negative breast cancer cells.

Triple-negative breast cancer does not express estrogen receptor-α, progesterone or the HER2 receptor making hormone or antibody therapy ineffective. Cisplatin may initiate p73-dependent apoptosis in p53 mutant cell lines through Fas trimerization and Caspase-8 activation and Bax up regulation and subsequent Caspase-9 activation. The triple-negative breast cancer, MDA-MB-231, overexpresses the protein Lifeguard, which inhibits Fas-mediated apoptosis by inhibiting Caspase-8 activation after Fas trimerization. The relationship between Fas, Lifeguard and cisplatin is investigated by down regulating Lifeguard via shRNA. Results demonstrate that cisplatin's efficacy increases when Lifeguard is down regulated. Lifeguard Knockdown MDA-MB-231 continue to decrease in cell viability from 24 to 48h after cisplatin treatment while no additional decrease in viability is observed in the Wild-Type MDA over the same period. Higher Caspase-8 activity in the Lifeguard knockdown MDA after cisplatin administration could explain the significant decrease in cell viability from 24 to 48h. This cell type is also more sensitive to Fas ligand-mediated reductions in cell viability, confirming Lifeguard's anti-apoptotic function through the Fas receptor. This research suggests that the efficacy of chemotherapy acting through the Fas pathway would increase if Lifeguard were not overexpressed to inhibit Fas-mediated apoptosis.

A multicenter, placebo-controlled, double-blind, randomized study of efficacy and safety of ocinaplon (DOV 273,547) in generalized anxiety disorder.

Preclinical studies demonstrated that ocinaplon, a positive allosteric modulator of GABA(A) receptors, possesses anxiolytic-like actions at doses devoid of the side effects typically associated with benzodiazepines. The aim of this study was to evaluate the effects of ocinaplon in a multicenter, double-blind proof-of-concept trial of male and female outpatients who met DSM-IV criteria for GAD with no coexisting depression, and had a baseline score of > or =20 on the Hamilton Scale for Anxiety (HAM-A). Patients with <20% reduction in HAM-A to placebo in a single-blind 7-day run-in period were randomly assigned to treatment with ocinaplon 90 mg t.i.d. (n = 31) or placebo for 28 days (n = 29). Ocinaplon was more effective than placebo in reducing HAM-A scores (P= 0.009). Patients assigned to ocinaplon exhibited a mean improvement of 14.2 points (SE = 2.6) on the total score of the HAM-A scale at the conclusion of the trial, while patients assigned to placebo obtained a mean improvement of 6.3 points (SE = 2.0). A significant (P= 0.023) difference in improvement between ocinaplon and placebo was observed beginning at and continuing from 1-week after the initiation of dosing. The proportion of patients with treatment-emergent adverse events (TEAE) was not statistically significant between ocinaplon and placebo. One serious adverse event (SAE) occurred in the ocinaplon group that was considered possibly related to study medication (icterus following transaminase elevations). The patient had preexisting medical conditions that may have contributed to this SAE. A full recovery was observed with no residual effects. The overall safety profile revealed no patterns of TEAEs, including those effects typically associated with other anxiolytic and/or benzodiazepine compounds, such as sedation. Ocinaplon appears to be a well-tolerated and effective treatment for GAD. It produces a rapid onset of anxiolytic action absent the side effects (e.g., dizziness, sedation) typically reported following anxiolytic doses of benzodiazepines.