5th Neurodegenerative Conditions Research and Development

SynuclereÔ represents a novel small molecule that specifically targets and markedly reduces aggregated a-synuclein, a protein critical in the underlying etiology of Parkinson’s Disease (PD).  In vitro (Thioflavin T, Congo red binding and CD spectroscopy) and A53T-alpha-synuclein expressing cell-based assays identified eight compounds that demonstrated a marked inhibition of alpha-synuclein aggregation and rotenone-induced toxicity.  These compounds also exhibited good CNS drug properties including non-binding to brain receptors, transporters and/or ion channels, no significant CYP450 inhibition, good plasma free fraction, moderate-to-high stability in microsomes, and acceptable pharmacokinetics following intraperitoneal injection.

The efficacy of these eight compounds was tested in a PD-relevant animal model: human wild-type alpha-synuclein transgenic mice (Line 61).  These studies identified the lead compound, SynuclereÔ, by demonstrating a marked reduction in a-synuclein aggregation/ accumulation in the substantia nigra, cortex and hippocampus following 3-months treatment in younger mice (45-90% reductions) or 6-months treatment in older mice (79-91% reductions), including reductions in soluble a-synuclein oligomers (by 69-72%).  Improved motor performance on the challenging beam traversal and pole tests accompanied reduced a-synuclein aggregates in SynuclereÔ-treated transgenic mice. A backup compound (PD-61-F2) that also dramatically reduced brain a-synuclein aggregates (by 62%-93%) was also identified.

Benefits of this talk include: better understanding of the efforts toward developing small molecule disease-modifying PD therapeutics; demonstration of a platform technology targeting misfolded proteins (a-synuclein) in CNS (Parkinson’s) disease; demonstration of using transgenic mice in the CNS drug discovery process; prime example of the potential impact of a biotechnology company in the drug discovery and development arena.

Orion Pharma has produced a series of a_2C-adrenoceptor (AR) selective compounds of which the most advanced compound ORM-12741 is currently under clinical Phase II studies. ORM-12741 is a very potent and selective a_2C-AR antagonist - a_2C-AR antagonism occurs in subnanomolar range in vitro and the subtype selectivity ratio to the other a₂-AR subtypes is 35 to 3800 fold, depending on the in vitro method. According to rodent behavioral pharmacology studies the drug candidate should have clinically beneficial effects on the symptoms of many neuropsychiatric disorders including Alzheimer’s disease, depression and schizophrenia. In Alzheimer’s disease patients the compound´s unique profile is expected to give therapeutic advantage for treatment of cognitive decline and associated depressive and behavioral symptoms either alone and/or in combination of the other available drug treatments. The presentation includes the review of the pharmacological validation of a_2C-AR antagonism concept for CNS disorders and preclinical results obtained with the various a_2C-AR selective lead compounds. In addition, results from animal and human brain positron emission tomography (PET) studies with a novel a_2C-AR selective PET tracer ¹¹C-ORM-13070 are presented. 

GW5074 is a 3’ substituted indolone that is highly protective in tissue culture and in vivo paradigms of neurodegeneration.  GW5074 protects neurons by activating B-Raf.  Inhibiting B-Raf activity blocks GW5074-mediated neuroprotection whereas overexpression of active B-Raf protects neurons in the absence of GW5074.  Our finding suggests that increasing B-Raf activity by pharmacological and other approaches could represent a strategy to reduce or prevent neurodegeneration in human neurological disorders. Downstream of B-Raf, protection by GW5074 involves the inhibition of expression of two genes that are pro-apoptotic in neurons, c-jun and ATF-3.  While highly neuroprotective, GW5074 displays toxicity when used at higher concentrations. Using a structure-activity relationship (SAR) approach, we have identified several 3’ substituted indolones that maintain the neuroprotective efficacy of GW5074 but that are not toxic in tissue culture systems. Our studies on the neuroprotective actions of GW5074 and these other 3’ substituted indolones will be discussed. We will also describe our recent identification of 1, 4- benzoxazines as a novel class of neuroprotective compounds.  One of these benzoxazines designated as HSB-13 has been found to be effective in a mouse model of Huntington’s disease and a Drosophila model of Alzheimer’s disease.  We have identified the likely cellular targets of HSB-13 and will present these results.  Based on these results, 3’ substituted indolones and 1, 4- benzoxazines are novel neuroprotective drugs that could have utility in the treatment of neurodegenerative diseases.

Mitochondrial dysfunction is a common, enduring feature of aging and neurodegeneration. Mitochondria have essential functions for synaptically active neurons via their ability to provide needed energy, buffer calcium and modulate cell signaling via the appropriate production of reactive oxygen species. An area of emerging interest in the field of mitochondrial therapeutics is mitochondrial homeostasis. Recent data indicate that the coactivator PGC-1a is necessary and sufficient to overcome mitochondrial toxicity in rodent models of Huntington’s disease (HD), Parkinson’s Disease and Alzheimer’s Disease. PGC 1a can be regulated by and interact with several transcription factors to recruit the basal transcriptional machinery to genes involved in mitochondrial biogenesis, mitochondrial function and antioxidant defense. We have recently identified a novel modulator of PGC1-a expression: Transglutaminase 2 (TG2). In a cellular model of HD, TG2 inhibition de-repressed PGC-1a and cytochrome c and reversed the susceptibility of several in vitro HD models to the mitochondrial toxin, 3-NP. A gene microarray analysis indicated that transglutaminase inhibition normalized expression of not only mitochondrial genes but also 40% of genes that are dysregulated in HD striatal neurons. The novel results and the general hypothesis on how TG2 modulates transcription in neurodegeneration will be presented. We will discuss about selective TG2 inhibition and its ability to correct transcriptional dysregulation broadly in HD and to define a potential novel HDAC-independent epigenetic strategy for treating neurodegeneration.