How To Treat A Variety Of Conditions With A Drug

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1 A new class of CB 2 agonists January 2013

2 Summary Endocannabinoid System Cannabinoid Receptors Cannabinoids and Therapeutic Perspectives C4T Project Results C4T Approaches Partnership Opportunities References Abbreviations ECS endocannabinoid system CB 1 cannabinoid receptor 1 CB 2 cannabinoid receptor 2 MAGL monoacylglycerol lipase FAAH fatty acid amide hydrolase THC Δ 9 - tetrahydrocannabinol CBD cannabidiol 2

3 Endocannabinoid System Endocannabinoid System The cannabinoid system (ECS) has attracted pharmacologists interest for its potential as therapeutic targets for several diseases ranging from obesity to Parkinson's disease and from multiple sclerosis to pain. The ECS is an ubiquitous signaling system involved in important regulatory functions, which consists of: Cannabinoid receptors: 1 CB 1, CB 2 and GPR55, the latter recently indicated as type 3 cannabinoid receptor 2 (CB 3 ) Endogenous ligands (endocannabinoids): 3 the most bioactive are anandamide (AEA) and 2-arachidonylglycerol (2-AG), released on demand from phospholipid precursors in both CNS and PNS Protein transporters and enzymes involved in their synthesis, cell uptake and degradation: 4 NAPE-PLD, DAGL, MAGL, FAAH and others. This system plays a critical role in many physiological processes such as learning and memory, appetite control, pain sensation, motor coordination, lipogenesis, modulation of immune response, and regulation of bone mass. Alterations in the endogenous cannabinoid system have been described in almost every category of disease. These changes can alternatively be protective or maladaptive, such as producing antinociception in neuropathic pain or fibrogenesis in liver disease, making the system an attractive therapeutic target. 3

4 Cannabinoid Receptors Cannabinoid Receptors The CBRs belong to the seven transmembrane spanning (7TM)/G protein-coupled receptor (GPCRs) family and are perhaps the most abundant GPCRs expressed at high levels in many regions of the mammalian brain. CB receptors are expressed in both central and peripheral nervous system (CNS and PNS, respectively) where they are involved in the modulation of the several physiological events. CB1 is heterogeneously expressed at high levels in the central nervous system (CNS) and in peripheral tissue (e.g., liver and adipocytes), while CB2 is localized mainly on immune cells and microglia and is associated with immune function 5 (Table 1). The varying degree of selectivity of endogenous and exogenous cannabinoids for CB 1 and CB 2 receptors accounts for their various psychotropic and peripheral effects. G protein-coupled receptor 55 (GPR55) was recently proposed as a novel component of this system, putative CB3 receptor and it has attracted much attention, potentially explaining physiological effects that are non-cb1/cb2 mediated. 6 Table 1: CB receptor localization and physiological pathway modulation 4

5 Cannabinoids and Therapeutic Perspectives Cannabinoids and Therapeutic Perspectives It is widely accepted that non-endogenous compounds that target CB 1 and/or CB 2 receptors possess therapeutic potential for the clinical management of an ever growing number of disorders, 7 including: Inflammatory and neuropathic pain Obesity and metabolic disorders Neurological diseases Cancer and others Just a few of these disorders are already treated with (9)-THC or nabilone, both CB 1 /CB 2 receptor agonists (Table 2). Table 2: CB 1 /CB 2 agonists in pharmaceutical market. Drug Company Therapeutic Area/ Diseases Notes Nabilone (Cesamet ) Lilly Chronic pain management Emesis and Anorexia: chemotherapyinduced nausea and vomiting and for anorexia treatment in patients with AIDS Synthetic derivative of THC Dronabinol (Merinol ) Solvay Pharm. Inc. Emesis and Anorexia: chemotherapyinduced nausea and vomiting and for anorexia treatment in patients with AIDS Medicinal product containing THC Nabiximols (Sativex ) GW-Pharm. Neuropathic pain and spasticity in MS patients Oromucosal mouth spray containing THC e CBD Bedrocan Bedrocan BV Pain in in patient with cancer, AIDS, MS Medicinal product based on THC and CBD There is now considerable interest in expanding the clinical applications of such agonists and also in exploiting CB 2 -selective agonists, peripherally restricted CB 1 / CB 2 receptor agonists and CB 1 /CB 2 antagonists and inverse agonists as medicines. Already numerous cannabinoid receptor ligands have been developed and their interactions with CB 1 and CB 2 receptors well characterized. Recently the possibility to target CB 2 has emerged as an alternative for the treatment of a multitude of disparate diseases and pathological conditions, 8 (i.e pain, atherosclerosis, cancer, inflammation). In particular, the main advantage of targeting CB 2 resides in the possibility to avoid the psychotropic side effects characteristic of targeting CB 1. 5

6 Cannabinoids and Therapeutic Perspectives Neuropathic Pain Persistent pains associated with inflammatory and neuropathic states are prevalent and debilitating diseases, which still remain without a safe and adequate treatment. Chronic pain represents a major health problem throughout the world, thus several companies and researchers have embarked on the search for new drugs and targets to treat the disease. Although CB 1 /CB 2 agonists, synthetic derivatives of THC and CBD, are in market in several countries for the treatment of neuropathic pain, many severe psychotropic effects are related to them due to central CB 1 activation. 9 From this perspective, CB 2 selective agonists may have potential in the treatment of neuropathic pain as demonstrated by several pre-clinical studies in a variety of rodent models, avoiding the central side effects CB 1 related. 10 For example, local or systemic delivery of CB 2 receptor agonists reversed hyperalgesia in models of both postoperative and neuropathic pain. 11 In other studies, CB 2 agonists reduced chronic constriction injury (CCI)-induced sensitivity to light mechanical touch (allodynia) and reversed allodynia caused by tight ligation of spinal nerves (SNL), spinal nerve transaction, brachial plexus avulsion partial sciatic nerve ligation (PSL), and others. 12 In this contest, new selective CB 2 agonists had so far reached clinical trials (see Table 3 for details). Table 3: CB 2 agonists in clinical trials for neuropathic pain management. Drug MoA Status Country Company JBT-101 CB1/CB2 agonist Phase 2 US JB Therapeutics KHK 6188 CB2 agonist Phase 1 JPN Kyowa Hakko Kirin GRC CB2 agonist Phase 1 US Glenmark CRA13 CB2 agonist Phase 1 CH Novartis 6

7 Cannabinoids and Therapeutic Perspectives Emesis, obesity and metabolic disorders Synthetic analogues of THC and CBD are today on the market in many countries as anti-emetic drugs in chemotherapy-induced nausea and vomiting 13 and for anorexia treatment in patients with AIDS (see Table 2). Based on orexigen effects of CB 1, the inhibition of this receptor seemed to represent a new frontier for the pharmacological treatment of obesity, especially with the entry into market in more than 62 countries of Rimonabant. However, the development of CB 1 antagonist and inverse-agonists was discontinued due to their psychiatric side effects related to CB 1 inhibition. 14 Selective CB 2 agonists, such as Hu-308, JWH-133 and JWH-015, instead, demonstrated their efficacy in rat model of alcoholic hepatic steatosis by decreasing the liver/ body weight ratio and hepatic triglyceride content, 15 representing a potential new alternative for treatment of some metabolic disorders. Neurodegenerative diseases The ECS system is emerging as a key regulator of neuronal cell fate and is able of conferring neuroprotection by the direct control of neurogenesis. 16 Although, CB 1 is the main receptor of CNS, the presence of CB 2 in the CNS, both in microglia and neuronal cells, suggests the possibility to use CB 2 agonists to treat various neurological conditions, including Alzheimer's and Parkinson's diseases without psychotropic side effects. 17 Cancer Cannabinoids have recently been shown to produce anti-tumor actions (reduction of inflammation, cell proliferation and cell survival properties) in different models of cancer (i.e., breast, prostate and bone cancer). In particular, recent experimental date demonstrate the ability of CB 2 agonists such as WIN55,212-2, CP,55940 and JWH-133 to inhibit both cell proliferation and migration by CB 2 activation, although a possible role for CB 1 was not assessed. 18 7

8 C4T Project C4T Project Since 2007, C4T focused its activities on the study of ECS, in particular on the identification of CB 2 modulators characterized by: Agonist or inverse agonist activity Chemical novelty patentability Selectivity over CB 1 and other members of the ECS Physical-chemical properties that make the compounds drug-like and potentially able to exert their effects at both peripheral and central system. In this field, C4T received awards and public funds from Ministero dell Istruzione, dell Università e della Ricerca (MIUR) and Regione Lazio (Filas-I DTB) Technology Platform for CB drug discovery To achieve the project aims, C4T developed a proprietary drug discovery platform for the identification of novel modulator of CB 2 receptor, by integrating computational and synthetic C4T approaches with the Medium-Throughput Screening (MTS) performed by the group of Prof. Maccarrone (Univ. of Rome Tor Vergata ). The platform includes: CB receptor homology models validated by in vitro screening results Max diverse/focused library generation MTS on CB receptors NETWORK C4T Design and synthesis University of Teramo Prof. M. Maccarrone In vitro screening and Biochemical Characterizations 8

9 Results Results C4T3116 series: a novel class of CB 2 selective agonists based on an innovative scaffold was identified by in silico approaches and rational drug design studies. The lead compound C4T 3116 represents an ideal candidate for lead optimization. The scaffold was identified by pharmacophore based virtual screening and a max diversity library was generated by exploring the three main scaffold chemical diversity points. By in silico studies, the C4T 3116 series shows: a common CB 2 binding mode two common pharmacophore features an undefined CB 1 binding mode Druglike properties Potential good passive oral absorption (e.g., PSA in the range of Å 2 ) The most representative results of the identified class are reported below (Table 4). The pool of compounds shows activity in the range nm on CB 2 and selectivity vs CB 1 in according with the in silico studies. Furthermore, no inhibitory activity towards MAGL and FAAH was observed up to a C4T agonist concentration of 100 M. Table 4: Activity and selectivity results of C4T CB 2- agonists ID EC 50 -CB2 (nm) EC 50 -CB1 (nm) C4T >10 4 C4T >10 4 C4T >10 4 C4T (a) C4T (a) C4T3151A (a) (a) CB 1 inverse-agonists Inverse agonists: From C4T 3116 Series, an inverse agonists focused library was obtained by a fine chemical modification of the prototypical structure in one pharmacophore point. The experimental data confirmed the in silico hypothesis showing a different binding mode with respect to the agonists. 9

10 Results C4T 3313 hit compound By an original integrated ligand structure-based approach, a second innovative scaffold of CB2 agonist was identified (Table 5). The hit compound C4T-3313 is an ideal candidate for the H2L : low molecular weight 3 chemical diversity points In silico known key interactions with CB 2 residues In silico nonspecific CB 1 binding mode Druglike properties. Table 5: Activity and selectivity results of C4T CB 2 Hit ID EC 50 -CB2 (M) EC 50 -CB1 (M) C4T >100 10

11 C4T Approaches C4T Approaches Design and synthesis Homology modeling of CBRs CB 1 e CB 2 receptor 3D models were generated and validated by in vitro screening Modeling of CB 1 e CB 2 receptors in their active and inactive state (CBR and CBR*, respectively) by using crystal structures of human b2- adrenergic receptor (pdb: 3d4s) and bovin rhodopsin (pdb: 1u19 and 1f88) as templates Refinement of CBR* models on the crystal structure of bovin rhodopsin in complex with a peptide fragment of its G-protein transducin (pdb: 2X72). The 3D models were used in docking simulation for selecting compounds from the original virtual libraries and for studying the potential binding mode and selectivity of C4T 3116 Class compounds. Organic Synthesis Study of synthetic feasibility of chemical scaffolds and parallel synthesis set-up Parallel synthesis of max diverse/focused libraries. 11

12 C4T Approaches Biological Screening Funnel (group of Prof. M. Maccarrone UTV/UniTe) Binding assay The affinity towards CB 1 and CB 2 was evaluated through MultiScreenHTS 96 well Plates for binding assays by using membranes over-expressing CB receptors (Millipore). The affinity, expressed as percentage of residual radioactivity of the reference compounds [3H] CP-55,940 (concentrations: 2.5 and 0.8 nm) in presence C4T compound (concentration = 100 nm), is determined by the ability of the analyzed compound to displace the specific binding of [3H] CP-55,940 (0.8 nm) to the receptor (fmol of ligand / mg of protein). I In the experiments, non-specific binding was determined in the presence of unlabeled CP-55,940 (concentration = 1 mm). The compounds able to displace at least the 30% of the specific binding of CP were submitted to the activity determination via functional assays. Funcional assays-[ 35 S]GTPS (0.6 nm) The determination of the activity of the C4T compounds is carried out by evaluating the coupling of CBR/G-protein, by using the radioligand [35S] GTPS (0.6 nm), II in the presence/absence of the reference standard CP-55,940 Fase 1: evaluation of the activity profile (agonist, antagonist or inverse-agonist) of C4T compounds at the two high concentrations of 10 M and 100 M in presence and in absence of the reference compound CP-55,940 Fase 2: determination of dose-response curve and EC 50 value at eight different compound concentration (range: M). Selectivity profile over MAGL and FAAH In addition, the potential inhibition of FAAH III and MAGL IV activities has been determined as percentage of enzyme activity inhibition with respect to the control. References I. Yao, B.B. et al., Br. J. Pharm., 2006, 149, ; II. Harrison, C. et al., Life Sci. 2003, ; III. Maccarrone, M. et al., J. Cell Sci. 2005, 118, ; IV. Dinh, T.P. et al., Proc. Natl. Acad Sci USA 99, 2002,

13 Partnership opportunities Partnership Opportunities C4T is interested in: Project results licensing out Partnership for further development of C4T Hit/Lead compounds Technology Offer A versatile drug discovery platform to drive and support a rational identification of novel CB modulators Novel CB2 agonists - C4T CB 2 selective agonist development (Lead optimization) - C4T CB 2 selective agonist development (Hit to Lead). 13

14 References References 1 Matsuda et al. Nature 1990, 346, Topai et al., Curr Med Chem 2010, 17, a) Okamoto et al. Vitam. Horm. 2009, 81, 1; b) Ueda et al. Biofactors 2011, 37, Masini et al. Curr. Drug Target. 2012, Mar Maccarrone et al., Front. Behav. Neurosci. 2012, 6,9. 6 Ryberg et al. Br. J. Pharm. 2007, 152, Pertwee. Br. J. Pharm. 2009, 156, Beltramo et al. J. Soc. Biol. 2009, 203, Murineddu et al. Recent Pat. CNS Drug Discov. 2012, 7, a) Brownjhon et al. Neuroscience 2012, 203, 180. b) Hsieh GC et al., Br. J. Pharmacol. 2011, 162, 428 Update. 11 a) Romero-Sandoval et al., Anesthes. 2008, 108, 722. b) Elmes et al., Eur. J. Neurosci. 2004, 20, a) Yao et al., Pharmacol. Exp. Ther. 2009, 328, 141. b) Leichsenring et al., Naunyn. Schmiedebergs Arch. Pharmacol. 2009, 379, 627. c) Paszcuk et al., PLoS One 2011, 6:e Di Marzo, Pharmacol Reseach 2009, 60, Wilner et al. J Palliat Med, 2006, 9, Riether, Exp Opin Ther Pat 2012, 22, Gowran et al. CNS Neurosci Ther 2011, 17, Chunget al. Brain Res. 2012, 1451, Guindon et al. Brit. J. Pharm. 2011, 163,