Drug Discovery Pipeline Brief Report 2011
Transcription
Drug Discovery Pipeline Brief Report 2011
Page 1 of 14 Drug Discovery Pipeline Brief Report 2011 Executive Summary The Drug Discovery Pipeline (DDP) was established in 2009 at the Guangzhou Institutes of Biomedicine and Health (GIBH). The mission of the DDP is to capture the best ideas developed within GIBH and translate those ideas into drug discovery projects. Prior to the creation of the DDP, there was no mechanism in place to transform concepts into drug discovery projects. However, after the formation of the DDP, GIBH now has the required expertise, platform technologies, centralization and necessary integration of disciplines to enable effective drug discovery research, which is not found at most institutes in China. Since its inception the DDP has achieved five important milestones, which include: (1) Centralization of key technology groups to support drug development; (2) Integration of project teams to enable the advancement of drugs; (3) Development of a sustainable pipeline of projects with novel intellectual property (IP); (4) Establishment of key international partnership for the co-development of drugs; and (5) Creation of new companies in Guangzhou using IP matured in the Pipeline. A 6th milestone, which includes advancing a new drug into clinical trials, is expected to be achieved in late 2012 /early 2013. I. Centralizing the key technology groups In order to effectively develop drugs at GIBH, it was necessary to first create and centralize several technology groups including High Throughput-Screening (HTS), Structural Biology, Pharmacokinetics (PK), Biomarkers, Medicinal Chemistry and BioTherapeutics. All of these groups have been established and are led by experienced senior scientists, many of who have strong drug discovery experience (Figure 1). Progress Report 2011 DDP Page 2 of 14 Figure 1: Structure of DDP Micky Tortorella (CTO) Administration 3 FTE* Chemistry Biology (Donghai Wu) (Zhengchao Tu) PK/ADME (Xiaorong Liu) Structure (Jinsong Liu) Biomarkers (Scott Spillman) 18 RA* 11 RA 5 RA 9 RA 1 RA 2 RA *FTE=Full Time Employee • HTS (Ding Ke) BioTherapeutics (Daiguan Yu) 2 RA RA=Research Associate HTS – This team is capable of screening thousands of compounds per week in various enzyme and cell based assays at a low price using new automated robotic equipment purchased in 2010. At this time the group has screened several thousand compounds and identified lead molecules for several drug discovery projects at GIBH in the areas of cancer, inflammation and infection (Table 1). Table 1: Productivity of High Throughput Screening. Targets(Related diseases) Protein Kinases ABL (CML) ABL (T315I) (CML) Abl(E255K)(CML) ABl(G250E)(CML) Abl(Y253F)(CML) ABl(Q252H)(CML) ABl(H396P)(CML) ABl(M351T)(CML) ALK(Cancer) Kit (GIST) (Cancer) EGFR (Breast and lung cancer) Progress Report Hits identified 351 351 231 231 231 231 231 231 5 231 347 2011 DDP Page 3 of 14 EGFR (T790M) (Breast cancer) EGFR(L858R)(Breast and lung cancer) EGFR(T790M&L868R)(Breast cancer) EGFR(L861Q)(Breast and lung cancer) Her2 (Breast cancer) AKT1(Cancer) AKT2 (Cancer) AKT3 (Cancer) Proteases DPPIV (Diabetes) DPP8 (Diabetes) DPP9 (Diabetes) NS3/4A (HCV) Furin (virous infection) Other molucular targets Neuraminidase S (Influenza) Neuraminidase S (Influenza) COX-1(Inflammation and RA) COX-2(Inflammation and RA) HDAC1(Cancer) HDAC7 (Cancer) Cell-based infectious diseases Influenza Ev71(Enterovirus infection) 347 305 305 305 84 35 35 35 50 17 38 1 1 32 32 1 1 15 15 62 1 • Structural Biology – The group is currently supporting the lead optimization of compounds for several drug discovery projects. The support they provide to the DDP include the expression of protein, crystallography, computer-aided drug design and high-throughput virtual screening. The team recently developed a new super computer platform, capable of virtually screening ~40M compounds per target. The team is enabling the design of inhibitors targeting ADAMTS4/5, p38 alpha, beta, delta, gamma, cKIT/AKT1/EGFR, Plasmepsin II/IV/V and G1B. • Pharmacokinetics/ADME – The team provides data regarding the drug metabolism, pharmacokinetics and acute safety of our lead compounds. These data are critical for the prioritization and development of new pharmaceutical drugs at GIBH. Currently the capabilities of the team include standard pharmacokinetics, blood brain barrier penetration, acute toxicity in rodents, metabolic stability of compounds, plasma protein binding of drugs, drug-drug interactions, Caco2 and Zebra fish toxicity. The team has analyzed over 100 compounds for the DDP, allowing the project teams to optimize and advance lead molecules in a timely manner. Progress Report 2011 DDP Page 4 of 14 Table 2: Productivity of Pharmacokinetics Analysis Number of Compounds Tested Pharmacokinetics 85 CNS penetration 7 Acute toxicity 10 Metabolic stability 35 Protein binding 28 Caco2 21 Drug drug interaction 81 Zebra Fish (Toxicity) 16 Rat air pouch inflammation model Drug toxicity in rat 2 Human hepatocyte culture 2 4 • Biomarkers - In collaboration with Plexera, novel biomarker based chips for rapid detection of thousands of proteins in the blood are being developed. The chips will be used as diagnostics to determine the safety and efficacy of our lead candidate drugs by monitoring the modulation of selected biomarkers in bodily fluids such as urine, synovial fluid and plasma. At this time the team has identified novel chip surfaces to reduce background and chip to chip variation . • Medicinal Chemistry – The newly integrated chemistry team has and is currently designing novel drugs in several different therapeutic indications. The group has made several hundred proprietary compounds targeting pathways in cancer, inflammation, infection, arthritis and metabolic diseases. Table 3: Productivity of Medicinal Chemistry Project/Traget Cancer Arthritis Alzheimer’s Diabetes Flu Malaria Pain Progress Report Number of compounds made 300 100 200 100 120 6 6 2011 DDP Page 5 of 14 • BioTherapeutics – Protein based therapeutics with an ephasis on proteases are currently being developed for the treatment of various blood disorders. Proteases are naturally occurring peptide-cleaving enzymes that regulate a wide variety of biological functions. In the DDP we are using the potential of these enzymes as bio-therapeutics by directing them to cleave specific proteins in the blood that promote health. Unlike standard drugs, a single proteinase molecule can inactivate or activate thousands of target molecules, resulting in higher efficacy and lower dosing regimens compared to small molecules or antibodies. Currently, the team is expressing a more active species of ADAMTS-13 for the tratment of thrombocyopenic disorders. II. Integration of project teams to enable the advancement of drugs To effectively enable drug development at GIBH, the DDP has been organized using a very different model that is not traditionally found at other institutes in China. In the DDP, there are no individual principle investigators (PIs) working in isolation. In contrast, all senior staff and corresponding reseacrh associates work in teams supporting specific projects that are deemed high priority. The DDP operates under a “Project” rather than “PI” centric system. The integration of medicinal chemistry and biology has been successful and current project teams are able to provide the critical mass and expertise needed to advance drugs and cultivate new intellectual property (Figure 2). Figure 2: Model of the “Project Centric” system employed in the DDP Project Chemistry Leader Biology Leader Team Members Protein Screening Enzymology Biomarker validation Animal models PK/ADME Safety Progress Report Team Members Molecule design Synthesis Purity Crystallography Scale-up Formulations 2011 DDP Page 6 of 14 III. Development of a sustainable pipeline of projects with novel intellectual property After only one and a half years after its inception, the DDP has cultivated a porfolio of drug targets that enjoy strong intellectual property. Current programs are developing drugs to treat Alzheimer's disease, leukemia, inflammation and infectious diseases. Two projects are at candidate selection, one project is at lead optimization, three projects are at hit identification and several projects are at early exploration (Table 4). Table 4: Pipeline of projects and estimated time to IND filing. Disease Leukeumia Alzheimer's Target Mutant forms of the Bcr-Abl Kinase Neural Inflammation Aggrecanase Stage Candidate Selection Joint Inflammation Inflammatory Genes Candidate Selection Lead Optimization Lead Optimization Malaria Plasmepsin V Hit Identification Osteoarthritis Thrombocyopenic Disorders Pain and Cancer ADAMTS-13 Early Exploration (Protein Therapy) COX-2 Hit Identification IP Compound, D824, a new kinase inhibitor Compound, HWH-2-130 Carboxylate inhibitors AS001: siRNA/Particle conjugate New aspartyl protease inhibitors ADAMTS-13 protein constructs Novel chromene inhibitors Time to IND 2012 (Oral, Small Molecule) 2012 (Oral, Small Molecule) TBD (Oral, Small Molecule) 2013 (Local Injectable) TBD (Oral, Small Molecule) TBD (Protein, IV) TBD (Oral, Small Molecule) *TBD = To Be Determined Summary of DDP projects expected for IND filing in 2012/13 1. Research and Development of a New Drug for the Treatment of Drug-Resistant Leukemia (Project Leader is Dr. Ding Ke) Background and Medical Need: Chronic myelogenous leukemia (CML) has a high mortality rate of 20%-30%, two years after a confirmed diagnosis. Approximate 25% of patients with CML die every year and the average survival time is just 3 to 5 years. The age of onset ranges from 20 to 50 and in China, there are 30,000 new cases diagnosed each year. Gleevec therapy alone can alleviate the condition in many patients suffering from CML. However, because of extensive usage of Gleevec, it is becoming less effective. Some CML patients are inherently resistant to Gleevec, and some respond to Gleevec in the beginning, but acquire secondary resistance over the course of the treatment. Progress Report 2011 DDP Page 7 of 14 Rationale for the Approach: The major cause of resistance to Gleevec is a secondary mutation in the kinase domain of target gene expression products. Research indicates that the common point mutation sites related to Gleevec resistance include E255K, E255V, T315I and D276G of Bcr-Abl and D816 of c-KIT. The Bcr/Abl, T315I mutation, one of the obstinate drug-resistant mutations is the most common mutation, representing about 20-30% of all cases. The clinical drug resistance mediated by the T315I mutation of Bcr-Abl remains a significant medical problem and at this time there are no drugs targeting the T315I point mutation on the market. As a result, it is urgent to develop novel drugs for the treatment of this type of drug-resistant leukemia. Validation of Lead Chemistry: Using the principles of rational and computeraided drug design, the project team has successfully designed and synthesized a series of leading compounds with strong intellectual property. In vitro data show that the novel compound, D824 has an activity 1000 times more potent than Gleevec on chronic myloid leukemia cells containing no mutations, but more importantly exhibits excellent activities on all cell lines that are resistant to Gleevec treatment. This series of compounds has excellent activities against the T315I mutation found in the Bcr-Abl kinase active site, which cannot be treated with current drugs. Domestic and international data report that neither the first-line drug Gleevec or the second-line drugs Dasatinib or Nilotinib (approved by FDA for the treatment of CML) are effective in patients with the T315I mutation, because their IC50 values all exceed > 50 µM. The IC50 of D824 is <10 nM and its activity is 5,000 times more active than current clinical therapeutic drugs. D824 was found to be efficacious in a rodent model of leukemia as well as models that measure solid tumors. Toxicity and pharmacokinetic experiments indicate that D824 has a reasonable safety index with excellent pharmacokinetic properties such as oral bioavailability and a very lon half-life, all within range for the requirements of a new drug. 2. Research and Development of a New Drug for the Treatment of Alzheimer's Disease (Project Leaders are Wenhui Hu and Donghai Wu) Background and Medical Need: Alzheimer’s disease (AD) is a major health and societal problem. It is extremely costly to the patients, their families and to society as a whole. In 2007, it was estimated that $100 billon was spent in the United States on health care expenses and lost wages for AD patients and their caregivers. Further estimates predict that $375 billion will be spent annually by 2050. Unfortunately, AD drug discovery has been disappointing as no disease modifying drugs are available. Current drugs used to treat AD only treat the symptoms of the disease. Rationale for the Approach: Alzheimer’s disease is characterized pathologically by the deposition of amyloid fibrils and neurofibrillary tangles in the brain. Many biochemical and genetic evidence heavily favors the “amyloid-β hypothesis” (Figure 3) . However, new data suggest that neuroinflammaiton may play a bigger role than previously thought in the development of the disease. The goal of the DDP is to advance inhibitors that block neuroinflammation as a means for attenuating the Progress Report 2011 DDP Page 8 of 14 progression of AD. Minozac, discovered by Dr. Wenhui Hu was one of the first drug candidates designed for blocking neuroinflammation, representing a new class of compounds for the treatment of Alzheimer’s disease. Recently, his team has discovered several new and highly potent inhibitors of neural inflammation with superior properties compared to the original lead molecule, Minozac. Validation of Lead Chemistry: The new series of compounds are thousands of times more potent than Minozac in variuos cell based assays of neural inflammation. The compounds are drug-like candidates as they possess excellent PK properties without apparent acute toxicity in rodents (safety index up to 1000x the efficaious dose). In addition, lead compound, HWH-2-130 has demostrated significant efficacy in several in vivo models of Alzheimers disease , stroke and rheaumatoid arthritis. IND filing is anticipated in 2012 pending chronic safety evaluation. Figure 3: Model of neural inflammation in AD. 3. Research and Development of Anti-Osteoarthritis and Anti-Rheumatoid Arthritis siRNA Drugs (Project Leader is Dr. Biliang Zhang) Background and Medical Need: Osteoarthritis (OA) is one of the leading causes of disability in the world, with more than 10% of the elderly population having symptomatic disease. Rheumatoid arthritis (RA) is a chronic, inflammatory disease that affects approximately 0.5 to 1 percent of adults worldwide and commonly results in joint destruction and significant impairment in the quality of life. Many pathogenic pathways of OA and RA have been revealed recently, which led to development of various novel therapies. During the past 20 years, most of the development of new therapies is in disease-modifying anti-rheumatic drugs (DMARDs) and disease modifying osteoarthritic drugs (DMOADs), especially biological DMARDs. With the discovery of new pathways and the application of drug delivery strategies, more growth is anticipated in this therapeutic field. Thus, significant opportunity exists for agents such as siRNAs that can stop or reverse disease progression and act as disease-modifying agents. Progress Report 2011 DDP Page 9 of 14 The current treatments of RA include 4 categories: non-steroidal antiinflammatory drugs (NSAIDs), glucocorticoids, non-biologic disease-modifying antirheumatic drugs (DMARDs) and biologic DMARDs. Till date, the pharmaceutical industry has failed to bring effective and safe disease modifying osteoarthritic drugs (DMOADs) to the millions of patients suffering from this serious and deliberating disease. RNA interference (RNAi) is a revolutionary discovery in life science and has become a powerful tool for studying the gene function, which mediates gene inactivation in organisms, mammalian cells and even animals. RNAi technology has the potential to create new therapies in humans including anti-OA and RA therapies. In this project, we are developing novel slow-releasing siRNA drugs as anti-OA and RA therapies. Rationale for the Approach: RNA interference has not only become a standard method of molecular biology—it has already made its way into the clinic. Around a dozen clinical studies based on RNAi are curently in progress and the initial results are promising. RNAi technology can be used against any disease in which a deleterious gene is over-expressed (for example, cancer, viral infections, inflammation). The advantage of employing RNAi in drug discovery is speed; progressing from target identification to preclinical evaluation can occur in as little as 6 to 9 months. However, the delivery of the siRNAs into cells presents one of the greatest challenges in the development of new RNAi therapies. The goal of this project is to develop a universal formulation for delivering anti-arthritic siRNAs locally via intra-articular injection into the joints of patients. Since articular cartilage and the surrounding synovial fluid (SF) is highly negatively charged, a formulation employing postively charged nano-partciles maybe an effective strategy for delivering anti-arthritic siRNAs selectively to the diseeased joints for a sustained period of time after only a single injection. Validated siRNA Targets and Delivery Formulation: A series of siRNAs have been made targeting key genes implicated in both osteoarthritis and rheumatoid arthritis including TNFα, ADAM-17, ADAMTS-5, PACE4, JAK3, CD44, CD36, NF-kB and RHAAM. The active siRNAs were screened against each gene in vitro. The IC50 has been determined for each individual active siRNA using synovial fibroblasts. The most active siRNA showed an IC50 as low as 10 pM. A proprietary formulation that uses positively charged particles to deliver the oligonucleotides has been identified. The major components of the formulation is a co-polymer with a low molecular weight polycation and a biodegradable polymer. The positively charged co-polymer can form nanoplexes or nanoparticles with siRNAs and these nanoplexed-siRNAs can effectively penetrate into synovial fibroblasts and supress the expression of inflammatory genes implicated in both OA and RA (Figure 4). IND filing is anticipated in 2013 pending chronic safety evaluation. Progress Report 2011 DDP Page 10 of 14 Figure 4: Bio-surgery concept for the treatment of inflammatory arthritis. IV. Establishment of key international partnership for the co-development of drugs In order to enhance the drug discovery efforts at GIBH, the DDP has established several international partnerships with premier scientists and institutions in the United States with the mission of co-developing drugs. Our international partners offer experience and innovation in drug discovery. In addition, these collaborations allow GIBH to share the risk and expenses associated with drug development. Currently, GIBH has two external partnerships with (1) The Center for World Health & Medicine at Saint Louis University to develop anti-malaria therapies and (2) Legacy Pfizer scientists to advance novel chromene based inhibitors of COX-2 that spare both the renal and cardiovascular risks associated with current celecoxibs (Figure 5). Progress Report 2011 DDP Page 11 of 14 Plasmepsin V Inhibitors for Malaria 3rd Gen. COX-2 Inhibitors for Dental Pain and Cancer The Center for World Health & Medicine, Saint Louis University Legacy Pfizer Scientists GIBH GIBH Washington University Figure 5: External partnerships at GIBH 1. Inhibitors of Plasmepsin V as Novel Anti-Malarial Agents (Project Leaders at GIBH are Xiaoping Chen and Ding Ke) Project Summary and Proposal Each year there are approximately 350-500 million cases of malaria, killing between one and three million people, the majority of whom are young children in subSaharan Africa, where ninety percent of malaria-related deaths occur. Although there are a number of drugs used to treat malaria, resistance to these drugs is becoming more widespread. Thus, therapies targeting novel modes of action are greatly needed. One promising new antimalarial target is the Plasmodium specific aspartyl protease, Plasmepsin V (PMV), recently discovered to be the key gate keeping protease responsible for the cleavage and translocation of several hundred PEXEL-containing proteins destined for export into the host erythrocyte. PMV and many of these downstream PEXEL-containing export proteins are essential for the survival of the parasite (Figure 6). The aim of this project is to identify potent inhibitors of PMV and demonstrate their therapeutic value for the treatment of malaria. Progress Report 2011 DDP Page 12 of 14 Figure 6: Life cycle of P. falciparum Project Progress HIV-1 aspartyl protease inhibitors lopinavir, ritonavir, saquinavir, and nelfinavir have been demonstrated to be weak inhibitors of PMV (~15-100 µM). This is not surprising, given the distant homology of PMV to other aspartyl proteases such as βsecretase and similarities between the PEXEL sequence in substrates for PMV and protein substrates of HIV-1 aspartyl protease. However, with molecular weights exceeding 700 and weak potencies, these HIV protease inhibitors are not good starting points for optimization towards an anti-malarial drug. Our approach to identifying a more suitable starting point for optimization involves screening collections of aspartyl protease inhibitors to be secured from commercial, literature, pharmaceutical donors, and our internal medicinal chemistry program . Recently a set of BACE-1 inhibitors has been identified as active agents against PMV and are being used as starting points for further optimization. The Center for World Health & Medicine, Saint Louis University (www.cwhm.org) The CWHM is a non-profit group whose expertise is the translation of basic science into the discovery and development of novel drugs for rare and neglected diseases. The CWHM consists of a highly skilled and successful team of former Pfizer drug discovery scientists. The scientists on this team have expertise at high throughput protease assay development, drug design and medicinal chemistry, in vivo pharmacology and pharmacokinetics, and preclinical development. 2. Chromene COX-2 Inhibitor Project (Project Leader at GIBH is Yanmei Zhang) Project Summary and Proposal The chromene pharmacophore represents a novel drug class of COX-2-selective inhibitors (coxibs) that have a carboxylate moiety and do not bind in the hydrophobic binding pocket of the COX-2 active site. As a class, they have been shown to confer Progress Report 2011 DDP Page 13 of 14 potency, efficacy, and selectivity on par with the diaryl heterocyclic coxibs (eg, celecoxib, valdecoxib, rofecoxib, and etoricoxib) in the standard rat models of inflammation and pain. The chromene coxib clinical candidate, SC-75416, was shown to be differentiated from the diaryl heterocyclic coxibs in that it conferred reduced tactile allodynia in a rat model of neurophathic pain. A testing scheme has been implemented and the synthesis of novel and potentially superior chromene coxib analogs has been initiated. The chromene pharmacophore may prove to provide advantages over the existing coxibs for the treatment of inflammation and pain, especially for those patients who are inadequately served by the analgesic medications available today. As a class, the chromene coxibs have the potential to be renal-sparing and thereby mitigate coxibinduced hypertension due to their intrinsic and distinct structural, pharmacological, and physiochemical properties. These combined properties, if borne out, could allow Chinese sFDA approval, as well as world-wide approval, including the United States, with first-in-class and best-in-class status. The overall goal is to (1) identify novel and potentially superior chromene coxibs for the treatment of acute and chronic pain/inflammation and, possibly, cancer. (2) The initial goal is to identify a chromene coxib clinical candidate within 18 months for the treatment of acute dental pain in China. Acute dosing (i.e., ≤7 days) will be targeted initially in order to avoid the cardiovascular side effects (i.e., hypertension, edema, myocardial infarction, and stroke) associated with chronic dosing of some coxibs (e.g., rofecoxib). (3) In parallel, the renal- and hypertension-sparing properties of the lead chromene coxibs will be evaluated. (4) Chronic indications of pain and inflammation (e.g., OA and RA) in China will be explored if the clinical chromene coxib candidate is renal- and hypertension-sparing. Project Status A testing scheme has been implemented to identify novel and potentially superior chromene coxib analogs. The chromene analogs, SC-75416 (R/S), 29b (R/S), and 34b (R/S), and celecoxib are being synthesized as comparator coxibs. The synthesis of novel and potentially superior chromene coxib analogs has been initiated. Distinguished scientists partnering with GIBH Dr. John Talley is an inventor and researcher with over 25 years experience with a broad background in organic and medicinal chemistry and an inventor of the COX-2 inhibitor, celecoxib (Celebrex™) and valdecoxib (Bextra™). Dr. Mark Obukowicz was a Senior Research Fellow at Pfizer Global Research and Development with >26 years experience in drug discovery and the discoverer of novel chromene, selective inhibitors of COX-2. V. Creation of new companies in Guangzhou In addition to drug development, a key mission of the Pipeline is to create spinoff companies based on intellectual property cultivated in the DDP. This will serve several purposes. First, it will ensure a focused effort on the development of lead drugs Progress Report 2011 DDP Page 14 of 14 into clinical trials; second, it will share the burden of drug discovery, cost and risk across GIBH and the new companies it creates; and third, stimulate the local economy in Guangzhou by employing people and investing in the local community. Establishment of local satellite companies will increase the scientific excellence within the city of Guangzhou and spur regional growth in the area of biotechnology. Currently the DDP has mediated the spin-off of two small companies in Guangzhou city including GZstem and Argo Biopharmaceuticals. 1. GZstem, Inc. GZstem, is a stem cell based company funded by the US Corporation, Sigma Aldrich. The product line of the company consists of 1. Induced pluripotent stem cells (iPSCs), derived from tissue of normal and diseased human specimens (25 lines currently available); 2. Protocols for directed differentiation of iPSCs, into different cell lineages; 3. human iPSCs containing reporter genes. GZstem employs 10 full time scientists with a total operating budget of ¥8.5M/yr. 2. Argo Biopharmaceuticals Argo Biopharmaceuticals is a technology based company funded by both a venture capital firm and the local government. The product line of the company is siRNA based therapeutics using novel nano-particle delivery systems. Argo Biopharmaceuticals employs 8 full time employees with a total operating budget of ¥6.5M/yr Progress Report 2011 DDP