Genes to the Brain

Genes to the Brain AG de Boer Outline presentation • Introduction • Drug Delivery to the Brain and its Consequences • Solution for Drug Delivery to the Brain • to-BBB’s alternative solution • Conclusions BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. We want to bring Drugs (e.g. genes) to the Brain… BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. …to treat Brain Diseases. Alzheimer’s Disease Parkinson’s Disease Multiple Sclerosis Stroke Tumors BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. There are many good Drugs to treat Brain Diseases… (bio)pharmaceutical drugs like Anti-tumor drugs Proteins (e.g. enzymes, growth factors) Genes iRNA (interference RNA) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. however, most do not pass the Blood-Brain Barrier and therefore cannot enter the Brain.  600 km capillaries (BBB)  20 m2  distance between capillaries: 40 m  every neuron has its own capillary BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Conventional Drug Delivery to the Brain Lipophilic drugs Influx transporters Hydrophilic drugs tight junctions BLOOD Efflux transporters Metabolism BRAIN BBB (Blood-Brain Barrier) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Consequences Lipophilic drugs (effective against metastasis of breast tumors) tight junctions Efflux transporters BRAIN Influx transporters Pgp BLOOD Gleevec: effective against Chronic Myeloid Leukemia and potentially against BBB Alzheimer’s Disease BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Solution: Invasive Drug Delivery to the Brain? (Gutman, R.L. et al., J. Contr. Rel. 2000, 65, 31-41) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Example I: Invasive (viral) delivery into brain tissue: intracavitary Intracavitary: biodegradable polymers, catheter implant, encapsulated cells (preclinical) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Example II: Invasive Drug Delivery by direct administration in the cerebrospinal fluid: intrathecal, intraventricular intrathecal / intraventricular: harmful and inefficient (effective only for leptomeningeal cq intraventricular applications) from Pardridge, Nat Rev Drug Discov (2002) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Alternative Solution: Vascular Drug Delivery to the Brain 1 km blood vessel per cm3 BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. via Transport Systems at the Blood-Brain Barrier: Receptor-Mediated Drug Delivery to the Brain drug blood carrier protein brain transport receptor The Trojan Horse Approach BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Example: Our Research on the Transferrin Receptor (TfR) (CC Visser et al.,, J. Drug Targeting 2004; 12(3): 145-150) (80 kDa) Tf (40 kDa) HRP 3 nm (bio)pharmaceuticals genes Characterization of the TfR 4 nm Tf Validation of the TfR for cargo PEG Tf Application of liposomes for delivery of (bio)pharmaceuticals 100 nm BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. -galactosidase Gene Delivery to the Rat Brain by the TfR-system After 2 days IgG-control (A similar liposomal system may be used to target Gleevec to the brain) (Shi, N, Boardo, R.J. and Pardridge, W.M. Pharm. Res. 2001, 18(8), 1091-1095) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. however, TfR-system is not applicable… • No carrier protein available for humans • Interference with iron homeostasis in the brain • Occupation of the transport-receptor by Transferrin in blood, therefore limited transport of drugs to the brain alternative: 2B-Trans™ technology BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Team & Partners to-BBB technologies BV scientific advisors • Douwe Breimer • Ron de Kloet • Joop van Gerven Pieter Gaillard CEO CSO Alfred Nijkerk Herb Heyneker CBO US/NL biotech entrepreneur Bert de Boer Herman de Boer academic partner NL biotech entrepreneur BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. CRM197 Carrier Protein 2B-Trans™ technology  safe, human applicable, non-toxic mutant Diphtheria Toxin protein  binds to the heparin-binding epidermal growth factor like receptor at the BBB (Trojan horse mechanism)  this receptor is preferentially present under inflammatory conditions at the BBB (Alzheimer, Parkinson, multiple sclerosis, tumors, etc.)  well characterized: – – In vitro and in vivo proof of principle known clinical profile – – – known manufactoring process known protein structure, receptor-binding domain & conjugation sites does not recognize its receptor in rat and mice Louie, et al., 1997, Molecular Cell 1 BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Use of CRM197 in… • Targeting growth factors to the brain (stroke, Parkinson Disease) • Targeting enzymes to the brain (lysosomal storage diseases like Gaucher, Fabry, etc.) • Targeting radionuclides and iRNA to the brain (tumors) • Targeting the neprilysin gene to the brain (Alzheimer Disease) • Targeting tyrosine hydroxylase gene to the brain (Parkinson Disease) BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Conclusions • The BBB is a major Barrier (physical, metabolic) for Drug Delivery to the Brain • Drug Delivery to the Brain via the Vascular BBB Route by our new human applicable Carrier Protein (2B-Trans™ technology) opens new ways for treating Brain Diseases BBB Research Group, Pharmacology, LACDR, University of Leiden This Week Discoveries A.G. de Boer, Ph.D. Aknowledgements CC Visser LH Voorwinden M Danhof L Van Bloois DJA Crommelin Utrecht Institute for Pharmaceutical Sciences PJ Gaillard AN Nijkerk A Brink