| The aim of this project is to develop gene therapy for lipoprotein lipase (LPL) deficient patients using an adeno-associated viral (AAV) vector expressing LPL. LPL is the principle enzyme involved in the clearance of triglycerides from plasma. Severe LPL deficiency is a disorder affecting approximately 5000-10000 individuals in the western world. These patients present with colicky pain, eruptive xanthomas, growth retardation and recurrent acute pancreatitis, resulting intensive care admissions, diabetes or death. There is currently no specific therapy available other than severe reduction of dietary fat, which is impossible to comply with in the long term. It is currently believed that long term correction of LPL deficiency with gene therapy is the only viable treatment option. Lipoprotein lipase (LPL) is the key enzyme in the metabolism of triglyceride-rich lipoproteins and is mainly produced in fat tissue, skeletal and heart muscle. Enzymatic activity of LPL mediates hydrolysis of triglycerides in chylomicrons and very low density lipoproteins (VLDL), resulting in the production of free fatty acids for either energy-expenditure or -storage. Consequently, these triglyceride-rich lipoproteins are rapidly cleared after every meal and the triglyceride levels in the circulation are reduced. LPL deficiency is an autosomal recessive inherited condition caused by homozygosity or compound heterozygosity for mutations in the LPL gene. The first LPL gene mutation responsible for this condition was not identified until 1989 (Langois et al, 1989). The aim of this project is to develop gene therapy for LPL deficient patients using an AAV vector expressing LPL. The following steps have to be executed to obtain proof of concept in human: pre-clinical experiments in several animal models (already executed), safety in GLP regulated animal studies (ongoing until October 2004), scaling of GMP production method for AAV-LPL (ongoing), submission of clinical protocol to CCMO (planned for August 2004), clinical grade production of AAV-LPL (ongoing), initiation of clinical trial (planned for Q1 2005). To treat LPL deficient patients, a gene therapy strategy is being developed to increase LPL activity and thus enhance triglyceride metabolism. AAV1-LPL is an investigational new therapeutic, which contains a specific form of the human LPL gene (variant LPLS447X) inserted in an adeno-associated virus (AAV) serotype 1 vector. The LPLS447X variant, found in 20% of Caucasians, is associated with lower plasma triglyceride levels, higher HDL cholesterol concentrations and lower rates of cardiovascular disease, when compared to the general population (Wittrup et al, 1999). Based on these findings, the LPLS447X gene is assumed to be a particularly suitable candidate for the indication pursued. Since skeletal muscle normally provides an endogenous source of LPL, and since the skeletal muscle is readily accessible for administration by simple injection, this tissue is the most appropriate target for gene therapy. AAV has been applied by many research groups as a tool for gene therapy approaches, demonstrating long-term ( GMP production: GMP production, purification and quality control of AAV-LPL using baculovirus system: |
