An update on gene therapy for the treatment of lipoprotein lipase deficiency

Abstract

Lipoprotein lipase (LPL) is responsible for clearance of triglyceride-rich lipoproteins from the blood. Deficiency or defects in this enzyme result in profound hypertriglyceridemia and susceptibility to chronic, life-threatening pancreatitis. Management of LPL deficiency has traditionally been restricted to palliative care and strategies to reduce the risk of pancreatitis, including severe dietary restrictions of fat. Recently, the European Commission approved the first gene therapy treatment in the West to treat this rare disease. Alipogene tiparvovec (Glybera®) was granted marketing authorization in November 2012 to treat LPL deficiency in a subset of patients that are at increased risk for pancreatitis. Designed as a one-time treatment, the drug uses adeno-associated virus (AAV1) delivery of transgenic LPL to muscle in patients lacking functional enzyme. Although statistically significant reduction of serum triglycerides was initially observed in trial subjects, this effect was found to be transient, with triglyceride levels eventually rebounding to basal levels by 26 weeks in all participants. Nevertheless, despite the return of triglycerides to pretreatment levels, alipogene tiparvovec was found to have a long-term impact on postprandial chylomicron metabolism by lowering the fraction of triglyceride found in this subset of lipoproteins. Furthermore, the drug led to a clinically significant reduction in the incidence of pancreatitis in LPL-deficient patients. The regulatory approval of alipogene tiparvovec was a historic process and serves as an example of the challenges that future orphan drugs will face.