Mipomersen, an antisense oligonucleotide directed against apolipoprotein B-100 (apoB), was investigated for its safety and efficacy in reducing low-density lipoprotein (LDL) cholesterol (C) as adjunctive treatment for patients with homozygous familial hypercholesterolemia (HoFH) in a Phase III, double-blind, randomized, controlled trial. HoFH patients are very rare in the general population (∼ 1:1,000,000) and have very high risk for cardiovascular events. HoFH patients respond poorly to statins and most other existing lipid-lowering therapies. Mipomersen (200 or 160 mg) administered subcutaneously to 34 HoFH patients for 26 weeks significantly reduced LDL-C by 24.7% from baseline. In addition, mipomersen lowered plasma lipoprotein (a). In most patients, mipomersen administration was most associated with injection-site reactions; influenza-like symptoms were also more common in mipomersen-treated patients. Four patients had elevated serum alanine aminotransferase (ALT) concentrations, one of whom also had a significant increase in intrahepatic triglyceride content. Another patient met the stopping rules for increased ALT concentrations. No patient developed steatohepatitis during the study. Thus, so far short-term data indicate that mipomersen is safe and effective as an adjunctive drug for lowering LDL-C. Despite these promising results, the longer-term safety and efficacy of mipomersen still needs to be determined.
Trial registration: ClinicalTrials.gov NCT00477594 NCT00707746.