Efficacy and safety of a microsomal triglyceride transfer protein inhibitor in patients with homozygous familial hypercholesterolaemia: a single-arm, open-label, phase 3 study

Summary Background Patients with homozygous familial hypercholesterolaemia respond inadequately to existing drugs. We aimed to assess the efficacy and safety of the microsomal triglyceride transfer protein inhibitor lomitapide in adults with this disease. Methods We did a single-arm, open-label, phase 3 study of lomitapide for treatment of patients with homozygous familial hypercholesterolemia. Current lipid lowering therapy was maintained from 6 weeks before baseline through to at least week 26. Lomitapide dose was escalated on the basis of safety and tolerability from 5 mg to a maximum of 60 mg a day. The primary endpoint was mean percent change in levels of LDL cholesterol from baseline to week 26, after which patients remained on lomitapide through to week 78 for safety assessment. Percent change from baseline to week 26 was assessed with a mixed linear model. Findings 29 men and women with homozygous familial hypercholesterolaemia, aged 18 years or older, were recruited from 11 centres in four countries (USA, Canada, South Africa, and Italy). 23 of 29 enrolled patients completed both the efficacy phase (26 weeks) and the full study (78 weeks). The median dose of lomitapide was 40 mg a day. LDL cholesterol was reduced by 50% (95% CI −62 to −39) from baseline (mean 8·7 mmol/L [SD 2·9]) to week 26 (4·3 mmol/L [2·5]; p