Alirocumab efficacy in patients with double heterozygous, compound heterozygous, or homozygous familial hypercholesterolemia

Background: Mutations in the genes for the low-density lipoprotein receptor (LDLR), apolipoprotein B, and proprotein convertase subtilisin/kexin type 9 have been reported to cause heterozygous and homozygous familial hypercholesterolemia (FH). Objective: The objective is to examine the influence of double heterozygous, compound heterozygous, or homozygous mutations underlying FH on the efficacy of alirocumab. Methods: Patients from 6 alirocumab trials with elevated low-density lipoprotein cholesterol (LDL-C) and FH diagnosis were sequenced for mutations in the LDLR, apolipoprotein B, proprotein convertase subtilisin/kexin type 9, LDLR adaptor protein 1 (LDLRAP1), and signal-transducing adaptor protein 1 genes. The efficacy of alirocumab was examined in patients who had double heterozygous, compound heterozygous, or homozygous mutations. Results: Of 1191 patients sequenced, 20 patients were double heterozygotes (n = 7), compound heterozygotes (n = 10), or homozygotes (n = 3). Mean baseline LDL-C levels were similar between patients treated with alirocumab (n = 11; 198 mg/dL) vs placebo (n = 9; 189 mg/dL). All patients treated with alirocumab 75/150 or 150 mg every 2 weeks had an LDL-C reduction of ≥15% at either week 12 or 24. At week 12, 1 patient had an increase of 7.1% in LDL-C, whereas in others, LDL-C was reduced by 21.7% to 63.9% (corresponding to 39–114 mg/dL absolute reduction from baseline). At week 24, LDL-C was reduced in all patients by 8.8% to 65.1% (10–165 mg/dL absolute reduction from baseline). Alirocumab was generally well tolerated in the 6 trials. Conclusion: Clinically meaningful LDL-C–lowering activity was observed in patients receiving alirocumab who were double heterozygous, compound heterozygous, or homozygous for genes that are causative for FH.