Abstract 15073: Response to PCSK9 Inhibition in Homozygous Familial Hypercholesterolemia Patients is Variable in Different Regions of the World and According to Age

Abstract

Background: Reductions in LDL-C with PCSK9-inhibition in HoFH subjects are highly variable even within populations with the same pathogenic variants. Whilst initial studies were done in HoFH patients of European decent, recent studies from India and other countries with novel pathogenic variants as well as studies in paediatric patients have shown substantially less response to PCSK9 inhibition. In the global phase 3 LIBerate-HoFH trial, we evaluated two different PCSK9 inhibitors, lerodacibep (LIB) 300 mg SC QM and evolocumab (EVO) 420 mg SC QM in genetically confirmed HoFH patients on stable background lipid lowering therapy. Methods: Eligible patients (age ≥10 years) were randomized to either LIB or EVO for 24 weeks (Period A) followed by an 8 week ‘washout’ and crossed over to the alternate drug for the next 24 weeks (Period B). In a post-hoc analysis, the mean reduction in average LDL-C with both drugs were evaluated according to various world regions and age. Results: Of 65 who entered Period A, 56 completed both periods: 31 in USA/Europe/Israel/South Africa; 15 in India and 10 in Turkey. Mean baseline LDL-C was 401 mg/dL; 55% were female and 19(34%) were adolescents aged <18 years. For the total population, the mean (SE) reduction in average LDL-C was -9.6% (3.25) on LIB and -11.7% (3.65) on EVO (p=0.44, NS). LDL-C reductions varied considerably in different regions and response was poorer in the adolescent subjects. However, reductions in LDL-C of ≥15% were seen in 26.8% (n=15) with LIB and 37.5% (n=21) with EVO - Table. Conclusions: Reductions in LDL-C achieved with PCSK9-inhibition in HoFH subjects are highly variable and differ according to region and age. However, given the clinically significant reductions in LDL-C in 1/3 of patients including patients from India and Turkey with null/null or novel variants, PCSK9 inhibition should remain part of standard of care for HoFH patients who remain with elevated LDL-C levels despite treatment with statin and ezetimibe.