Despite the use of high-dose statins and the recent addition of proprotein convertase subtilisin/kexin type 9 inhibitors as a treatment option, many patients with homozygous FH fail to achieve optimal reductions of LDL-c levels.
Autosomal dominant hypercholesterolemia, being referred to as familial hypercholesterolemia (FH), is mainly due to defective LDL receptor (LDLR) function, but is also associated with variants in genes encoding APOB (LDLR ligand) and PCSK9, the catabolic regulator of LDLR.
Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) reduce low-density lipoprotein cholesterol (LDL-C) levels and are approved for patients with familial hypercholesterolemia or atherosclerotic cardiovascular disease who require additional LDL-C lowering.
A separate meta-analysis of trials recruiting familial hypercholesterolemia patients has showed a tendency to harm for all outcomes with PCSK9 antibodies.
Recently the fully human monoclonal antibodies against proprotein convertase subtilisin/kexin 9 (PCSK9), alirocumab (Praluent®) and evolocumab (Repatha®), which have been shown to decrease LDL-C by up to 70% have been approved in Europe for use in patients with primary hypercholesterolemia not at LDL-C target while on maximally tolerated lipid-lowering therapy and specifically for patients with statin intolerance and in the USA for patients with atherosclerotic cardiovascular disease or familial hypercholesterolemia requiring additional LDL-C lowering.
Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9is) are an innovative treatment option for patients with familial hypercholesterolemia or clinical atherosclerotic cardiovascular disease who require further lowering of low-density lipoprotein cholesterol.
Patients with autosomal dominant hypercholesterolemia (ADH), caused by mutations in either low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin-kexin type 9 (PCSK9) are characterized by high low-density lipoprotein cholesterol levels and in some studies also high lipoprotein(a) (Lp(a)) levels were observed.
This study was aimed at screening the LDLR, APOB and PCSK9 genes in Hypercholesterolemic patients to define the genetic spectrum of FH in Indian population.
While relatively high cost can be given as a problem, PCSK9 inhibitors are able to reduce LDL cholesterol dramatically even in FH patients who could not achieve targets until now.
PCSK9 inhibitor plus statin did not show good cost-effectiveness for triple-vessel CAD; however, it showed good cost-effectiveness for patients with triple-vessel CAD and poorly controlled FH in Japan.
Nevertheless, rare clinical presentations in families with extreme phenotypes can sometimes identify novel pathways that can serve as therapeutic targets, such as the discovery of PCSK9 inhibitors for familial hypercholesterolemia or small molecular inhibitors of myosin ATPase activities for hypertrophic cardiomyopathy.
Definite FH includes: (1) elevated LDL-C (≥ 8.50 mmol/L); or (2) LDL-C ≥ 5.0 mmol/L (for age 40 years or older; ≥ 4.0 mmol/L if age younger than 18 years; and ≥ 4.5 mmol/L if age is between 18 and 39 years) when associated with at least 1 of: (1) tendon xanthomas; or (2) causal DNA mutation in the LDLR, APOB, or PCSK9 genes in the proband or first-degree relative.
In 2016, the National Lipid Association conducted an online survey on PCSK9 inhibitor use and barriers to prescription among experienced healthcare workers who provide care to high-risk patients with ASCVD or familial hypercholesterolemia (FH).
Among the 3381 index cases included with these characteristics in the French registry for familial hypercholesterolemia, 2054 underwent molecular diagnosis and 1150 (56%) were found to have mutations (93.5% in LDL Receptor (LDLR), 4.7% in apolipoprotein B and 1.8% in Proprotein convertase subtilisin/kexin type 9).
The aim of this study is to investigate the relation between lipoprotein(a) [Lp(a)] and proprotein convertase subtilisin/kexin type 9 (PCSK9) concentrations, and their complex, in patients with potential familial hypercholesterolemia (FH), depending on apo(a) phenotype.
This highlights the likelihood of a complex, polygenic inheritance of FH in Sri Lankan patients, indicating the need for a comprehensive genetic evaluation that includes the screening for mutations in other genes that cause FH, such as APOB, PCSK9, and LDLRAP1.
Mutations in the low-density lipoprotein (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin 9 (PCSK9), and LDLRAP1 genes have been associated with FH.
Moreover, PCSK9 inhibitors have been approved for patients with either familial hypercholesterolemia or atherosclerotic cardiovascular disease, who require additional reduction of LDL-C.