New Therapeutic Approaches for Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a common genetic condition characterized by elevated plasma levels of low-density lipoprotein cholesterol (LDL-C), premature atherosclerotic cardiovascular disease, and considerable unmet medical need with conventional LDL-C-lowering therapies. Between 2012 and 2015, the US Food and Drug Administration approved four novel LDL-C-lowering agents for use in patients with FH based on the pronounced LDL-C-lowering efficacy of these medicines. We review the four novel approved agents, as well as promising LDL-C-lowering agents in clinical development, with a focus on their mechanism of action, efficacy in FH cohorts, and safety.

Abstract 279: Using the Familial Hypercholesterolemia ICD-10 Code to Track Clinical Management of Patients at a Tertiary Academic Center

Background: Many guidelines suggest a target LDL-C of <100 mg/dL in individuals with familial hypercholesterolemia (FH) to avoid the lifelong burden of high LDL-C and onset of cardiovascular disease. However, the clinical characteristics and management of patients with FH in the United States remain poorly described. In 2016, a distinct ICD-10 for FH was introduced into clinical care settings to track FH patients.

Objective: To determine the cardiovascular disease burden and treatment patterns among patients with the ICD-10 code for FH at a tertiary academic center.

Methods: A retrospective query was conducted in The University of Pennsylvania Health System (UPHS) using the ICD-10 code, E78.01.

Results: The query returned 1417 FH patients (703 seen in the lipid clinic, 714 seen elsewhere in UPHS) identified by E78.01. Among all patients, median age at initiation of lipid-lowering therapy was 52 years, and median age at FH diagnosis was 55 years. Prevalent coronary heart disease was reported in 30% (425 of 1417) of all patients, and 27% (382 of 1417) exhibited a family history of cardiovascular disease. Median untreated low-density lipoprotein cholesterol (LDL-C) was 197 mg/dL and median treated LDL-C was 112 mg/dL. Among all patients, 35% (495 of 1417) were taking high-intensity statin therapy, 24% (340 of 1417) were taking PCSK9 inhibitor (PCSK9i) therapy, and 29% (410 of 1417) were taking ezetimibe. Providers in the Penn Lipid Clinic prescribed approximately 71% (557 of 785) of all high-intensity statin and PCSK9i therapy to FH patients of whom 50% (392 of 785) achieved an LDL-C of <100 mg/dL and 24% (188 of 785) achieved an LDL-C <70 mg/dL. Factors associated with LDL-C <100 mg/dL included use of a PCSK9 inhibitor (odds ratio 1.96; confidence interval 1.55-2.48) and consultation with a lipid clinic provider (1.81; 1.45-2.25). Factors associated with prevalent coronary heart disease included hypertension (2.92; 2.31-3.70) and smoking (1.64; 1.30-2.09).

Conclusions: The ICD-10 code for FH identifies a cohort of patients with a phenotype consistent with FH. A large minority of FH patients are not taking high-intensity statin or PCSK9i therapy, especially those who have not seen a provider in a dedicated lipid clinic. These findings highlight a way to monitor the clinical management of FH patients while explaining need for education about FH in an academic center.

Abstract 435: An Electronic Health Records Query for Severe Hypercholesterolemia Identifies Individuals With Undiagnosed Clinical and Molecular FH at a Tertiary Academic Centre

Background: Familial hypercholesterolemia (FH) is a common heritable disorder of elevated low density lipoprotein cholesterol (LDL-C) with an estimated prevalence of 1/200-300 in the US; however, fewer than 10% of cases have been identified. We wanted to examine whether a simple EHR query for severe hypercholesterolemia could be used to identify clinically and genetically defined cases of FH.

Objectives/Purpose: We tested the hypothesis that querying the EHR using an LDL-C criterion would be a novel way to screen for and ultimately identify undiagnosed cases of FH.

Methods: An EHR screening query was used to identify active adult patients with LDL-C ≥ 220 mg/dL in the University of Pennsylvania outpatient EHR database. Patients with secondary causes of hypercholesterolemia and those who had previous genetic testing for FH were excluded. The query identified 3,475 individuals, 120 were subsequently consented and enrolled for molecular testing. This was performed with next-generation sequencing using Progenika’s SEQPRO LIPO IS platform, targeting LDLR, APOB, PCSK9 and LDLRAP1 . A literature search was performed to gather information on identified LDLR variants of unknown significance (VUS). In addition, in-silico analysis was employed to evaluate the pathogenicity of the LDLR and LDLRAP1 VUS.

Results: Among the 120 subjects, 53 (44.2%) met the Dutch Lipid Clinic Network (DLCN) criteria for probable or definite clinical FH. Molecularly, 19 FH-related pathogenic mutations were found in 18 (15%) individuals. Four had a common APOB ( R3500Q) mutation, 14 had a LDLR mutation. One individual had a double heterozygous mutation in PCSK9 and LDLR. In addition, 17 LDLR VUS were identified in 16 (13.9%) individuals. A literature review and in-silico analysis predicted that 8 VUS found in 10 subjects were “disease causing”. Therefore, a total of 28 (24.3%) subjects from our cohort carried either a FH causal mutation or likely pathogenic variant. Overall, 59 subjects (49.2%) in our cohort were ascertained to have either a clinical or molecular diagnosis of FH.

Conclusion: The use of an EHR screening query for severe hypercholesterolemia was a novel, low investment but relatively high yield approach for identifying undiagnosed cases of FH at a tertiary academic centre.

Recent Developments in Gene Therapy for Homozygous Familial Hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a life-threatening Mendelian disorder with a mean life expectancy of 33 years despite maximally tolerated standard lipid-lowering therapies. This disease is an ideal candidate for gene therapy, and in the last few years, a number of exciting developments have brought this approach closer to the clinic than ever before. In this review, we discuss in detail the most advanced of these developments, a recombinant adeno-associated virus (AAV) vector carrying a low-density lipoprotein receptor (LDLR) transgene which has recently entered phase 1/2a testing. We also review ongoing development of approaches to enhance transgene expression, improve the efficiency of hepatocyte transduction, and minimize the AAV capsid-specific adaptive immune response. We include a summary of key gene therapy approaches for HoFH in pre-clinical development, including RNA silencing of the gene encoding HMG-CoA reductase (HMGCR) and induced pluripotent stem cell transplant therapy.

Recent advances in the pharmacological management of hypercholesterolaemia

The recent developments in pharmacological interventions that reduce LDL cholesterol have been remarkable, coming more than a decade after the approval of the last LDL-cholesterol-lowering drug, the cholesterol absorption inhibitor ezetimibe. Within just a few years, four new LDL-cholesterol-lowering agents have received regulatory approval. Lomitapide and mipomersen inhibit the production of LDL, but also increase hepatic fat and are licensed specifically for homozygous familial hypercholesterolaemia. Alirocumab and evolocumab are monoclonal antibodies that bind to proprotein convertase subtilisin/kexin type 9 (PCSK9), lowering LDL by about 50-60%. These drugs are approved for use in patients with cardiovascular disease or familial hypercholesterolaemia whose LDL cholesterol levels are insufficiently controlled on standard agents. Although definitive clinical efficacy and long-term safety data are still needed, antibody-based PCSK9 inhibitors promise to meet much of the unmet medical need in the treatment of raised LDL cholesterol. However, several additional approaches to inhibiting PCSK9, as well as other classes of LDL-lowering therapies, are in clinical development. Here we summarise the science behind the development of the newly approved LDL-cholesterol-lowering drugs and critically review their efficacy and safety data, highlighting unanswered research questions. Finally, we discuss emerging LDL-lowering therapies in clinical development.