PCSK9 Inhibitors for Homozygous Familial Hypercholesterolemia

Long-term effectiveness and safety of lomitapide in patients with homozygous familial hypercholesterolemia: an observational case series

BACKGROUND

We assessed long-term real-world effectiveness and safety of lomitapide in patients with homozygous familial hypercholesterolemia (HoFH).

METHODS

Retrospective case series of six patients with HoFH treated with lomitapide in an Italian clinic. Changes in low-density lipoprotein cholesterol (LDL-C) during lomitapide treatment were assessed. The effect on LDL-C of PCSK9 inhibitors, apheresis and lomitapide was evaluated. Additionally, high-density lipoprotein cholesterol (HDL-C), gastrointestinal tolerability, hepatic steatosis/elasticity, transaminases, and cardiovascular events and symptoms were assessed.

RESULTS

Median age at HoFH clinical and molecular diagnoses was 25 (range 2-49) and 40 (29-71) years, respectively. Five (83.3%) had prior cardiovascular events. One patient received apheresis, which was subsequently discontinued. All patients received PCSK9 inhibitors but discontinued due to minimal effectiveness. Median (range) age at lomitapide initiation was 44 (28-73) years, with a median 47 (18-85) months' treatment (mean dose 17.5 [5-40] mg/day). Mean (SD) baseline LDL-C was 263.2 (148.1) mg/dL, which decreased by 80% at nadir (52.8 [19.2] mg/dL) and 69% at last follow-up (81.3 [30.5] mg/dL). Four patients (66.7%) achieved LDL-C < 70 mg/dL sometime during follow-up, all of whom also achieved LDL-C < 55 mg/dL. Adverse events (AEs) were generally mild to moderate, hepatic steatosis was either absent or mild/moderate and hepatic elasticity remained normal in all but two patients (> 70 years old). All patients with reported cardiovascular symptoms had improvements in symptoms, and all patients reported stabilization or regression of intima-media thickness and atheromatous plaques.

CONCLUSIONS

These long-term, real-world data demonstrate that lomitapide substantially reduced LDL-C for up to seven years. Most patients achieved LDL-C goal at some point, consistent with published Phase III trial and real-world evidence data. No patient discontinued lomitapide treatment. Further long-term follow-up in a larger patient population will be important to determine cardiovascular and other outcomes.

Proprotein convertase subtilisin/kexin type 9-inhibition across different patient populations

PURPOSE OF REVIEW

Monoclonal antibodies (mAb) targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) have been established in cardiovascular risk prevention. The purpose of this review is to summarize the effects of PCSK9 inhibitors across different patient populations.

RECENT FINDINGS

Long-term data on the use of evolocumab and alirocumab shows persisting low- density lipoprotein cholesterol (LDL-C) lowering and good tolerability. PCSK9 inhibitors are effective and safe in both sexes, in pediatric patients as well as in the elderly. Initiation of PCSK9 mAb during acute myocardial infarction is safe and leads to beneficial morphological plaque changes. The PCSK9 inhibitors evolocumab, alirocumab and inclisiran lower LDL-C in patients with heterozygous familial hypercholesterolemia (FH), while the response of patients with homozygous FH is heterogeneous. New areas of application beyond lipid lowering are currently investigated.

SUMMARY

PCSK9 inhibitors are safe, well tolerated, and effective in primary and secondary prevention in a wide range of patient populations.

Failure of lipid control by PCSK9 inhibitors in compound heterozygous familial hypercholesterolemia complicated with premature myocardial infarction: A case report

Key Clinical Message

A certain level of low-density lipoprotein receptor activity is crucial for the efficacy of PCSK9i. Therapeutic strategies for familial hypercholesterolemia patients should consider drug efficacy, and genetic testing will be helpful.

Abstract

Familial hypercholesterolemia (FH) is a serious autosomal dominant disorder. Managing blood lipids in FH patients poses greater challenges for clinicians. Drug therapy may not always yield satisfactory results, particularly in individuals with low-density lipoprotein receptor (LDLR) negative mutations. Herein, we report a young female harboring an LDLR frameshift mutation. This patient developed xanthomas at 7 months old and underwent several years of treatment involving four classes of lipid-lowering drugs, including PCSK9i. However, the response to drug therapy was limited in this patient and eventually culminated in premature myocardial infarction. The efficacy of PCSK9i depends on the activity of LDLR. The inefficacy of PCSK9i may arise from the extensive mutations which leading to loss of LDLR activity. Therapy plans for these patients should take into account the efficacy of drug therapy. Early genetic testing is crucial for clinicians to make informed decisions regarding therapy options.

New Oral PCSK9 Inhibitor: "MK-0616"

MK-0616, a novel oral macrocyclic peptide inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9), represents a significant advancement in the treatment of hypercholesterolemia. Unlike current PCSK9 inhibitors, which are injectable monoclonal antibodies and siRNA molecules, MK-0616 offers a patient-friendly alternative. The development of MK-0616 involved innovative synthetic chemistry and in vitro mRNA display technology. This cutting-edge approach led to the creation of an orally administered peptide with the ability to cover a larger portion of PCSK9 compared to smaller, linear peptides. Phase 1 and 2b clinical trials have demonstrated MK-0616's safety, efficacy, and pharmacokinetics. These trials indicate the drug's dose-dependent systemic absorption and long half-life. Notably, MK-0616 has exhibited comparable low-density lipoprotein cholesterol-lowering effects to currently available PCSK9 inhibitors, all while maintaining good tolerability in diverse patient populations, including those concurrently on statin therapy. As MK-0616 advances to Phase 3 trials, its lipid-lowering potential for heterozygous familial hypercholesterolemia and its impact on reducing the time to adverse cardiac events will be evaluated in a broad and diverse population, including underrepresented groups. The results achieved so far are promising for individuals with hypercholesterolemia, as they offer a potential solution for effectively lowering low-density lipoprotein cholesterol in patients on statin therapy and mitigating the risk of cardiovascular events. Ongoing research and monitoring will be critical to establish its long-term safety and efficacy, but MK-0616 may emerge as a valuable addition to the array of lipid-lowering therapies available to patients.

Does Genotype Affect the Efficacy of PCSK9 Inhibitors in the Treatment of Familial Hypercholesterolemia?

PURPOSE OF REVIEW

This review discusses whether patients' genotype affects the efficacy of PCSK9 inhibitors in treating familial hypercholesterolemia and how this might influence clinical management.

RECENT FINDINGS

Currently, available evidence consistently demonstrates and is in good agreement that, in general, the LDL-C-lowering effect of PCSK9 inhibitors is similar across genotypes, except for compound heterozygous and homozygous familial hypercholesterolemia (FH). However, it remains to be seen whether the comparable therapeutic effect in lowering LDL-C level also leads to a comparable degree of cardiovascular risk reduction with different genotypes. Generally, the level of LDL-C reduction following PCSK9 inhibitor treatment is similar within different genotypes. Hence, genotype is a less reliable predictor for further LDL-C level reduction on PCSK9 inhibitor therapy, and attention should be given to other external influences, especially for heterozygous FH.

How Genetic Variants in Children with Familial Hypercholesterolemia Not Only Guide Detection, but Also Treatment

Familial hypercholesterolemia (FH) is a hereditary disorder that causes severely elevated low-density lipoprotein (LDL-C) levels, which leads to an increased risk for premature cardiovascular disease. A variety of genetic variants can cause FH, namely variants in the genes for the LDL receptor (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin type 9 (PCSK9), and/or LDL-receptor adaptor protein 1 (LDLRAP1). Variants can exist in a heterozygous form (HeFH) or the more severe homozygous form (HoFH). If affected individuals are diagnosed early (through screening), they benefit tremendously from early initiation of lipid-lowering therapy, such as statins, and cardiovascular imaging to detect possible atherosclerosis. Over the last years, due to intensive research on the genetic basis of LDL-C metabolism, novel, promising therapies have been developed to reduce LDL-C levels and subsequently reduce cardiovascular risk. Results from studies on therapies focused on inhibiting PCSK9, a protein responsible for degradation of the LDLR, are impressive. As the effect of PCSK9 inhibitors (PCSK9-i) is dependent of residual LDLR activity, this medication is less potent in patients without functional LDLR (e.g., null/null variant). Novel therapies that are expected to become available in the near future focused on inhibition of another major regulatory protein in lipid metabolism (angiopoietin-like 3 (ANGPTL3)) might dramatically reduce the frequency of apheresis in children with HoFH, independently of their residual LDLR. At present, another independent risk factor for premature cardiovascular disease, elevated levels of lipoprotein(a) (Lp(a)), cannot be effectively treated with medication. Further understanding of the genetic basis of Lp(a) metabolism, however, offers a possibility for the development of novel therapies.

EFFICACY AND SAFETY OF LOMITAPIDE IN HOMOZYGOUS FAMILIAL HYPERCHOLESTEROLEMIA: THE PAN-EUROPEAN RETROSPECTIVE OBSERVATIONAL STUDY

BACKGROUND

Lomitapide is a lipid-lowering agent indicated as adjunct therapy for adult HoFH.

OBJECTIVES

This study evaluated the medium-term effectiveness and safety of lomitapide in a large cohort of HoFH patients in Europe.

METHODS

In a multicenter retrospective, observational study including 75 HoFH patients treated with lomitapide in a real-world clinical setting from 9 European countries, LDL-C changes, adverse events (AEs) as well as major adverse cardiovascular events (MACE) were assessed.

RESULTS

After a median 19 months (IQR 11-41 months) of treatment with a mean dosage of 20 mg of lomitapide. LDL-C decreased by 60%, from baseline 280.5 mg/dL (191.8-405.0 mg/dl) to 121.6 mg/dl (61.0-190.5 mg/dl). At the last visit, 32.0% of patients achieved LDL-C < 100mg/dL and 18.7% <70 mg/dL. At baseline, 38 HoFH patients were receiving LDL apheresis (LA), but after initiation of lomitapide 36.8% of patients discontinued LA. During follow-up, lomitapide was permanently interrupted in 13% of patients. Gastrointestinal (GI) AEs occurred in 40% and liver transaminases increased (3-5 x ULN) in 13% of patients. Among patients with liver ultrasound evaluation (n = 45), a modest increase in hepatic steatosis was noted during treatment; however liver stiffness measured by elastography in 30 of them remained within the normal range. Among HoFH patients exposed to lomitapide for at least 2 years, MACE incident rate was 7.4 per 1000 person-years in the 2 years after as compared to 21.2 per 1000 person-years before treatment with lomitapide.

CONCLUSIONS

In this medium-term real-world experience, lomitapide proved to be very effective in reducing LDL-C in HoFH. GI AEs were common, but liver safety was reassuring with no sign of increased risk of liver fibrosis. A signal of cardiovascular protection was also observed.

Use of apheresis in the age of new therapies for familial hypercholesterolaemia

PURPOSE OF REVIEW

Lipoprotein apheresis has been first line therapy for homozygous familial hypercholesterolaemia (FH) and other severe and refractory forms of dyslpidaemia for over 40 years but the recent advent of novel and potent LDL-lowering compounds necessitates a reappraisal of its role.

RECENT FINDINGS

During the past decade a substantial amount of evidence has accumulated describing the effect of LDL-lowering with apheresis and conventional drug therapy upon the cardiovascular outcomes associated with homozygous and statin-refractory heterozygous FH. This has necessitated re-defining the target levels of LDL cholesterol needed to arrest progression of atherosclerosis in these situations. At the same time, evidence has accrued regarding the pathogenicity of raised levels of lipoprotein (a) and the promising role of apheresis in mitigating the adverse effects of the latter. The latest advance in treatment has been the introduction of three classes of novel and potent LDL-lowering compounds in the shape of inhibitors of Propertin convertase subtilisin kexin 9 (PCSK9), microsomal triglyceride transfer protein and angiopoietin-like 3.

SUMMARY

These recent developments raise the question of whether these compounds will be used as adjuvants to bolster lipoprotein apheresis in FH homozygotes or whether they will render it obsolete, as is already occurring with PCSK9 inhibitors in FH heterozygotes.