Contemporary Homozygous Familial Hypercholesterolemia in the United States: Insights From the CASCADE FH Registry

Newborn screening for lipid disorders

PURPOSE OF REVIEW

Newborn screening is one of the most successful public health programs of the last century and offers unparalleled access to universal screening for a variety of metabolic and other disorders. Interest in development of newborn screening for lipid disorders has intensified in recent years. Screening newborns for lipid disorders has important implications for the health of the newborn as well as their relatives, and in the case of more common lipid disorders like familial hypercholesterolemia, could have important public health implications.

RECENT FINDINGS

Recent studies have demonstrated feasibility of measuring biomarkers for heterozygous familial hypercholesterolemia from newborn screening dried blood spot specimens. Another lipid disorder, cerebrotendinous xanthomatosis, is currently amenable to newborn screening utilizing currently available assays. New research in next-generation sequencing as a primary screen in newborns will also identify both common and rare lipid disorders in newborns.

SUMMARY

Historically, newborn screening for lipid disorders was not done for many reasons, but new research has developed testing methods that may successfully identify common and rare lipid disorders. This will impact the health of the newborn but could also impact family members and public health.

A machine-learning algorithm using claims data to identify patients with homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is an underdiagnosed and undertreated ultra-rare disease. We utilized claims data from the Komodo Healthcare Map database to develop a machine-learning model to identify potential HoFH patients. We tokenized patients enrolled in MyRARE (patient support program for those prescribed evinacumab-dgnb in the United States) and linked them with their Komodo claims. A true positive HoFH cohort (n = 331) was formed by including patients from MyRARE and patients with prescriptions for evinacumab-dgnb or lomitapide. The negative cohort (n = 1423) comprised patients with or at risk for cardiovascular disease. We divided the cohort into an 80% training and 20% testing set. Overall, 10,616 candidate features were investigated; 87 were selected due to clinical relevance and importance on prediction performance. Different machine-learning algorithms were explored, with fast interpretable greedy-tree sums selected as the final machine-learning tool. This selection was based on its satisfactory performance and its easily interpretable nature. The model identified four useful features and yielded precision (positive predicted value) of 0.98, recall (sensitivity) of 0.88, area under the receiver operating characteristic curve of 0.98, and accuracy of 0.97. The model performed well in identifying HoFH patients in the testing set, providing a useful tool to facilitate HoFH screening and diagnosis via healthcare claims data.

Sex differences in the presentation, treatment and outcomes of patients with homozygous familial hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is a rare, autosomal semi-dominant lipid metabolism disorder characterized by extremely high low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease. The objective of this study was to investigate sex-differences in the treatment and outcomes of patients with HoFH.

METHODS

We examined clinical characteristics, lipid-lowering therapy (LLT), and cardiovascular events using descriptive statistics of patients in the Canadian HoFH registry. Major adverse cardiovascular events (MACE) were defined as the composite of cardiovascular death, non-fatal myocardial infarction, and stroke. Sex differences between continuous and categorical variables were analyzed using Mann-Whitney U test and Fisher's Exact test, respectively.

RESULTS

This study included 48 patients (27 (56%) female). The median age at diagnosis in females was 14.0 (interquartile range (IQR) 9.0-30.0) and in males was 8.0 (IQR 2.0-23.0) (p = 0.07). Baseline clinical characteristics were comparable between both sexes. The median baseline LDL-C was 12.7 mmol/L (10.0-18.3) in females and 15.3 (10.5-20.0) in males (p = 0.51). Follow up LDL-C levels were 7.6 mmol/L (IQR 4.8-11.0) in females and 6.3 (IQR 4.6-7.5) in males (p = 0.1). Most patients were taking 3 or more LLTs, with comparable proportions in both sexes (p = 0.26). Apheresis was similar in both sexes, 14 (51.8%) vs. 10 (47.6%) (p = 0.2). Over a mean of 10 years of follow-up, MACE occurred in 3 females (11.1%) and 4 males (19.1%) (p = 0.2).

CONCLUSION

Lipid levels and treatment were similar between sexes. MACE occurred in similar proportions between sexes, indicating that HoFH offsets the inherently lower cardiovascular risk in pre-menopausal females. Further investigation into sex-differences in HoFH in larger sample sizes is warranted.

Contemporary lipid-lowering management and risk of cardiovascular events in homozygous familial hypercholesterolaemia: insights from the Italian LIPIGEN Registry

AIMS

The availability of novel lipid-lowering therapies (LLTs) has remarkably changed the clinical management of homozygous familial hypercholesterolaemia (HoFH). The impact of these advances was evaluated in a cohort of 139 HoFH patients followed in a real-world clinical setting.

METHODS AND RESULTS

The clinical characteristics of 139 HoFH patients, along with information about LLTs and low-density lipoprotein cholesterol (LDL-C) levels at baseline and after a median follow-up of 5 years, were retrospectively retrieved from the records of patients enrolled in the LIPid transport disorders Italian GEnetic Network-Familial Hypercholesterolaemia (LIPIGEN-FH) Registry. The annual rates of major atherosclerotic cardiovascular events (MACE-plus) during follow-up were compared before and after baseline. Additionally, the lifelong survival free from MACE-plus was compared with that of the historical LIPIGEN HoFH cohort. At baseline, LDL-C level was 332 ± 138 mg/dL. During follow-up, the potency of LLTs was enhanced and, at the last visit, 15.8% of patients were taking quadruple therapy. Consistently, LDL-C decreased to an average value of 124 mg/dL corresponding to a 58.3% reduction (Pt < 0.001), with the lowest value (∼90 mg/dL) reached in patients receiving proprotein convertase subtilisin/kexin type 9 inhibitors and lomitapide and/or evinacumab as add-on therapies. The average annual MACE-plus rate in the 5-year follow-up was significantly lower than that observed during the 5 years before baseline visit (21.7 vs. 56.5 per 1000 patients/year; P = 0.0016).

CONCLUSION

Our findings indicate that the combination of novel and conventional LLTs significantly improved LDL-C control with a signal of better cardiovascular prognosis in HoFH patients. Overall, these results advocate the use of intensive, multidrug LLTs to effectively manage HoFH.

Evinacumab for Pediatric Patients With Homozygous Familial Hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is a rare genetic disorder characterized by severely elevated low-density lipoprotein cholesterol (LDL-C) levels due to profoundly defective LDL receptor (LDLR) function. Given that severely elevated LDL-C starts in utero, atherosclerosis often presents during childhood or adolescence, creating a largely unmet need for aggressive LDLR-independent lipid-lowering therapies in young patients with HoFH. Here we present the first evaluation of the efficacy and safety of evinacumab, a novel LDLR-independent lipid-lowering therapy, in pediatric patients with HoFH from parts A and B of a 3-part study.

METHODS

The phase 3, part B, open-label study treated 14 patients 5 to 11 years of age with genetically proven HoFH (true homozygotes and compound heterozygotes) with LDL-C >130 mg/dL, despite optimized lipid-lowering therapy (including LDLR-independent apheresis and lomitapide), with intravenous evinacumab 15 mg/kg every 4 weeks.

RESULTS

Evinacumab treatment rapidly and durably (through week 24) decreased LDL-C with profound reduction in the first week, with a mean (SE) LDL-C reduction of -48.3% (10.4%) from baseline to week 24. ApoB (mean [SE], -41.3% [9.0%]), non-high-density lipoprotein cholesterol (-48.9% [9.8%]), and total cholesterol (-49.1% [8.1%]) were similarly decreased. Treatment-emergent adverse events were reported in 10 (71.4%) patients; however, only 2 (14.3%) reported events that were considered to be treatment-related (nausea and abdominal pain). One serious treatment-emergent adverse event of tonsillitis occurred (n=1), but this was not considered treatment-related.

CONCLUSIONS

Evinacumab constitutes a new treatment for pediatric patients with HoFH and inadequately controlled LDL-C despite optimized lipid-lowering therapy, lowering LDL-C levels by nearly half in these extremely high-risk and difficult-to-treat individuals.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04233918.

Long-term outcomes of liver transplantation for homozygous familial hypercholesterolaemia in Australia and New Zealand

BACKGROUND AND AIMS

Homozygous familial hypercholesterolaemia (FH) causes severe cardiovascular disease from childhood. Conventional drug therapy is usually ineffective; lipoprotein apheresis (LA) is often required. Liver transplantation (LT) can correct the metabolic defect but is considered a treatment of last resort. Newer drugs including lomitapide and evinacumab might reduce the need for apheresis and LT. We sought to determine the long-term outcomes following LT in Australia and New Zealand.

METHODS

We analysed demographic, biochemical and clinical data from all patients in Australia and New Zealand who have received LT for homozygous FH, identified from the Australia and New Zealand Liver and Intestinal Transplant Registry.

RESULTS

Nine patients (five female; one deceased; seven aged between 3 and 6 years at the time of LT and two aged 22 and 26 years) were identified. Mean follow-up was 14.1 years (range 4-27). Baseline LDL-cholesterol off all treatment was 23 ± 4.1 mmol/L. Mean LDL-cholesterol on medical therapy (including maximal statin therapy in all patients, ezetimibe in three and LA in five) was 11 ± 5.7 mmol/L (p < 0.001). After LT, mean LDL-cholesterol was 2.6 ± 0.9 mmol/L (p = 0.004) with three patients remaining on statin therapy and none on LA. One patient died from acute myocardial infarction (AMI) three years after LT. Two patients required aortic valve replacement, more than 10 years after LT. The remaining six patients were asymptomatic after eight to 21 years of follow-up. No significant adverse events associated with immunosuppression were reported.

CONCLUSIONS

LT for homozygous FH was highly effective in achieving substantial long-term reduction in LDL-cholesterol concentrations in all nine patients. LT remains an option for severe cases of homozygous FH where drug therapy combined with apheresis is ineffective or unfeasible.