Dataset Information

Association Between Circulating Baseline Proprotein Convertase Subtilisin Kexin Type 9 Levels and Efficacy of Evolocumab.

ABSTRACT:

Importance

Levels of proprotein convertase subtilisin kexin type 9 (PCSK9) vary markedly across the population and are influenced by genetic and nongenetic factors. Evolocumab is a fully human, monoclonal antibody against PCSK9 that reduces low-density lipoprotein cholesterol (LDL-C) levels by 55% to 75%. Whether the efficacy of evolocumab varies based on an individual's baseline PCSK9 level remains unknown.

Objective

To characterize variability in PCSK9 levels and determine whether the LDL-C level reduction achieved with evolocumab differs based on PCSK9 levels.

Design, setting, and participants

This study included pooled data from 3016 patients from 4 phase 3 randomized clinical trials of evolocumab as part of the Program to Reduce LDL-C and Cardiovascular Outcomes Following Inhibition of PCSK9 in Different Populations. Circulating PCSK9 levels were measured at baseline using quantitative enzyme-linked immunosorbent assays and used to stratify patients into quartiles, and LDL-C level was measured at baseline and weeks 10 and 12. In an additional 138 patients enrolled in a pharmacokinetic and pharmacodynamic substudy from 4 phase 2 trials, circulating PCSK9 levels were measured at baseline and then weekly at weeks 8 through 12.

Main outcomes and measures

Placebo-controlled percentage change in LDL-C level with evolocumab, 140 mg every 2 weeks and 420 mg once monthly, across quartiles of baseline PCSK9 levels.

Results

Of the 3016 patients, 1492 (49.5%) were female and 2758 (91.4%) were white. The median baseline circulating PCSK9 level was 323 ng/mL (interquartile range, 258-406 ng/mL). Patients with higher levels of PCSK9 were more likely to be receiving intensive statin therapy (56%, 36%, 25%, and 13% in the fourth through first quartiles; P < .001) and had significantly lower baseline LDL-C level (123 mg/dL, 124 mg/dL, 128 mg/dL, and 137 mg/dL in the fourth through first quartiles; P < .001). After stratifying by statin use, there was no correlation between PCSK9 levels and LDL-C levels (ρ = 0.03 [95% CI, -0.04 to 0.10] for nonstatin users, P = .39, and ρ = 0.03 [95% CI, -0.01 to 0.08] for statin users, P = .12). Across all quartiles of baseline PCSK9 levels, both evolocumab 140 mg every 2 weeks and 420 mg once monthly suppressed circulating PCSK9 levels by 90% to 100% within 1 week of administration. Both evolocumab 140 mg every 2 weeks and 420 mg once monthly were associated with significant reductions in LDL-C levels between 64% and 71% (P < .001), regardless of PCSK9 levels (P for interaction = .76 and .21, respectively).

Conclusions and relevance

Regardless of baseline PCSK9 levels, the doses of evolocumab being studied in a large cardiovascular outcomes trial suppress PCSK9 levels and consistently and substantially reduce LDL-C levels.

SUBMITTER: Desai NR

PROVIDER: S-EPMC5814982 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Proprotein convertase subtilisin/kexins (PCSKs) constitute a family of nine related proteases: PCSK1-7, MBTPS1, and PCSK9. Apart from PCSK9, little is known about PCSKs in cardiovascular disease. Here, we aimed to investigate the expression landscape and druggability potential of the entire PCSK family for CVD. We applied an integrative approach, combining genetic, transcriptomic and proteomic data from three vascular biobanks comprising carotid atherosclerosis, thoracic and abdominal aneurysms, with patient clinical parameters and immunohistochemistry of vascular biopsies. Apart from PCSK4, all PCSK family members lie in genetic regions containing variants associated with human cardiovascular traits. Transcriptomic analyses revealed that FURIN, PCSK5, MBTPS1 were downregulated, while PCSK6/7 were upregulated in plaques vs. control arteries. In abdominal aneurysms, FURIN, PCSK5, PCSK7, MBTPS1 were downregulated, while PCSK6 was enriched in diseased media. In thoracic aneurysms, only FURIN was significantly upregulated. Network analyses of the upstream and downstream pathways related to PCSKs were performed on the omics data from vascular biopsies, revealing mechanistic relationships between this protein family and disease. Cell type correlation analyses and immunohistochemistry showed that PCSK transcripts and protein levels parallel each other, except for PCSK9 where transcript was not detected, while protein was abundant in vascular biopsies. Correlations to clinical parameters revealed a positive association between FURIN plaque levels and serum LDL, while PCSK6 was negatively associated with Hb. PCSK5/6/7 were all positively associated with adverse cardiovascular events. Our results show that PCSK6 is abundant in plaques and abdominal aneurysms, while FURIN upregulation is characteristic for thoracic aneurysms. PCSK9 protein, but not the transcript, was present in vascular lesions, suggesting its accumulation from circulation. Integrating our results lead to the development of a novel 'molecular' 5D framework. Here, we conducted the first integrative study of the proprotein convertase family in this context. Our results using this translational pipeline, revealed primarily PCSK6, followed by PCSK5, PCSK7 and FURIN, as proprotein convertases with the highest novel therapeutic potential.