In:
Arteriosclerosis, Thrombosis, and Vascular Biology, Ovid Technologies (Wolters Kluwer Health), Vol. 35, No. suppl_1 ( 2015-05)
Abstract:
Introduction: Monoclonal antibodies (Mabs) that neutralize proprotein convertase subtilisin-kexin type 9 (PCSK9) have been shown to lower LDL-C in human trials. It is known that PCSK9 is cleaved by furin at Arg218 and that the cleaved PCSK9 is inactive in modulating LDLR. Antibodies whose epitopes are near the EGFA binding domain are more efficacious in increasing LDLR but may interfere with furin cleavage and thus normal PCSK9 clearance. Here we describe a unique antibody (LY) that both lowers LDL-C and allows for normal PCSK9 cleavage by furin. Hypothesis: An antibody with an epitope that permits furin cleavage of PCSK9 will show more durable LDL lowering compared to one with an epitope that interferes with cleavage. Methods: Furin cleavage of recombinant PCSK9 was evaluated by electrophoresis in the presence of antibodies. Antibodies were studied in mice expressing wild-type or a non-cleavable variant of human PCSK9. Results: We determined that LY3015014 (LY) permits furin cleavage of PCSK9 while Mab A, which shares the epitope of a Mab tested in humans, does not. LY’s epitope is completely N-terminal of the cleavage site, while the conformational epitope of Mab A spans the Arg218 cleavage site. To assess the impact of PCSK9 cleavage on antibody efficacy in vivo, we generated two human PCSK9 overexpressing mouse models; one with WT PCSK9 and one with a non-cleavable variant (R215A, R218A). In mice expressing WT human PCSK9, LY showed a longer duration of LDL lowering and a slower clearance rate than Mab A. Additionally, we found that PCSK9 did not accumulate in the serum of mice given LY, likely due to cleavage and release from the antibody. In mice expressing the non-cleavable variant PCSK9, the clearance and LDL durability benefits of LY compared to Mab A were lost. Additionally, in the non-cleavable model, PCSK9 accumulated in the serum of mice given LY, presumably due to lack of furin cleavage. Conclusions: LY allows normal cleavage and inactivation of bound PCSK9 while maintaining LDL-C lowering. This proteolysis reduces the antibody’s clearance rate and extends the therapeutic durability of LY in mice relative to Mab A which interferes with proteolytic degradation. We have shown that cleavage is the mechanism of durability through the use of non-cleavable PCSK9.
Type of Medium:
Online Resource
ISSN:
1079-5642
,
1524-4636
DOI:
10.1161/atvb.35.suppl_1.538
Language:
English
Publisher:
Ovid Technologies (Wolters Kluwer Health)
Publication Date:
2015
detail.hit.zdb_id:
1494427-3
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