Therapeutic RNAi targeting PCSK9 acutely lowers plasma cholesterol in rodents and LDL cholesterol in nonhuman primates.
Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates low density lipoprotein receptor (LDLR) protein levels and function. Loss of PCSK9 increases LDLR levels in liver and reduces plasma LDL cholesterol (LDLc), whereas excess PCSK9 activity decreases liver LDLR levels and increases plasma LDLc. Here, we have developed active, cross-species, small interfering RNAs (siRNAs) capable of targeting murine, rat, nonhuman primate (NHP), and human PCSK9. For in vivo studies, PCSK9 and control siRNAs were formulated in a lipidoid nanoparticle (LNP). Liver-specific siRNA silencing of PCSK9 in mice and rats reduced PCSK9 mRNA levels by 50-70%. The reduction in PCSK9 transcript was associated with up to a 60% reduction in plasma cholesterol concentrations. These effects were shown to be mediated by an RNAi mechanism, using 5'-RACE. In transgenic mice expressing human PCSK9, siRNAs silenced the human PCSK9 transcript by >70% and significantly reduced PCSK9 plasma protein levels. In NHP, a single dose of siRNA targeting PCSK9 resulted in a rapid, durable, and reversible lowering of plasma PCSK9, apolipoprotein B, and LDLc, without measurable effects on either HDL cholesterol (HDLc) or triglycerides (TGs). The effects of PCSK9 silencing lasted for 3 weeks after a single bolus i.v. administration. These results validate PCSK9 targeting with RNAi therapeutics as an approach to specifically lower LDLc, paving the way for the development of PCSK9-lowering agents as a future strategy for treatment of hypercholesterolemia.
Frank-Kamenetsky
Maria
M
Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA.
Grefhorst
Aldo
A
Anderson
Norma N
NN
Racie
Timothy S
TS
Bramlage
Birgit
B
Akinc
Akin
A
Butler
David
D
Charisse
Klaus
K
Dorkin
Robert
R
Fan
Yupeng
Y
Gamba-Vitalo
Christina
C
Hadwiger
Philipp
P
Jayaraman
Muthusamy
M
John
Matthias
M
Jayaprakash
K Narayanannair
KN
Maier
Martin
M
Nechev
Lubomir
L
Rajeev
Kallanthottathil G
KG
Read
Timothy
T
Röhl
Ingo
I
Soutschek
Jürgen
J
Tan
Pamela
P
Wong
Jamie
J
Wang
Gang
G
Zimmermann
Tracy
T
de Fougerolles
Antonin
A
Vornlocher
Hans-Peter
HP
Langer
Robert
R
Anderson
Daniel G
DG
Manoharan
Muthiah
M
Koteliansky
Victor
V
Horton
Jay D
JD
Fitzgerald
Kevin
K
D000818:Animals; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans; D008099:Liver / Q000201:enzymology; D051379:Mice; D018345:Mice, Knockout; D015394:Molecular Structure; D011323:Primates / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D051381:Rats; D012697:Serine Endopeptidases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
D008078:Cholesterol, LDL; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012697:Serine Endopeptidases