I have published this Merck research previously on HC. I think that they have lost interest in it. I have previously suggested to PF that he explore obtaining the rights to the work, but that would take money we don't have or the issue of more shares.
Efficient target modulation in a translational animal model is necessary to evaluate candidate target drug targets and to inform decision. Recombinant adeno-associated viral vector serotype 8 (AAV8) is a very attractive means for delivery of cDNAs to the liver in preclinical species including non-human primates (NHP) and most recently in human clinical trial of hemophilia disorders. Our group has achieved significant success in using AAV8 delivery of short hairpin RNAs (shRNA) to knockdown genes of interest in mouse liver. To investigate the applicability of this approach in a large translational animal model we sought to use AAV delivery of shRNA in the nonhuman primate. To assess the feasibility and safety of AAV-RNAi in NHP liver, we selected proprotein convertase subtilisin/kexin type 9 (PCSK9), a well validated LDL cholesterol lowering target, for the proof-of-concept study. PCSK9, a secreted protein mainly from liver, binds and directs low density lipoprotein receptor (LDLR) to lysosomes for degradation, and thus controlling plasma LDL cholesterol level. A number of shRNAs were designed against cynomolgus monkey Pcsk9 and cloned into AAV cis plasmid. Three Pcsk9 shRNA leads were identified through initial screening in cells stably expressing cynomolgus monkey Pcsk9 and selected for AAV8 vector production. The lead shRNA was selected by subsequent ranking in primary cynomolgus hepatocytes and ultimately testing in an in vivo mouse cotransduction system. After rigorous in vitro and in vivo quality-control, self complementary AAV8 expressing Pcsk9shRNA driven by H1 promoter (AAV8-shPcsk9) was administrated into six 2-4 year old male cynom olgus monkeys that were selected for the lack of detectable neutralizing antibody to AAV8 capsid. AAV8- shPcsk9 treatment was in general well tolerated in all monkeys. Transduction of AAV8- shPcsk9 resulted in up to 88% reduction of plasma PCSK9 and up to 62% reduction of LDL-c relative to baseline, starting from day 3, while HDL cholesterol level of animals treated with AAV control vector remains unchanged. The data from the ongoing study revealed that plasma PCSK9 inhibition is maintained at 57% at 8 weeks following single AAV-shRNA dose injection. Our study demonstrates the safety and efficacy of AAV8-shRNA mediated inhibition of plasma PCSK9 and concurrent LDL cholesterol lowering. These results indicate that in addition to successful AAV-cDNA overexpression, AAV-RNAi is a promising approach to achieve long-term silencing of liver target genes in primates.
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