title: Bioavailability and efficacy of antisense morpholino oligomers targeted to c-myc and cytochrome P-450 3A2 following oral administration in rats.
abstract: Antisense phosphorodiamidate Morpholino oligomers (PMO) are resistant to degradation by cellular hydrolases, DNases, RNases, and phosphodiesterases, but remain sensitive to prolonged exposure to low pH. The present studies evaluate the oral fractional bioavailability, stability, and efficacy of two distinct PMO sequences targeted to c-myc and cytochrome P-450 (CYP) 3A2. The c-myc antisense 20-mer, AVI-4126 (5'-ACGTTGAGGGGCATCGTCGC-3'), slowed the regenerative process in the rat liver after a 70% partial hepatectomy (PH). Rats were administered 3.0 mg/kg AVI-4126 in 0.1 mL saline via a bolus intravenous injection or in 0.5 mL sterile phosphate-buffered saline via gavage immediately following PH. The areas under the plasma concentration versus time curves revealed a fractional oral availability of 78.8% over a period of 10 min through 24 h. Immunoblot analysis of liver tissue from rats treated orally with AVI-4126 demonstrated a sequence-specific reduction in the target protein c-Myc, as well as secondary proliferation markers: proliferating cell nuclear antigen (PCNA), cyclin D1, and p53. The CYP3A2 antisense 22-mer AVI-4472 (5'-GAGCTGAAAGCAGGTCCATCCC-3') caused a sequence-dependent reduction of approximately five-fold in the rat liver CYP3A2 protein levels and erythromycin demethylation activity in 24 h following oral administration at a dose of 2 mg/kg. It is concluded that oral administration of PMOs can inhibit c-myc and CYP3A2 gene expression in rat liver by an antisense-based mechanism of action. These studies highlight the potential for development of PMOs as orally administered therapeutic agents.
authors.affiliation: AVI BioPharma, 4575 SW Research Way, Suite 200, Corvallis, Oregon 97333, USA. varora@avibio.com
authors.forename: Vikram
authors.initials: V
authors.lastname: Arora
authors.forename: Derek C
authors.initials: DC
authors.lastname: Knapp
authors.forename: Muralimohan T
authors.initials: MT
authors.lastname: Reddy
authors.forename: Dwight D
authors.initials: DD
authors.lastname: Weller
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Iversen
mesh_terms: D000284:Administration, Oral; D000818:Animals; D016375:Antisense Elements (Genetics) / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D001682:Biological Availability; D015415:Biomarkers / Q000032:analysis; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D008115:Liver Regeneration / Q000187:drug effects / Q000502:physiology; D008297:Male; D017553:Phosphorus Compounds / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013250:Steroid Hydroxylases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D016375:Antisense Elements (Genetics); D015415:Biomarkers; D065607:Cytochrome P-450 Enzyme Inhibitors; D017553:Phosphorus Compounds; D016271:Proto-Oncogene Proteins c-myc; D003577:Cytochrome P-450 Enzyme System; C436301:phosphorodiamidic acid; D013250:Steroid Hydroxylases; C022657:steroid hormone 6-beta-hydroxylase