Vol. 303, Issue 3, 1334-1343, December 2002

Phase I Trial of ISIS 104838, a 2'-Methoxyethyl Modified Antisense Oligonucleotide Targeting Tumor Necrosis Factor-

K. Lea Sewell, Richard S. Geary, Brenda F. Baker, Josephine M. Glover, Timothy G. K. Mant, Rosie Z. Yu, Joseph A. Tami and F. Andrew Dorr

Isis Pharmaceuticals Inc., Carlsbad, California (K.L.S., R.S.G., B.F.B., J.M.G., R.Z.Y., J.A.T., F.A.D.); and Guy's Drug Research Unit Ltd., London, United Kingdom (T.G.K.M.)

ISIS 104838 is a 20-mer phosphorothioate antisense oligonucleotide (ASO) that binds tumor necrosis factor- (TNF-) mRNA. It carries a 2'-methoxyethyl modification on the five 3' and 5' nucleotide sugars, with 10 central unmodified deoxynucleotides. ISIS 104838 was identified from a 264 ASO screen in phorbol myristate acetate-activated keratinocytes, and the dose response was assessed in lipopolysaccharide (LPS)-activated monocytes. Healthy males received multiple intravenous (i.v.) ISIS 104838 infusions in a placebo-controlled dose escalation trial (0.1-6 mg/kg). Additional volunteers received single or multiple subcutaneous (s.c.) injections. ISIS 104838 suppressed TNF- protein by 85% in stimulated keratinocytes. The IC₅₀ for TNF- mRNA inhibition in stimulated monocytes was <1 µM. For i.v., C_max occurred at the end of infusion. The effective plasma half-life was 15 to 45 min at 0.1 to 0.5 mg/kg and 1 to 1.8 h for higher doses. The apparent terminal plasma elimination half-life approximated 25 days. Obese subjects had higher plasma levels following equivalent mg/kg doses. For s.c. injections, C_max occurred at 2 to 4 h and was lower than with equivalent i.v. dosing. Plasma bioavailability compared with i.v. was 82% following a 200 mg/ml s.c. injection. Transient activated partial thromboplastin time prolongation occurred after i.v. infusions and minimally after s.c. injections. Two subjects experienced rash, one a reversible platelet decrease, and mild injection site tenderness was noted. TNF- production by peripheral blood leukocytes, induced ex vivo by LPS, was decreased by ISIS 104838 (p < 0.01). ISIS 104838, a second-generation antisense oligonucleotide, was generally well tolerated intravenously and subcutaneously. The pharmacokinetics support an infrequent dosing interval. Inhibition of TNF- production ex vivo was demonstrated.