Positive results form INX-189 Phase 1b trial against hepatitis C virus

Inhibitex, Inc. today reported positive preliminary interim safety and antiviral data from the first two monotherapy cohorts of its ongoing Phase 1b clinical trial of INX-189, an oral NS5b nucleotide inhibitor being developed to treat chronic infections caused by hepatitis C virus (HCV).

“We are pleased with the interim results of the trial to-date and the rapid and potent antiviral activity demonstrated at these low doses of INX-189”

The trial, which is being conducted under an IND in the United States, is a double-blind, placebo-controlled, dose escalation study designed to evaluate the safety, tolerability, pharmacokinetics and antiviral activity of INX-189, administered orally once-daily for seven days, for the treatment of HCV genotype 1 treatment naïve patients. Each treatment cohort in the study is comprised of 10 patients, eight that receive INX-189 and two that receive placebo. In addition to the 9 mg and 25 mg dose cohorts, the Company plans to enroll up to three more INX-189 monotherapy cohorts in the study, as well as two cohorts that will receive different doses of INX-189 once daily for seven days in combination with ribavirin.

INX-189, dosed once-daily at 9mg and 25mg for seven days, demonstrated potent antiviral activity with a mean HCV RNA reduction from baseline levels of -0.71 and -1.03 log₁₀ IU/mL, respectively. The mean HCV RNA decline from baseline levels observed in patients that received placebo was -0.06 log₁₀ IU/mL. The HCV RNA declines from baseline were statistically significant from placebo, with p-values of 0.0156 and 0.0006 in the 9 mg and 25 mg cohorts, respectively. In addition to the mean reductions in viral load, clinically meaningful decreases in alanine transaminase (ALT) levels were observed for patients receiving INX-189 at both dose levels and no patients experienced viral breakthrough.

Preliminary assessments of the data available from the first two cohorts in the Phase 1b study indicate that INX-189 was well tolerated. There were no serious adverse events reported, no discontinuations due to an adverse event, and no adverse events related to changes in clinical laboratory evaluations. All reported adverse events were mild or moderate and were not dose dependent. In addition, the pharmacokinetics of the 9mg and 25mg doses in HCV-infected patients were comparable to those observed in healthy volunteers, and continue to support the evaluation of INX-189 as a once-daily therapy.

"We are pleased with the interim results of the trial to-date and the rapid and potent antiviral activity demonstrated at these low doses of INX-189," commented Joseph M. Patti, Ph.D., Inhibitex's CSO and Senior Vice-President of Research. "We look forward to completing the remaining monotherapy cohorts and evaluating the potential antiviral synergies of INX-189 in combination with ribavirin in this ongoing study, and anticipate reporting additional safety, antiviral and pharmacokinetic data from the study upon its completion later this quarter."