Idenix Pharmaceuticals Reports Positive Results With IDX184 From Interim Analysis of Phase IIa Hepatitis C Study

CAMBRIDGE, Mass., April 15 /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals, Inc. (Nasdaq: IDIX), a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases, today announced interim data from a 14-day, phase IIa clinical trial evaluating IDX184, a novel liver-targeted nucleotide prodrug of 2'-methyl guanosine monophosphate, in HCV-infected patients. Data are being presented at the 45th annual meeting of the European Association for the Study of the Liver being held in Vienna, Austria.  

The phase IIa clinical trial, initiated in the fourth quarter of 2009, is a randomized, double-blind, placebo-controlled, sequential dose-escalation study evaluating the safety, tolerability, pharmacokinetics and antiviral activity of IDX184 in combination with PegIFN/RBV in treatment-naive HCV genotype 1-infected patients. Patients receive a daily dose of IDX184 or placebo, plus pegIFN/RBV for 14 days and then continue on PegIFN/RBV for an additional 14 days. The study is evaluating four dosing regimens of IDX184 ranging from 50 to 200 mg per day. In the 100 mg and 200 mg cohorts, once daily (QD) and twice daily (BID) regimens are compared. Each cohort includes 20 patients randomized 4:1, IDX184:placebo.

In the data presented today, IDX184 demonstrated potent dose-dependent antiviral activity when combined with PegIFN/RBV. At Day 14, mean (+/- standard deviation) viral load reductions were 1.2 (+/- 1.1), 2.7 (+/- 1.3), 4.0 (+/- 1.7) and 4.2 (+/- 1.9) log(10) IU/mL in the placebo (n=8), 50 mg IDX184 QD (n=16), 50 mg IDX184 BID (n=8) and 100 mg IDX184 QD (n=8) cohorts, respectively. Half of the subjects receiving a total daily dose of 100 mg IDX184 achieved undetectable virus levels (< 15 IU/mL) by Day 14. Liver injury parameters (ALT and AST) improved (normalized) with all doses of IDX184. Antiviral activity and safety parameters measured after a total daily dose of 100 mg IDX184 did not differ between a QD or BID dosing regimen. The side effect profile of the three-drug combination was consistent with the known side effect profile of PegIFN/RBV alone. The most common adverse events reported were fatigue, myalgia, headache and nausea. No virologic breakthrough was observed during treatment with IDX184 in combination with PegIFN/RBV.

"We are very encouraged by these interim data for IDX184 combined with pegylated interferon and ribavirin as the viral load reductions for the 100 mg cohorts are on par with the first-generation nucleoside in development but at a fraction of the dose," said Douglas Mayers, M.D., Idenix's executive vice president and chief medical officer. "We are currently enrolling the 150 mg once-daily dose cohort and look forward to reporting full data later this year. We believe that with the favorable antiviral activity, safety and resistance profile seen to date, IDX184 could be a potential component of future direct-acting antiviral combination regimens."

"With a high barrier to resistance and broad genotypic coverage, nucleosides and/or nucleotides could become an important part of future combination therapy for hepatitis C patients," said Dr. Fred Poordad, a principal investigator in the study, Chief of Hepatology at the Liver Disease and Transplant Center at Cedars-Sinai Medical Center in Los Angeles. "The interim 50 and 100 mg cohort data for IDX184 in combination with pegylated interferon and ribavirin have been promising and we look forward to the continued clinical development of this drug candidate."

About HCV

Hepatitis C virus is a common blood-borne pathogen infecting three to four million people worldwide annually. Currently, an estimated 170 million people are infected worldwide, representing a nearly 5-fold greater prevalence than human immunodeficiency virus.(1)

About IDX184

IDX184 is a novel, liver-targeted nucleotide prodrug of 2'-methyl guanosine, which includes Idenix's proprietary liver-targeting technology. This technology enables the delivery of nucleoside monophosphate to the liver, leading to the formation of high levels of nucleoside triphosphate, potentially maximizing drug efficacy and limiting systemic side effects with low, once-daily dosing.

About Idenix

Idenix Pharmaceuticals, Inc., headquartered in Cambridge, Massachusetts, is a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases. Idenix's current focus is on the treatment of infections caused by hepatitis C virus. For further information about Idenix, please refer to www.idenix.com.

Forward-looking Statements  

This press release contains "forward-looking statements" for purposes of the safe harbor provisions of The Private Securities Litigation Reform Act of 1995, including but not limited to the statements regarding the company's future business and financial performance.  For this purpose, any statements contained herein that are not statements of historical fact may be deemed forward-looking statements.  Without limiting the foregoing, the words "expect," "plans," "anticipates," "will," "expects," "goal," "estimates," "projects," "would," "could," "targets," and  similar expressions are also intended to identify forward-looking statements, as are expressed or implied statements with respect to the company's clinical development programs or commercialization activities in hepatitis C, or any potential pipeline candidates, including any expressed or implied statements regarding the efficacy and safety of IDX184, the likelihood and success of any future clinical trials involving IDX184 or successful development of novel combinations of direct-acting antivirals for the treatment of hepatitis C. Actual results may differ materially from those indicated by such forward-looking statements as a result of risks and uncertainties, including but not limited to the following:  there can be no guarantees that the company will advance any clinical product candidate or other component of its potential pipeline to the clinic, to the regulatory process or to commercialization; management's expectations could be affected by unexpected regulatory actions or delays; uncertainties relating to, or unsuccessful results of, clinical trials, including additional data relating to the ongoing clinical trials evaluating its product candidates; the company's ability to obtain additional funding required to conduct its research, development and commercialization activities; the company's dependence on its collaborations with Novartis Pharma AG and GlaxoSmithKline; changes in the company's business plan or objectives; the ability of the company to attract and retain qualified personnel; competition in general; and the company's ability to obtain, maintain and enforce patent and other intellectual property protection for its product candidates and its discoveries. Such forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause actual results to be materially different from any future results, performance or achievements expressed or implied by such statements.  These and other risks which may impact management's expectations are described in greater detail under the heading "Risk Factors" in the company's annual report on Form 10-K for the year ended December 31, 2009, as filed with the Securities and Exchange Commission (SEC) and in any subsequent periodic or current report that the company files with the SEC.

All forward-looking statements reflect the company's estimates only as of the date of this release (unless another date is indicated) and should not be relied upon as reflecting the company's views, expectations or beliefs at any date subsequent to the date of this release. While Idenix may elect to update these forward-looking statements at some point in the future, it specifically disclaims any obligation to do so, even if the company's estimates change.

(1) Lavanchy (2009) Liver International. 29(s1):74-81.

Idenix Pharmaceuticals Contact:

Teri Dahlman (617) 995-9905

SOURCE Idenix Pharmaceuticals, Inc.