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) --

Idenix Pharmaceuticals'


experimental hepatitis C drug IDX184 looks to be safe (whew!) but doesn’t appear to work particularly fast (uh oh….)

On Monday morning, relief over the apparently clean safety report for IDX184 combined with a healthy dose of

hepatitis C drug takeover speculation

was all the fuel needed to send Idenix shares up $2.84, or 43%, to $10 in the pre-market session.

Achillion Pharmaceuticals

(ACHN) - Get Achison, Inc. Class A Report

share, likewise, are up 35% to $10.65 on takeover speculation and positive data reported on its pipeline of hepatitis C drugs.

Idenix's lead drug, IDX184, belongs to the same "nucleoside" or "nuc" class of oral Hep C drugs as



PSI-7977 and

TheStreet Recommends


( INHX) INX-189. Since both were acquired for huge premiums recently, popular thinking is that Idenix's turn at the M&A altar is imminent.

After 31 hepatitis C patients completed 28 days of treatment with IDX184 in combination with weekly interferon and ribavirin, no serious adverse events were reported and an independent safety monitoring board recommended that more patients can be enrolled in the phase II study, Idenix said Monday.

Based on this clean safety report, Idenix plans to ask U.S. regulators to remove a clinical hold on IDX184 put in place last year. The company reported the new IDX184 in advance of its presentation this afternoon at the J.P. Morgan Healthcare Conference.

Idenix said that 73% of patients treated with a 100 mg dose of IDX184 reported undetectable levels of the hepatitis C virus after 28 days. At a median treatment duration of 8 weeks in the study, 87% of these patients are now undetectable.

For patients treated with a lower, 50 mg dose of IDX184, 63% were undetectable at 28 days and 94% were undetectable at a median treatment duration of 8 weeks. None of these patients in the study have so far reported a re-emergence of the hepatitis C virus in their systems.

These efficacy data suggest that IDX184 works slower and perhaps is not as potent as the competing "nucs" being developed by Pharmasset and Inhibitex. For example, Pharmasset's PSI-7977 demonstrated a 4-week early response rate of 98% in a similar setting and patient population. Moreover, Idenix enrolled relatively healthier hepatitis C patients for this initial IDX184 study, suggesting that the drug may further underperform when hepatitis C patients with more advanced disease are treated.

"For us, this trial was about solidifying the safety profile of IDX184 as much as anything else. We believe we have demonstrated that and hope the FDA agrees with us. Our goal is to get to interferon-free regimens as soon as possible," said Idenix CEO Ron Renaud, in an email.

Renaud downplayed questions about the speed at which IDX184 can clear the hepatitis C virus, arguing that combinations of different types of oral drugs will likely be needed ultimately, but it's not clear yet what those combinations might be.

It's certainly true that big players in the race to develop an all-oral hepatitis C therapy --

Bristol-Myers Squibb

(BMY) - Get Bristol-Myers Squibb Company Report


Gilead Sciences

(GILD) - Get Gilead Sciences, Inc. Report

most prominently -- are betting on a "nuc" being the backbone of whatever regimen emerges. And right now, Idenix is sitting on a nuc -- IDX184 -- that appears safe and is certainly available to any interested bidder for the right price.

--Written by Adam Feuerstein in San Francisco.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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