--Initiation of human studies of Idenix drug IDX20963 delayed by
regulators
--Third Idenix drug to be put on hold by FDA since last
August
--Shares fall 22% to $4 after-hours
(Updated to add details and analyst comment.)
By Joseph Walker
Idenix Pharmaceuticals Inc. (IDIX) said planned clinical trials
for one of its experimental hepatitis C drugs have been put on hold
after regulators requested additional safety data, dealing a blow
to what analysts said is the company's most promising compound.
The delay to the drug, known as IDX20963, sent shares plummeting
22% to $4 in after-hours trading Thursday.
It is the third time since last summer safety questions have
halted development of the company's hepatitis C drugs, cutting
Idenix's market value in half over the past 12 months through the
close. Development of the company's other two drugs were
discontinued in February.
Idenix had been seeking permission from the U.S. Food and Drug
Administration to test the drug in humans, but the company said it
now must provide a satisfactory response to regulators before
trials can begin in the U.S.
IDX20963 is the company's lead uridine nucleotide prodrug
candidate, part of a class of drugs known as "nukes" that have
shown strong efficacy in the trials of other companies. However,
nukes are also thought to have the potential for safety risks, a
perception that led to the discontinuation of the other two Idenix
drugs.
"They're going after a class of compounds where it's very, very
hard to make safe drugs," said David Ferreiro, an Oppenheimer &
Co. analyst.
Idenix is one of several companies racing to develop drugs for
hepatitis C, a blood-borne virus that afflicts an estimated four
million Americans and 170 million people world-wide. Gilead
Sciences Inc. (GILD) and AbbVie Inc. (ABBV) are considered by many
analysts to be in the lead in developing the new treatments.
Idenix's drug was similar in structure to one of Gilead's nukes,
Mr. Ferreiro said, which also gave the program promise in the eyes
of investors.
"Even though it was preclinical, it was thought to be more
valuable than their clinical compounds," he said. "People were
holding on to the hope they had something."
Idenix said it recently submitted an investigational new drug
application--needed to begin clinical studies--to the FDA that
included preclinical data demonstrating potent, pan-genotypic
activity for IDX20963. The FDA has requested additional preclinical
safety data for one of the biopharmaceutical company's hepatitis C
treatments, which will delay the start of clinical trials.
Despite the setback, the Cambridge, Mass., firm still had $205.3
million in cash and cash equivalents at the end of March, as well
as patent claims that could be used to extract royalty payments on
Gilead's hepatitis C drugs. However, a recent court decision in
that case put the burden of proof on Idenix to prove infringement,
which analysts said would make it harder for Idenix to prevail.
"I find this to be a very hard stock to own right now," said Mr.
Ferreiro. However, he cautioned the Idenix drug may eventually
prove to be safe enough to advance into clinical trials and that
the FDA may just be acting with extreme caution.
Hepatitis C is often contracted during sex or by sharing
needles. Current treatments require long courses of sometimes
painful injections and often don't work.
-Nathalie Tadena contributed to this report.
Write to Joseph Walker at joseph.walker@dowjones.com
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