By Kristin Jones
Vertex Pharmaceuticals Inc. (VRTX) said the U.S. Food and Drug
Administration has put a partial clinical hold on a mid-stage study
of its experimental hepatitis C treatment VX-135 because of
toxicity concerns.
Vertex shares fell 9.1% to $79.66 in after-hours trading.
The drug developer said the hold affects the 200-milligram dose
of VX-135, a drug known as a nucleotide polymerase inhibitor, or
"nuke," which is designed to combat hepatitis C infection inside
liver cells. Vertex joins Bristol-Myers Squibb Co. (BMY) and Idenix
Pharmaceuticals Inc. (IDIX) in having to halt certain trials of
nuke drugs because of toxicity concerns.
The FDA put a hold on VX-135 after elevated levels of liver
enzyme were found in patients involved in a study in Europe
examining a 400-milligram dose of the drug in combination with
ribavirin, an approved hepatitis C treatment. No serious adverse
events have been reported, and no liver or cardiac safety issues
have been identified, the company said.
A study of a lower dose of VX-135 is continuing, testing the
drug at 100 milligrams in combination with ribavirin.
"We are committed to continuing to work closely with the FDA to
provide the data needed to support evaluation of a 200 milligram
dose of VX-135 in the U.S.," Vertex Chief Medical Officer Robert
Kauffman said.
Companies are racing to bring new hepatitis C treatments to
market, seeking to tap what is expected to be a multibillion-dollar
market for such a therapy. The hope is that the new all-oral
treatments will be easier to tolerate, shorter in duration and
potentially more effective than the current standard of care.
Treatment for hepatitis C is considered lucrative because the
disease is prevalent in large sections of the global population.
The virus, which can be transmitted through use of shared needles
or by syringe injuries in medical settings, affects some 170
million people world-wide.
So-called nuke drugs have been considered among the most
promising because preliminary studies suggested they could cure
higher percentages of patients in as little as 12 weeks. However,
at high doses, nucleotides also have showed signs of increased
toxicity.
Gilead Sciences Inc. (GILD) and AbbVie Inc. (ABBV) are
considered by many analysts to be in the lead in developing the new
hepatitis C treatments. Gilead's drug also is considered a nuke but
has so far avoided the toxicity issues seen with similar drugs.
Shares of Gilead, which also reported second-quarter results,
rose 5.8% in after-hours trading to $64.40, while Abbvie shares
increased 1.7% to $45.01.
Vertex has reported a string of quarterly losses amid slumping
sales of its hepatitis C treatment Incivek. But its cystic fibrosis
sales have been a bright spot, as strong demand in international
markets have boosted sales of its drug Kalydeco, which treats the
potentially fatal lung disease.
In addition, shares of Vertex have doubled this year in part
because of optimism about other cystic fibrosis drugs in
development.
Write to Kristin Jones at kristin.jones@dowjones.com
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