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 Doctors at the annual meeting of the American College of Cardiology,
where the studies were presented, called the results "encouraging,"
but said larger, controlled trials are needed to fully understand
the drugs, known as PCSK9 inhibitors.
An analysis of about 4,500 patients who stayed on treatment for
nearly a year after completing earlier trials of Amgen Inc's Repatha,
also known as evolocumab, found that 0.95 percent of those given the
drug and standard therapy suffered a cardiovascular event, compared
with 2.18 percent of the group on standard treatment, which ranged
from diet changes to drugs such as statins.
Amgen defined "event" as death, heart attack, stroke or
"mini-stroke," unstable chest pain or heart failure requiring
hospitalization, or the need for a procedure to restore bloodflow to
the heart.
Side effects more frequent, but still rare, in patients treated with
Repatha included neurocognitive problems, such as confusion,
something the U.S. Food and Drug Administration has said should be
monitored closely.
Scott Wasserman, Amgen's head of cardiovascular and metabolic
therapies, told Reuters that the company does not believe there is a
safety issue.
Neurocognitive side effects were also more common in the treatment
arm of an 18-month, 2,300-patient trial of a rival PCSK9 drug being
developed by Sanofi SA and Regeneron Pharmaceuticals Inc.
The drug, Praluent, was shown to reduce the risk of cardiovascular
problems from 3.3 percent for placebo patients to 1.7 percent for
the treatment group. "Events" in this trial were defined only as
death, heart attack, stroke and chest pain requiring
hospitalization.
"Some of the endpoints in these trials are kind of soft, and they
aren't prospective studies," said Dr. Anthony DeMaria, director of
the cardiovascular center at the University of California San Diego
who was not involved in the trials. "It's encouraging that the
larger trials are likely to succeed, but we still need those
trials."
Dr Marc Sabatine, lead investigator of the Repatha study, said data
for both drugs "are very consistent ... it appears that cutting LDL
by 61 percent translates to a roughly 50 percent reduction in
cardiovascular events."
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Numerous trials have shown that PCSK9 inhibitors significantly lower
blood levels of "bad" LDL cholesterol, but investors expect
widespread use will hinge on whether the drugs are proven to prevent
death, heart attacks and other serious heart problems.
The experimental drugs are antibodies, given by injection, designed
to target the PCSK9 protein that maintains LDL cholesterol in the
bloodstream. They work differently from statins - pills, now
available as low-cost generics, that block the liver's production of
LDL cholesterol in the first place.
Both Amgen and Sanofi/Regeneron have filed for FDA approval of their
drugs, based on trials showing that they lower LDL in patients whose
cholesterol is not controlled by other drugs, those who cannot
tolerate other drugs and people genetically predisposed to high
cholesterol.
The FDA is slated to decide on Amgen's application for Repatha by
Aug. 27, while the regulatory deadline for Praluent, also known as
alirocumab, is July 24.
Health insurers are already bracing for the impact on drug spending.
Express Scripts Holding Co, the largest manager of prescription drug
plans for U.S. employers, projects an annual cost as high as $10,000
per patient for PCSK9 drugs, which it says could be used for 10
million Americans.
Both Amgen and Sanofi/Regeneron do not expect definitive data on
cardiovascular outcomes for their drugs until larger trials conclude
in 2017. Pfizer Inc,, which has not yet filed for regulatory
approval of its PCSK9 drug, said it expects outcomes data in a
similar time frame.
(Reporting by Deena Beasley; Editing by Marguerita Choy and Frances
Kerry)
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