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 The panel voted 11-2 that the company should complete a second trial
to confirm results seen in a smaller study that, while positive,
were not robust enough to convince the committee that they could be
reproduced.
Panel members expressed concern about a potential increased risk of
secondary cancers in patients receiving the drug, olaparib, as well
as side effects such as nausea and gastrointestinal disturbances.
The FDA is not obliged to follow the advice of its advisory panels
but typically does so.
"We are disappointed with today’s recommendation, and strongly
believe that olaparib has the potential to provide patients with
relapsed BRCA-mutated ovarian cancer and their doctors with a
much-needed treatment option," Briggs Morrison, chief medical
officer at AstraZeneca, said.
As well as continuing to work with the FDA, AstraZeneca will
continue its Phase III clinical program on olaparib, a study it aims
to complete by the end of 2015, he said.
Olaparib is one of several cancer drugs AstraZeneca flagged as
having strong potential in its defense of a $118 billion take-over
bid by Pfizer Inc.
It is designed as a maintenance therapy for patients with relapsed
ovarian cancer whose tumors have responded completely or partially
to platinum-based chemotherapy. The panel was asked by the FDA to
weigh whether data submitted by AstraZeneca from the initial study
is strong enough to allow the drug on the market pending results
from a second, confirmatory trial.
Olaparib, whose proposed brand name is Lynparza, blocks the activity
of Poly (ADP-ribose) polymerase (PARP), an enzyme that plays a key
role in cell repair. Patients taking the drug in a clinical trial
had a seven-month median improvement in progression-free survival, a
benchmark that measures the amount of time a patient lives without
the disease getting worse.
But both the FDA, in a review published on Monday, and the advisory
committee members, noted that the way the company conducted its
analysis created uncertainty about the validity of the results.
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The drug is aimed at women with certain hereditary BRCA gene
mutations that account for an estimated 10-15 percent of all cases
of ovarian cancer, or about 2,000 cases a year in the United States.
Patients with the mutations tend to respond better to chemotherapy
so they are likely to undergo multiple rounds. Periods away from
chemotherapy allow the patient to recover from side effects before
undergoing a new round.
In theory, olaparib would extend that period of recovery time. But
AstraZeneca collected some of the data retrospectively using
archived blood samples, calling into question the reliability of the
real benefit. Data also showed there was no difference in overall
survival between patients who received the drug and those who got a
placebo.
AstraZeneca has said sales of olaparib could reach $2 billion a
year, although some Wall Street analysts see sales at less than half
that amount.
Ovarian cancer is the fifth leading cause of cancer death in U.S.
women, with an estimated 22,000 new cases diagnosed and 14,270
deaths in the United States in 2014.
Olaparib's most common side effects were nausea, fatigue, abdominal
pain, vomiting, diarrhea and anemia.
(Reporting by Toni Clarke in Washington; Editing by Bill Trott,
Sandra Maler and Leslie Adler)
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