Portola Pharmaceuticals Announces Second Part of Phase 3 ANNEXA(TM)-R Study: Andexanet Alfa and Rivaroxaban Meets Primary and...
22 Septembre 2015 - 2:46AM
Portola Pharmaceuticals (Nasdaq:PTLA) today announced that the
second part of its Phase 3 ANNEXA™-R (Andexanet Alfa a Novel
Antidote to the Anticoagulant Effects of FXa Inhibitors –
Rivaroxaban) study achieved all primary and secondary endpoints
with high statistical significance. Andexanet alfa, a U.S. Food and
Drug Administration (FDA)-designated breakthrough therapy, is a
recombinant protein specifically designed to reverse the
anticoagulant activity of Factor Xa inhibitors. Portola is
developing andexanet alfa as a universal reversal agent for
patients anticoagulated with an oral or injectable Factor Xa
inhibitor who suffer a major bleeding episode or require emergency
surgery. Full data from this part of the study have been accepted
for presentation during a Late Breaking Clinical Trial session at
the American Heart Association's (AHA) Scientific Sessions 2015 in
November.
"These positive topline data from Part 2 of the ANNEXA-R study
mark the successful completion of our Phase 3 clinical program for
andexanet alfa. We believe that the findings support the potential
of andexanet alfa to become the first approved universal reversal
agent for Factor Xa inhibitors and a standard of care to manage
major bleeding associated with these novel anticoagulants," said
John T. Curnutte, M.D., Ph.D., executive vice president, research
and development for Portola "We now have results from both parts of
each of our two Phase 3 ANNEXA studies and four parts of our Phase
2 proof-of concept, dose-finding study demonstrating that andexanet
alfa can rapidly reverse the anticoagulation activity of oral and
injectable Factor Xa inhibitors and sustain that reversal.
The ANNEXA-R study evaluated the safety and efficacy of
andexanet alfa in reversing the anticoagulant effect of the Factor
Xa inhibitor rivaroxaban, as measured by anti-Factor Xa activity,
in older healthy volunteers. Part 1 of the study demonstrated rapid
reversal with a bolus infusion, and Part 2 of the study now shows
the ability of andexanet alfa to sustain that reversal. Topline
data from Part 2 show that andexanet alfa, which was administered
as an intravenous (IV) bolus followed by a continuous two-hour
infusion, produced rapid reversal of the anticoagulant effect of
rivaroxaban and sustained it for the duration of the infusion. In
the study, andexanet alfa was well tolerated, with no serious
adverse events, thrombotic events, or antibodies to Factor X or Xa
reported.
"Just as with the ANNEXA-A study with apixaban, we now have
clinical evidence that andexanet alfa can rapidly and significantly
reverse the anticoagulant effect of rivaroxaban when administered
as a bolus only or a bolus plus continuous infusion," continued Dr.
Curnutte. "This means that andexanet alfa has the potential to
treat patients who may need only short-duration reversal of their
Factor Xa inhibitor anticoagulant as well as those who might
require longer-duration reversal, such as those experiencing a
severe intracranial hemorrhage or requiring emergency surgery."
About the ANNEXA-R Study
The randomized, double-blind, placebo-controlled Phase 3
ANNEXA-R study evaluated the safety and efficacy of andexanet alfa
in reversing rivaroxaban-induced anticoagulation in healthy
volunteers ages 50-68 years. Efficacy was evaluated using biomarker
endpoints, with anti-Factor Xa levels as the primary endpoint.
Secondary endpoints included plasma levels of free unbound
rivaroxaban and endogenous thrombin potential (ETP), a measure of
thrombin generation.
In Part 1, 41 healthy volunteers were given rivaroxaban 20 mg
once daily for four days to steady state. They were then randomized
in a 2:1 ratio to receive either andexanet alfa administered as an
800 mg IV bolus (n=27) or placebo (n=14).
Full results of Part 1 were presented at the American College of
Cardiology's (ACC) 64th Annual Scientific Session in March 2015.
Part 1 met all primary and secondary endpoints with high
statistical significance. Results demonstrated that andexanet alfa
rapidly and significantly reversed the anticoagulant effect of
rivaroxaban as measured by anti-Factor Xa activity (>90 percent
reduction of mean anti-Factor Xa activity within five minutes of
the end of administration) compared with placebo (p<0.0001).
Additionally, there was a significant reduction in the level of
free (unbound) rivaroxaban in the plasma, and thrombin generation
was rapidly restored to within the normal baseline range following
administration of andexanet alfa. Andexanet alfa was well
tolerated, with no serious or severe adverse events, no thrombotic
events, and no antibodies to Factor X or Xa observed.
In Part 2, 39 healthy volunteers were given rivaroxaban 20 mg
once daily for four days and were then randomized in a 2:1 ratio to
receive either andexanet alfa administered as an 800 mg IV bolus
followed by a continuous infusion of 8 mg/min for 120 minutes
(n=26) or placebo (n=13). Part 2 of ANNEXA-R met all the primary
and secondary endpoints with high statistical significance.
Full data from Part 2 of the ANNEXA–R study have been accepted
for presentation during a Late Breaking Clinical Trial session at
the American Heart Association's (AHA) Scientific Sessions 2015 in
November.
About Portola Pharmaceuticals, Inc.
Portola Pharmaceuticals is a biopharmaceutical company
developing product candidates that could significantly advance the
fields of thrombosis and other hematologic diseases. The Company is
advancing its three wholly-owned programs using novel biomarker and
genetic approaches that may increase the likelihood of clinical,
regulatory and commercial success of its potentially life-saving
therapies. These programs include betrixaban, an oral, once-daily
Factor Xa inhibitor being evaluated in the APEX Phase 3 study for
prophylaxis of venous thromboembolism; andexanet alfa, a
recombinant protein designed to reverse the anticoagulant effect in
patients treated with an oral or injectable Factor Xa inhibitor;
and cerdulatinib, a Syk/JAK inhibitor in development to treat
hematologic cancers. Portola's partnered program is focused on
developing selective Syk inhibitors for inflammatory conditions.
For more information, visit www.portola.com and follow the Company
on Twitter @Portola_Pharma.
Forward-looking Statements
Statements contained in this press release regarding matters
that are not historical facts are "forward-looking statements"
within the meaning of the Private Securities Litigation Reform Act
of 1995. Because such statements are subject to risks and
uncertainties, actual results may differ materially from those
expressed or implied by such forward-looking statements. Such
statements include, but are not limited to, statements regarding:
andexanet alfa's potential to treat patients needing reversal of
Factor Xa anticoagulation effects, Portola's plans for pursuit of
regulatory approval of andexanet alfa, and the likelihood of
clinical, regulatory and commercial success for andexanet alfa and
Portola's other product candidates. Risks that contribute to the
uncertain nature of the forward-looking statements include: the
accuracy of Portola's estimates regarding its ability to initiate
and/or complete its clinical trials; the success of Portola's
clinical trials and the demonstrated efficacy of Portola's product
candidates to the satisfaction of regulatory authorities; the
accuracy of Portola's estimates regarding its expenses and capital
requirements; Portola's ability to manufacture andexanet alfa;
regulatory developments in the United States and foreign countries;
Portola's ability to obtain and maintain intellectual property
protection for its product candidates; and the loss of key
scientific or management personnel. These and other risks and
uncertainties are described more fully in Portola's most recent
filings with the Securities and Exchange Commission, including its
Annual Report on Form 10-K, which was filed on March 2, 2015, and
Quarterly Report on Form 10-Q, which was filed on August 5, 2015.
All forward-looking statements contained in this press release
speak only as of the date on which they were made. Portola
undertakes no obligation to update such statements to reflect
events that occur or circumstances that exist after the date on
which they were made.
CONTACT: Investor Contact:
Michele Mantynen
Portola Pharmaceuticals
ir@portola.com
Media Contact:
Julie Normart
W2O Group
jnormart@w2ogroup.com
Portola Pharmaceuticals (NASDAQ:PTLA)
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