Myogen Reports Positive Top Line Results for Ambrisentan LFT Rescue Study In Pulmonary Arterial Hypertension
February 13 2006 - 8:30AM
PR Newswire (US)
Patients with PAH Who Previously Discontinued Other ERA Therapy Due
to Liver Function Abnormalities Treated with Long-term Ambrisentan
Therapy DENVER, Feb. 13 /PRNewswire-FirstCall/ -- Myogen, Inc.
(NASDAQ:MYOG) today announced positive top line results of the
AMB-222 study, an open-label study of ambrisentan in patients with
pulmonary arterial hypertension (PAH) who have previously
discontinued bosentan and/or sitaxsentan treatment due to liver
function abnormalities. None of the 36 patients enrolled in the
study had a recurrence of liver function abnormalities that
resulted in discontinuation of ambrisentan during the initial
12-week evaluation period (the primary endpoint of the study). One
patient had a transient serum aminotransferase test result greater
than three-times the upper limit of the normal range (3xULN) at
week 12 that resulted in dose reduction from 5 mg to 2.5 mg
ambrisentan. This patient remains on ambrisentan therapy and has
not had a recurrence of serum aminotransferases greater than 3xULN.
Patients have continued to receive ambrisentan therapy for periods
up to 9 months (mean exposure of 6 months) and no further
occurrence of serum aminotransferase concentrations greater than
3xULN has been observed. "These results suggest that for patients
who have had to stop treatment with other endothelin receptor
antagonists due to liver function abnormalities, ambrisentan may
offer an opportunity to resume treatment," stated Michael J.
Gerber, MD, Senior Vice President of Clinical Development and
Regulatory Affairs for Myogen. "I believe ambrisentan has the
potential to be an important therapeutic option for these patients
with PAH and their physicians. The low incidence and severity of
liver function test abnormalities demonstrated in the ARIES-2 trial
and the AMB-222 rescue study are very encouraging. Ambrisentan has
a chemical structure that differs from those of bosentan and
sitaxsentan. We believe that this distinction may underlie
ambrisentan's low propensity to cause liver function
abnormalities." Myogen announced the initiation of AMB-222 in May
2005 with a target enrollment of 30 patients. A total of 36
patients were enrolled in the study, of which 31 (86%) had
discontinued bosentan, 2 (6%) had discontinued sitaxsentan and 3
(8%) had discontinued both bosentan and sitaxsentan, sequentially,
due to serum aminotransferase abnormalities. Also, 17 (47%) of the
patients were receiving concomitant sildenafil therapy. Patients
received 2.5 mg of ambrisentan once daily for 4 weeks and then the
dose was increased to 5 mg of ambrisentan once daily. The last
patient reached the 12-week endpoint evaluation in January 2006.
All patients had the option to continue ambrisentan therapy after
the initial 12-week assessment period. The primary endpoint of the
trial was the incidence of serum aminotransferase concentrations
greater than 3xULN during the 12-week evaluation period that were
related to ambrisentan and resulted in discontinuation of drug. The
top line results of the ARIES-2 and AMB-222 trials, as well as the
results to date of Myogen's Phase 2 trial of ambrisentan in PAH
(AMB-220) and related long-term study (AMB-220-E) have
demonstrated: * Improvement in exercise capacity that is
significant, early in onset and durable * Significant improvement
in time to clinical worsening * Comparable benefit in exercise
capacity for patients with WHO functional class II and class III
symptoms * An apparent survival benefit when compared with
predicted survival based on the National Institutes of Health
Registry formula * Effectiveness with once-daily dosing and the
potential for dose flexibility * Low incidence and severity of
liver function test abnormalities at all doses * Potential utility
in resuming endothelin receptor antagonist (ERA) treatment in
patients who have discontinued bosentan or sitaxsentan treatment
due to liver function abnormalities * No apparent drug-drug
interactions with warfarin-type anticoagulants Based on results to
date and the properties of ambrisentan, Myogen believes that, if
ambrisentan is ultimately approved, it may offer significant
clinical benefit to PAH patients not provided by other PAH
therapies. About Pulmonary Arterial Hypertension PAH is a highly
debilitating disease characterized by severe constriction of the
blood vessels in the lungs leading to very high pulmonary arterial
pressures. These high pressures make it difficult for the heart to
pump blood through the lungs to be oxygenated. Patients with PAH
suffer from extreme shortness of breath as the heart struggles to
pump against these high pressures causing such patients to
ultimately die of heart failure. PAH can occur with no known
underlying cause, or it can occur secondary to diseases such as
connective tissue disease, congenital heart defects, cirrhosis of
the liver and HIV infection. PAH afflicts approximately 200,000
patients worldwide. About Ambrisentan Ambrisentan is an
investigational drug being developed as a once daily oral therapy
for patients with PAH and has been granted orphan drug designation
for the treatment of PAH in both the United States and European
Union. Ambrisentan is a non-sulfonamide, propanoic acid-class,
type-A selective endothelin receptor antagonist. Endothelin is a
small peptide hormone that plays a critical role in the control of
blood flow and cell growth. Elevated endothelin blood levels are
associated with several cardiovascular disease conditions,
including pulmonary arterial hypertension, chronic renal disease,
coronary artery disease, hypertension and chronic heart failure.
The Company believes that agents that block the detrimental effects
of endothelin may provide significant benefits in the treatment of
these conditions. About Myogen Myogen is a biopharmaceutical
company focused on the discovery, development and commercialization
of small molecule therapeutics for the treatment of cardiovascular
disorders. Myogen currently has two product candidates in
late-stage clinical development: ambrisentan for the treatment of
patients with pulmonary arterial hypertension and darusentan for
the treatment of patients with resistant hypertension. The Company
also conducts a target and drug discovery research program focused
on the development of disease-modifying drugs for the treatment of
chronic heart failure and related cardiovascular disorders. Please
visit Myogen's website at http://www.myogen.com/. Safe Harbor
Statement This press release contains forward-looking statements
that involve significant risks and uncertainties, including summary
statements relating to the top line results of the Company's
AMB-222 clinical trial, summary statements relating to the top line
results of the ARIES-2 trial and results of the Company's Phase 2
trial of ambrisentan in patients with PAH and the related extension
trial, and summary statements relating to the potential efficacy
and safety profile of ambrisentan. Actual results could differ
materially from those projected and the Company cautions investors
not to place undue reliance on the forward-looking statements
contained in this release. Results from clinical trials, including
the Company's AMB-222 trial, are not necessarily predictive of
future clinical results, including results of the ARIES-1 trial of
ambrisentan in patients with PAH. Top line results may not be
confirmed upon full analysis of the detailed results of a trial and
additional information relating to the safety, efficacy or
tolerability of the Company's product candidates, including
ambrisentan, may be discovered upon further analysis of trial data
and upon review and analysis of additional trial data, including
data from the Company's ongoing ARIES-1 trial and its Phase 2 and
Phase 3 extension trials of ambrisentan in patients with PAH. If
the Company's product candidates do not meet safety or efficacy
endpoints in clinical evaluations, they will not receive regulatory
approval and the Company will not be able to market them. Even if
the Company's product candidates meet safety and efficacy
endpoints, regulatory authorities may not approve them, the Company
may not be able to successfully market them, or the Company may
face post-approval problems that require the withdrawal of its
product from the market. There can be no assurance that Myogen's
product candidates, including ambrisentan, will be proven safe and
effective for use in humans. Abnormal elevations of liver function
test results, including elevated serum aminotransferase
concentrations, have been reported in trials of other endothelin
receptor antagonists. The Company's results may be affected by its
effectiveness at managing its financial resources, its ability to
successfully develop and market its product candidates, its ability
to obtain and enforce patent protection for its products,
competition from other biotechnology and pharmaceutical companies,
difficulties or delays in manufacturing its products, and
regulatory developments involving current and future products.
Delays in initiating or conducting clinical trials, whether caused
by competition, adverse events, patient enrollment rates,
regulatory issues or other factors, could adversely affect the
Company's financial position and prospects. If the Company is
unable to raise additional capital when required or on acceptable
terms, it may have to significantly delay, scale back or
discontinue one or more of its drug development or discovery
research programs. Myogen is at an early stage of development and
may not ever have any products that generate significant revenue.
Additional risks and uncertainties relating to the Company and its
business can be found in the "Risk Factors" section of Myogen's
Form 10-K for the year ended December 31, 2004 and Myogen's reports
on Form 10-Q and Form 8- K. It is Myogen's policy to only update or
reconfirm its public guidance by issuing a press release or filing
a periodic or current report with the Securities and Exchange
Commission. The Company generally plans to provide guidance as part
of its annual and quarterly earnings releases but reserves the
right to provide guidance at different intervals or to revise its
practice in future periods. All information in this press release
is as of February 13, 2006. Myogen undertakes no duty or obligation
to update any forward- looking statements contained in this release
as a result of new information, future events or changes in the
Company's expectations. The Company also disclaims any duty to
comment upon or correct information that may be contained in
reports published by the investment community. DATASOURCE: Myogen,
Inc. CONTACT: Derek K. Cole, Director, Investor Relations of
Myogen, Inc., 303-464-3986, or Web site: http://www.myogen.com/
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