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Abstract: Poster Presentations |

A SHORT-TERM DELAY OF ENDOTHELIN RECEPTOR ANTAGONIST THERAPY RESULTS IN A DECREASED LONG-TERM IMPROVEMENT IN EXERCISE CAPACITY FREE TO VIEW

Aaron B. Waxman, MD*; on behalf of the ARIES Study Group
Author and Funding Information

Massachusetts General Hospital, Harvard Medi, Boston, MA


Chest


Chest. 2009;136(4_MeetingAbstracts):56S. doi:10.1378/chest.136.4_MeetingAbstracts.56S
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Abstract

PURPOSE:  Ambrisentan, an ETA-selective endothelin receptor antagonist (ERA), improved 6-minute walk distance (6MWD) and delayed clinical worsening in two placebo-controlled, 12-week, pulmonary arterial hypertension studies (ARIES-1 and ARIES-2). Patients receiving placebo or ambrisentan in ARIES-1 or ARIES-2 received ambrisentan treatment in a long-term study (ARIES-E).

METHODS:  Two-year clinical outcomes were examined for 100 patients who received 12 weeks of placebo followed by long-term ambrisentan therapy (PLB/ABS) and 197 patients who received long-term ambrisentan (ABS/ABS) treatment. Data are presented for the approved doses of ambrisentan (5 and 10 mg once-daily) and baseline was defined as the time of randomization in ARIES-1 or ARIES-2.

RESULTS:  Baseline characteristics were comparable between the subgroups prior to treatment. The mean change from baseline 6MWD (± SEM) was substantially lower in PLB/ABS group at 1 and 2 years (11 ± 9.6 meters and 10 ± 10.0 meters, respectively) compared to the ABS/ABS group (38 ± 6.0 meters and 30 ± 7.1 meters, respectively). Kaplan-Meier estimates (± SEM) of clinical worsening (percent event-free) were slightly lower in the PLB/ABS group compared to the ABS/ABS group at 1 year (76 ± 4.3% versus 84 ± 2.7%, respectively) but were similar at 2 years of treatment (70 ± 4.7% versus 71 ± 3.4%, respectively). Kaplan-Meier estimates of survival were similar in the PLB/ABS group compared to the ABS/ABS group at 1 year (92 ± 2.8% versus 93 ± 1.9%, respectively) and 2 years (86 ± 3.7% versus 88 ± 2.5%, respectively). Long-term ABS therapy was generally well tolerated and similar between the two groups.

CONCLUSION:  A 12-week delay of ambrisentan treatment resulted in a sustained decrease in 6MWD improvement but did not substantially increase the long-term risk of clinical worsening or death.

CLINICAL IMPLICATIONS:  Initiation of ambrisentan should not be delayed in patients who are appropriate candidates for ERA therapy.

DISCLOSURE:  Aaron Waxman, Consultant fee, speaker bureau, advisory committee, etc. Investigator for Gilead Sciences, United Therapeutics, Pfizer, and EPIX. Advisory board for Gilead Science and United Therapeutics.; No Product/Research Disclosure Information

Tuesday, November 3, 2009

12:45 PM - 2:00 PM


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