PRESS RELEASE: Encysive Pharmaceuticals to Conduct Phase III Study With Thelin in Pulmonary Arterial Hypertension

Encysive Pharmaceuticals to Conduct Phase III Study With Thelin (Sitaxsentan Sodium) in Pulmonary Arterial Hypertension

HOUSTON, Sep 24, 2007 -- Encysive Pharmaceuticals Inc. (Nasdaq:ENCY) today announced that the Company will move forward with plans to conduct an additional Phase III study evaluating Thelin(tm) (sitaxsentan sodium) in patients with Pulmonary Arterial Hypertension (PAH).
The company has been discussing possible protocols for the trial, to be called STRIDE 5, with its Scientific Advisory Board and other experts. The company will now work with the FDA to finalize the protocol. After the Company has concluded its protocol discussions with the FDA, it will announce the details of the study, including timing and the number of patients.

Encysive believes it had successfully addressed all of the questions raised by the U.S. FDA in its New Drug Application (NDA) for Thelin in PAH. However, the Company has concluded after consulting with external experts that the best path forward for commercializing Thelin in the U.S. is to conduct an additional Phase III study. As a result, Encysive will not continue to pursue the formal dispute resolution process with the FDA.


Following receipt of the June 15, 2007 "approvable" letter from the FDA, the Company filed a request for formal dispute resolution with the FDA over its decision. Dispute resolution is a process where companies can challenge regulatory decisions by bringing the dispute to the attention of FDA supervisors. In September of 2007 the Agency replied that, while the data in the NDA are suggestive of the effectiveness of Thelin, it did not provide the substantial evidence of effectiveness needed for approval, and recommended an additional Phase III trial as the best path forward.

About Encysive Pharmaceuticals

Encysive Pharmaceuticals Inc. is a global biopharmaceutical company engaged in the discovery, development and commercialization of novel, synthetic, small molecule compounds to address unmet medical needs. Our research and development programs are predominantly focused on the treatment and prevention of interrelated diseases of the vascular endothelium and exploit our expertise in the area of the intravascular inflammatory process, referred to as the inflammatory cascade, and vascular diseases. To learn more about Encysive Pharmaceuticals please visit our web site:

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This press release contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements are subject to certain risks, trends and uncertainties that could cause actual results to differ materially from those projected. Among those risks, trends and uncertainties are: a delay in the timeline for initiating the Thelin PAH clinical trial; delays in the timelines for enrolling patients and obtaining results of the Thelin PAH clinical trial; the statistical significance of the results of such trial; decisions by the FDA regarding whether and when to approve our NDA for Thelin(tm); our ability to attract and retain qualified key clinical development personnel; our estimate of the sufficiency of our existing capital resources to fund our operations, including conducting the Thelin PAH trial; the unpredictability of the FDA formal dispute resolution process; our ability to raise additional capital to fund cash requirements for future commercial and research and development operations including the Thelin PAH trial; as well as more specific risks, trends and uncertainties facing Encysive such as those set forth in its reports on Forms 8-K, 10-Q and 10-K filed with the U.S. Securities and Exchange Commission. Given these risks, trends and uncertainties, any or all of these forward-looking statements may prove to be incorrect. Therefore you should not rely on any such forward-looking statements. Furthermore, Encysive undertakes no duty to update or revise these forward-looking statements. The Private Securities Litigation Reform Act of 1995 permits this discussion.