October 29, 2003

News Release: Sonus Pharmaceuticals Receives FDA Fast Track Designation for TOCOSOL Paclitaxel in Bladder Cancer Indication

Sonus Pharmaceuticals, Inc. (Nasdaq:SNUS) today announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation for TOCOSOL(TM) Paclitaxel for the treatment of metastatic or locally advanced, inoperable transitional cell carcinoma (TCC) of the urothelium. The most common form of urothelial TCC is bladder cancer.

Under the FDA Modernization Act of 1997, the Fast Track program is designed to facilitate the development and expedite the review of new drugs that are intended to treat serious or life-threatening conditions and that demonstrate the potential to address unmet medical needs. In addition to the Fast Track designation, the FDA will also accept portions of a New Drug Application (NDA) that support the TCC indication as they are completed, which is known as a 'rolling NDA.' 'The FDA's Fast Track designation of TOCOSOL Paclitaxel for the treatment of patients with bladder cancer recognizes the potential of our drug to treat a serious disease for which no chemotherapeutic agent is currently approved,'said Michael A. Martino, Sonus Pharmaceuticals President and CEO. 'Additionally, this designation further supports our mission to secure FDA approval for TOCOSOL Paclitaxel as quickly as possible.'

Sonus has completed patient enrollment in three Phase 2a studies using TOCOSOL Paclitaxel for the treatment of bladder, ovarian and non-small cell lung cancers. Based on encouraging clinical results to date, the Company is preparing to initiate new clinical studies of TOCOSOL Paclitaxel to provide data that would be the basis for regulatory approval of the product. Concurrent with the plan to pursue product approval for the treatment of bladder cancer, Sonus will also seek approval of TOCOSOL Paclitaxel for other indications through a separate development program comparing the product to Taxol(R) (the currently marketed paclitaxel product), leading to a 505(b)(2) NDA.

About TOCOSOL Paclitaxel

TOCOSOL Paclitaxel is a novel reformulation of paclitaxel, one of the world's most widely prescribed anti-cancer drugs. TOCOSOL Paclitaxel, a ready-to-use formulation, does not require reconstitution, dilution or preparation as with the currently marketed paclitaxel products and other paclitaxel formulations under development. In clinical studies to date, TOCOSOL Paclitaxel is demonstrating favorable anti-tumor activity in cancer patients who have failed prior chemotherapeutic regimens. The product is also showing excellent tolerability over multiple treatment cycles, and as a result, most patients do not need to have doses reduced or delayed. TOCOSOL Paclitaxel is administered to patients in a short 15-minute infusion, compared to the prolonged three-hour infusion required with available paclitaxel products.

About Sonus Pharmaceuticals

Sonus is developing a number of potential product candidates for the treatment of cancer and other serious diseases utilizing its proprietary TOCOSOL(TM) drug delivery technology. The development of therapeutic drugs with the TOCOSOL technology may result in products that can be delivered more safely and effectively. The Company's news releases and other information are available on the Sonus web site at www.sonuspharma.com.

Certain statements made in this press release are forward-looking such as those, among others, relating to the development of drug delivery products and potential applications for these products. As discussed in Sonus Pharmaceuticals'filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K filed on March 10, 2003, actual results could differ materially from those projected in the forward-looking statements as a result of the following factors, among others: the Company's products will require extensive clinical testing and approval by regulatory authorities; such approvals are lengthy and expensive and may never occur; risks that clinical studies with TOCOSOL Paclitaxel will not be successful or demonstrate increased efficacy; risks of successful development of additional drug delivery products.

Taxol(R) is a registered trademark of Bristol-Myers Squibb Company.

SOURCE: Sonus Pharmaceuticals, Inc.

Sonus Pharmaceuticals, Inc. Pamela L. Dull, 425-487-9500

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