Sonus Pharmaceuticals Presents TOCOSOL Paclitaxel Phase 2a Clinical Data at Chemotherapy Foundation Symposium and AACR-NCI-EORTC Cancer Conferences.

Business Editors/Health/Medical Writers

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BOTHELL, Wash.--(BUSINESS WIRE)--Nov. 19, 2003

Clinical Results Continue to Indicate that TOCOSOL Paclitaxel is

Safe and Effective

Sonus Pharmaceuticals, Inc. (Nasdaq:SNUS) recently presented data from three Phase 2a studies for its lead cancer drug, TOCOSOL(TM) Paclitaxel, at the Chemotherapy Foundation Symposium in New York City and the AACR-NCI-EORTC Molecular Targets and Cancer Therapeutics conference in Boston. Highlights of these data had been previously reported on Sonus' quarterly conference call held November 5. TOCOSOL Paclitaxel is a proprietary formulation of paclitaxel, the active ingredient in the leading cancer drug Taxol(R). To date, treatment with TOCOSOL Paclitaxel has been safe and well tolerated, and the product is demonstrating promising anti-tumor efficacy. The Company is currently initiating additional studies of TOCOSOL Paclitaxel to provide data that would be the basis for FDA's decision on regulatory approval of the product.

The full details of the clinical data presented at the cancer conferences are available on Sonus' web site at www.sonuspharma.com/abstracts.html. Key highlights of the Phase 2a clinical data update for TOCOSOL Paclitaxel include:

-- Three Phase 2a studies in ovarian, bladder and non-small cell

lung (NSCL) cancers are fully enrolled with a total of 122

patients.

-- No neuropathy in 70% of patients; Grade 3 in 9%; Grade 4

neuropathy in none.

-- Grade 3-4 neutropenia observed in one third of patients;

febrile neutropenia reported in only 2% of patients.

-- Objective anti-tumor responses:

-- 31% in ovarian cancer (2 complete responses plus 14

partial responses in 52 patients)

-- 33% in bladder cancer (2 complete responses plus 7 partial

responses in 27 patients)

-- 21% in NSCLC (3 complete responses plus 6 partial

responses in 43 patients)

"We have now completed the initial efficacy evaluations for all patients enrolled in our Phase 2a studies, and we continue to see results to support our belief that TOCOSOL Paclitaxel is a convenient, safe and effective product," said Michael B. Stewart, M.D., Sonus Pharmaceuticals Chief Medical Officer. "With the strength of the clinical data and implementation of the regulatory strategy for TOCOSOL Paclitaxel, we are moving one step closer to translating the promise of the product into real benefits for cancer patients."

TOCOSOL Paclitaxel Regulatory Plan

Sonus is implementing a three-part regulatory strategy for TOCOSOL Paclitaxel, which is focused on obtaining market entry as quickly as possible. One part of the strategy is to seek approval of TOCOSOL Paclitaxel through a 505(b)(2) New Drug Application by comparing the product to Taxol. In parallel with the 505(b)(2) program, the Company is pursuing approval of TOCOSOL Paclitaxel for the treatment of inoperable or metastatic urothelial transitional cell cancers, which are mostly bladder cancers. Sonus has recently received Fast Track designation from the U.S. Food and Drug Administration for the bladder cancer program. As the third part of the regulatory strategy for TOCOSOL Paclitaxel, the Company will initiate studies in ovarian and breast cancers to explore potentially higher efficacy resulting from increased dose levels or dose densities compared to approved paclitaxel dosing regimens.

About Sonus Pharmaceuticals

Sonus is currently developing a number of potential product candidates for the treatment of cancer utilizing its proprietary TOCOSOL 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; and risks of successful development of additional drug delivery products.

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