Sonus Pharmaceuticals Presents Encouraging Phase 2 Efficacy and Safety Data on TOCOSOL(R) Paclitaxel at San Antonio Breast Cancer Symposium.

SAN ANTONIO -- Multinational Phase 3 pivotal study evaluating use of TOCOSOL Paclitaxel in metastatic breast cancer treatment ongoing

Sonus Pharmaceuticals, Inc. (Nasdaq: SNUS) today presented encouraging safety and efficacy data from the Phase 2 clinical program for TOCOSOL(R) Paclitaxel at the San Antonio Breast Cancer Symposium. The data included promising anti-tumor activity in an ongoing Phase 2 trial of 47 women with first-line metastatic breast cancer. TOCOSOL Paclitaxel is an injectable, novel ready-to-use formulation of the widely prescribed anti-cancer drug paclitaxel. Paclitaxel is a member of the taxane group of chemotherapy drugs and is the active ingredient in approved drug products that are used to treat many forms of cancer.

Based on the results of the Phase 2 program to date, which include studies in metastatic breast, non-small cell lung, bladder and ovarian cancers, a multinational Phase 3 pivotal study of TOCOSOL Paclitaxel for the potential treatment of metastatic breast cancer was initiated in September 2005. The Phase 3 study is being conducted under a Special Protocol Assessment from the U.S. Food and Drug Administration. Schering AG, Germany (FSE: SCH, NYSE: SHR) licensed exclusive worldwide development and commercialization rights to TOCOSOL Paclitaxel from Sonus in October 2005. Under the agreement, Schering AG will be responsible for the worldwide marketing and distribution of TOCOSOL Paclitaxel. If approved, the product will be marketed in the U.S. by Berlex Oncology, a unit of Berlex Inc., a member of the Schering AG group.

"The continuing strength of the efficacy and safety data being observed in the Phase 2 studies reinforces our belief that TOCOSOL Paclitaxel may one day offer a promising new treatment option for cancer patients that is efficacious, well tolerated, more convenient to administer and does not require advance preparation," said Michael B. Stewart, M.D., Senior Vice President and Chief Medical Officer of Sonus Pharmaceuticals.

"The Phase 2 study in metastatic breast cancer -- initiated as a precursor study for our Phase 3 pivotal trial of TOCOSOL Paclitaxel -- is demonstrating an investigator-reported confirmed objective response rate of 53% and an independent radiologist-reported confirmed objective response rate of 49%. These data are compelling as they are at the upper end of published objective response rates for weekly taxane therapy in metastatic breast cancer. In addition, the agreement between investigator-reported responses and the independent radiologist-reported responses supports the robustness of the study conduct," commented Dr. Stewart.

Efficacy in First-line Treatment of Metastatic Breast Cancer:

Confirmed objective response rates in Phase 2 study of patients with
     metastatic breast cancer treated with TOCOSOL Paclitaxel 120
                         mg/m(2)/week (n = 47)
----------------------------------------------------------------------


             ORR after Week 8 treatment   ORR after Week 16 treatment
          (confirmatory scan at Week 12)(confirmatory scan at Week 20)
               (95% Confidence Interval)   (95% Confidence Interval)
------------- ------------------------------ -------------------------
Treating investigator     35%                          53%
 and site radiologist   (21-50%)                     (38-68%)
------------- ------------------------------ -------------------------
Independent               30%                          49%
 radiologist            (18-46%)                     (34-64%)
------------- ------------------------------ -------------------------

    --  Best objective response was observed by Week 16 of treatment
        in all patients:
        -  1 complete response, 24 partial responses

    --  Median progression-free survival is currently 7.2 months (95%
        Confidence Interval: 5.5-9.8 months; 17 patients have not yet
        progressed and are continuing to be monitored)

Safety and Tolerability in Phase 2 Studies:

In 197 patients treated to date in the Phase 2 studies in metastatic breast, non-small cell lung, bladder and ovarian cancers, TOCOSOL Paclitaxel given weekly at doses of 100 or 120 mg/m(2) appears to be well tolerated, with patients staying on treatment over extended periods:

--Febrile neutropenia has occurred in only 2% of patients. There have been no septic deaths.

--No Grade 4 peripheral neuropathy has occurred in any patient; Grade 3 peripheral neuropathy developed in only 12% of patients.

--No Grade 4 infusion-related toxicities have been observed. For over 3,000 doses given in the Phase 2 studies to date, Grade 3 infusion-related toxicities were reported in association with only 25 doses (0.8%).

The TOCOSOL Paclitaxel abstract presented at the San Antonio Breast Cancer Symposium can be accessed at www.sonuspharma.com/abstracts.html .

About TOCOSOL Paclitaxel

Utilizing Sonus' proprietary TOCOSOL technology, TOCOSOL Paclitaxel is a ready-to-use paclitaxel formulation that is cremaphor-free, which allows for shorter infusion times (15 minutes) and may improve patient tolerability and reduce treatment-limiting side effects. As demonstrated in a clinical pharmacology study presented at the American Society of Clinical Oncology (ASCO) 2005 annual meeting, TOCOSOL Paclitaxel delivers nearly 70 percent higher exposure to unbound paclitaxel than an equivalent dose of Taxol(R). When used as single-agent therapy at doses of 100 or 120 mg/m(2) weekly, TOCOSOL Paclitaxel has shown promising anti-tumor response rates, time-to-progression and survival duration in Phase 2 studies. TOCOSOL Paclitaxel has generated encouraging safety data in the Phase 2 program and appears to be well tolerated when given weekly for extended periods of time. The ability to deliver higher weekly doses of paclitaxel on a sustained basis, and to achieve a higher exposure to paclitaxel for an individual dose, may result in improved efficacy for cancer patients. A pivotal Phase 3 study in metatastic breast cancer is currently underway to evaluate the potential advantages of TOCOSOL Paclitaxel. The Phase 3 trial will compare weekly dosing of TOCOSOL Paclitaxel to Taxol.

About Sonus Pharmaceuticals

Headquartered near Seattle, Sonus Pharmaceuticals is focused on the development of novel drugs that provide better therapeutic alternatives for cancer patients, including improved safety, tolerability and efficacy as well as more convenient administration. For additional information on Sonus, including past press releases, please visit www.sonuspharma.com.

Safe Harbor

Certain statements made in this press release are forward-looking such as those, among others, relating to the development, safety and efficacy 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 23, 2005 and Quarterly Form 10-Qs for 2005, 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 the Company will not be able to complete the Phase 3 clinical trial for TOCOSOL Paclitaxel; risks that clinical studies with TOCOSOL Paclitaxel will not be successful; risks that the FDA may not approve the Company's proposed New Drug Application; risks of successful development of additional drug delivery products; risks that the Company may not be successful in obtaining funding from third parties or completing a financing necessary to support the costs and expenses of clinical studies as well as research and development activities; and risks that the Company will not obtain regulatory clearance of the license agreement with Schering AG under the Hart-Scott-Rodino Antitrust Improvements Act. The Company undertakes no obligation to update the forward-looking statements contained herein or to reflect events or circumstances occurring after the date hereof.

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