Peregrine Pharmaceuticals Announces New DOD Grant to Study Bavituximab (Tarvacin) in Breast Cancer

• Researchers at UT Southwestern Medical Center Awarded Competitive, Peer-Reviewed Grant for Preclinical Studies in Metastatic Breast Disease
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  -Will Assess Bavituximab's Utility as an Immunoconjugate for Imaging and Therapy
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  Bavituximab Research Studies Underway Funded by 5 Grants Totaling $3.6 Million

TUSTIN, Calif., April 25 /PRNewswire-FirstCall/ -- Peregrine Pharmaceuticals, Inc. (Nasdaq: PPHM), a biopharmaceutical company with a portfolio of innovative, clinical-stage product candidates for hepatitis C virus and cancer, today announced the U.S. Department of Defense (DOD) has awarded a new grant totaling $460,000 to its collaborators at the University of Texas Southwestern Medical Center at Dallas to study Peregrine's first-in-class anti-phospholipid (PS) agent bavituximab (formerly Tarvacin) as an imaging and therapeutic agent for recurrent breast cancer. Bavituximab is currently in a Phase I clinical trial for advanced refractory solid tumors.

In this new project, bavituximab will be labeled with radioactive isotopes to assess its potential as an imaging agent to identify tumor metastases and as a radioimmunoconjugate to treat metastatic disease. Despite recent medical advances in management of recurrent breast cancer, the prognosis remains poor for many patients and 40,000 women in the U.S. die from metastatic breast disease each year.

Bavituximab is a monoclonal antibody that binds selectively to cells that line tumor blood vessels. It has already shown promising activity in preclinical models of breast cancer. Previously published data in Cancer Research showed that a mouse equivalent of bavituximab in combination with docetaxel resulted in a 93% inhibition of human breast cancer growth in mouse cancer models. At the AACR Annual Meeting earlier this month, researchers reported that combination treatment with a bavituximab equivalent and cisplatin doubled survival time in a preclinical model of cisplatin-resistant breast cancer. Bavituximab's phospholipid target has been shown to be amplified when exposed to radiation, and recent preclinical studies also presented at AACR demonstrated that bavituximab plus radiation was significantly more effective in a brain cancer model than either therapy alone.

"Data from this project could open the door for use of bavituximab as an agent to identity, measure and ultimately destroy the metastases that kill most cancer patients," said Steven W. King, president and CEO of Peregrine. "We are particularly pleased since this is the third competitive, peer-reviewed grant awarded by DOD with the potential to expand the clinical applications of bavituximab. We look forward to the results of these studies that will assess its utility as a new class of imaging and therapeutic agents for breast cancer."

Bavituximab works by binding to certain phospholipids, specific components of the cell structure that are usually located inside normal cells, but which become exposed on the outside of cells that line the blood vessels of tumors, creating a highly specific target for anti-cancer treatments. Once bound to the tumor blood vessels, bavituximab alerts the body's immune system to attack the tumor's blood supply, stopping the flow of oxygen and nutrients to the tumor cells and resulting in tumor cell death. By linking bavituximab to an isotope to form a radioimmunoconjugate, researchers hope to be able to use it to image tumor cells for diagnosis and disease management, as well as to destroy additional cancer cells as a result of the radiation the radioimmunoconjugate transports to the tumor blood vessels.

"This new DOD project will enable us to assess bavituximab's utility for both tumor detection and therapy in breast cancer," said Ralph Mason, Ph.D., professor of radiology at UT Southwestern and a principal investigator of the study. "Since bavituximab's unique target is expressed on blood vessels in tumors but not in normal tissues, it may have both safety and efficacy advantages compared to other antibodies. We are eager to assess the utility of a bavituximab radioimmunoconjugate for the identification and treatment of metastatic breast disease."

The Department of Defense manages the Congressional Special Interest Medical Research Programs (CSI) encompassing breast, prostate, and ovarian cancers, neurofibromatosis, military health, and other areas. Since fiscal year 1992, CSI programs have handled approximately $3.4 billion in Congressional appropriations for peer-reviewed research aimed to prevent, control, and cure disease. Breast cancer is among the most commonly diagnosed cancers in women and remains a leading cause of cancer deaths. Currently, there is no cure for metastatic breast cancer.

Similar to its mechanism of action in cancer, bavituximab also targets phospholipids exposed on the cell surface when the cell is infected with certain viruses, mobilizing the immune system to attack and destroy both the viruses and the infected cells. In February Peregrine successfully completed planned enrollment in a Phase l clinical trial of bavituximab for the treatment of chronic hepatitis C virus infection, reporting that the drug appeared to be safe and well tolerated. Repeat dose and combination therapy studies are now being planned. Bavituximab is also in pre-clinical studies for potential use against influenza, HIV, cytomegalovirus and other life-threatening viruses.

About Peregrine

Peregrine Pharmaceuticals, Inc. is a biopharmaceutical company with a portfolio of innovative product candidates in clinical trials for the treatment of cancer and hepatitis C virus infection. The company is pursuing three separate clinical trials in cancer and hepatitis C virus infection with its lead product candidates bavituximab (formerly Tarvacin) and Cotara®. Peregrine also has in-house manufacturing capabilities through its wholly-owned subsidiary Avid Bioservices, Inc. (www.avidbio.com), which provides development and bio-manufacturing services for both Peregrine and outside customers. Additional information about Peregrine can be found at www.peregrineinc.com.

Safe Harbor Statement: Statements in this press release which are not purely historical, including statements regarding Peregrine Pharmaceuticals' intentions, hopes, beliefs, expectations, representations, projections, plans or predictions of the future are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. The forward-looking statements which include statements with respect to the potential therapeutic benefits and successful development of drug candidates, involve risks and uncertainties including, but not limited to, the uncertainties of tumor inhibition rates in future animal models, the risk that pre-clinical animal model results will not correlate to efficacy studies in human clinical trial, the risk that the results will not support a future clinical trial with bavituximab as a combination therapy agent, or the risk that safety and efficacy studies in the Phase I solid cancer tumor study may not correlate to safety and efficacy data generated from preclinical animal models or the Phase I clinical trial of bavituximab for the treatment of chronic hepatitis C virus infection. It is important to note that the company's actual results could differ materially from those in any such forward-looking statements. Factors that could cause actual results to differ materially include, but are not limited to, uncertainties associated with completing pre-clinical and clinical trials for our technologies; the early stage of product development; the significant costs to develop our products as all of our products are currently in development, pre-clinical studies or clinical trials; obtaining additional financing to support our operations and the development of our products; obtaining regulatory approval for our technologies; anticipated timing of regulatory filings and the potential success in gaining regulatory approval and complying. Our business could be affected by all a number of other factors, including the risk factors listed from time to time in the Company's SEC reports including, but not limited to, the annual report on Form 10-K for the year ended April 30, 2005, and the quarterly report on Form 10-Q for the quarter ended January 31, 2006. The Company cautions investors not to place undue reliance on the forward-looking statements contained in this press release. Peregrine Pharmaceuticals, Inc. disclaims any obligation, and does not undertake to update or revise any forward-looking statements in this press release.

SOURCE Peregrine Pharmaceuticals, Inc.

CONTACT: Investors, Betsy Brod, or Jonathan Schaffer, both of Brod&Schaffer, +1-800-987-8256, ir@peregrineinc.com, for Peregrine Pharmaceuticals, Inc.; or Media, Stephen Gendel, or Barbara Lindheim, both of GendeLLindheim BioCom Partners, +1-212-918-4650, for Peregrine Pharmaceuticals, Inc.