SOURCE: PDL BioPharma

December 10, 2007 05:00 ET

PDL BioPharma Presents Data on Novel Monoclonal Antibody for Multiple Myeloma at the 2007 American Society of Hematology Annual Meeting

Preclinical and Clinical Presentations Highlight Antibody's Potential as a Single and Combination Agent in Multiple Myeloma

REDWOOD CITY, CA--(Marketwire - December 10, 2007) - PDL BioPharma, Inc. (NASDAQ: PDLI) announced that clinical and preclinical data on HuLuc63 were presented at the 48th Annual Meeting of the American Society of Hematology (ASH) taking place from December 8 to 11 in Atlanta, Georgia. HuLuc63 is a humanized monoclonal antibody that binds to human CS1, a cell-surface glycoprotein that is highly expressed on multiple myeloma cells but minimally expressed on normal cells. The antibody is currently being evaluated in a phase 1 clinical study as a monotherapy for the treatment of relapsed/refractory multiple myeloma.

Investigators presented interim results of the ongoing phase 1 dose-escalation study in patients with advanced relapsed or refractory multiple myeloma. Additional presentations included preclinical results suggesting that combining HuLuc63 with other currently approved drugs could lead to an enhanced effect beyond that of the individual treatments alone. Preclinical data were also presented offering further evidence to support the antibody's mechanism of action and target expression.

"HuLuc63 is one of several novel antibodies in our pipeline, and we're pleased with how the program is progressing with these early results," said Mark McCamish, M.D., Ph.D., senior vice president and chief medical officer of PDL. "We are looking forward to further data from this study as we continue to advance this program."

Phase 1 Interim Results

On Saturday, December 8, Jeffrey Zonder, M.D., Assistant Professor of Medicine and Oncology at Wayne State University School of Medicine and Barbara Ann Karmanos Cancer Institute in Detroit, presented interim results of the phase 1 study in the first 13 patients with multiple myeloma who have relapsed or stopped responding to at least two prior treatments [Abstract # 1180: "Phase 1 Trial of HuLuc63 in Relapsed/Refractory Multiple Myeloma"]. The primary objectives of the study are to establish the maximum tolerated dose and evaluate the safety of HuLuc63 in patients with advanced relapsed or refractory multiple myeloma. Each course of HuLuc63 was given intravenously every two weeks for a total of four doses. The first 10 patients, whose median age is 65, had relapsed after an average of five prior therapies before entering the study. Two patients from different dose cohorts were evaluated to have stable disease after receiving four doses of HuLuc63.

One dose-limiting toxicity which occurred in the 2.5 mg/kg cohort was a grade 4 increase in serum creatinine which was assessed by the investigator as related to study drug; therefore, by study protocol three additional patients were enrolled into the 2.5 mg/kg cohort. Other HuLuc63 adverse events included Grade 1 and 2 toxicities in five of the first 10 patients during or after the first dose including chills, flushing, pyrexia, dyspnea and fatigue. Patients who reported first dose reactions were pretreated with acetaminophen and diphenhydramine for subsequent doses. Enrollment of new patients in the study at higher doses is ongoing.

Preclinical Studies

Also on Saturday, Kenneth C. Anderson, M.D., chief of the Division of Hematologic Neoplasia and director of the Jerome Lipper Multiple Myeloma Center at Harvard Medical School's Dana-Farber Cancer Institute in Boston, presented results of the study, "Low levels of circulating CS1, a newly identified multiple myeloma (MM) antigen for a novel humanized HuLuc63 monoclonal antibody, is detected in MM patient sera and correlates with active disease" [Abstract # 1509].

"HuLuc63 is the only antibody in development aimed at attacking cells with high levels of CS1," said Kenneth C. Anderson, M.D. "We now have further evidence that myeloma cells express CS1 at far higher rates than normal, healthy cells, which indicates that HuLuc63 has the potential to single out the myeloma cells and become a targeted treatment against this currently incurable hematologic cancer."

Another preclinical study ("HuLuc63 in Combination Regimens with Conventional and Targeted Therapies Has Additive and Synergistic Anti-Tumor Activity in Pre-Clinical Models of Myeloma" [Abstract # 2517]) explores the use of HuLuc63 as a combination treatment. The purpose of this study, presented on Sunday, December 9, was to examine whether using HuLuc63 in combination with a panel of drugs having distinct modes of action could result in therapeutic benefit and provide a rationale for future trials. The strongest anti-myeloma activity was observed when HuLuc63 was combined with Velcade® (bortezomib), which appeared to result in a synergistic inhibition of tumor cell growth. None of the agents changed the CS1 expression level on the myeloma cells or diminished HuLuc63's anti-myeloma activity.

PDL is planning to start two additional phase 1 trials in 2008 to examine HuLuc63 as a combination agent.

"Instead of attacking the myeloma cells from one direction, combination therapy allows a two-front approach and a potentially greater chance at combating the malignant cells," said Dr. McCamish. "The positive results in the Velcade-plus-HuLuc63 preclinical study provide significant rationale for us to run clinical trials studying this drug as a combination therapy in myeloma patients. We look forward to advancing HuLuc63 and our other key antibody development programs in hopes of bringing new treatment options to cancer patients and those suffering from difficult immunological disorders."

About Multiple Myeloma

Multiple myeloma is the second most common hematologic malignancy in the U.S., accounting for about 10 percent of all hematologic malignancies and one percent of all malignancies. In 2005, approximately 50,000 Americans were reported to have multiple myeloma, and about 16,000 Americans were newly diagnosed with the disease. More than 11,000 patient deaths due to multiple myeloma were reported in the U.S. in 2005. The average five-year survival is 32 percent and the average 10-year survival is three percent.

Multiple myeloma is characterized by malignant plasma cells that form tumors in the bone marrow. These plasma cell tumors can spread throughout the bone marrow, thereby disrupting the production of red blood cells and platelets, which normally occur in the bone marrow. Excessive amounts of malignant plasma cells also may decrease the number of white blood cells, which are important in fighting off infections.

About PDL

PDL BioPharma, Inc. is a biopharmaceutical company focused on discovering, developing and commercializing innovative therapies for severe or life-threatening illnesses. For more information, please visit http://www.pdl.com.

Forward-looking Statements

This press release contains forward-looking statements regarding PDL's plan to start two additional phase 1 trials of HuLuc63 in 2008 and advance the HuLuc63 development program, which involve risks and uncertainties. Actual results may differ materially from those, express or implied, in these forward-looking statements. Only a small number of research and development programs result in commercialization of a product. The interim results observed in the phase 1 trial of HuLuc63 may not be predictive of future results. Additional evaluations and clinical studies would be necessary to demonstrate HuLuc63 to be safe and effective in the treatment of patients with relapsed/refractory multiple myeloma. PDL cannot assure that it will initiate subsequent clinical trials of HuLuc63, including the two additional phase 1 trials, which PDL is currently planning to start in 2008. In addition, even if PDL is able to significantly further the development of HuLuc63, PDL may not be able to meet applicable regulatory standards or regulatory authorities may fail to approve HuLuc63. Actual results also could differ from current expectations because of delays in contracting with clinical sites, slow enrollment rates, lack of availability of clinical materials and safety or manufacturing issues. Other factors that may cause PDL's actual results to differ materially from those expressed or implied in the forward-looking statements in this press release are discussed in PDL's filings with the Securities and Exchange Commission (SEC), including the "Risk Factors" sections of its annual and quarterly reports filed with the SEC. Copies of PDL's filings with the SEC may be obtained at the "Investors" section of PDL's website at www.pdl.com. PDL expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in PDL's expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based for any reason, except as required by law, even as new information becomes available or other events occur in the future. All forward-looking statements in this press release are qualified in their entirety by this cautionary statement.

PDL BioPharma and the PDL BioPharma logo are considered trademarks of PDL BioPharma, Inc. Velcade® is a registered trademark of Millennium Pharmaceuticals, Inc.

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