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Protein Design Labs Reports Positive Results in Phase II Clinical Trial Of Daclizumab in Asthma
Monday March 15, 8:03 am ET
Full Presentation of Data at AAAAI Meeting, March 23


FREMONT, Calif., March 15 /PRNewswire-FirstCall/ -- Protein Design Labs, Inc. (PDL) (Nasdaq: PDLI - News) today reported positive results from the initial clinical study of the humanized antibody daclizumab in patients with chronic, persistent asthma whose disease is not well controlled with high doses of inhaled corticosteroid therapy. The primary endpoint, percent change in FEV1 from baseline to 12 weeks (day 84), met statistical significance (p=0.05). Secondary clinical endpoints also supported these findings.
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The Phase II randomized, double-blind, placebo-controlled clinical trial was conducted at 24 centers in the United States and treated a total of 114 patients. In the assessment of the primary endpoint, patients receiving daclizumab experienced a mean increase in FEV1 of 4.4% of baseline, compared to placebo patients who experienced a mean decrease of 1.5% (p=0.05). Other spirometric measures (FEV1/FVC, FEF25-75%) were consistent with these results. Patients receiving daclizumab also demonstrated a statistically significant increase in the time to asthma exacerbation requiring oral corticosteroid rescue (p=0.024). Peripheral eosinophil counts were significantly reduced in the daclizumab treatment group compared to the placebo group (p=0.04). Statistically significant (p less than or greater than 0.007) within-group changes in the daclizumab group revealed improvements from baseline in diary symptom scores, as well as morning and nighttime peak expiratory flow rates. There were no significant within-group changes seen in the placebo group.

Treatment with daclizumab was generally well tolerated. The overall frequency and severity of adverse events did not differ between daclizumab and placebo groups.

Phase II Study Design

After a run-in period to verify dependence on inhaled corticosteroids, patients were randomized to receive daclizumab or placebo in a 3:1 ratio. Daclizumab was administered at two-week intervals, for a total of 10 doses. During the initial 12-week treatment period, daclizumab or placebo was used in combination with a stable dose of inhaled corticosteroids. Patients in the daclizumab treatment group received an initial dose of 2 mg/kg intravenously (I.V.), followed by subsequent doses of 1 mg/kg I.V. During the final eight weeks of the dosing regimen, the use of inhaled corticosteroids was gradually reduced, while patients continued receiving daclizumab or placebo. Patients were followed for a period of 16 weeks at the end of treatment. The primary efficacy endpoint was the change in pulmonary function as assessed by the percent change from baseline FEV1 at day 84. Data has been analyzed through the first 12 weeks.

"Based on this encouraging data, we intend to further study daclizumab as a potential long-term treatment for asthmatic patients whose disease has proven difficult to control," said Steven Benner, M.D., Senior Vice President and Chief Medical Officer, PDL. "We expect that the next trial of daclizumab in asthma will be a Phase II trial in which daclizumab is administered subcutaneously."

William W. Busse, M.D., Charles E. Reed Professor of Medicine and Head, Allergy and Immunology, University of Wisconsin Medical School, Madison, Wis., will report additional data from this initial Phase II study of daclizumab in asthma in poster presentation #1043, session 5402, at 11 a.m., March 23, 2004, at the Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI) in San Francisco.

Dr. Busse, said, "These are very encouraging results with daclizumab having met the primary endpoint and showing consistent effects in regard to secondary endpoints, as well. Given the large, unmet need for novel asthma treatments, I believe daclizumab clearly merits additional clinical study."

Richard Shames, M.D., Medical Director for PDL's daclizumab program, explained that daclizumab is directed at the alpha chain of the human IL-2 receptor (CD25). This receptor is found primarily on activated T lymphocytes. "Because of the important role of activated T cells in asthma, CD25 is an intriguing target for asthma therapy," Dr. Shames added. "By targeting CD25-expressing cells with daclizumab to prevent the further activation of these cells, we may inhibit the cascade of immune events that leads to airway inflammation and damage in asthma."

About Daclizumab

The FDA approved daclizumab for use in transplantation in December 1997, making it the first humanized antibody to gain marketing clearance in the United States. Daclizumab currently is marketed as Zenapax® by PDL partner Roche for prevention of acute rejection in kidney transplantation. In September 2003, PDL and Roche announced that PDL had re-acquired from Roche the rights to market and manufacture daclizumab in indications other than transplantation. PDL currently is conducting a Phase II clinical trial of daclizumab in moderate-to-severe ulcerative colitis and expects to report results from the trial by June 2004. Preparatory work continues for a PDL-conducted clinical trial of daclizumab in multiple sclerosis.

About Asthma

Asthma is among the most common chronic medical conditions in the United States and worldwide, affecting more than 20 million people in the United States, according to the American Lung Association (ALA) and the American Academy of Allergy, Asthma & Immunology (AAAAI). The disease is responsible for about 5,000 deaths annually in the United States and an estimated $14 billion in direct and indirect health care costs, according to ALA.

About Protein Design Labs

Protein Design Labs is a leader in the development of humanized antibodies to prevent or treat various disease conditions. PDL currently has antibodies under development for autoimmune and inflammatory conditions, asthma and cancer. PDL holds fundamental patents for its antibody humanization technology. Further information on PDL is available at www.pdl.com.

The foregoing contains forward-looking statements involving risks and uncertainties and PDL's actual results may differ materially from those in the forward-looking statements. Factors that may cause such differences are discussed in the Company's Annual Report on Form 10-K for the year ended December 31, 2003, and other filings made with the Securities and Exchange Commission. In particular, results obtained in the Phase II study may not be predictive of results to be obtained in the additional evaluations that would be necessary to demonstrate the antibody to be safe and effective in the treatment of asthma, nor can there be assurance that PDL will initiate subsequent clinical trials in asthma.