ZymoGenetics Announces Presentation Of TACI-Ig Phase 1 Preliminary Findings In Multiple Myeloma At American Society of Hematology Meeting

SEATTLE, Dec. 12 /PRNewswire-FirstCall/ -- ZymoGenetics, Inc. announced that preliminary data were presented from a Phase 1 study of TACI-Ig in patients with multiple myeloma (MM) and Waldenstrom’s macroglobulinemia (WM). Based on nine patients enrolled to date, study authors observed that treatment with TACI-Ig reduced circulating polyclonal immunoglobulin levels and had an acceptable tolerability profile with few treatment-related adverse events in these patients. This presentation and one discussing preclinical use of Interleukin 21 (IL-21) with Rituxan(R) were given at the American Society of Hematology annual meeting held in Atlanta, Georgia.

Jean-Francois Rossi, M.D., Ph.D., of the Hematology-Oncology Department, University Hospital Montpellier, France presented a poster titled “A Phase I/II study of TACI-Ig to neutralize APRIL and BLyS(R) in patients with refractory or relapsed multiple myeloma or active previously-treated Waldenstrom’s macroglobulinemia” (Abstract #2566). The ongoing open-label, dose-escalation study was designed to determine the maximum tolerated dose and the optimal biological dose of TACI-Ig in these patient populations. Patients are receiving five weekly subcutaneous injections of TACI-Ig at either 2, 4, 7 or 10 mg/kg.

Preliminary results of the first three cohorts of the dose-escalation study with patients who received 2, 4 and 7mg/kg, consisting of six patients with MM and three patients with WM, showed:

-- No dose limiting toxicity has been observed to date.

-- TACI-Ig was well tolerated with few adverse events and fewer drug- related adverse events. All drug-related adverse events were mild in severity.

-- Two patients with MM and two patients with WM demonstrated a stabilization of disease at the end of the first treatment cycle. Two of the four patients continue to have stable disease after three treatment cycles, and one patient is undergoing extension treatment and will be evaluated at a later date.

-- In accord with the expected TACI-Ig mode of action, polyclonal immunoglobulins decreased significantly during treatment with TACI-Ig.

The presentation concluded that these early results were encouraging and that higher doses up to 10mg/kg and/or prolonged treatment might be necessary to obtain more sustained responses. Patients are being recruited for treatment at higher doses of TACI-Ig.

In another ASH presentation delivered today, Steven D. Hughes, Ph.D., highlighted findings from a preclinical study: “IL-21 Improves Rituximab-Mediated B Cell Depletion” (Abstract # 345). Dr. Hughes reported that addition of IL-21 to a standard weekly 4-dose regimen of rituximab was well tolerated in nonhuman primates, and resulted in more complete and durable depletion of CD20-expressing target cells in blood and lymphoid tissues. These data support the concept that IL-21 can enhance the activity of rituximab and provide evidence for evaluating IL-21 and rituximab combination therapy in patients with advanced CD20 positive malignancies.

Abstracts

The presentations and abstracts will be available at www.zymogenetics.com in the “What’s New” section on the home page.

About TACI-Ig

ZymoGenetics is developing TACI-Ig for the treatment of autoimmune diseases. TACI-Ig is a soluble receptor that binds to BLyS and APRIL, TNF family cytokines that promote B-cell survival and the production of harmful autoantibodies, which cause certain autoimmune diseases such as systemic lupus erythematosus (SLE). Preclinical data indicate that levels of BLyS and APRIL are elevated in patients with rheumatoid arthritis, SLE and B-cell malignancies. TACI-Ig has been shown to affect several stages of B-cell development and may inhibit the survival of cells responsible for making antibodies. ZymoGenetics is developing TACI-Ig in collaboration with Serono S.A. and is conducting Phase 1b studies in patients with SLE, rheumatoid arthritis and advanced B-cell malignancies, such as multiple myeloma, B-cell non-Hodgkin’s lymphoma and chronic lymphocytic leukemia.

About Interleukin 21 (IL-21)

Interleukin 21 (IL-21) has potent biological activity in regulating key classes of immune cells, including cytotoxic T cells and natural killer cells. These cell types play key roles in surveillance of the body to eliminate malignant and infected cells. Based upon the ability of IL-21 to inhibit tumor growth in a number of animal models, ZymoGenetics is developing IL-21 for the treatment of cancer, initially in metastatic melanoma and renal cell carcinoma, and has retained commercialization rights for IL-21 in North America. The company licensed commercialization rights outside of North America to Novo Nordisk A/S.

About ZymoGenetics

ZymoGenetics is a biopharmaceutical company focused on the discovery, development and commercialization of therapeutic proteins for the prevention or treatment of human diseases. The Company is developing a diverse pipeline of potential proprietary product candidates that are moving into and through clinical development. These candidates span a wide array of clinical opportunities that include bleeding, autoimmune diseases and cancer. ZymoGenetics intends to commercialize these product candidates through internal development, collaborations with partners, and out-licensing of patents from its extensive patent portfolio. For further information, visit www.zymogenetics.com.

This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on the current intent and expectations of the management of ZymoGenetics. These statements are not guarantees of future performance and involve risks and uncertainties that are difficult to predict. ZymoGenetics’ actual results and the timing and outcome of events may differ materially from those expressed in or implied by the forward-looking statements because of risks associated with our unproven discovery strategy, preclinical and clinical development, regulatory oversight, intellectual property claims and litigation and other risks detailed in the company’s public filings with the Securities and Exchange Commission, including the company’s Annual Report on Form 10-K for the year ended December 31, 2004. Except as required by law, ZymoGenetics undertakes no obligation to update any forward-looking or other statements in this press release, whether as a result of new information, future events or otherwise.

ZymoGenetics, Inc.

CONTACT: investors, John Calhoun, MD, MBA, Director, CorporateCommunications & Investor Relations, +1-206-442-6744, or media, Susan W.Specht, MBA, Corporate Communications Manager, +1-206-442-6592, both ofZymoGenetics, Inc.

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