GPC Biotech Presents Preliminary Clinical Data on Anticancer Monoclonal Antibody 1D09C3 at ASH

Martinsried/Munich (Germany), Waltham, Mass. and Princeton, N.J., December 11, 2006 – GPC Biotech AG (Frankfurt Stock Exchange: GPC; TecDAX index; NASDAQ: GPCB) today announced the presentation of preliminary clinical data on its anticancer monoclonal antibody 1D09C3 at the 48th Annual Meeting of the American Society of Hematology (ASH) in Orlando, Florida. 1D09C3 is currently in a Phase 1 clinical program that is evaluating the antibody in patients with relapsed or refractory B-cell lymphomas, who have failed prior standard therapy. The objectives of the Phase 1 program are to determine the maximum tolerated dose and to establish a recommended dose for a Phase 2 efficacy trial.



The poster entitled, “Two Phase 1 Open-Label Studies of the Fully Human IgG4 Monoclonal Antibody 1D09C3 in Patients with Relapsed and/or Refractory B-Cell Lymphoproliferative Neoplasias on a Weekly and Bi-Weekly Dosing Scheme,” (Abstract #2730) presented initial results from the ongoing Phase 1 clinical program. These preliminary data from 25 patients suggest that 1D09C3 is well tolerated in this heavily pre-treated patient population. A maximum tolerated dose had not yet been reached. Hints of antitumor activity were observed in two patients.



“We are pleased with the initial clinical data from our antibody program,” said Marcel Rozencweig, M.D., Senior Vice President, Drug Development and Chief Medical Officer. “Importantly, 1D09C3 seems to be well tolerated by this heavily pre-treated patient population. The early signs of anti-tumor activity are encouraging at these low doses. We expect to see the final results from our Phase 1 clinical program in mid 2007. Should the data continue to be promising, we anticipate moving into Phase 2 testing thereafter.”



Dr. Rozencweig continued: “While good progress has been made in recent years in treating lymphoid cancers with antibodies, there remains a major need for additional therapies to treat patients who have relapsed or become resistant to currently available treatments. 1D09C3 has key attributes differentiating it from marketed therapies; thus, it could hold the potential to become an important new therapy for treating lymphomas and leukemias.”



New preclinical data under the title “Interferon-Gamma Enhances the Anti-Myeloma Activity of the Fully Human Anti-HLA-DR Monoclonal Antibody 1D09C3” (Abstract #656) will also be presented. The findings suggest that interferon-gamma induces up-regulation of HLA-DR, the target of 1D09C3, resulting in a potent enhancement of the in vivo anti-myeloma activity of 1D09C3.



About 1D09C3
1D09C3 is an anti-MHC (major histocompatibility complex) class II monoclonal antibody. The antibody was isolated in collaboration with MorphoSys from its HuCAL® library of human antibodies. 1D09C3 binds to MHC class II molecules on the cell surface and selectively kills activated, proliferating tumor cells, which include B-cell and T-cell lymphomas. In 2005, it was estimated that more than 56,000 people in the U.S. and about 70,000 people in the European Union were diagnosed with non-Hodgkin’s lymphoma, the most common form of lymphoma. In preclinical studies 1D09C3 has been shown to induce programmed cell death and does not require a functioning immune system for its cell-killing effect. A Phase 1 clinical program evaluating 1D09C3 in patients with relapsed or refractory B-cell lymphomas, such as Hodgkin’s and non-Hodgkin’s lymphomas and chronic lymphocytic leukemia (CLL), who have failed prior standard therapy, is currently underway at major cancer centers in Europe. 1D09C3 has been granted orphan medicinal product designation in the European Union for the treatment of Hodgkin’s lymphoma, chronic lymphocytic leukemia and multiple myeloma. Additional information on 1D09C3 can be found in the Anticancer Programs section of the Company’s Web site at www.gpc-biotech.com.



About GPC Biotech
GPC Biotech AG is a publicly traded biopharmaceutical company focused on discovering, developing and commercializing new anticancer drugs. GPC Biotech’s lead product candidate – satraplatin – is an oral platinum-based compound that has shown highly statistically significant results for progression-free survival in a Phase 3 registrational trial as a second-line chemotherapy treatment in hormone-refractory prostate cancer. The U.S. FDA has granted fast track designation to satraplatin for this indication, and the rolling NDA submission process for this compound is underway. GPC Biotech in-licensed satraplatin from Spectrum Pharmaceuticals, Inc. in 2002. GPC Biotech is also developing a monoclonal antibody with a novel mechanism-of-action against a variety of lymphoid tumors, currently in Phase 1 clinical development, and has ongoing drug development and discovery programs that leverage its expertise in kinase inhibitors. GPC Biotech AG is headquartered in Martinsried/Munich (Germany), and its wholly owned U.S. subsidiary has sites in Waltham, Massachusetts and Princeton, New Jersey. For additional information, please visit GPC Biotech’s Web site at www.gpc-biotech.com.



This press release contains forward-looking statements, which express the current beliefs and expectations of the management of GPC Biotech AG, including summary statements relating to topline results of the SPARC trial, initial clinical results with the 1D09C3 monoclonal antibody and summary statements relating to the potential efficacy and safety profile of satraplatin and of 1D09C3. Such statements are based on current expectations and are subject to risks and uncertainties, many of which are beyond our control, that could cause future results, performance or achievements to differ significantly from the results, performance or achievements expressed or implied by such forward-looking statements. Actual results could differ materially depending on a number of factors, and we caution investors not to place undue reliance on the forward-looking statements contained in this press release. In particular, there can be no guarantee that results from the clinical trials discussed in this press release will be confirmed upon full or final analysis of the results of the trials and additional information relating to the safety, efficacy or tolerability of satraplatin or of 1D09C3 may be discovered upon further data analysis. We cannot guarantee that satraplatin or 1D09C3 will be approved for marketing in a timely manner, if at all, by regulatory authorities nor that, if marketed, either product will be a commercial success . We direct you to GPC Biotech’s Annual Report on Form 20-F for the fiscal year ended December 31, 2005 and other reports filed with the U.S. Securities and Exchange Commission for additional details on the important factors that may affect the future results, performance and achievements of GPC Biotech. Forward-looking statements speak only as of the date on which they are made and GPC Biotech does not undertake any obligation to update these forward-looking statements, even if new information becomes available in the future.



The scientific information discussed in this press release related to satraplatin and to 1D09C3 is preliminary and investigative. Neither satraplatin nor 1D09C3 has been approved by the FDA in the U.S., the EMEA in Europe or any other regulatory authority and no conclusions can or should be drawn regarding its safety or effectiveness. Only the relevant regulatory authorities can determine whether satraplatin and 1D09C3 are safe and effective for the use(s) being investigated.

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Laurie Doyle

Director, Investor Relations & Corporate Communications

GPC Biotech AG

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