IDM and Cambridge Laboratories sign an exclusive marketing agreement for Junovan ™ (Mepact) in the United Kingdom and Ireland Paris, France – June 21, 2005. IDM (Immuno-Designed Molecules), a privately held biopharmaceutical company, the shareholders of which recently entered into an agreement to combine with Epimmune Inc. (Nasdaq: EPMN), today announced that it has signed an exclusive marketing agreement for Junovan (Mepact or L-MTP-PE) in the United Kingdom and Ireland with Cambridge Laboratories Ltd, a privately owned British pharmaceutical company. Junovan, known as Mepact throughout clinical development, is the brand name the product will be marketed under worldwide, upon obtaining necessary regulatory approvals. In exchange, IDM will receive an upfront license fee and milestone payments throughout the development of the product prior to launch, as well as royalties calculated on product sales. Junovan is an immune system stimulator designed to destroy cancer cells by activating macrophages present in the patient. Results from a phase III, randomized clinical trial demonstrated that in 664 patients suffering from non-metastatic osteosarcoma that was amenable to resection, Junovan, given with chemotherapy compared to chemotherapy alone, significantly extended survival without relapse as well as overall survival. Severe adverse events were those typically associated with high dose chemotherapy and surgery. Adverse events associated with Junovan are related to its biologic activity and generally include mild to moderate fever, chills, rigors, fatigue, nausea and increases in serum proteins associated with macrophage activation. The clinical trial was conducted in the United States by the Children’s Oncology Group, in children with newly diagnosed high grade osteosarcoma, and the results were presented at the American Society of Pediatric Hematology/Oncology (ASPHO) Annual Meeting in May 2005. Junovan was granted orphan drug status for the treatment of osteosarcoma in the U.S. in 2001 and in Europe in 2004. Junovan is currently limited to clinical investigational use only; its safety and efficacy have not been reviewed or approved for commercial distribution by any regulatory agency. IDM plans to file a marketing application with regulatory authorities in the U.S. and Europe in the first half of 2006. Jean Loup Romet-Lemonne, Chairman and Chief Executive of IDM said, “Cambridge is an excellent partner for IDM, given their focus on the development and commercialization of innovative medicines. They have a dynamic sales and marketing team that we are confident will maximize the potential for Junovan in the UK and Ireland.” Mark Evans, Chief Executive of Cambridge Laboratories commented, “Junovan is a significant addition to our exciting pipeline of new medicines and we are delighted to have made this deal with IDM. The clinical results are very encouraging, in light of the fact that no new agent has been available in the treatment of osteosarcoma over the last 20 years.” Osteosarcoma is the most common form of pediatric bone tumor. Approximately 900 new cases are diagnosed each year in the United States, with a similar number in Europe. For further information please contact Press contact IDM : Nadine Sciacca, Directeur Communication Tel.: +33 (0) 1 40 09 04 11 E-mail: nsciacca@idm-biotech.com Press contact Cambridge Mark Evans, Chief Executive Officer Tel: 44 191 296 9370 Euro RSCG C&0: Marie-Carole de Groc/Florence Macaire +33 (0)1 58 47 95 07/+33 (0)1 58 47 95 18 marie-carole.de-groc@eurorscg.fr florence.macaire@eurorscg.fr FourGritti Healthcare Joanna Marchant/ Martin Sutton Tel: +44 7747 610310 or +44 7884 495293 About IDM To date, approximately 98% of IDM’s shareholders have entered into a definitive agreement to combine IDM with Nasdaq publicly traded Epimmune Inc. in an all-stock transaction expected to close in the third quarter of 2005. Epimmune has filed a proxy statement with the United States Securities and Exchange Commission in connection with the transaction, which is subject to approval by the Epimmune stockholders and certain other closing conditions. IDM is a biopharmaceutical company focused on the development of innovative products to treat and control cancer while maintaining the patient's quality of life. IDM is currently developing two lines of products: one aiming at the destruction of residual cancer cells after the use of traditional therapies, and the other to prevent tumor recurrence by triggering an immune response. IDM's most advanced product has completed a Phase III clinical trial, five other products are in clinical trials and five are in preclinical development. For more information, visit www.idm-biotech.com. About Cambridge Laboratories Ltd Cambridge Laboratories is a successful, privately owned pharmaceutical company which focuses on the development and commercialisation of innovative medicines, with particular emphasis on the central nervous system, oncology and specialist therapy areas. Through effective in-licensing and acquisition it has established a strong portfolio of products as well as an exciting pipeline of new medicines. The Company has a dynamic sales and marketing organisation, which operates via a unique international network of distribution partnerships helping patients throughout the world Where You Can Find Additional Information About IDM’s Proposed Combination with Epimmune Epimmune Inc. has filed a preliminary proxy statement concerning its proposed combination with IDM with the Securities and Exchange Commission (SEC). Investors and security holders are advised to read the proxy statement related to the proposed transaction because it contains important information related to the transaction. Investors and security holders may obtain a free copy of the proxy statement and other documents filed by Epimmune with the SEC at the SEC’s website at www.sec.gov. The proxy statement and any other documents filed by Epimmune with the SEC may also be obtained free of charge from Epimmune by directing such request to Epimmune’s Secretary at the following address: 5820 Nancy Ridge Drive, San Diego, California 92121. Information Concerning Participation in Epimmune’s Proxy Solicitation IDM and Epimmune and their respective executive officers and directors may be deemed to be participants in the solicitation of proxies from the stockholders of Epimmune with respect to the proposed transaction between Epimmune and IDM. Information regarding Epimmune's executive officers and directors is included in Epimmune’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2004. This document is available free of charge at the SEC’s website at www.sec.gov and from Epimmune at www.epimmune.com. Investors and security holders may obtain additional information about the interests of the respective executive officers and directors of Epimmune and IDM in the proposed transaction between Epimmune and IDM by reviewing the proxy statement related to the transaction filed with the SEC.