ROCKVILLE, MD, April 11, 2005—EntreMed, Inc. (Nasdaq: ENMD) today announced the presentation of positive preclinical data for 2-methoxyestradiol (2ME2) in rheumatoid arthritis. The data were presented in two separate presentations by EntreMed scientists and their collaborator, Andrew Issekutz, M.D., Professor of Pediatrics and Pathology, Dalhousie University, Halifax, Nova Scotia, during the 18th annual meeting of the Canadian Society for Immunology, which was held April 6-10 in Whistler, British Columbia.

Data from a preclinical study, conducted by Dr. Andrew Issekutz, demonstrated activity of 2ME2 in an adjuvant-induced arthritis animal model. Results from this study demonstrated that administration of 2ME2 inhibits disease development and severity in an animal model of arthritis using multiple clinical measures. The study also demonstrated that 2ME2 treatment significantly inhibited both inflammatory cell migration to the joints and articular (joint) cartilage damage, which further suggests a direct role for 2ME2 in the treatment of rheumatoid arthritis.

Dr. Issekutz commented on the results of the study, “These data demonstrate the impact of 2ME2 on inflammation and disease progression and suggests the potential of 2ME2 as a disease modifying anti-rheumatic drug (DMARD).”

Results from a separate preclinical study of rheumatoid arthritis presented by EntreMed at the annual meeting of the American Association of Immunologists last week also demonstrated the anti-arthritic activity of 2ME2. Highlights of the data included the demonstration that oral administration of 2ME2 resulted in a dose-dependent decrease in clinical severity of arthritic disease as determined by clinical measurements. The decrease in clinical symptoms with 2ME2 administration was accompanied by a pronounced inhibition of tissue and joint damage.

Carolyn F. Sidor, MD, EntreMed Vice President and Chief Medical Officer commented on the presentations, “The study by Dr. Issekutz represents the second report of 2ME2’s activity in a preclinical model of rheumatoid arthritis. Taken together, both studies point to the potential of 2ME2 as a disease modifying anti-rheumatic drug candidate. As we continue to evaluate the potential of 2ME2 (Panzem® Capsules and Panzem® NCD) in oncology studies, the current preclinical results of 2ME2 in rheumatoid arthritis indicate additional clinical opportunities for this compound.”

To view EntreMed’s poster presentation, visit Scientific Presentations under the Therapeutic Pathways section of the Company’s website at http://www.entremed.com.

About Rheumatoid Arthritis and Inflammation

Rheumatoid arthritis (RA), one of the most common forms of arthritis, is a systemic disease that is characterized by the inflammation of the membrane lining of the joint, which causes pain, stiffness, redness, swelling, and loss of function in the joint. The inflamed joint lining, called the synovium, releases enzymes that destroy bone and cartilage, causing the joint to lose its shape and alignment. This process can result in joint pain, loss of movement, and deformity. RA may also cause inflammation of internal organs, leading to organ damage. DMARDs are drugs that have the ability to slow down disease progression in rheumatoid arthritis and other autoimmune diseases.

Inflammation is the process involving the reaction of tissue to injury or disease. The condition may be either local or systemic and can be divided into acute (immediate) and chronic (prolonged) patterns. The endothelial cell responses involved in angiogenesis (formation of new blood vessels) and homeostasis are central to inflammatory diseases. In contrast to acute inflammation, which is manifested by vascular changes, edema, and largely neutrophil infiltration, chronic inflammation is characterized by infiltration with mononuclear leukocytes, tissue destruction, angiogenesis, and fibrosis. As a result, the cellular pathways involved in acute and chronic inflammation can be overlapping or distinct. Inflammation is a process that is associated with many pathologies, including cancer, cardiovascular disease and arthritis. A number of EntreMed’s compounds have demonstrated anti-inflammatory properties in preclinical models.

About EntreMed

EntreMed, Inc. (Nasdaq: ENMD) is a clinical-stage pharmaceutical company developing therapeutic candidates primarily for the treatment of cancer and inflammation. Panzem® (2-methoxyestradiol or 2ME2), the Company’s lead drug candidate, is currently in clinical trials for cancer, as well as in preclinical development for non-oncology indications. EntreMed’s goal is to develop and commercialize new compounds based on the Company’s expertise in angiogenesis, cell cycle regulation and inflammation—processes vital to the treatment of cancer and other diseases. Additional information about EntreMed is available on the Company’s website at http://www.entremed.com and in various filings with the Securities and Exchange Commission.

Forward Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act with respect to the outlook for expectations for future financial or business performance, strategies, expectations and goals. Forward-looking statements are subject to numerous assumptions, risks and uncertainties, which change over time. Forward-looking statements speak only as of the date they are made, and no duty to update forward-looking statements is assumed. Actual results could differ materially from those currently anticipated due to a number of factors, including those set forth in Securities and Exchange Commission filings under “Risk Factors,” including risks relating to the need for additional capital and the uncertainty of additional funding; the early-stage products under development; uncertainties relating to clinical trials; success in the clinical development of any products; dependence on third parties; future capital needs; and risks relating to the commercialization, if any, of the Company’s proposed products (such as marketing, safety, regulatory, patent, product liability, supply, competition and other risks).