NEW YORK--(BUSINESS WIRE)--Sept. 25, 2008--ImClone Systems Incorporated (NASDAQ: IMCL), a global leader in the development and commercialization of novel antibodies to treat cancer, today announced that its disease-directed randomized Phase 2 clinical trial of IMC-A12, ImClone's fully human, IgG1 anti-insulin-like growth factor-1 receptor (IGF-1R) monoclonal antibody, in women with advanced breast cancer has commenced patient enrollment. In this study, patients with hormone receptor expressing advanced breast cancer whose disease had progressed on an antiestrogen therapy are being randomized to treatment with either IMC-A12 as a single agent or IMC-A12 in combination with same dose and schedule of the last antiestrogen therapy to which their disease became refractory.

"This study of IMC-A12 is based on preclinical results indicating that the insulin-like growth factor receptor modulates the responsiveness of hormone receptor expressing breast cancers to antiestrogen therapy, as well as the development of resistance to antiestrogens," said Eric K. Rowinsky, M.D., Chief Medical Officer and Executive Vice President of ImClone. "The study is efficiently designed to assess the activity of IMC-A12 as a single agent in breast cancer, as well as the relative activities of IMC-A12 and IMC-A12 plus antiestrogens following the development of progressive disease on the same therapy. Since sensitivity to antiestrogens often confers clinical benefit with minimal side effects, we are seeking to further increase the responsiveness of antiestrogens and the durability of response."

This multicenter randomized Phase 2 study will enroll approximately 90 women with advanced breast cancer whose disease had progressed on antiestrogen therapy. The primary objective of this randomized Phase 2 study is to evaluate the efficacy of both IMC-A12 alone and IMC-A12 combined with the last antiestrogen therapy to which the patient's cancer became refractory. The study will also characterize the safety of IMC-A12 given alone and combined with antiestrogen therapy. IMC-A12 will be administered on an every-two-week schedule.

IMC-A12 is a fully human IgG1 monoclonal antibody. It is designed to specifically target the human IGF-1R, thereby inhibiting certain ligands known as IGFs 1 and 2 from binding to and activating the receptor. This action blocks a signaling pathway that enhances tumor cell proliferation and survival. In 2007, ImClone completed enrollment into two Phase 1 studies of IMC-A12, which demonstrated favorable safety and pharmacokinetic profiles, as well as preliminary evidence of antitumor activity as a single agent when administered either weekly or every two weeks. In addition to this Phase 2 study of IMC-A12 in hormone expressing advanced breast cancer, Phase 2 studies of IMC-A12 in patients with soft tissue sarcoma (adults and adolescents) and advanced prostate, pancreatic, colorectal, liver, head and neck cancers, as well as a series of Phase 1/2 studies in pediatric malignancies and another evaluating the combination of IMC-A12 and temsirolimus, have begun to enroll patients. Additional disease-directed studies of IMC-A12 sponsored by both ImClone and the National Cancer Institute under a development agreement are advancing towards initiation.

About ImClone Systems

ImClone Systems Incorporated is a fully integrated global biopharmaceutical company committed to advancing oncology care by developing and commercializing a portfolio of targeted biologic treatments designed to address the medical needs of patients with a variety of cancers. The Company's research and development programs include growth factor blockers and angiogenesis inhibitors. ImClone Systems' headquarters and research operations are located in New York City, with additional administration and manufacturing facilities in Branchburg, New Jersey. For more information about ImClone Systems, please visit the Company's web site at http://www.imclone.com.

Certain matters discussed in this news release may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and the Federal securities laws. Although the company believes that the expectations reflected in such forward-looking statements are based upon reasonable assumptions it can give no assurance that its expectations will be achieved. Forward-looking information is subject to certain risks, trends and uncertainties that could cause actual results to differ materially from those currently expected. Many of these factors are beyond the company's ability to control or predict. Important factors that may cause actual results to differ materially and could impact the company and the statements contained in this news release can be found in the company's filings with the Securities and Exchange Commission, particularly those factors identified as "risk factors" in the Company's most recent annual report of Form 10-K and in its quarterly reports on Form 10-Q and current reports on Form 8-K. For forward-looking statements in this news release, the company claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. The company assumes no obligation to update or supplement any forward-looking statements whether as a result of new information, future events or otherwise.

CONTACT: ImClone Systems Incorporated
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Tracy Henrikson, 908-243-9945
or
Rebecca Gregory, 646-638-5058
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SOURCE: ImClone Systems Incorporated