ImClone Systems Incorporated Highlights Advancements in Several Preclinical Pipeline Programs.

Business Editors/Health/Medical Writers

AACR-NCI-EORTC 2003 International Conference

on Molecular Targets and Cancer Therapeutics

BOSTON--(BUSINESS WIRE)--Nov. 19, 2003

Data on Several Antibody Development Programs

Presented at the AACR-NCI-EORTC 2003 International Conference on

Molecular Targets and Cancer Therapeutics

ImClone Systems Incorporated (NASDAQ: IMCL) provided updates on several preclinical programs at the AACR-NCI-EORTC 2003 International Conference on Molecular Targets and Cancer Therapeutics, currently being held in Boston, Massachusetts. The Company presented a number of posters on monoclonal antibody therapeutics being developed as angiogenesis and growth factor inhibitors, including:

VEGF Receptor-1 Research - Abstract B242

ImClone Systems researchers presented preclinical data suggesting that an investigational fully human monoclonal antibody, designated 18F1, that targets the Vascular Endothelial Growth Factor Receptor-1 (also known as VEGFR-1 or FLT-1) effectively blocked the binding of growth factors VEGF and Placental Growth Factor (PIGF) and inhibited tumor cell growth in a xenograft mouse model of VEGFR-1-expressing human breast cancer. VEGFR-1 is known to play an important role in blood vessel growth and, more recently, its expression has been identified on a number of human cancers.

These preclinical data suggest that a fully-human monoclonal antibody directed against VEGFR-1 may be a promising therapeutic approach to treating VEGFR-1-expressing breast cancer. Furthermore, these data corroborate anti-tumor activity previously observed in preclinical studies using a murine antibody used for research purposes.

Based on previously published data, Company researchers also believe that this approach may be promising in the inhibition of tumor angiogenesis. These data suggest that an antibody directed against the murine form of VEGFR-1 can lead to inhibition of tumor growth in mice.

Research into the inhibition of VEGFR -1 using 18F1 is ongoing.

FLT-3 Research - Abstract B223

ImClone Systems scientists presented preclinical data on the use of an investigational fully human monoclonal antibody designed to bind to and inhibit the FLT-3 Receptor as a method of inhibiting the growth of human Acute Myeloid Leukemia (AML) tumor cells.

In the study, Company researchers used a monoclonal antibody, referred to as EB10, in a xenograft mouse model of human FLT-3 expressing AML containing normal tumor cells (referred to as wild-type) or tumor cells carrying a specific mutation (known as internal tandem duplication or ITD). The findings suggest that EB10 blocked binding of the FLT-3 ligand, thereby preventing activation of FLT-3 signaling in AML cells and subsequent inhibition of tumor growth.

This early research is suggestive of the potential of a FLT-3 antibody directed against normal or mutated FLT-3-expressing cells as a therapeutic approach to AML. Additional research in this area is underway.

Fibroblast Growth Factor Receptor-3 Research - Abstract B241

ImClone Systems scientists presented preclinical data on the use of an antibody designed to inhibit the Fibroblast Growth Factor Receptor-3 (FGFR-3) in a xenograft mouse model of human prostate cancer. FGFR-3 has been shown to be involved in the development of certain cancers, such as prostate carcinoma, multiple myeloma and bladder carcinoma.

To investigate the utility of targeting FGFR-3 to inhibit tumor growth, Company researchers developed D11, a fully human investigational monoclonal antibody designed to bind and inhibit FGFR-3. The findings suggest that D11 suppressed tumor growth without causing any noticeable adverse effects.

These findings suggest that FGFR-3 can be specifically targeted with a neutralizing antibody and that FGFR-3 may be a target for anti-tumor therapeutics. The Company is planning to conduct additional preclinical studies on the use of antibodies against FGFR-3 and other FGF receptors relevant to tumor growth.

Platelet-Derived Growth Factor Receptor Alpha Research - Abstract B218

ImClone Systems scientists presented preclinical data on the use of an antibody to block the binding of Platelet-Derived Growth Factor (PDGF) to one of its receptors, known as PDGF Receptor alpha (PDGFR(alpha)), as a method of inhibiting growth of xenograft human tumors. PDGFR(alpha) is a receptor found in connective tissue and smooth muscle cells, as well as in a variety of tumor types.

Company researchers developed a PDGFR(alpha)-targeting antibody designated 3G3, which was administered to mice with xenograft models of glioblastoma and leiomyosarcoma. The findings of the study suggest that treatment with 3G3 inhibited the growth of the tumors over the course of the experiment.

The study findings suggest that a monoclonal antibody directed against PDGFR(alpha) could be a useful therapeutic approach to targeting PDGFR(alpha) - expressing tumor cells. The Company is planning to conduct additional preclinical studies on the use of antibodies against PDGFR(alpha).

gp75/TRP-1 Research - Abstract B222

ImClone Systems researchers presented data on the therapeutic use of recombinant fully human monoclonal antibodies directed against the gp75/TRP-1 melanoma antigen on melanoma cells. The objective of the study was to determine whether recombinant human antibodies could be generated to bind to the gp75/TRP-1 antigen on melanoma cells and, by doing so, elicit an immune response against the cancer. In the study, mice with xenograft models of melanoma were treated with human anti-gp75/TRP-1 antibodies. The study findings suggest that human anti-gp75/TRP-1 antibodies suppressed the growth of the melanoma tumors in the mice when compared to controls.

These results suggest that human anti-gp75/TRP-1 monoclonal antibodies may be potent therapeutics for the treatment of malignant melanoma. Additional research in this area is ongoing.

"ImClone Systems continues to make progress in the preclinical evaluation of therapeutic antibodies that target novel cellular mechanisms involved in the development and proliferation of cancer," stated Daniel S. Lynch, Acting Chief Executive Officer of ImClone Systems Incorporated. "We are committed to maximizing our talent and resources to advance this and other research in our antibody programs for the purpose of identifying product candidates for evaluation in future clinical trials."

About ImClone Systems Incorporated

ImClone Systems Incorporated is committed to advancing oncology care by developing a portfolio of targeted biologic treatments, designed to address the medical needs of patients with a variety of cancers. The Company's three programs include growth factor blockers, cancer vaccines and angiogenesis inhibitors. ImClone Systems' strategy is to become a fully integrated biopharmaceutical company, taking its development programs from the research stage to the market. ImClone Systems is headquartered in New York with manufacturing facilities in Branchburg, New Jersey.

The matters discussed in this news release may include forward-looking statements which involve potential risks and uncertainties. Important factors that may cause actual results to differ materially include, but are not limited to, the risks and uncertainties associated with completing pre-clinical and clinical trials of the company's compounds that demonstrate such compounds' safety and effectiveness; manufacturing losses and risks associated therewith; obtaining additional financing to support the company's operations; obtaining and maintaining regulatory approval for such compounds and complying with other governmental regulations applicable to the company's business; obtaining the raw materials necessary in the development of such compounds; consummating and maintaining collaborative arrangements with corporate partners for product development; achieving milestones under collaborative arrangements with corporate partners; developing the capacity to manufacture, market and sell the company's products, either directly or with collaborative partners; developing market demand for and acceptance of such products; competing effectively with other pharmaceutical and biotechnological products; obtaining adequate reimbursement from third party payers; attracting and retaining key personnel; legal costs and the outcome of outstanding legal proceedings and investigations including but not limited to our investigations pertaining to withholding tax issues; complying with covenants in the indenture for the company's Convertible Subordinated Notes and with the terms of other contractual obligations; obtaining patent protection for discoveries and risks associated with commercial limitations imposed by patents owned or controlled by third parties. The company does not undertake any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.