ImClone reports phase IB/IIA results for lead cancer therapeutic, C225, in head and neck and non-small cell lung cancers at ASCO meeting.

NEW YORK--(BW HealthWire)--May 19, 1997--

Data Supports Broader Clinical Strategy For EGFr Antagonist Development

ImClone Systems Incorporated (Nasdaq: IMCL) today announced at the 33rd Annual Meeting of the American Society of Clinical Oncology (ASCO) encouraging results of the Company's Phase Ib/IIa dose-escalation study of C225, an epidermal growth factor (EGFr) antagonist, in combination with the chemotherapeutic agent cisplatin. The trial was designed to evaluate safety and pharmacokinetics in patients with head and neck and non-small cell lung cancer. No dose-limiting toxicities were experienced in this twenty-two patient study which evaluated doses ranging from 5 mg/m(2) to 400 mg/m(2) of C225. Pharmacologically relevant concentrations of C225 were achieved at dose levels of 100 mg/m(2) and optimal saturation was achieved at approximately 200 mg/m(2). Evidence strongly suggestive of biologic activity was noted at doses of 100, 200 and 400 mg/m(2). Of the nine patients with advanced disease treated at these dose levels: one showed disease progression; six demonstrated stable disease; and two achieved partial responses.

"The demonstration of safety and strong suggestion of anti-tumor activity at biologically relevant doses of C225 is very promising," said Harlan W. Waksal, M.D., Executive Vice President and Chief Operating Officer of ImClone Systems. "We are continuing to explore and validate the synergistic effect of C225 used in combination with cisplatin, and are looking forward to advancing this product candidate through clinical evaluation."

The Company also reported in a poster session on Sunday, May 18, preliminary results of the Company's Phase Ib/IIa dose-escalation study of C225, an epidermal growth factor (EGFr) antagonist, in combination with the chemotherapeutic agent doxorubicin, to treat late-stage prostate cancer. Of 30 patients currently evaluated, results showed a strong suggestion of biologic activity and stabilization of disease. Previous regimens using other therapies on these patients had failed. Preliminary pharmacokinetic analyses suggest that the optimal biologic dose of C225 has not yet been reached. As a result, additional patients are currently being enrolled in the trial and receiving a 200 mg/m(2) dose of C225.

Background on C225 and the Clinical Strategy

C225 is designed to block the EGF receptor, which has been shown to be over-expressed in the cells of approximately one-third of all solid cancers. Antibodies directed against EGFr may inhibit the uncontrolled cancer cell growth that has been shown to be associated with activation of this receptor. When used in combination with chemotherapy or radiation, ImClone researchers believe that C225 will eliminate cancerous cells through a mechanism involving the induction of apoptosis, the natural process of cell death.

The Company's strategy for evaluating C225 in head and neck cancer currently includes three Phase Ib/IIa dose-escalation trials in combination with other anti-cancer therapies in the treatment of head and neck cancer. One trial, being conducted at Memorial Sloan-Kettering Cancer Center in New York and M.D. Anderson Cancer Center in Houston is studying the effectiveness of C225 in conjunction with the chemotherapeutic agent cisplatin. A second, NCI-sponsored trial at the University of Alabama at Birmingham is measuring the effectiveness of C225 in conjunction with radiation therapy. A third trial using C225 in a single-agent regimen in conjunction with surgery is being planned at the University of Virginia.

Upon completion of these Phase Ib/IIa safety and pharmacokinetic studies, ImClone expects to initiate Phase II/III studies to evaluate the potential of C225 in various tumor types. Two of these tumor targets will include renal cell cancer where C225 will be used alone, and head and neck cancers where C225 will be used in combination with chemotherapy. These targets present opportunities for near-term demonstration of C225 activity, effectiveness and subsequent market approval.

ImClone Systems Incorporated, headquartered in New York, is a biopharmaceutical company developing novel therapeutic products including interventional therapeutics, cancer vaccines and blood cell growth factors for the treatment of cancer and cancer-related disorders.

Except for the historical information contained herein, the matters discussed in this news release include forward-looking statements. Actual results may differ materially from those predicted in such forward-looking statements due to the risks and uncertainties inherent in the Company's business, including, without limitation, risks and uncertainties in obtaining and maintaining regulatory approval, market acceptance of and continuing demand for the Company's products, the impact of competitive products and pricing, and the Company's ability to obtain additional financing to support its operations.

CONTACT: Andrea F. Rabney

Director of Corporate Development and

Investor Relations

ImClone Systems Incorporated

212/645-1405

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