Cell Pathways Advised That NDA for FAP Not Approvable At This Time.

Business Editors/Health and Medical Writers

HORSHAM, Penn.--(BW HealthWire)--Sept. 22, 2000

Cell Pathways, Inc. (Nasdaq:CLPA) today announced that the U.S. Food and Drug Administration (FDA) has orally notified the company that the agency has completed its initial review of Cell Pathways' New Drug Application (NDA) for Aptosyn(TM) (exisulind) for the indication of familial polyposis (FAP). The Agency is expected to send the Company a letter noting the deficiencies in the NDA and indicating that it is not being approved at this time. The Company anticipates that, upon receipt of the Agency's letter, it will request a meeting with the Agency to discuss the NDA and, thereafter, determine its next steps with respect to the FAP indication.

"While responding to the Agency's initial action with respect to the NDA," said Robert J. Towarnicki, president and chief executive officer of Cell Pathways, Inc. "we remain confident of the promise of Aptosyn(TM) for the prevention and treatment of cancer and precancerous lesions. This is based on the laboratory, animal and human data we have gathered in a wide variety of indications."

Mr. Towarnicki added, "We want to assure the forty-one patients currently on Aptosyn(TM) in extension trials for FAP that it is our intent that they will continue to have access to Aptosyn(TM) since they have responded so well to drug treatment. These patients have been on drug from two to five years. And, of course, our current clinical studies of Aptosyn(TM) in other precancer and cancer indications are expected to remain unchanged."

Aptosyn(TM) (exisulind) is Cell Pathways' lead drug from a novel class of compounds under development by the company, called Selective Apoptotic Anti-Neoplastic Drugs (SAANDS). SAANDS inhibit a novel form of cyclic GMP phosphodiesterase and selectively induce apoptosis (programmed cell death) in abnormally growing precancerous and cancerous cells. In addition to developing Aptosyn(TM) as a new treatment for patients with FAP, Cell Pathways is conducting additional clinical studies with this compound as a single agent and in combination with conventional chemotherapeutic drugs in a variety of other cancer and precancerous indications. The company's second SAAND compound, CP 461, recently completed Phase Ib human clinical studies as a single agent.

Cell Pathways, Inc., headquartered in Horsham, Pennsylvania, is a development stage pharmaceutical company focused on the research and development of novel and unique medications to prevent and treat cancer. For additional information on Cell Pathways, Inc. visit the Company's website at http://www.cellpathways.com.

Certain statements made herein, and oral statements made in respect hereof, constitute "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements are those which express plan, anticipation, intent, contingency or future development and/or otherwise are not statements of historical fact. These statements are subject to risks and uncertainties, known and unknown, which could cause actual results and developments to differ materially from those expressed or implied in such statements. Such risks and uncertainties relate to, among other factors, the absence of approved products; history of operating losses; early stage of development; the costs, delays and uncertainties inherent in basic pharmaceutical research, drug development, clinical trials and the regulatory approval process, with respect to both the Company's current product candidates and its future product candidates, if any; dependence on development of Aptosyn(TM) (exisulind); the limitations on, or absence of, the predictive value of data obtained in laboratory tests, animal models and human clinical trials when planning additional steps in product development; the uncertainty of obtaining regulatory approval, including uncertainty of approval of the New Drug Application submitted for Aptosyn(TM) (exisulind) for familial adenomatous polyposis (a rare disease that puts those afflicted at high risk of developing colon cancer), whether in connection with the adequacy of the data generated in the clinical trials of Aptosyn(TM) (exisulind) or otherwise; the uncertainty of the effect of product approval, if achieved, on the market price of the Common Stock; the timing and scope of any approval which might be received for any compound for any indication in the future; acceptance by providers of healthcare reimbursement; the validity, scope and enforceability of patents; the actions of competitors; dependence upon third parties; product liability; and the need for further financing. These and other risks are detailed in the Company's reports filed from time to time under the Securities Act of 1933 and/or the Securities Exchange Act of 1934, including the sections entitled "Business," "Risk Factors," "Management's Discussion and Analysis of Financial Condition and Results of Operations" and "Other Events" in the Company's reports on Form 10-K for the year ended December 31, 1999, Form 10-Q for each of the first three quarters of 2000, Form 8-K for the month of August 1999, and Form S-3 filed in December 1999. You are encouraged to read these filings as they are made from time to time. They are available over the Internet from the SEC in its EDGAR database. Given the uncertainties affecting pharmaceutical companies in the development stage, current and prospective investors are cautioned not to place undue reliance on any such forward-looking statements, any of which may turn out to be wrong due to inaccurate assumptions, unknown risks, uncertainties or other factors. Both forward-looking statements and statements of historic fact must be understood in the context of the risks referred to above which characterize the Company's development stage business. The Company undertakes no obligation to update or revise the statements made herein or the factors which may relate thereto.