Cell Pathways to Market Aventis' Nilandron to Urologists; Hormonal Treatment Becomes First Product in Company's Bid to Build Cancer Franchise.

Business Editors/Health & Medical Writers

HORSHAM, Pa.--(BW HealthWire)--July 5, 2000

Cell Pathways, Inc. (Nasdaq:CLPA) today announced that the company has obtained the rights from Aventis Pharmaceuticals, Inc (NYSE:AVE) to market Nilandron(R) (nilutamide) to urologists in the United States and Puerto Rico for use in patients who suffer from prostate cancer.

Nilandron(R) is a hormonal therapy that blocks the production of testosterone and is used to increase survival time and promote disease regression in men with advanced prostate cancer.

Under the terms of the agreement Cell Pathways will receive a percentage of sales. The Company will utilize its relationship with Innovex, a leading provider of contract sales and marketing solutions in the healthcare industry, to hire and train a dedicated sales force to market Nilandron(R).

"We are very pleased to be able to promote Nilandron(R) to physicians engaged in the treatment of patients with prostate cancer," said Robert J. Towarnicki, president and chief executive officer of Cell Pathways. "This agreement represents an important and strategic first step in Cell Pathways' plans to establish a sales and marketing presence in cancer treatment. The Company is committed to becoming a force in the cancer market and continues to seek partners to help establish this presence."

"Using Cell Pathways to promote Nilandron(R) to physicians treating prostate cancer will help increase awareness of the product, one step in Aventis' commitment of reaching and improving the lives of prostate cancer patients in the United States," said Marty Duvall, vice president of oncology marketing, Aventis Pharma.

"Promoting this product will allow Cell Pathways to begin building a dedicated urology and oncology sales force," said Lloyd Glenn, vice president of sales and marketing. "We feel Nilandron(R) offers urologists several benefits such as convenient once-a-day dosing, a favorable side effect profile, a significant increase in survival time in post-orchiectomy patients, and is reasonably priced."

Glenn continued, "We also plan to supplement the sales force with a new managed care team which will enable Cell Pathways to develop relationships with key managed care organizations. This is a significant opportunity for our company."

Nilandron(R) is a nonsteroidal anti-androgen indicated for use in combination with surgical castration for the treatment of men with metastatic prostate cancer. Nilandron(R) binds strongly with androgen receptors and prevents the normal androgenic response, resulting in complete peripheral anti-androgenic activity when combined with surgical castration. Results of well-controlled clinical trials have demonstrated that Nilandron(R) in combination with surgical castration increases survival time and relieves metastatic bone pain.

Aventis Pharmaceuticals, headquartered in Parsippany, N.J., conducts the U.S. pharmaceutical business of Aventis Pharma AG, the pharmaceutical company of Aventis S.A. Aventis Pharmaceuticals is dedicated to treating and preventing human disease through discovery, development, manufacture and sale of innovative pharmaceutical products aimed at satisfying unmet medical needs.

Aventis Pharmaceuticals focuses on important therapeutic areas such as cardiology, oncology, infectious diseases, arthritis, allergies and respiratory disorders, diabetes and central nervous system disorders.

Cell Pathways, Inc., headquartered in Horsham, Pa., is a development stage pharmaceutical company focused on the research, development and commercialization of novel and unique medications to prevent and treat cancer. The Company's lead product, Aptosyn(TM) (exisulind) is currently under review by the U.S. Food and Drug Administration as a potential new therapy for the prevention and treatment of precancerous colon polyps in patients with familial adenomatous polyposis.

The company is also conducting further studies with Aptosyn, both on its own and in combination with conventional chemotherapeutics, for the treatment of a variety of cancerous and precancerous indications including the prevention of recurrent prostate cancer. For additional information on Cell Pathways, Inc., visit the Company's Web site 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. The Company undertakes no obligation to update or revise the statements made herein or the factors which may relate thereto.