Cell Pathways to Conduct Cancer Studies With Aptosyn and Gemzar.

Business Editors/Health & Medical Writers

HORSHAM, Pa.--(BW HealthWire)--Feb. 29, 2000

Cell Pathways, Inc. (Nasdaq: CLPA) today announced that Eli Lilly and Company and Cell Pathways, Inc. plan to cooperate in supporting clinical trials to investigate the therapeutic potential of Aptosyn(TM) (exisulind) in combination with Lilly's Gemzar(R) (gemcitabine HCl).

The trials will investigate the use of Aptosyn(TM) and Gemzar(R) for the treatment of pancreatic, non-small cell lung, and bladder cancers. In the U.S., Gemzar already is approved in the treatment of pancreatic cancer and non-small cell lung cancer (the latter in combination with cisplatin).

Cell Pathway's lead drug, Aptosyn(TM), is an oral anti-cancer medication that has a unique mechanism of action, which has none of the severe side effects seen with traditional chemotherapeutic agents, such as neutropenia, nausea, vomiting, hair loss and weight loss.

Initial Phase I safety studies will evaluate escalating doses of Aptosyn(TM) in combination with a standard regimen of Gemzar (R). The companies may then pursue Phase II efficacy studies of the drug combination designed to support future large scale studies and potential product registration.

"Patients with pancreatic, bladder, and non-small cell lung cancers have limited therapeutic options and new therapies are critically needed," said Rifat Pamukcu, M.D., Chief Scientific Officer and Senior Vice President of Research and Development at Cell Pathways. "We are interested in studying the combination of Aptosyn(TM), and Gemzar(R) to see what the combination may offer these patients. This is one more step in Cell Pathways efforts to develop new treatment options for oncology patients."

Promising data from the University of Wisconsin Medical School on the activity of the combination of exisulind and gemcitabine provide the initial clinical rationale for this cooperation. "The preclinical studies with exisulind and gemcitabine showed that both compounds were active against human lung tumors in cell culture. Moreover, the combination of the two drugs inhibited tumor growth more than either drug alone. Based on these promising preclinical results, we are very encouraged to take the combination of exisulind and gemcitabine into human clinical trials," said Joan H. Schiller, M.D., professor in the Department of Medicine, University of Wisconsin Medical School.

"By working with a major pharmaceutical company, we will explore potential new uses, patient benefits, and market opportunities for Aptosyn(TM)," said Robert J. Towarnicki, President and Chief Executive Officer of Cell Pathways. "This work with Lilly, as well as our work with Aventis, and Roche, are examples of the commitment Cell Pathways has for building an oncology franchise in the prevention and treatment of cancer."

Cancer is most commonly treated today with a combination of therapeutic agents in hopes of achieving better results than can be obtained with any one product alone. Aptosyn(TM) has a novel mechanism of action that research has demonstrated to be complementary to that of a number of important chemotherapeutic drugs. Therefore, Aptosyn(TM) offers not only the potential for synergistic activity with chemotherapeutic drugs, but also for avoiding overlapping toxicities.

Aptosyn(TM) (exisulind) is the first product candidate from a novel class of compounds under development by Cell Pathways, called Selective Apoptotic Anti-Neoplastic Drugs (SAANDS). SAANDS inhibit cyclic GMP phosphodiesterase and selectively induce apoptosis (programmed cell death) in abnormally growing precancerous and cancerous cells. Because SAANDs do not induce apoptosis in normal cells, they do not produce the serious side effects normally associated with traditional chemotherapeutic agents. They also do not inhibit cyclooxygenase (COX I or COX II) and have not exhibited the gastric and renal toxicities reported to be associated with non-steroidal anti-inflammatory drugs (NSAIDs), including the COX II inhibitors. A New Drug Application for Aptosyn(TM) as a treatment for patients with familial adenomatous polyposis, a precancerous condition that often leads to colon cancer, is currently under review by the U.S. Food and Drug Agency (FDA). The compound is also undergoing further clinical evaluation in a variety of additional precancer and cancer indications.

Cell Pathways, Inc., headquartered in Horsham, Pennsylvania, is a development stage pharmaceutical company focused on the research, development and commercialization 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 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, 1998, Form 10-Q for each of the first three quarters of 1999, Form 8-K in the month of August 1999, and Form S-3 filed in December 1999. Given these uncertainties, 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.