Cell Pathways to Conduct Cancer Studies With Aptosyn and Roche's Xeloda.

Business Editors/Health &Medical Writers

HORSHAM, Pa.--(BW HealthWire)--Feb. 2, 2000

Cell Pathways, Inc. (Nasdaq:CLPA) today announced it will conduct clinical trials investigating the therapeutic potential of Aptosyn(TM) (exisulind) in combination with Roche Laboratories Inc.'s Xeloda(R) (capecitabine). The trials will investigate the use of Aptosyn(TM) and Xeloda(R) combinations in the treatment of breast and colorectal cancers. Cell Pathways' 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.

The initial trials will be Phase I safety studies to evaluate escalating doses of Aptosyn(TM) in combination with a standard regimen of Xeloda(R). Upon successful completion, Cell Pathways and Roche will pursue Phase II efficacy studies of the drug combination. These trials will be designed to support future large-scale studies and potential product registration. Currently, a Phase I/II study is in development at M.D. Anderson Cancer Center, Houston, Texas to evaluate the safety and efficacy of Xeloda(R) and Aptosyn(TM) in patients with previously treated metastatic breast cancer.

&uot;We are excited to evaluate the combination of Aptosyn(TM) and Xeloda(R) in patients with breast and colorectal cancers,&uot; said Rifat Pamukcu, M.D., chief scientific officer and senior vice president of research and development at Cell Pathways. &uot;The combination of Aptosyn(TM) with Xeloda(R), a well-tolerated oral chemotherapeutic agent, should provide enhanced activity with little toxicity. Additionally, this is a completely oral regime making it an easy to use out-patient treatment. Xeloda(R) is currently the only approved agent for the treatment of advanced breast cancer that has failed to respond to taxane or anthracycline-based therapies. Xeloda is also growing in use for the treatment of colorectal cancer making a study of its use with Aptosyn(TM) of particular interest.&uot;

&uot;This is our second collaboration with a major pharmaceutical company where we will jointly explore potential new uses, patient benefits, and market opportunities for Aptosyn(TM), while retaining all of our product rights,&uot; said Robert J. Towarnicki, President and Chief Executive Officer of Cell Pathways. &uot;Relationships like this one and our previously announced collaboration with Aventis, where we are exploring the combination of Aptosyn(TM) and Taxotere(R) in a series of cancer indications, are an integral part of Cell Pathways' strategy for building an oncology franchise encompassing the treatment and prevention of cancer.&uot;

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 the potential not only 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 &uot;forward-looking statements&uot; 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 &uot;Business,&uot; &uot;Risk Factors,&uot; &uot;Management's Discussion and Analysis of Financial Condition and Results of Operations&uot; and &uot;Other Events&uot; 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 for 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.