Cell Pathways' Aptosyn Commercialization Plan Remains On Track.

Business Editors/Health & Medical Writers

HORSHAM, Pa.--(BW HealthWire)--Feb. 22, 2000

Cell Pathways, Inc. (Nasdaq:CLPA) today affirmed that preparations for commercializing Aptosyn(TM) (exisulind), the Company's lead investigational drug for the treatment of familial adenomatous polyposis (FAP), are proceeding as anticipated.

"Our interactions with the FDA, including our January 25th meeting, have been productive," said Robert J. Towarnicki, president and chief executive officer of Cell Pathways. "We will continue to respond expeditiously to any requests for additional information or clarification that may arise during the review process."

While the FDA review process continues, the Company has begun implementation of the arrangements under its previously announced third party contracts with respect to the recruitment and education of a sales force and the distribution and reimbursement of the product.

The company is seeking FDA approval for the use of Aptosyn(TM) to regress and prevent precancerous colon polyps in patients with the inherited disease, familial adenomatous polyposis. During the Jan. 25 meeting with the FDA, CPI presented a comprehensive review of Aptosyn's efficacy and safety data, including data from all Phase I, II and III studies and their extensions covering over 3-1/2 continuous years and 450 patient-years of exposure to the drug. The FDA is continuing its detailed review of the data and is expected to have an end-of-review meeting with CPI. As previously announced, the company has been advised that the FDA will evaluate Aptosyn for approval without requiring input from its Oncologic Drugs Advisory Committee (ODAC).

In a Phase I polyp regression study commenced with funding from the National Cancer Institute in August of 1995, Aptosyn(TM) exisulind demonstrated a statistically significant dose-dependent prevention and regression response, as well as dose-dependent increase in rates of apoptosis. The results of this study, which were submitted to the FDA in 1997 and portions of which were recently published, provided the earliest indication of a dose-response effect for Aptosyn(TM) in the treatment of FAP. In the extensions of that study, which have included patients on Aptosyn(TM) for periods of up to 42 months, Aptosyn(TM) has demonstrated continued durable effect in the reduction of polyps and prevention of their occurrence. These findings were associated with a statistically significant increase in the rate of apoptosis in regressing adenomatous tissue.

In a Phase III polyp prevention study which concluded in January of 1999, Aptosyn(TM) demonstrated a statistically significant difference of approximately 50% in the new polyp formation rate between drug and placebo groups in the primary analysis of all eligible patients. In extensions of this study, after six months all patients who crossed over from placebo to Aptosyn(TM) showed a 58% reduction in polyp formation rate from what they had demonstrated during the prior year, while all patients continuing on Aptosyn(TM) further reduced their new polyp formation rate to 50% of what they had demonstrated during the prior year achieving approximately a 75% reduction in polyp formation over the eighteen months of treatment.

"All of the patients treated with Aptosyn(TM) in the Phase I/II and Phase III studies currently under my care, are free of any clinically significant polyps," commented Dr. Carol Burke of the Cleveland Clinic Foundation.

"Significant reductions in polypectomies have been consistently observed and sustained over long periods at clinical sites in the U.S., U.K., Sweden and Israel. This sustained reduction in the number of polypectomies is an important characteristic of any drug intended to be used for lifelong treatment in these patients," said Rifat Pamukcu, M.D., chief scientific officer and senior vice president of research and development at Cell Pathways.

While achieving clinically and statistically significant regression and prevention of polyps, Aptosyn(TM) continues to be well tolerated and to lack the adverse side effects associated with either standard chemotherapeutic agents or NSAIDs, including the COX-II inhibitors.

Since filing the NDA for Aptosyn(TM) in August 1999, Cell Pathways has entered into collaborations with Aventis (formerly Rhone-Poulenc Rorer) and with Roche for combination cancer therapy trials based on pre-clinical data suggesting that Aptosyn(TM) enhances the activity of a number of chemotherapeutic agents without increasing toxicity. In combination with Aventis' Taxotere(R), Aptosyn(TM) is planned to be tested against cancers of the breast, lung, prostate and pancreas. In combination with Roche's Xeloda(TM), Aptosyn(TM) is planned to be tested against cancers of the breast and colon.

About FAP

FAP is a relatively rare hereditary condition characterized by the development of hundreds to thousands of adenomatous polyps in the colon and rectum during adolescence and early adulthood. Experts consider adenomatous polyps to be precursor lesions to colorectal cancer. Left untreated, virtually all patients with FAP develop colorectal cancer by age 40-50. There are no drugs approved for the long-term regression and prevention of polyps in the care of FAP, and these patients have very few disease management options.

As FAP typically manifests itself during childhood and teenage years, the Company is studying the effect of Aptosyn in regressing and preventing colonic polyps in the pediatric FAP population

Millions of adults are afflicted with the related precancerous condition commonly referred to as sporadic colonic polyps. These patients are monitored on a regular basis and may produce one to ten polyps over periods of one to five years. Clinically significant polyps are removed by polypectomy. These sporadic colonic polyps are genetically and histologically similar to the polyps of FAP patients, but grow less rapidly and are far less numerous. Later this year the Company will complete a one-year clinical trial seeking to measure the ability of Aptosyn(TM) to achieve regression of sporadic colonic polyps in adults.

Cell Pathways, headquartered in Horsham, is a development stage pharmaceutical company focused on the research, development and commercialization of products 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 Dec. 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.