Cell Pathways Completes Phase I Safety Assessment of Aptosyn and Weekly Taxotere in Solid Tumors; Initiates Phase II Trial in Non-Small Cell Lung Cancer.

Business Editors/Health & Medical Writers

BIOWIRE2K

HORSHAM, Pa.--(BW HealthWire)--Sept. 6, 2001

Cell Pathways, Inc., (Nasdaq:CLPA) today announced the completion of a Phase I safety assessment of a study of Aptosyn(TM) (exisulind) and weekly Taxotere(R) (docetaxel) treatment in patients with a variety of solid tumors. The company also announced, based on these initial results, that it has advanced its study of this treatment regimen to a Phase II clinical trial in patients with advanced non-small cell lung cancer (NSCLC) at the University of Colorado Cancer Center and the University of Chicago. The treatment regimen in this Phase II study differs from that of the Phase III trial in NSCLC already underway.

Data from the Phase I trial suggests that patients generally tolerated the daily Aptosyn(TM)/weekly Taxotere(R) combination regimen well. Moreover, seven (7) of the 15 treated patients exhibited stable disease. "We observed little toxicity for the combination regimen beyond that expected with Taxotere(R) alone," commented S. Gail Eckhardt, M.D., principal investigator for the Phase I study at the University of Colorado Cancer Center. "The results of this initial safety study clearly support moving investigations of this regimen forward in a variety of solid tumor types."

The Phase II portion of the study is an open-label trial evaluating daily Aptosyn(TM) with six weekly treatments of Taxotere(R) in patients with advanced non-small cell lung cancer (NSCLC). Patients responding to and tolerating the regimen will be eligible to continue on treatment.

"Taxotere(R) is the only currently approved therapy for second-line treatment of non-small cell lung cancer," said Paul Bunn, M.D. of the University of Colorado Cancer Center. "Preclinical studies of implanted human NSCLC in an animal model have demonstrated synergistic activity for the Aptosyn(TM)/Taxotere(R) combination compared to either drug alone. In addition, clinical research reported by others regarding the weekly administration of taxane drugs suggests this dosing frequency might offer particular benefits. As a result, we are very excited about furthering studies of this combination in NSCLC patients."

"This study is an expansion of our commitment to studying Aptosyn(TM) and Taxotere(R) in NSCLC beyond our previously initiated Phase III trial of daily Aptosyn(TM) with Taxotere(R) administered every three weeks. The results of the Phase II study will add to our understanding of how the combination of the drugs behave under the two dosing regimens of Taxotere(R) used in clinical practice," said Rifat Pamukcu, M.D., chief scientific officer of Cell Pathways, Inc.

Aptosyn(TM) (exisulind) is Cell Pathways' lead SAAND (selective apoptotic antineoplastic drug) compound, designed to treat cancer by selectively triggering programmed cell death, or apoptosis, in abnormal cells but not normal cells. Preclinical research studies in a variety of tumor models suggest the combination of Aptosyn(TM) and Taxotere(R) has synergistic anticancer activity. Thus Cell Pathways is exploring this investigational drug regimen in human clinical trials against multiple tumor types. The company began testing daily Aptosyn(TM) with Taxotere(R) every three weeks in a double-blind, placebo-controlled Phase III trial in patients with relapsed or refractory non-small cell lung cancer in March 2001. The company is also planning a Phase III trial in patients with hormone-refractory prostate cancer.

Cell Pathways, Inc., headquartered in Horsham, 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 web site at http://www.cellpathways.com.

Certain statements made in this release, and oral statements which may be made with respect to this release, 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, 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 risk that the company does not conduct the clinical studies it may have planned to conduct or does not pursue development plans it may have planned to pursue; uncertainty that additional studies, if any, may not be positive; uncertainty of obtaining regulatory approval of any compound for any disease indication; the risks that clinical studies do not result in the safety and efficacy necessary to obtain regulatory approvals; the risks of conducting clinical trials of our drugs in combination with other drug therapies; the absence of approved products; history of operating losses and the need for further financing; early stage of development; the costs, delays and uncertainties inherent in scientific research, basic pharmaceutical research, drug development, clinical trials and the regulatory approval process, with respect to both our current product candidates and our future product candidates, if any; dependence on the development and market acceptance of one or more of our product candidates for one or more significant disease indications; uncertainty and adversity arising from the action of the U.S. Food and Drug Administration in issuing a "not approvable" letter with respect to the New Drug Application submitted for Aptosyn(TM) (exisulind) for familial adenomatous polyposis; the timing and scope of any approval which might be received, or any failure to receive approval, for any compound for any indication in the future whether due to adequacy of the development program, changing regulatory requirements or otherwise; the commercial risk and risk of liability in promoting Nilandron(R) (nilutamide) manufactured by Aventis Pharmaceuticals; the risk that the Company may enter into, or may fail to enter into, licensing, partnership or other collaborative arrangements which accord to other companies rights with respect to one or more Company compounds or in which the Company acquires new rights and obligations; the volatility of the market price of our common stock; our ability to sell securities registered under the shelf registration statement; acceptance of any product candidates by physicians and providers of healthcare reimbursement; the actions of competitors; the pace of technological changes in the biopharmaceutical industry; dependence upon third parties; the validity, scope and enforceability of patents; the risk of our pending class action securities litigations; potential product liability claims; and availability and adequacy of insurance. These and other risks are detailed in our reports filed from time to time under the Securities Act and/or the Securities Exchange Act, including the sections entitled "Business," "Risk Factors," "Management's Discussion and Analysis of Financial Condition and Results of Operations" and "Other Events" in our annual reports on Form 10-K, quarterly reports on Form 10-Q and periodic reports on Form 8-K and in such registration statements on Form S-3 as we may file from time to time. You are encouraged to read these filings as they are made. They are available over the Internet from the SEC in its EDGAR database at http://www.sec.gov and from the Company. Given the uncertainties affecting pharmaceutical companies in the development stage, you are cautioned not to place undue reliance on any forward-looking statements, any of which may turn out to be wrong due to inaccurate assumptions, unknown risks, uncertainties or other factors. No forward-looking statement can be guaranteed; actual future results may vary materially. Both forward-looking statements and statements of historic fact must be understood in the context of the risks referred to above which characterize our development-stage business. We undertake no obligation to update or revise the statements made herein or the risk factors that may relate thereto.

Editors Note: Aptosyn(TM)is a trademark of Cell Pathways, Inc. and Taxotere(R)is a registered trademark of Aventis Pharmaceuticals Inc.