Cell Pathways Expands Study of Exisulind in Treatment of Children With APC; Company Also Notes Analysis of Phase III APC Trial Ongoing.

HORSHAM, Pa.--(BW HealthWire)--March 17, 1999--Cell Pathways, Inc. (Nasdaq:CLPA) today announced that it had initiated an open label Phase II efficacy study of its lead investigational drug (exisilund) as a treatment for precancerous colon polyps in children with adenomatous polyposis coli (APC).

The company also reiterated that it is continuing to evaluate the data from its Phase III study of exisulind in adults with APC.

The decision to expand pediatric studies of exisulind results from clinical analysis of the six children who participated in the initial Phase I pediatric safety study of that investigational drug, which commenced in July 1998 at Children's Hospital in Denver.

"Preliminary results suggest that exisulind is safe to use and warrants further study as a medical treatment for children with familial polyposis and Gardner Syndrome," said Edward Hoffenberg, M.D., principal investigator for the trial. The new trial will enroll 20 children, all of whom will receive exisulind therapy.

In February, Cell Pathways announced that a preliminary evaluation of the unblinded data from the Phase III trial of exisulind for the treatment of precancerous polyps in patients with APC suggested that the study did not achieve a statistically significant clinical response when compared to placebo. This initial observation was unexpected and inconsistent with the prior preclinical and clinical results observed with exisulind.

"Detailed evaluation of clinical trial data and patient records is time consuming," said Robert Towarnicki, president and chief executive officer of Cell Pathways. "In this case, it requires us to complete a detailed review of historical patient records from seven U.S. and three international clinical sites, including the translation of patient records from multiple foreign languages. We have also had to await receipt of laboratory assays performed by contract labs. We are moving as promptly as possible to complete the analysis."

Cell Pathways, Inc., headquartered in Horsham, is a pharmaceutical company focused on the research, development and commercialization of products to prevent and treat cancer.

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 planning, anticipation, 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 risk and uncertainties relate to, among other factors, the costs, delays and uncertainties inherent in basic pharmaceutical research, drug development and clinical trials; the uncertainty of obtaining regulatory approval, and the timing and scope of any approval received; acceptance by providers of healthcare reimbursement; the validity, scope and enforceability of patents; the actions of competitors; dependence upon third parties; product liability; and other risks detailed in Cell Pathways, Inc. reports filed under the Securities and Exchange Action of 1934, including a Registration Statement on Form S-4 filed in September 1998. The Company undertakes no obligation to update or revise the statements made herein."