By Randall Osborne

West Coast Editor

With three deals signed to market Aptosyn (exisulind), its drug for familial polyposis, Cell Pathways Inc. heard late Friday from the FDA that a "not approvable" letter was forthcoming - news that sent the company's stock (NASDAQ:CLPA) tumbling 69 percent Monday, closing at $9.312, down $20.687.

The FDA told Horsham, Pa.-based Cell Pathways the agency had completed its first review of the company's new drug application (NDA). Company officials were in Japan, and could not be reached for comment, but said in a conference call that a meeting would be sought with the FDA as soon as the letter is received.

The firm is not widely covered by analysts, but Heather Morris, with Philadelphia-based Janney Montgomery Scott LLC, downgraded her rating of the stock to "hold," writing in a report that "significant uncertainty surrounds the status of Aptosyn's filing and the potential for significant increase in time until any approval may be seen."

Aptosyn is the lead drug from Cell Pathways' platform called Selective Apoptotic Anti-Neoplastic Drugs, which inhibit a novel form of cyclic GMP phosphodiesterase and selectively induce apoptosis (programmed cell death) in cells that are cancerous or growing abnormally.

The company filed its NDA just over a year ago. In a small Phase III study that tested Aptosyn in patients with polyposis, which puts patients at high risk for colon cancer, Cell Pathways failed to reach statistical significance last year, but the company later found the subjects had generated more polyps than expected, so positive results were deemed harder to come by and the failure was not deemed as serious. (See BioWorld Today, Feb. 3, 1999, p. 1; and June 16, 1999, p. 1.)

Analyzing the data further, the company found that, of 34 patients who did develop the number of polyps expected, 15 Aptosyn patients showed a reduction of more than 50 percent in new polyp formation, compared to those on placebo.

Early this year, the company signed three agreements for sales and distribution of Aptosyn, which also is being tested in other cancer indications. (See BioWorld Today, Jan. 27, 2000, p. 1.)

Cell Pathways has an ongoing 282-patient Phase II/III study in sporadic polyps, which could support the NDA, but the data remain blinded in that study. Another Phase II, open-label trial is evaluating Aptosyn in juveniles. The company has enough cash to last about one year, Morris wrote in her research note.

The company said in the conference call that, although it will not be getting income from Aptosyn as soon as expected, the financial picture for the firm should remain largely unchanged. In any case, Cell Pathways has potential cash from at least one solid source other than investors. This summer, it obtained rights from Parsippany, N.J.-based Aventis Pharmaceuticals Inc. to market the approved non-steroidal antiandrogen Nilandron (nilutamide) as a hormonal, testosterone-blocking treatment for prostate cancer. Sales have ranged from approximately $6 million to $14 million per year. (See BioWorld Today, July 6, 2000, p. 1.)

Meanwhile, 41 patients now receiving Aptosyn in extension trials will continue with the drug, the company said.

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