By Jim Shrine

Aronex Pharmaceuticals Inc. filed a new drug application (NDA) for Atragen, its liposomal injectable formulation of all-trans retinoic acid.

The NDA is the first for the 12-year-old company, which seeks approval of Atragen for treating acute promyelocytic leukemia (APL) patients who need tretinoin therapy but require intravenous administration. There are about 2,000 to 2,500 APL patients in the U.S. and Europe; perhaps 10 to 20 percent of those patients need intravenous administration.

"The fact that it's our first NDA is very important," Aronex's chairman and CEO, Geoffrey Cox, told BioWorld Today. "This is a stepping stone for us and starts to take the company into the transition of a fully operating company. We also are very interested in the opportunity retinoids present in broader fashion."

Aronex, of The Woodlands, Texas, has been in collaboration on Atragen since 1993 with Genzyme Corp., of Cambridge, Mass., but whether Genzyme will remain involved with the drug has not been decided, Cox said.

Under a March 1997 amendment to the original deal, Genzyme, which paid $2 million to Aronex in 1993, could get marketing rights by paying another $3 million. Aronex, though, could reacquire marketing rights by paying back the money to Genzyme.

Cox said Genzyme's main interest initially was in the development of Atragen for Kaposi's sarcoma, a market that has changed significantly since the development of HIV drug regimens. Cox said Aronex and Genzyme have not yet discussed whether Genzyme will exercise its commercialization rights.

Phase II Program Believed Sufficient

The NDA is based on Phase II trials of patients with APL, which affects blood-cell division, as well as earlier safety and Kaposi's sarcoma studies. The company believes the Phase II program will support an NDA filing.

The drug, a vitamin A derivative, induces cell differentiation and eventually apoptosis. It can be used in combination with chemotherapy, Cox said, and there is some evidence it represses expression of the signal transduction protein BCL-2.

The drug has been studied in about 200 patients, Cox said, but the company is not disclosing trial results, deferring instead to clinical investigators.

Atragen also is in Phase II studies for hormone-refractory prostate cancer and progressive non-Hodgkin's lymphoma.

Aronex last month registered for a public offering of 4.5 million shares. At the stock's (NASDAQ:ARNX) Monday closing price of $2.75, down $0.25, the offering would gross $12.38 million. As of Sept. 30, Aronex had cash and investments of $14.7 million and about 15.5 million shares outstanding. Its net loss for the first nine months of 1998 was $16.5 million.

Aronex's second product, Nyotran, is an injectable liposomal formulation of nystatin for treating fungal infections. Last month, the company signed a potential $40 million deal giving Abbott Laboratories, of Abbott Park, Ill., worldwide rights.

That deal involved an up-front payment to Aronex of $2.85 million, and the purchase of 837,989 Aronex shares for $3 million, at $3.58 per share. (See BioWorld Today, Nov. 17, 1998, p. 1.) n

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