By Lisa Seachrist

Washington Editor

The FDA delivered a non-approvable letter late Friday to Aronex Pharmaceuticals Inc. for its lead product, Atragen.

In August, the agency informed Aronex during a conference call that deficiencies in the new drug application for Atragen as a therapy for acute promyelocytic leukemia (APL) would prevent the Oncologic Drugs Advisory Committee from considering the drug at its Sept. 17 meeting The non-approvable letter served as the first documentation of FDA's concerns. (See BioWorld Today, Aug. 6, 1999, p. 1.)

"We've been in limbo waiting for FDA to detail the nature of the deficiencies since the conference call in August," said Connie Stout, associate director for corporate communications for The Woodlands, Texas-based Aronex. "We've been staying in touch with the agency all along, but now we can start to address the deficiencies. We want to give them what they need."

Stout said the company would digest the contents of the letter and schedule a meeting with the agency to establish what the company needs to do in order to get Atragen back on track.

Atragen is an injectable liposomal formulation of all-trans retinoic acid (tretinoin), a vitamin A derivative. The drug is intended for APL patients who can't take the oral formulation of the drug. Atragen works by inducing cell differentiation and eventually apoptosis. It can be used in combination with chemotherapy.

Aronex has an ongoing study of the drug in patients with hormone-refractory prostate cancer and has recently expanded its Phase II study of the drug in patients with relapsed or refractory non-Hodgkin's lymphoma.

Aronex's stock (NASDAQ:ARNX) closed at $3.687 a share Monday, down 93.75 cents, or 20 percent. The stock had fallen 35 percent, to $4.50, when the FDA first informed Aronex of the deficiencies in August.