By Lisa Seachrist

Washington Editor

The FDA informed Aronex Pharmaceuticals Inc. that the company's lead drug, Atragen, won't be considered by the Oncologic Drugs Advisory Committee on Sept. 17 due to deficiencies in the new drug application (NDA).

The news sent shares of The Woodlands, Texas-based company's stock (NASDAQ:ARNX) down $2.437 Thursday, or 35 percent, to close at $4.50.

The agency failed to detail the deficiencies it had uncovered in its Wednesday conference call with the company because it said the review wasn't finished. Nevertheless, the FDA deemed the issues significant enough to remove the product from the advisory committee's agenda. The company filed an NDA in December to market Atragen for the treatment of patients with acute promyelocytic leukemia (APL).

"We are obviously deeply disappointed about the decision," said Geoffrey Cox, chairman and CEO of Aronex. "Until we hear more from the FDA we won't know how to proceed. We remain very committed to the clinical utility of the drug."

Cox said the company will be meeting with the agency as soon as possible to understand the problems the FDA has with the NDA. In the meantime, the company will proceed with its European filing in the same indication.

Atragen, a vitamin-A derivative, is an injectable liposomal formulation of all-trans retinoic acid (tretinoin). The drug is intended for APL patients who can't take the oral formulation of the drug for reasons such as inability of the intestine to absorb the drug or the need for intravenous delivery.

The company estimated 10 percent to 20 percent of the 2,000 to 2,500 patients who develop APL need intravenous administration of tretinoin.

Atragen works by inducing cell differentiation and eventually apoptosis. It can be used in combination with chemotherapy.

The APL submission was based on Phase II data. Cox doesn't believe the fact that the company submitted only Phase II data is the likely problem.

"We filed Phase II data as a result of full discussion with the FDA," Cox said. "We believe we met all the criteria which were previously discussed."

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. (See BioWorld Today, June 29, 1999, p. 1.)

The non-Hodgkin's lymphoma indication would be a much larger indication than what is sought with this APL NDA, encompassing as many as 55,000 patients. The company also is exploring the drug as a therapy for superficial bladder cancer and renal cell carcinoma.

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

Cox said the company intends to work through the issues FDA has with Atragen to ensure the product's ultimate approval.

"We are going to maintain a good working relationship with the FDA in order to move this drug through approvability," Cox said. "We are committed to this drug and we are committed to APL."