By Lisa Seachrist

Washington Editor

GAITHERSBURG, Md. - An FDA advisory panel unanimously endorsed Orphan Medical Inc.'s Busulfex as a conditioning agent to be used in bone marrow transplantation to treat chronic myelogenous leukemia (CML).

The Oncologic Drugs Advisory Committee voted 15-0 to recommend the agency grant marketing approval to Busulfex for effectively destroying a patient's bone marrow prior to receiving a bone marrow or stem cell transplant for the treatment of CML. The committee wanted more information on using the drug in transplants for the treatment of other blood cancers before offering its recommendation.

"We're very pleased with the committee's recommendation," said John Howell Bullion, CEO of the Minneapolis-based company. "CML is where the data were, so we were expecting that. With the other [indications] we need more data, and we are prepared to get that."

Busulfex was granted priority review by the agency on Aug. 4, 1998, which obligates the agency to make a decision on the drug by Feb. 4.

Bone marrow transplantation and stem cell transplantation are the treatments of choice for a number of diseases, including leukemias, lymphomas and other hematologic and non-hematologic cancers. The procedures offer cure for some and longer survival for others. In 1999, about 20,000 people will have bone marrow transplants in the U.S.

Bone marrow transplantation requires that a patient undergo "conditioning," or myeloablative therapy, to eliminate the cells in their bone marrow, allowing the transplanted cells the opportunity to engraft. Patients receive either total body irradiation or a combination of the chemotherapy agents busulfan and cyclophosphamide to achieve that result.

Oral busulfan, however, requires that already-nauseated patients take a large number of pills every six hours for several days. As a result, patients get a wide range of dosages of oral busulfan. Busulfex is an injectable formulation of busulfan solubilized with dimethyl acetamide polyethylene glycol, which Orphan Medical designed to address this issue.

In two Phase II studies of the drug, the company showed that patients receiving 0.8 milligrams/kilogram infusions of Busulfex every six hours for four days beginning seven days before the transplant not only received their entire scheduled dose of the drug, but all patients had their bone marrow ablated and the new graft take. The trials were conducted in high-risk patients with advanced hematologic malignancies.

The committee unanimously found that the Busulfex is just as effective as oral busulfan in conditioning patients for bone marrow transplant.

The FDA is not bound by the decisions of its advisory panels, but usually chooses to follow them. Should the agency approve the drug, the company intends to make it available as soon as possible.

"We are looking forward to continuing to work with the agency to get an approval for Busulfex," Bullion said. "And we are prepared to move very quickly after that approval."

Approximately 20 percent of all bone marrow transplants use oral busulfan to condition patients for bone marrow transplantation.

Orphan Medical's stock (NASDAQ:ORPH) closed Wednesday at $8.625, down 87.5 cents per share. n