In a move to launch its second product in the U.S., ILEX Oncology Inc. filed the first part of a rolling new drug application on Wednesday for Clofarabine to treat refractory or relapsed acute leukemia in children.

"The beginning of an NDA filing is truly the ultimate goal," said Jeff Buchalter, CEO and president of San Antonio-based ILEX. "Campath is on the market now, and the Clofarabine NDA gives us another drug moving toward a final regulatory decision."

Clofarabine received fast-track designation in September for refractory or relapsed pediatric acute lymphoblastic leukemia (ALL).

Interim Phase II results presented in May at the American Society of Clinical Oncology meeting showed an overall response rate of 28 percent for Clofarabine in heavily pretreated children with ALL or acute myelogenous leukemia (AML). The overall response rate included complete remission, complete marrow remission in the absence of platelet recovery and partial remission. The Phase II trials were initiated in 2002 and remain open, continuing to enroll new patients.

"We've seen significant activity in these children who have really failed whatever's left," Buchalter told BioWorld Today. "They have a poor prognosis."

A pivotal Phase II study was sufficient for the NDA filing, and a Phase III trial is not needed.

"These are children with really no alternative therapy to go on, so it's impossible to randomize a study," Buchalter said. "There's nothing to randomize them on."

Clofarabine is a next-generation purine nucleoside antimetabolite that affects DNA synthesis. ILEX licensed exclusive development, marketing and manufacturing rights for Clofarabine in the U.S. and Canada from London-based Bioenvision Inc. (See BioWorld Today, March 16, 2001.)

The Southern Research Institute in Birmingham, Ala., which licensed the product to Bioenvision, discovered the drug.

As part of its deal with Bioenvision, ILEX will receive royalty payments on Clofarabine sales outside North America, and ILEX will pay Bioenvision royalties on sales within North America. Clofarabine is not marketed anywhere in the world yet.

Buchalter said that while priority review usually means an FDA decision could come six months after the NDA filing is complete, it is the FDA's "discretion as to how long they take." He expects the filing will be complete within the first half of 2004, but did not want to make a prediction on a possible launch time.

In the meantime, ILEX will develop Clofarabine for other indications.

"We have a very broad and extensive development plan for this drug," Buchalter said. Early next year the company will unveil its plans to develop Clofarabine for adult acute leukemias, as well as large solid cancers, such as colon cancer, he added.

Besides Clofarabine, the company has three other products in clinical trials. Elfornitine is in Phase III for bladder cancer and Apomine is in Phase II work in women with osteoporosis. Buchalter said the accrual of the Phase II trial should be completed by the end of the year.

ILEX also has ILX-651 in a Phase II trial begun earlier this month in patients with recurrent or metastatic melanoma. The trial is being conducted at 19 U.S. sites. ILX-651 is a third-generation synthetic pentapeptide analogue of the natural substance dolastatin. It targets tubulin and has shown significant antitumor activity in preclinical models. ILEX expects to begin a Phase II trial in non-small-cell lung cancer later this year.

ILEX received marketing approval of Campath (alemtuzumab) to treat leukemia in May 2001. It is indicated for refractory chronic lymphocytic leukemia patients, but ILEX is studying the drug for other indications, such as multiple sclerosis and non-Hodgkin's lymphoma.

On Wednesday, the company reported that the global net sales of Campath for the first nine months of 2003 were $53.3 million, compared to $32.4 million in the first nine months of 2002. Campath is partnered with Berlin-based Schering AG and its U.S. affiliate Berlex Laboratories Inc., of Montville, N.J. Millennium Pharmaceuticals Inc., of Cambridge, Mass., co-developed the drug with ILEX. ILEX's share of the Campath profit and royalty revenues came to $17.6 million for the first nine months of the year, compared to $8.3 million for the same period last year.

As of Sept. 30, ILEX had $228.6 million in cash and marketable securities. It completed a public offering in the summer that raised $87.5 million net for the company. (See BioWorld Today, July 31, 2003.)

ILEX's stock (NASDAQ:ILXO) rose 13 cents Wednesday to close at $19.84.

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