By Matthew Willett

Ilex Oncology Inc. and Bioenvision Inc. will co-develop clofarabine, a nucleoside analogue being developed for hematological malignancies, including lymphocytic leukemia and acute myelogenous leukemia, in addition to solid tumors.

Ilex, of San Antonio, aims to develop clofarabine, a Phase II-stage 2-fluoro-2-chloro substituted purine nucleoside analogue, in the U.S. and in Canada, where it will have exclusive manufacturing and marketing rights. London-based Bioenvision will maintain exclusive marketing and manufacturing rights outside North America.

Ilex Chief Financial Officer Gregory Weaver called the deal a "strong addition to our cancer pipeline."

"That's where the company is focused in internal product development," Weaver told BioWorld Today. "[Clofarabine] is a nucleoside analogue that's shown positive results in the treatment of patients with several types of cancer, especially ALL [acute lymphocytic leukemia] and AML [acute myelogenous leukemia], and we think it's an exciting addition to our pipeline that's consistent with our strategy of in-licensing candidates that have already proven clinical benefit and that will enhance our pipeline."

Ilex will pay $1.1 million in an up-front licensing fee and pay milestones Weaver called "consistent with our other deals in this space."

Ilex also will make royalty payments in exchange for North American marketing and development rights to clofarabine, which was discovered by the Southern Research Institute in Birmingham, Ala., which licensed the drug to Bioenvision.

Ilex will receive royalty payments on clofarabine sales outside North America.

"We think it's a good addition," Weaver said. "It has a high probability for success, according to key opinion leaders in oncology. The clinical data and preclinical data are encouraging in leukemia and solid tumors, and it's a compound entering later-stage development that helps to consolidate our position in the leukemia space, where we consider ourselves leaders."

Ilex's lead anticancer candidate, Campath, remains in regulatory limbo. Ilex expected to hear of Campath's approval by late February, but after a letter from the FDA at that time, the wait was pushed back to the spring.

"The FDA has given us a letter, on Feb. 20, that gave us the expectation that we'd get a more definitive indication from the FDA within 60 days, which leads us to believe that on or around April 20 we'll have approval," Weaver said.

Late last year, the FDA's Oncologic Drugs Advisory Committee recommended approval of Campath, a monoclonal antibody for patients with chronic lymphocytic leukemia who have been treated with alkylating agents and who have failed fludarabine therapy. (See BioWorld Today, Dec. 15, 2000.)

Campath is being developed in a 50-50 joint venture with Cambridge, Mass.-based Millennium Pharmaceuticals Inc., which acquired its rights to Campath through its December 1999 acquisition of LeukoSite Inc., also of Cambridge. Richmond, Calif.-based Berlex Laboratories, a division of Berlin-based Schering AG, will distribute and market Campath. (See BioWorld Today, Aug. 25, 1999, and Dec. 27, 1999.)

"The two follow-up items the FDA brought to our attention regarding regulatory approval are the label package design and content and the specific design of the follow-on clinical trial," Weaver said. "For both we don't anticipate any significant problem with the FDA, and we're working closely with the FDA to expedite the process for approval."

The leukemia market is an important one to Ilex, Weaver said. "The ALL and AML leukemias are, we think, in excess of 10,000 patients in the U.S., and that's a significant market size in leukemia. That's what caught our interest," he said.

Separately, Ilex plans this year to complete accrual of a Phase III trial of eflornithine for superficial bladder cancer, and initiate another trial of the drug in combination with celecoxib in patients with familial adenomatus polyposis.

Also on tap for Ilex is the pivotal trial of Oxyprim, for gout in patients who cannot tolerate allopurinol, and the company will begin Phase II trials of ILX23-7553, its vitamin D3 analogue, as well as other studies. Of its 23 trials under way or starting, three are Phase III or pivotal Phase II trials, five are Phase II trials and 15 are Phase I trials, the company said.

Clofarabine could move forward in clinical development quickly if Ilex has its way, Weaver said.

"The plan is a proactive one to aggressively move this compound through its Phase II studies, and we're going to move aggressively on the Phase II study and submit an NDA as soon as possible, we hope within a three-year time frame," Weaver said.

As of Dec. 31, Ilex had $202.8 million in cash and cash equivalents. It logged a net loss of $7.9 million for the fourth quarter of 2000 (excluding $14.6 million of in-process research and development), compared to a net loss of $2.8 million in the fourth quarter of 1999.

Ilex's stock (NASDAQ:ILXO) fell 35.9 cents on the news Thursday, closing at $15.516. n