With a revised agreement giving partner Immunex Corp. authority over development and marketing, Abgenix Inc. has a clearer plan for clinically advancing its cancer antibody, ABX-EGF.

Fremont, Calif.-based Abgenix will assume manufacturing responsibilities, as well as gain access to $60 million to fund its share of development costs. Abgenix formed the collaboration in July 2000 with Immunex, which is now a wholly owned subsidiary of Amgen Inc. (See BioWorld Today, July 28, 2000.)

"ABX-EGF is a very important molecule for us and we're excited by its prospects," said Sabrina Johnson, the director of external communications for Thousand Oaks, Calif.-based Amgen. "Both companies are really committed to bringing this molecule to market as quickly and efficiently as possible."

At the time of the original agreement, ABX-EGF was in a Phase I trial. It has since moved into five Phase II trials in colorectal, non-small-cell lung, prostate and renal cancer. Two of the trials are in colorectal cancer, one studying it as a monotherapy in advanced patients and the other studying it as a combination therapy with chemotherapy. The antibody also is in a Phase I trial in various tumors to determine a maximum tolerated dose.

"This would be a potential competitor to ImClone's antibody, Erbitux," said Ami Knoefler, Abgenix's director of corporate communications and investor relations.

ImClone Systems Inc., of New York, filed in August for FDA approval of Erbitux to treat colorectal cancer. The FDA recently accepted the application and granted it priority review. (See BioWorld Today, Aug. 15, 2003, and Oct. 14, 2003.)

Phase II data of ABX-EGF in colorectal cancer in which patients were given intravenous infusions weekly for an eight-week treatment cycle, up to six cycles, showed that four of 40 patients had partial responses and 22 had stable disease.

ABX-EGF is a fully human monoclonal antibody designed to target the epidermal growth factor receptor (EGFR), which is overexpressed in a variety of cancers. Erbitux is an IgG1 monoclonal antibody also designed to target EGFR.

Knoefler said it was premature to set a timeline for Phase III development or a potential launch, but analysts have said a launch could occur in late 2005 or early 2006.

Until then, Immunex will have decision-making authority for development and commercialization activities. Abgenix will manufacture both clinical and early commercial supplies of the antibody. The companies will continue to share program costs and later would share any profits equally.

To enable Abgenix to fund its 50 percent share of development and commercialization costs, Immunex is making available $60 million in advance money for the company. Abgenix can draw down the money after it contributes $20 million toward development costs in 2004.

"It gives us an additional vehicle for financing the drug's development outside of our existing cash resources," Knoefler told BioWorld Today.

The $60 million, plus interest, will be repaid out of profits from sales of ABX-EGF, unless commercialization is not reached.

"Abgenix is not obligated to repay any portion of the loan if ABX-EGF does not reach commercialization," Johnson said.

Aside from the ABX-EGF deal, Amgen and Abgenix have a technology licensing agreement through which Amgen has advanced an antibody product candidate into clinical trials, as well as a discovery and development agreement for antibodies to oncology targets.

Abgenix also is collaborating with Pfizer Inc. on the development of fully human therapeutic antibodies, two of which have entered clinical trials. And the company has one other product in a Phase I trial, ABX-MA1, to treat melanoma.

Abgenix's stock (NASDAQ:ABGX) fell $1.10 Wednesday to close at $13.48. Amgen's stock (NASDAQ:AMGN) dropped $1.48 to close at $65.33.

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