By Matthew Willett

Abgenix Inc. and Immunex Corp. said they will initiate a Phase II tolerability and efficacy trial of the monoclonal antibody ABX-EGF as a monotherapy against kidney cancer.

The 80-patient North American trial will evaluate multiple doses of the antibody and its efficacy. Abgenix, of Fremont, Calif., and Immunex, of Seattle, joined forces on ABX-EGF development in July. (See BioWorld Today, July 28, 2000.)

ABX-EGF is a fully human antibody created with Abgenix¿s XenoMouse technology that¿s directed against the human epidermal growth factor receptor (EGFr), a receptor that lies on the outer surface of many cells. This receptor is a prime target for anticancer agents because it is overexpressed in a large number of the most common human tumor types.

Immunex¿s executive vice president and chief technology officer, Doug Williams, said ABX-EGF is exciting as an anticancer agent in many indications because of its target.

¿There¿s a very high percentage of overexpressed EGF receptors, the target of this antibody,¿ Williams said. ¿Thirty percent to 90 percent [of cancers] will overexpress this receptor, and within almost every solid tumor category there¿s a very high percentage of patients who could benefit. It includes all the biggies: non-small-cell lung, pancreatic, head and neck, renal cancers; the list goes on and on.¿

The fact isn¿t lost on Abgenix CEO Scott Greer, either, and he added that the companies will pursue several avenues of ABX-EGF development.

¿The EGF receptor target is overexpressed in a number of solid tumors: lung, breast, bladder, prostate, colorectal, head and neck cancers, a whole panoplasia of tumors,¿ Greer told BioWorld Today. ¿All of those tumors are excellent candidates for this therapy, and we¿re looking at Phase II studies for a number of those.¿

The initial Phase II test will carry tumor shrinkage as an endpoint, and could support regulatory filing.

¿I think there¿s an opportunity with cancer to gain approval with robust Phase II data, but it would depend on how good the data is,¿ Williams said. ¿This shows how strongly we feel about the benefit the therapeutic provides, but it would be premature to determine whether we¿ll go forward on a filing or whether we¿ll go forward with a more traditional approach and into a Phase III trial. We¿ll try to move it along as quickly as we possibly can.¿

Williams said it could be six to nine months before the Phase II trial completes accrual. Data from the ongoing Phase I trial, however, will be available shortly.

¿I can tell you that the [Phase I] data will be presented at ASCO [the American Society of Clinical Oncology meeting in May],¿ Williams said. ¿The announcement that we¿re moving forward into Phase II should lead you to believe that there were no show-stoppers in terms of safety issues that were uncovered in this study or in this data. We¿re confident about moving forward, and that¿s what we¿re going to do, and the Phase I data will be forthcoming at ASCO.¿

Meanwhile, the companies will focus on kidney cancer, a pervasive cancer with little in the way of effective treatments.

¿Kidney cancer is a very different tumor to treat,¿ Greer said. ¿There are about 12,000 deaths each year in the U.S. caused by kidney cancer, and another 30,000 or more diagnosed each year. Today there are not very effective treatments for these patients. There are biologics like IL-2 [interleukin-2] that are being used, but their success rate is relatively modest. This is an area where there is a clear therapeutic need.¿

Between the therapeutic need and the promise of EGFr, both companies are excited about the antibody¿s potential. One could gauge the potential ABX-EGF carries by looking at its near-relative, HER-2.

¿It¿s a very hot area today, and to some extent this road is paved with Genentech¿s work with another EGF receptor, HER-2,¿ Greer said. ¿The success of the Herceptin product has made a number of folks recognize the importance of this receptor and developing inhibitors of it. The clinical research of those and the studies look very interesting ¿ it¿s an interesting target. It¿s too early to say it¿s proven, but it¿s clearly a very exciting opportunity.¿

Abgenix¿s stock (NASDAQ:ABGX) rose $5.68 Wednesday, or 20 percent, to close at $34.57. Immunex¿s shares (NASDAQ:IMNX) rose $1.921, a 13 percent gain, to close at $16.77.

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