ImClone and Erbitux (cetuximab) partner Bristol-Myers Squibb plan to consult with the FDA on a "registrational submission" for the oncologic in metastatic colon cancer based on "the totality of the results" from two Phase III trials, the companies said Nov. 6.

Data from the first trial, which compared the EGFR inhibitor plus best supportive care to best supportive care alone in 572 patients with refractory disease, met its primary efficacy endpoint, showing a statistically significant improvement in overall survival, the companies announced.

"These are the first data of an anticancer therapy to demonstrate overall survival in this refractory treatment setting," the companies pointed out in the announcement.

Data from a second Phase III trial, testing Erbitux as a combination therapy with irinotecan, were not as clearly promising. In the second randomized study, Erbitux or Erbitux with irinotecan was randomized to approximately 1,300 patients whose disease was not responding to first-line oxaliplatin-based chemotherapy.

The primary endpoint was overall survival; upon disease progression the study was stopped and further treatment was at the discretion of the physician.

Though "the primary endpoint of overall survival was not met," secondary endpoints of progression-free survival and response rate "strongly favored" the combination therapy, the sponsors assert.

"Efforts to interpret these confounded results are ongoing," the companies said. A preliminary data review found that "a considerable number of patients" randomized to irinotecan crossed over to either the combination or Erbitux alone after failing irinotecan.

The companies said they would share the full data analysis at an unnamed 2007 scientific meeting.

The Erbitux data could cast a shadow on efforts by Amgen to win new colon cancer indications for its EGFR inhibitor Vectibix (panitumumab). While Erbitux' stumble could open the door for Vectibix, the results might also suggest a class-wide difficulty in the indication.

Vectibix was approved in September for treatment of patients with metastatic colorectal cancer following standard chemotherapy (¹ Also see "Amgen Vectibix Approved For Metastatic Colorectal Cancer" - Pink Sheet, 27 September, 2006.). It competes with Erbitux in that space.

Amgen is testing Vectibix in combination with Genentech's VEGF inhibitor Avastin (bevacizumab) for front-line use in colon cancer, and release of some response rate data is anticipated in January. Data from a Phase III study of Erbitux in front-line patients is likely to be available early in the first half of 2007.

ImClone has been in a protracted legal battle with the Israeli firm Yeda Research and Development Company over a patent that covers the use of an anti-EGFR antibody used in combination for chemotherapy (² Also see "Erbitux Patent Holder Yeda Responds to ImClone Suit" - Pink Sheet, 1 November, 2006.).

- Shirley Haley (s.haley@elsevier.com)

Erbitux Colon Cancer Data “Encouraging,” ImClone Says

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