ASCO GI: EGFR Inhibitors Demonstrate Efficacy in Gastrointestinal Malignancies

ORLANDO, Jan. 29 -- Epidermal growth factor receptor inhibitors (EGFR) vary in their efficacy in gastrointestinal cancers, researchers here reported.

"We know that a subgroup of patients are helped by drugs such as panitumumab (Vectibix) but what we don't have a good handle on is exactly who will benefit," said J. Randolph Hecht, M.D., a clinical professor of medicine and director of the University of California Los Angeles Gastrointestinal Oncology Program.

Dr. Hecht chaired an industry-sponsored satellite symposium, Impact of EGFR-Targeted Therapies on Management of Carcinoma of the Colon and Rectum, which was presented in conjunction with a gastrointestinal cancers symposium here.

"Perhaps more importantly than who is going to benefit, it is more pressing to find out who will be adversely affected by these medications," he added.

One well-recognized sign of response to EGFR inhibition is an acne-like rash.

Marc Peeters, M.D., Ph.D., of University Hospital in Ghent, Belgium, said researchers were still unsure of the exact mechanism of the rash, but he noted that EGFR receptors are present in a number of organs in the body-including the skin.

The rash can be embarrassing and in some patients. For example the rash can be severe in Asian-Americans. While physicians often regard the rash as an encouraging sign of efficacy, it can have an adverse effect on quality of life, he said.

He said researchers were also investigating ways of combining EGFG inhibitors with other targeted agents. "No one expects this type of cancer to only be a 'one-hitter.' Right now it would seem the best approach for future research will be with a combination of different drugs being used in the best ways possible."

The lead-off talk in the seminar, EGFR Signaling Pathway: Predictive and Prognostic Implications in the Management of Colorectal Cancer, was presented by Axel Grothey, M.D., a Mayo Foundation scholar at the Mayo Clinic College of Medicine in Rochester, Minn.

Dr. Grothey described studies aimed at determining which patients would benefit and who would be adversely affected by treatment.

Other speakers included Howard Hochster, M.D., a professor of medicine, at the New York University Cancer Institute, who discussed clinical trials of anti-EGFR monoclonal antibodies in gastrointestinal malignancies, and Chris Takimoto, M.D., Ph.D., an associate professor of medical oncology at the University of Texas Health Science Center at San Antonio, who addressed combination therapy.

The Gastrointestinal Cancers Symposium was jointly sponsored by American Society of Clinical Oncology, the American Society for Therapeutic Radiology and Oncology, the American Gastroenterological Association Institute, and the Society of Surgical Oncology.