Dr. Saltz and his colleagues evaluated cetuximab(Drug information on cetuximab) monotherapy
in 57 patients with colorectal cancer that had progressed on irinotecan(Drug information on irinotecan) or
irinotecan-based chemotherapy. All had tumors that were immunohistochemically
positive for EGFR. Treatment included diphenhydramine(Drug information on diphenhydramine) premedication plus a
cetuximab test dose on the first day of treatment. On that same day, patients
received a loading dose of 400 mg/m2
of cetuximab. Subsequently, they received weekly
doses at 250 mg/m2.
Partial responses were seen in 6 patients (10.5%), while 21 (36.8%) had stable disease or a minor response. Median time to progression was 50 days (range, 14 to 211 days). As of the ASCO presentation, median survival had not been reached.
Three patients experienced allergic reactions (two cases were grade 3-4). No neutropenia or thrombocytopenia has been seen. Other adverse effects included diarrhea (25% all grades, 0% grade 3-4) and nausea/vomiting (46% all grades, 4% grade 3-4).
One common toxicity was an acne-like rash (86% of patients, 18% grade 3-4), which investigators now consider a class effect for EGFR inhibitors. Dr. Saltz said it appears to peak 3 to 4 weeks after treatment and then improve spontaneously somewhat. There is no standard, confirmed treatment for this rash. "The application of antibiotics has been tried, but not systematically," he said.