Different patterns of toxicity after sequential administration of two anti-EGFR monoclonal antibodies.

A 40-year-old woman with liver metastasis resulting from colorectal adenocarcinoma suffered from a severe hypersensitivity reaction to cetuximab. She also experienced grade 3 skin toxicity. The administration of cetuximab was suspended, and she was offered panitumumab as an alternative treatment. Whereas she did not experience another infusion reaction, her skin rash worsened with the administration of panitumumab, a fully human anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibody (MAb).