Background: The epidermal growth factor receptor (EGFR) is part of the ErbB family of receptor tyrosine kinases and is known to be variably expressed in breast cancers. Cetuximab is a humanized monoclonal antibody directed against the EGFR that works by blocking the downstream signaling function of this protein and thereby interfering with cancer cell proliferation. Preclinical studies have indicated a synergistic effect for the combination of anti-EGFR therapy plus paclitaxel in breast cancer models.
Patients and methods: Hence, we conducted a dose-escalation phase I trial using cetuximab/paclitaxel in patients with metastatic breast cancer to evaluate the feasibility of this combination. Patients with EGFR-positive metastatic breast cancer treated with <or= 1 previous therapy, excluding taxanes, were eligible. Treatment consisted of weekly cetuximab therapy and every-3-week paclitaxel, with dose escalation of cetuximab until the maximum tolerated dose was reached.
Results: Twelve patients were enrolled to 3 treatment cohorts. Two of 6 patients on the second cohort (cetuximab 100 mg/m2) developed dose-limiting toxicities, presenting as grade 3 rash. The third cohort was amended to allow the same cetuximab dose but to modify the paclitaxel to a weekly schedule. Despite this, 1 of 3 patients in this group also developed grade 3 skin toxicity as a dose-limiting toxicity; thus, the trial was stopped. Ten of the 12 patients were evaluable for response, and of these, 2 patients experienced stable disease, and 8 patients experienced disease progression.
Conclusion: Because of prohibitive dermatologic toxicity and disappointing preliminary efficacy, the combination of paclitaxel/cetuximab was not considered promising in this population, although further study of this regimen might be warranted.