Backgrounds: Efficacy of gefitinib therapy strongly depends on epidermal growth factor receptor (EGFR)-mutation status in Asian patients with non-small cell lung cancer. Recently, the survival advantage of erlotinib, another tyrosine kinase inhibitor, was not affected by EGFR mutation status in a phase III trial, indicating that patients with EGFR-wild-type (EGFR-wt) tumors might also benefit from this tyrosine kinase inhibitor. The aim of this trial was to evaluate the efficacy and toxicity of erlotinib in Japanese patients with EGFR-wt tumors.
Methods: The primary end point was an objective response. Patients with EGFR-wt tumors previously receiving one to three chemotherapy regimens were enrolled in this trial. The mutation status was assessed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. Erlotinib was administered (150 mg/d) until disease progression or unacceptable toxicities occurred.
Results: Thirty patients were enrolled between January and December 2008. Objective response was observed in one patient (3.3%), and the disease became stable in 18 patients (60.0%). Skin rash was the most common side effect. Grades 3-4 adverse events included pulmonary embolism, keratitis, and anemia. Two other patients developed interstitial lung disease (grades 1 and 2). Nevertheless, all these events were reversible, resulting in no treatment-related deaths. With a median follow-up time of 10.7 months, the median survival time and median progression-free survival times were 9.2 and 2.1 months, respectively.
Conclusion: This is the first prospective biomarker study showing that erlotinib therapy for pretreated patients with EGFR-wt tumors seems to have a modest activity with no irreversible toxicity.