The concentration of erlotinib in the cerebrospinal fluid of patients with brain metastasis from non-small-cell lung cancer

It has been demonstrated that erlotinib is effective in treating patients with brain metastasis from non-small-cell lung cancer. However, the number of studies determining the erlotinib concentration in these patients is limited. The purpose of this study was to measure the concentration of erlotinib in the cerebrospinal fluid of patients with brain metastasis from non-small-cell lung carcinoma. Six patients were treated with the standard recommended daily dose of erlotinib (150 mg) for 4 weeks. All the patients had previously received chemotherapy, but no brain radiotherapy. At the end of the treatment period, blood plasma and cerebrospinal fluid samples were collected and the erlotinib concentration was determined by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS.MS). The average erlotinib concentration in the blood plasma and the cerebrospinal fluid was 717.7 +/- 459.7 and 23.7 +/- 13.4 ng/ml, respectively. The blood-brain barrier permeation rate of erlotinib was found to be 4.4 +/- 3.2%. In patients with partial response (PR), stable disease (SD) and progressive disease (PD), the average concentrations of erlotinib in the cerebrospinal fluid were 35.5 +/- 19.0, 19.1 +/- 8.7 and 16.4 +/- 5.9 ng/ml, respectively. In addition, the efficacy rate of erlotinib for metastatic brain lesions was 33.3%, increasing to 50% in patients with EGFR mutations. However, erlotinib appeared to be ineffective in cases with wild-type EGFR. In conclusion, a relatively high concentration of erlotinib was detected in the cerebrospinal fluid of patients with brain metastases from non-small-cell lung cancer. Thus, erlotinib may be considered as a treatment option for this patient population.