Serum levels of surfactant protein D predict the anti-tumor activity of gefitinib in patients with advanced non-small cell lung cancer

Gefitinib is an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) that has dramatic effects in selective patients with non-small cell lung cancer (NSCLC). A simple non-invasive method for predicting the efficacy of gefitinib is preferable in clinical settings. In this study, we evaluated prospectively whether surfactant protein-A (SP-A) and -D (SP-D) may be new conventional predictors of the efficacy of gefitinib treatment. We measured serum SP-A and SP-D levels on days 0 and 29 in 40 patients with advanced NSCLC treated with 250 mg gefitinib daily. Eligibility criteria included performance status a parts per thousand currency sign3, age a parts per thousand currency sign80 years, and stage IIIB-IV disease. In addition, EGFR mutations were analyzed in 24 patients. Multivariate analysis showed that favorable progression-free survival (PFS) after gefitinib treatment was associated with adenocarcinoma and high serum SP-D levels before treatment. EGFR mutation analysis of 24 patients showed that 16 patients had exon 19 deletion and/or exon 21 point mutations. EGFR mutations were significantly correlated with response to gefitinib and serum SP-D levels before treatment was significantly high in patients with the EGFR mutations. Serum SP-A levels were not associated with PFS. The present study showed that measurement of serum SP-D levels before treatment in patients with NSCLC may be a new surrogate marker for predicting the response to gefitinib.