Changes in Plasma Mass-Spectral Profile in Course of Treatment of Non-small Cell Lung Cancer Patients with Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Introduction: Our previous study showed that pretreatment serum or plasma Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry may predict clinical outcome of non-small cell lung cancer (NSCLC) patients treated with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). In this study, plasma proteomic profiles of NSCLC patients were evaluated in the course of EGFR TKIs therapy. Materials and Methods: Plasma samples were collected at baseline, in the course of gefitinib therapy and at treatment withdrawal. Samples were analyzed by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. Acquired spectra were classified by the VeriStrat test into good and poor profiles. The association between VeriStrat classification and progression-free survival (PFS) and overall survival (OS), and types of clinical progression, was analyzed. Results: Plasma samples from 111 NSCLC patients treated with gefitinib were processed. VeriStrat good classification at baseline correlated with longer PFS (hazard ratio [HR], 0.54; 95% confidence interval, 0.35-0.83; p = 0.005) and OS (HR, 0.40; 95% confidence interval, 0.26-0.61; p < 0.0001), when compared with VeriStrat poor. Multivariate analysis confirmed longer PFS (HR, 0.52; p = 0.025) and OS (HR, 0.44; p = 0.001) in patients classified as VeriStrat good, when VeriStrat was considered as a time-dependent variable. About one-third of baseline good classifications had changed to poor at the time of treatment withdrawal; progression in these patients was associated with the development of new lesions. Conclusions: Our findings support the role of VeriStrat in the assistance in treatment selection of NSCLC patients for EGFR TKI therapy and its potential utility in treatment monitoring.