The study retrospectively evaluated VeriStrat classification prior to the start of treatment with gefitinib, during the course of treatment, and at progression or withdrawal from treatment. VeriStrat is a serum proteomic test that classifies non-small cell lung cancer (NSCLC) patients according to an algorithm developed in a study of NSCLC patients treated with epidermal growth factor receptor (EGFR) inhibitors, such as erlotinib (Tarceva®) or gefitinib (Iressa®). The test identifies patients who are likely to have good (VeriStrat “Good”) or poor (VeriStrat “Poor”) outcomes after treatment with EGFR tyrosine kinase inhibitors (TKIs).
Blood samples from 111 patients with advanced NSCLC treated with gefitinib underwent VeriStrat testing. The study confirmed previous data that patients who tested VeriStrat Good prior to receiving gefitinib had longer median progression free survival (PFS) and overall survival (OS) as compared to patients who tested VeriStrat Poor. While during the course of treatment most patients (88%) maintained their baseline VeriStrat classification, at the time of treatment withdrawal or disease progression 30% of patients changed their VeriStrat classification. The majority of these changes were patients shifting from VeriStrat Good to VeriStrat Poor. Changes from Good to Poor at progression were associated with the development of new lesions, while the majority of patients maintaining their baseline VeriStrat Good classification had progression identified from metastases to the brain or increase of lesion diameter by RECIST criteria. The authors conclude that this finding may support the potential utility of VeriStrat in treatment monitoring, although more research is needed to support the use of VeriStrat in this setting.
Authors also surmise that the study results suggest that a VeriStrat Poor classification at baseline may be related to unknown resistance mechanisms to EGFR-TKI therapy, while a shift from VeriStrat Good classification to VeriStrat Poor may indicate a specific type of progression with the development of new cancer lesions. Biodesix is engaging in further research to explore the longitudinal behavior of VeriStrat classification and make VeriStrat available to researchers developing targeted therapies to further understand its potential in helping physicians guide therapy and to provide additional information on patient response to therapies.