Clinical and analytical performance of non-small cell lung cancer biomarkers.

11070 Background: A variety of biomarkers are currently used to help guide treatment decisions for patients with non-small cell lung cancer (NSCLC). These include mutation analysis for the EGFR and KRAS genes, along with gene rearrangement analysis for the ALK and ROS1 loci. In this study we have evaluated the clinical and analytical performance features of these assays in a series of formalin-fixed paraffin-embedded (FFPE) tissue samples. Methods: FFPE samples submitted for analysis of the EGFR, KRAS, ALK and ROS1 genes were evaluated using molecular and FISH assays. EGFR mutation analysis was performed using Sanger nucleic acid sequencing methods for exons 18-21. KRAS mutations were detected using allele specific PCR or pyrosequencing methods. Rearrangements involving the ALK gene were detected using break-apart FISH probes (Abbott Molecular). Genetic alterations involving the ROS1 gene were determined using FISH probes (Kreatech Diagnostics). Over 6,200 test results for these 4 markers are included in this analysis. Results: Mutations in the EGFR gene were detected in 10.1% of samples evaluated (n=3,872). A slightly higher percentage of samples from female patients (13%) had a detectable mutation compared to samples from males (7%) (chi-square p<0.0001). Deletions in exon 19 (51%) were the most common alterations detected, followed by point mutations in exon 21 (35%). KRAS mutations were detected in approximately 22% of specimens. ALK gene rearrangements were observed in 3.1% of samples (n=1,524). Specimens from individuals <50y of age were more likely to provide a positive result (11%) compared to samples from individuals >50y of age (2.5%) (chi-square p<0.0001). Gene amplification for the ALK gene was a common finding in the NSCLC samples evaluated. ROS1 alterations were detected in 2.8% of the specimens. In this cohort, no specimens were positive for both an EGFR mutation and an ALK gene rearrangement. Conclusions: Biomarker testing is well established in clinical practice for NSCLC, with results from the tests used to guide important therapy decisions. Assays for biomarkers such as EGFR, KRAS, ALK and ROS1 are robust, allowing for the analysis of multiple analytes in FFPE samples, even when the amount of tissue may be limiting.