Coexistent genetic alterations involving ALK, RET, ROS1 or MET in 15 cases of lung adenocarcinoma

In lung cancer, targetable activating alterations in cancer genes, such as EGFR, ALK, RET, ROS1 and MET, are usually mutually exclusive. Rare lung cancer cases with coexistent alterations of EGFR and ALK or EGFR mutations with RET or ROS1 rearrangements have been reported. In this study, we report 15 patients (3 men and 12 women; 14 Caucasians and 1 African American) with ages ranging from 43 to 81 years (median 60 years) with lung adenocarcinoma in which coexistent alterations of two cancer-associated genes, including ALK, ROS1, or RET rearrangement or MET amplification were present. The combination of alterations detected by fluorescence in situ hybridization included ALK combined with ROS1 (n=4), ALK with MET (n=3), ALK with RET (n=1); RET with MET (n=4), RET with ROS1 (n=2), and ROS1 combined with MET (n=1). The frequencies of involvement were similar for all 4 genes, 53% for both ALK and MET (n=8), 47% for both RET and ROS1 (n=7). Activating gene mutations were also detected by next-generation sequencing for TP53 (n=6), EGFR (n=5), KRAS (n=3) and STK11 (n=2). Nine patients reported a smoking history (8 heavy and 1 light) and 6 patients were non-smokers. These findings suggest the need for assessing a panel of genes in lung cancer. Since targetable agents are available for each of these activating alterations, treatment with more than one targeted agent may be beneficial for this rare group of patients.