(ChemotherapyAdvisor) – Identifying ROS1 mutations is important for detecting lung cancers and for developing personalized therapies, according to team of Chinese researchers. This conclusion is based on a study entitled “Analysis of Receptor Tyrosine Kinase ROS1-Positive Tumors in Non-Small Cell Lung Cancer: Identification of a FIG-ROS1 Fusion,” which was published in the August issue of Clinical Cancer Research.

Previous studies have demonstrated that the ROS1 mutation is found in nearly 2% of all lung cancers and is related to the anaplastic lymphoma kinase (ALK) mutation. Chemotherapeutic agents, such as crizotinib, designed to treat lung cancers that express the ALK mutation, have also been effective in treating ROS1-positive lung cancer.

In the current study, the investigators aimed to gain an understanding of mutant ROS1 expression, localization, and frequency in non-small cell lung cancer (NSCLC). Gaining such an understanding would enable greater molecular profiling and personalized treatment of NSCLC tumors. To meet their aim, the investigators used immunochemical and molecular biological methods to assess NSCLC tumors (N=556) for ROS1 protein expression and localization, as well as expression of ALK, EGFR L858R, and EGFR E746-A750del mutations.

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The investigators found, in a NSCLC cohort of Chinese patients, 9 (1.6%) tumors expressed ROS1 and 22 (4.0%) tumors expressed ALK, which is consistent with previous studies. They also identified fusion partners of ROS1 as CD74-ROS1, SLC34A2-ROS1, and FIG-ROS1 fusions, and tumors containing these gene fusions may have also harbored EGFR mutations.

The investigators concluded that “NSCLC tumors with ROS1 rearrangements are uncommon in the Chinese population and represent a distinct entity of carcinomas.” However, they stated that the ROS1 assay described in this article is “a valuable tool for identifying patients expressing mutant ROS1 and could be routinely applied in clinical practice to detect lung cancers that may be responsive to targeted therapies.”