(ChemotherapyAdvisor) – A rapid test for ROS1 gene rearrangements in non-small cell lung cancer (NSCLC) tumors is now available, allowing better detection of potentially crizotinib-sensitive tumors for personalized treatment planning, reported Response Genetics, Inc., a Los Angeles, CA-based molecular oncology diagnostics biotechnology company.

The company now offers both fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) ROS1 testing. FISH was already in use for ROS1 testing. But according to Thomas Bologna, chairman and CEO of Response Genetics, PCR provides additional information useful for personalizing patients’ treatment plans.

ROS1 is a tyrosine kinase gene; rearrangements at this locus are found in a small subset of NSCLCs. ROS1-rearrangement NSCLCs represent “an addition 1 to 2% of patients who may be candidates for crizotinib therapy,” Bologna said.

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The biomarker testing enables “results on very small biopsies including fine needle aspirates,” Bologna noted.

He pointed to recent studies at Massachusetts General Hospital, supporting ROS1-driven NSCLC tumors’ sensitivity to crizotinib therapy. A FISH study published March 2012 in the Journal of Clinical Oncology found 1.7% of NSCLC tumors include ROS1 rearrangements and that 2.9% of NSCLC tumors are ALK-rearranged. (See abstract.) “Crizotinib shows in vitro activity and early evidence of clinical activity in ROS1-rearranged NSCLC,” the authors of that study concluded.

“Compared with the ROS1-negative group, patients with ROS1 rearrangements were significantly younger and more likely to be never-smokers (each P<0.001),” the authors reported. “All of the ROS1-positive tumors were adenocarcinomas, with a tendency toward higher grade.” However, overall survival (OS) rates were similar between patients whose NSCLC tumors harbored ROS1 rearrangements and those whose tumors did not, the study’s authors noted.

Abstract for 2012 study of ROS1 rearrangements and crizotinib in NSCLCs

Response Genetics, Inc. ROS1 website