Treatment with the targeted therapy drug crizotinib effectively halts the growth of lung tumors driven by rearrangements of the ROS1 gene.
In an article receiving Online First publication in the New England Journal of Medicine to coincide with a presentation at the European Society for Medical Oncology meeting, an international research team reports that crizotinib treatment led to significant tumor shrinkage in 36 of 50 study participants and suppressed tumor growth in another 9.
“Prior to this study, there were a handful of reports describing marked responses to crizotinib in individual patients with ROS1-positive lung tumors,” says Alice Shaw, MD, PhD, of the Massachusetts General Hospital (MGH) Cancer Center, lead author of the NEJM report. “This is the first definitive study to establish crizotinib’s activity in a large group of patients with ROS1-positive lung cancer and to confirm that ROS1 is a bona fide therapeutic target in those patients.”
Crizotinib currently is FDA-approved to treat non-small-cell lung cancers (NSCLC) driven by rearrangments in the ALK gene, which make up around 4 percent of cases. An MGH Cancer Center report published in 2012 reported that 1 to 2 percent of NSCLCs are driven by rearrangements in ROS1, which encodes a protein with significant structural similarities to that encoded by the ALK gene.
The current study, an expansion of the original phase 1 crizotinib trial, enrolled 50 patients with ROS1-positive NSCLC, beginning in late 2010. Patients received twice daily doses of crizotinib. As noted above, tumor size was significantly reduced in 72 percent of patients and tumor growth was halted in an additional 18 percent. The average duration of response was over 17 months. At the end of the study, 25 of the 50 patients were still receiving crizotinib with no evidence of tumor progression.
