The drug Pfizer Inc’s Xalkori (known chemically as crizotinib) that treats lung cancer patients with a specific gene mutation, has been proven effective in shrinking tumors in those with an even rarer form of the disease.
According to a study presented at a medical meeting this may provide the first targeted treatment for these patients.
The study published in the New England Journal of Medicine(NEJM) is an expansion of the original Phase 1 clinical trial of Xalkori in patients with the ALK gene mutation. The study involved 50 patients with ROS1-positive non-small cell lung cancers (NSCLC), beginning in late 2010. Researchers reported that Xalkori reduced tumor in 36 of them, that accounts to 72 percent, and stopped tumor growth in other 9 patients. The patients were given twice daily doses of crizotinib.
The findings also showed that Xalkori effectiveness for about 18 months in patients, which was more than the average 8 to 12 months seen for some other targeted treatments.
Xalkori, with annual sales of $400 million was approved in 2011 by the US Center for Disease Control and Prevention (CDC) for lung cancer patients who have a specific mutation in ALK gene, along with a companion diagnostic test to find those with the mutation, that accounts for about 4% of NSCLC as determined by an approved diagnostic test.
Xalkori is not yet approved to treat ROS1-positive patients.
The study was presented at the European Society for Medical Oncology (ESMO) meeting in Madrid.
“Prior to this study, there were a handful of reports describing marked responses to crizotinib in individual patients with ROS1-positive lung tumors,” said Alice Shaw, MD, PhD, of the Massachusetts General Hospital (MGH) Cancer Center, also the 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,” added Shaw.
According to a report published in 2012 by MGH Cancer Center 1 to 2 percent of NSCLCs are driven by rearrangements in ROS1, that encodes a protein with certain structural similarities to that encoded by the ALK gene.
Patients with a mutation to the ROS1 gene are often younger and usually aren’t smokers, Shaw said.
“We’re hopeful that because of showing how well this drug works in ROS1 patients, this will let pathologists know they need to screen their patients for this genetic abnormality,” Shaw said. “In lung cancer there’s been a lot of progress made in targeted therapies.”
“This is a great example of success in personalized medicine,” said Dr. John Iafrate, medical director of Massachusetts General’s Center for Integrated Diagnostics and one of the study’s leaders. He called the results “incredibly important for ROS patients.”
In an e-mail issued by Sally Beatty, a company spokeswoman, she said, “Pfizer continues to support clinical research of Xalkori in patients with ROS1 rearrangements to better understand the compound’s activity in this population.”