A study conducted by Dr. Alice Shaw and colleagues from Massachusetts General Hospital Cancer Center in Boston has shown the efficacy of Pfizer’s drug Xalkori, chemically known as crizotinib in reducing tumours in non-small cell lung cancers (NSCLC). The drug targets patients with a specific gene mutation, effectively shrinking tumors in patients with NSCLC.

“This is the first definitive study to establish crizotinib’s activity in a large group of patients with ROS1-positive lung cancer and confirms that ROS1 is a bona fide therapeutic target in those patients,” said Dr. Shaw.

The study, published in the prestigious New England Journal of Medicine, looked at 50 NSCLC patients with mutation of the ROS1 gene, a mutation that causes two genes to fuse that are usually separate in healthy individuals. Results found tumour shrinkage in 36 of the 50 patients, that is approximately 72 percent. The results further found halted tumour growth in 9 patients, according to researchers.

Researchers further added that the average duration of response to Xalkori taken orally twice daily was a remission period of 17 months, with half the patients still receiving treatment despite lack of tumour progression. “The remissions induced by crizotinib in ROS1-positive patients are quite prolonged, and (treatment) resistance appears to emerge much later, on average, than what we have seen with other targeted therapies for lung cancer and melanoma,” said Dr. Shaw.

Each year, an estimated 1.5 million individuals are diagnosed with NSCLC globally. The drug has been originally approved and used to treat patients with ALK gene mutation, a cohort that makes up approximately four percent of all NSCLC patients. Approximately one to two percent of all NSCLC patients are estimated to have the ROS1 mutation.

“If you devote the diagnostic laboratory resources to find that 1 to 2 percent of patients, you will make a real difference,” commented Dr. John Iafrate, medical director of Massachusetts General’s Center for Integrated Diagnostics. He acknowledged the incredible importance of the research to ROS patients. Although Xalkori has not yet received approval for treatment in ROS1 patients, Pfizer issued a statement confirming its approval and support of Xalkori’s use in clinical research for ROS1 patients.