The US Food and Drug Administration is undertaking a speedy review of Pfizer’s kinase inhibitor Xalkori for the treatment of patients with metastatic non-small cell lung cancer whose tumours are ROS1-positive.

Xalkori (crizotinib) is already in use to treat patients with metastatic NSCLC whose tumours are anaplastic lymphoma kinase (ALK)-positive, as detected by an FDA-approved test, and could now also become the first FDA-approved biomarker-driven therapy for the treatment of ROS1-positive forms of the disease.

“ROS1 represents the second molecular subgroup of NSCLC in which Xalkori has demonstrated a level of anti-tumour activity that can potentially make a meaningful difference for patients,” said Mace Rothenberg, chief medical officer for Pfizer Oncology. 

The filing contains data from a multicenter, single-arm Phase I study showing that Xalkori exhibited marked anti-tumour activity in patients with ROS1-positive metastatic NSCLC, with no new safety signals. 

Epidemiology data suggest that ROS1 rearrangements occur in around 1% of NSCLC cases, which means that roughly 15,000 cases a year may be driven by oncogenic ROS1 fusions, Pfizer said.