Four out of 8 patients (50 %) with crizotinib resistance harbored a G2032R mutation in the ROS1 kinase domain….Resistance to crizotinib correlated with the G2032R mutation in the ROS1 kinase domain.

Additionally, we identified 16 patients who underwent a total of 17 repeat biopsies following progression on crizotinib. ROS1 resistance mutations were identified in 53% of specimens, including 9/14 (64%) non-brain metastasis specimens. ROS1 mutations included: G2032R (41%), D2033N (6%), and S1986F (6%).

We report an 85-year-old female patient with ROS1-rearranged NSCLC, who developed drug-induced interstitial lung disease (DI-ILD) 2 months after crizotinib treatment, and was treated with prednisolone followed by entrectinib. Entrectinib treatment resulted in stable disease with a marginal response after a partial response to crizotinib. Entrectinib treatment following crizotinib cessation due to DI-ILD was efficacious, which suggested that ROS1-G2032R gatekeeper mutation, frequently observed in crizotinib-resistant disease, was absent.

ROS1 kinase domain mutations were examined in fresh tumor tissues from two NSCLC patients....The ROS1 G2032R mutation was identified in crizotinib-resistant tumors from one patient…

We performed a biopsy of a resistant tumor and identified an acquired mutation leading to a glycine-to-arginine substitution at codon 2032 in the ROS1 kinase domain. Although this mutation does not lie at the gatekeeper residue, it confers resistance to ROS1 kinase inhibition through steric interference with drug binding. The same resistance mutation was observed at all the metastatic sites that were examined at autopsy.