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Caroline G. McCarthy
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P1.14 - Targeted Therapy (ID 182)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Targeted Therapy
- Presentations: 1
- Now Available
- Moderators:
- Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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P1.14-50 - A Phase 2 Trial of Cabozantinib in ROS1-Rearranged Lung Adenocarcinoma (Now Available) (ID 2753)
09:45 - 18:00 | Author(s): Caroline G. McCarthy
- Abstract
Background
To date, no ROS1 inhibitor is approved for the treatment of ROS1-rearranged lung cancers after progression on crizotinib. Progression on crizotinib can be mediated by the acquisition of ROS1 kinase domain mutations (e.g. ROS1G2032R or ROS1D2033N). Cabozantinib is a highly potent ROS1 tyrosine kinase inhibitor that has superior activity over lorlatinib against these mutations. We evaluated the activity of cabozantinib in patients with ROS1-rearranged lung cancers on a phase 2 trial.
Method
In this single-center, open-label, Simon two-stage, phase 2 study, eligible patients had ROS1-rearranged unresectable/metastatic non-small cell lung cancer, a Karnofsky performance status >70%, and measurable disease. ROS1 fusion was identified by local testing in a CLIA-compliant environment. Cabozantinib was dosed at 60 mg once daily. The primary endpoint was objective response (RECIST v1.1). In the first stage of this trial, 1 response was required to move to the second stage. Secondary endpoints included safety.
Result
Six patients received cabozantinib in the ongoing first stage of this study. All patients had >1 prior ROS1 inhibitor. The median age was 59 years; all were never smokers. The best response to therapy was: 1 partial response (-92%, confirmed), 1 unconfirmed partial response (-31%), and 4 stable disease. All patients had disease regression (-7 % to -92%); no patients had primary progressive disease. The only patient with a confirmed partial response was a patient whose cancer acquired a ROS1D2033N solvent front mutation after crizotinib. None of the other five ROS1 inhibitor pre-treated patients (who did not have a confirmed response) had a known on-target acquired resistance mutation in their cancer. After progression on cabozantinib (9.1 months after therapy initiation), the patient whose cancer harbored the ROS1D2033N mutation acquired a METD1228N kinase domain mutation on paired sequencing of pre-cabozantinib and post-progression tumor. The most common grade 3 treatment-related adverse events were hypertension (50%), and mucositis, palmar-plantar erythrodysesthesia, and hypophosphatemia (each in 17%). Most patients (83%) required a dose reduction.
Conclusion
Cabozantinib can re-establish disease control in ROS1-rearranged lung cancers after progression on a prior ROS1 inhibitor. The first stage of this ongoing trial met its prespecified endpoint for efficacy to move into the second stage. Response was only observed in the setting of a known ROS1 kinase domain resistance mutation.