Abstract

PURPOSE: Ripretinib is a switch-control tyrosine kinase inhibitor that broadly inhibits KIT and platelet-derived growth factor receptor alpha kinase signalling. Ripretinib showed preliminary efficacy in patients with advanced gastrointestinal stromal tumour (GIST) in a phase I study across a range of doses. Results were confirmed in the phase III INVICTUS study, and ripretinib 150mg once daily (QD) was subsequently approved as a =fourth-line therapy. Here, we report the phase I study results of intrapatient dose escalation (IPDE) in patients with GIST treated across second, thirdand later lines of therapy.METHODS: Patients with advanced GIST who experienced disease progression (PD) at ripretinib 150mg QD could dose escalate to 150mg twice daily (BID). Progression-free survival (PFS) 1 was calculated from the date of the first dose of ripretinib 150mg QD to PD (as per Response Evaluation Criteria in Solid Tumours 1.1); PFS2 was from the date of IPDE (150mg BID) to PD or death. Treatment-emergent adverse events (TEAEs) were summarised by dosing periods and compared descriptively.RESULTS: Of 142 patients with GIST receiving ripretinib 150mg QD, 67 underwent IPDE. IPDE provided benefit across all lines of therapy; the median PFS2 was 5.6, 3.3and 4.6 months for patients on second-, third-and =fourth-line therapy, respectively. A partial metabolic response after IPDE was demonstrated in 13 of 37 patients with available positron emission tomography scans. TEAEs reported at both doses were similar.CONCLUSION: Ripretinib IPDE after PD provided continued clinical benefit in advanced GIST across second, third and later lines of therapy with a similar safety profile to that observed with the QD regimen.

View details for DOI 10.1016/j.ejca.2021.07.010

View details for PubMedID 34391056