China-based CStone Pharmaceuticals (HKG: 2616) announced that new data from a post hoc analysis of the global Phase I NAVIGATOR and Phase I/II China bridging (CS3007-101) studies for Ayvakit (avapritinib) in advanced gastrointestinal stromal tumor (GIST) were presented in a poster discussion session at the 2023 American Society of Clinical Oncology (ASCO) annual meeting.
Global NAVIGATOR Study and China Bridging Study Overview
The global NAVIGATOR study (NCT02508532) is a Phase I, open-label clinical trial designed to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and antineoplastic activity of Ayvakit, administered orally, in adult patients with unresectable GIST or other relapsed or refractory solid tumors. The China bridging Phase I/II study (NCT04254939; CS3007-101) is a Phase I/II, open-label, multicenter clinical trial designed to evaluate the safety, PK, and clinical efficacy of avapritinib in Chinese patients with unresectable or metastatic GIST.
Post Hoc Analysis Results
A total of 160 patients with advanced KIT-mutant GIST were evaluated in the post hoc analysis reported at ASCO, with 131 patients from the NAVIGATOR study and 29 patients from the CS3007-101 study. The median follow-up duration for this patient population was 22.0 months. The data cutoff dates were March 31, 2021, for the NAVIGATOR study and June 30, 2021, for the CS3007-101 study. KIT-AL mutations were more frequently detected compared to KIT ATP-binding pocket (ABP) mutations. Among the patients, 60 (37.5%) had KIT-AL mutations without KIT-ABP mutations (the ALposABPneg group), while the remaining 100 patients were designated as KIT OTHERS. Across all lines of therapy, the adjusted median progression-free survival (mPFS) was longer for the ALpos ABPneg group than for the KIT OTHERS group (9.1 vs 3.4 months; HR=0.47, 95% CI 0.32–0.68; P<0.0001), and the adjusted objective response rate (ORR) was higher (31.4% vs 12.1%; odds ratio 3.31, 95% CI 1.44–7.58; P=0.0047).-Fineline Info & Tech
