Final results of the multicenter randomized phase II PAZOGIST trial evaluating the efficacy of pazopanib (P) plus best supportive care (BSC) vs BSC alone in resistant unresectable metastatic and/or locally advanced gastrointestinal stromal tumors (GIST).

10506 Background: GIST is the most common mesenchymal neoplasm of the gastrointestinal tract. Imatinib followed by sunitinib then regorafenib is the usual sequence in advanced setting. P is effective in soft tissue sarcomas; it has never been evaluated in a randomized setting in GIST. Methods: Eligible patients (pts) were randomized (1:1; stratification on number of prior drugs (2 vs ≥3)) to receive P+BSC or BSC. Primary endpoint was Progression-Free Survival (PFS). 80 pts were planned to detect an improvement in the 4-month PFS rate (PFS-4m) from 15% (BSC) to 45% (P+BSC) with 5% two-sided α and 80% power. Secondary objectives included Best Overall Response (BOR), Overall Survival (OS), safety and trough plasma P concentrations (Ct). Results: From Apr 11 to Dec 13, 81 pts (P+BSC: 40, BSC: 41) were randomized. Arms were well balanced; median age: 63y (27-85), 70% males and 54% with ≥ 3 prior drugs. The intent-to-treat analysis based on investigator-assessed progressive disease (PD) showed an improved PFS w...