Evaluation of nilotinib in advanced GIST previously treated with imatinib and sunitinib

Purpose: Patients with advanced GIST following standard imatinib and sunitinib often have good performance status and need additional therapy. This study tested nilotinib, a second-generation tyrosine kinase inhibitor, in patients with advanced GIST refractory to standard therapies. Methods: This single-center open-label phase II study has a primary objective to determine progression-free survival at 6 months. Using a novel statistical design, 17 patients were to be enrolled; if ≥10 were progression free (PF) at 2 months, 19 additional patients would be enrolled. The therapy was considered of benefit if ≥13 of 36 patients were PF at 6 months. All patients signed informed consent and entry criteria included normal cardiac function. Exploratory analyses correlating genotype with response were also performed. Results: Thirteen patients were treated; 2 had received agents after imatinib and sunitinib. Treatment was well tolerated with one grade 4 anemia attributed to nilotinib. No measurable responses were observed; median time to progression was 2 months. One patient remained on study with stable disease for 12 months. Mutation testing is available from 10 primary tumors with 7 exon 11 mutations, 1 exon 9 mutation, and 2 without KIT/PDGFR mutations. Two samples from recurrent disease had 2 mutations, both primary exon 11 mutations with an additional exon 17 mutation, including the patient with prolonged stable disease. Conclusions: Nilotinib was well tolerated in these patients with advanced GIST. Accrual was halted due to insufficient clinical benefit. However, nilotinib may provide benefit to specific subsets of advanced GIST with exon 17 mutations.