KIT T670I

Despite the small-sized cohort, our data suggests that for patients with severe imatinib-toxicity, nilotinib may represent a well-tolerated alternative – particularly in the context of its imminent patent expiration. We show for the first time a secondary mutation in exon 9 as mechanism of resistance to a highly specific KIT inhibitor that lacks activity against primary exon 9 mutations. Additional analyses are currently being performed to gain insight into the properties of nilotinib and imatinib to support the observations from clinical and in vitro settings.

Background: The genotype of primary mutations predicts imatinib response in untreated metastatic GIST...Regorafenib showed similar activity regardless of KIT mutational status and the location of KIT mutation... Hybrid capture-based plasma sequencing detects ctDNA in the majority of patients with advanced TKI-resistant GIST, including heterogeneity of KIT mutations. This study is the first to show that ctDNA sequencing correlates with outcomes in pretreated GIST. Identification of ABP (exon13/14) KIT mutations negatively correlates with avapritinib activity.

In vivo antitumor activity was also observed in several xenograft GIST models. Considering the well-documented safety and pharmacokinetic (PK) profiles of nintedanib, this finding provides evidence for the repurposing of nintedanib as a new therapy for the treatment of GIST patients with de novo or acquired resistance to imatinib.

The comparison between the explored ligands and well-known drugs highlights the possibility to overcome tumor-acquired resistance. The best-selected structures (630705 and SML1348) provide valuable binding affinities with the mutated c-Kit forms (respectively T670I and V654A).