Genomic Subtypes of GISTs for Stratifying Patient Response to Sunitinib following Imatinib Resistance: A Pooled Analysis and Systematic Review

Molecular landscape and clinical significance of exon 11 mutations in KIT gene among patients with gastrointestinal stromal tumor: a retrospective exploratory study

Objective

This aim of this study was to investigate the prognostic significance of KIT exon 11 mutation subtypes in patients with GISTs.

Methods

A total of 233 consecutive patients diagnosed with GISTs at the First Affiliated Hospital of Zhengzhou University from January 2013 to August 2018 were included in this study. The prevalence and mutation landscape of exon 11 in KIT was presented. The clinicopathological characteristics and prognosis among the different mutation subtypes were analyzed. All the statistical analyses were performed by SPSS22.0.

Results

Somatic mutational analysis indicated that point mutations were the most frequently detected mutations followed by deletions & compound mutations and insertion and tandem duplication mutations in the stomach. Point mutations showed a low mitotic count and a high risk of recurrence, and deletions and compound mutations have a high mitotic count while insertions and tandem duplication mutations showed a low mitotic count with an intermediate recurrence risk. Point mutations and deletions frequently occurred in sequence region codons 550-560 of exon 11, while compound mutations, insertion, and tandem duplication were mainly detected in codons 557-559, 572-580, and 577-581, respectively. The multi-variation analysis demonstrated that tumor diameter and high recurrence risk groups had worse prognostic values. However, mutation types were not significant predictors of relapse-free survival (RFS) in GISTs. Survival analysis suggested no significant difference in RFS between the 557/558 deletion and the other deletions.

Conclusion

This study suggested that mutations in exon 11 of the KIT gene were common with intermediate/high recurrence risk in GISTs patients. Tumor diameter ≥5 cm, and deletions mutations might predict a worse prognosis.

A literature review and database of how the primary KIT/PDGFRA variant of a gastrointestinal stromal tumour predicts for sensitivity to imatinib

It is well recognized that the primary KIT or PDGFRA variant of a gastrointestinal stromal tumour (GIST) can predict sensitivity to imatinib. However, these data are currently spread across a wide range of publications and have not been collated as one reference. A broad-ranging literature search was therefore performed to assemble such a database which should help optimize imatinib-based management of GIST patients henceforth. Having excluded wild type GISTs and results for imatinib used as adjuvant therapy, 79 publications (dated August 2001 to March 2022) underwent data extraction. These data on imatinib sensitivity were either derived from in vitro studies, predicted by in silico analysis or based on in vivo clinical patient response. Data interpretation carried some caveats: there was a potential for replication of patient-derived data between older and new publications; only predicted protein sequences were presented; the criteria used to record clinical response were not uniform across all publications; and imatinib dosage could vary between different clinical publications. However, these data showed broad agreement of imatinib sensitivity amongst similar subtypes of KIT or PDGFRA variant. There was also agreement between in vivo versus in vitro/in silico derived sensitivity data for most variants when both data types were available.

Rare c-KIT c.1926delA and c.1936T>G Mutations in Exon 13 Define Imatinib Resistance in Gastrointestinal Stromal Tumors and Melanoma Patients: Case Reports and Cell Experiments

Background: Target therapies play more and more important roles in gastrointestinal stromal tumors (GISTs) and melanoma with the advancement of clinical drugs that overcome the resistance caused by gene mutations. c-KIT gene mutations account for a large portion of GIST patients, which are known to be sensitive or resistant to tyrosine kinase inhibitors. However, the role rare mutations play in drug efficacy and progression-free duration remains elusive.

Methods: Two rare mutations were identified using Sanger sequencing from the GIST and melanoma cases. Cell experiments were further carried out to demonstrate their role in the imatinib resistance.

Results:c-KIT c.1926delA p.K642S*FS mutation in primary and recurrent GIST patients and c-KIT c.1936T>G p.Y646D point mutation in melanoma patients in exon 13 were first demonstrated to be novel targets resistant to imatinib agent.

Conclusion:c-KIT mutations c.1926delA and c.1936T>G in exon 13 are clinically significant targets that exhibit resistance to imatinib. This study provides guidance to GIST and melanoma treatments.

The current state of chemotherapy for the treatment of gastrointestinal stromal tumors with different genotypes: a narrative review

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm of the digestive system and are not sensitive to traditional chemotherapy. Therefore, historically, surgical resection was the only effective therapy. However, the emergence of tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of GISTs, because they target c-Kit and PDGF receptor-α (PDGFRA), which are important in GIST development and progression. As research into c-Kit and PDGFRA continues, an increasing number of different TKIs are being used in the clinical setting. This review aims to discuss the current state of chemotherapy for the treatment of GISTs with different genotypes.

Efficacy evaluation of nilotinib treatment in different genomic subtypes of gastrointestinal stromal tumors: A meta-analysis and systematic review

Nilotinib has been used as a third-line drug for gastrointestinal stromal tumors (GISTs) after a failure of sunitinib. In this study, we aimed to evaluate the efficacy of nilotinib in different genomic subtypes of GISTs. We searched the English articles through EMBASE, Cochrane Library and PubMed Database regarding to the use of nilotinib on GISTs, which published up to February 15, 2019. Inclusion criteria were: GISTs patients received nilotinib in a clinical trial and had detailed genetic subtype records (such as KIT exon 9, KIT exon 11, or PDGFRA mutations, or wild-type). The clinical benefit rate was used to assess the efficacy of nilotinib. A total of 3 studies involving 218 GISTs were included in this meta-analysis. The overall OR (KIT group vs WT group) was 3.26 (95% CI: 1.14-9.28; P = 0.027, Pheterogeneity = 0.613). The overall OR in KIT exon 11 group vs WT group was 5.30 (95% CI: 1.79-15.68; P = 0.003, Pheterogeneity = 0.409). The overall OR in KIT exon 9 group vs WT group was 0.13 (95% CI: 0.02-0.86; P = 0.035, Pheterogeneity = 0.229). The overall OR in KIT exon 11 group vs exon 9 group was 9.96 (95% CI: 0.39-254.66; P < 0.0001, Pheterogeneity = 0.024). Different genotypes of GISTs showed different responses to nilotinib, and KIT exon 11-mutant GISTs mostly benefited from nilotinib, followed by KIT exon 9-mutant or WT one.

Potential insights from population kinetic assessment of progression-free survival curves

Progression-free survival (PFS) curves follow first order kinetics on exponential decay nonlinear regression analysis (EDNLRA). Some exhibit 1-phase-decay, some have 2-phase-decay, some are convex. We digitized, performed EDNLRA and generated log-linear plots for 887 published PFS curves for incurable solid tumors treated with various systemic therapies. Proportion of curves fitting 2-phase-decay varied by therapy (p < 0.0001). For 13 therapies, >64 % of PFS curves had 2-phase-decay. This included epidermal growth factor receptor inhibitors in unselected lung cancer patients (some with, some without mutations), immune checkpoint inhibitors, interferon, breast cancer hormonal therapies, and selected others, suggesting 2 distinct, potentially identifiable subpopulations with differing progression rates. For 22 other therapies, <25 % of PFS curves had 2-phase-decay. Only 1 therapy was in the mid-range. Small cell lung and colon carcinomas were particularly likely to yield highly convex curves (p < 0.006), probably from discontinuation of effective therapies. PFS curve shape may yield biological and clinical insights.