Concurrent inhibition of CDK2 adds to the anti-tumor activity of CDK4/6 inhibition in GIST
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ABSTRACT: Background: Advanced gastrointestinal stromal tumor (GIST) is characterized by genomic perturbations of key cell cycle regulators. Oncogenic activation of CDK4/6 results in RB1 inactivation and cell cycle progression. Given that single-agent CDK4/6 inhibitor therapy failed to show clinical activity in advanced GIST, we evaluated strategies for maximizing response to therapeutic CDK4/6 inhibition. Methods: Targeted next-generation sequencing and multiplexed protein imaging were used to detect cell cycle regulator aberrations in GIST clinical samples. The impact of inhibitors of CDK2, CDK4, and CDK2/4/6 was determined through cell proliferation and protein detection assays. CDK-inhibitor resistance mechanisms were characterized in GIST cell lines after long-term exposure. Results: We identify recurrent genomic aberrations in cell cycle regulators causing co-activation of the CDK2 and CDK4/6 pathways in clinical GIST samples. Therapeutic co-targeting of CDK2 and CDK4/6 is synergistic in GIST cell lines with intact RB1, through inhibition of RB1 hyperphosphorylation and cell proliferation. Moreover, RB1 inactivation and a novel oncogenic cyclin D1 resulting from an intragenic rearrangement (CCND1::chr11.g:70025223) are mechanisms of acquired CDK inhibitor resistance in GIST. Conclusions: These studies establish the biologic rationale for CDK2 and CDK4/6 co-inhibition as therapeutic strategy in patients with advanced GIST, including metastatic GIST progressing on tyrosine kinase inhibitors.
ORGANISM(S): Homo sapiens
PROVIDER: GSE206257 | GEO | 2022/11/01
REPOSITORIES: GEO
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