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    4ms
    Role of PIK3CA as a predictive biomarker in metastatic, imatinib-resistant GIST: A ct-DNA substudy of the VOYAGER trial (ESMO 2024)
    Background: The VOYAGER-trial compared avapritinib (ava) with regorafenib (rego) in patients (pts) with advanced gastrointestinal stromal tumors (GIST) in a 3rd-line setting. In a 3rd-line setting, pathogenic PIK3CA mutations represent the most common genomic event in an oncogenic KIT signaling intermediate but were found in only 4.7% of pts using ctDNA sequencing. The presence of PIK3CA mutations in plasma did not preclude prolonged disease control to ava or rego. Limitations of this analysis are the small sample size and the possibility of clonal hematopoiesis of indeterminate potential (CHIP) as PIK3CA mutations were not confirmed in tumor samples.
    Circulating tumor DNA • Metastases
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    PIK3CA (Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) • KIT (KIT proto-oncogene, receptor tyrosine kinase) • PDGFRA (Platelet Derived Growth Factor Receptor Alpha)
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    PIK3CA mutation • KIT mutation • PDGFRA mutation • KIT T670I • PIK3CA H1047L • KIT A829P
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    Guardant360® CDx
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    imatinib • Stivarga (regorafenib) • Ayvakit (avapritinib)