A Phase Ib Study of Alpelisib (BYL719), a PI3Kα-Specific Inhibitor, with Letrozole in ER+/HER2− Metastatic Breast Cancer
Mayer IA, Abramson VG, Formisano L, Balko JM, Estrada MV, Sanders ME, Juric D, Solit D, Berger MF, Won HH, Li Y, Cantley LC, Winer E, Arteaga CL. A Phase Ib Study of Alpelisib (BYL719), a PI3Kα-Specific Inhibitor, with Letrozole in ER+/HER2− Metastatic Breast Cancer. Clinical Cancer Research 2017, 23: 26-34. PMID: 27126994, PMCID: PMC5085926, DOI: 10.1158/1078-0432.ccr-16-0134.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedAntineoplastic Combined Chemotherapy ProtocolsAromatase InhibitorsBiomarkers, TumorBreast NeoplasmsCell Line, TumorDNA Mutational AnalysisFemaleHumansIn Situ Hybridization, FluorescenceLetrozoleMaximum Tolerated DoseMiddle AgedMutationNeoplasm MetastasisNeoplasm StagingNitrilesPhosphatidylinositol 3-KinasesPhosphoinositide-3 Kinase InhibitorsReceptor, ErbB-2Receptor, Fibroblast Growth Factor, Type 1Receptors, EstrogenThiazolesTreatment OutcomeTriazolesConceptsMaximum-tolerated doseBreast cancer cellsEndocrine therapyClinical benefitCommon drug-related adverse eventsDrug-related adverse eventsMutant breast cancer cellsBreast cancer refractoryPIK3CA mutation statusPIK3CA-mutated tumorsClinical benefit ratePhase Ib studyPI3K catalytic subunit p110αDose-limiting toxicityCancer cellsSelective oral inhibitorOverexpression of FGFR1Combination of letrozoleSynergistic antitumor activityCatalytic subunit p110αCancer refractoryFGFR1/2 amplificationMetastatic ERAdverse eventsObjective response