biostudies-literatureUnknown30(10)Goetz MPn/a<h4>Purpose</h4>To identify potential predictors of response and resistance mechanisms in patients with hormone receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) treated with the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor abemaciclib ± endocrine therapy (ET), baseline and acquired genomic alterations in circulating tumor DNA (ctDNA) were analyzed and associated with clinical outcomes.<h4>Experimental design</h4>MONARCH 3: postmenopausal women with HR+, HER2- ABC and no prior systemic therapy in the advanced setting were randomly assigned to abemaciclib or placebo plus nonsteroidal aromatase inhibitor (NSAI). nextMONARCH: women with HR+, HER2- metastatic breast cancer that progressed on/after prior ET and chemotherapy were randomly assigned to abemaciclib aClinical cancer research : an official journal of the American Association for Cancer Research2233-2244https://www.ebi.ac.uk/biostudies/studies/S-EPMC11094424biostudies-literatureLandscape of Baseline and Acquired Genomic Alterations in Circulating Tumor DNA with Abemaciclib Alone or with Endocrine Therapy in Advanced Breast Cancer.PMC11094424Graham HCampone MJerusalem GToi MHamilton EPHurvitz SAWang HLlombart-Cussac AJansen VMLitchfield LMGoetz MPCortes JMartin MJohnston SKaufman PAfalseLandscape of Baseline and Acquired Genomic Alterations in Circulating Tumor DNA with Abemaciclib Alone or with Endocrine Therapy in Advanced Breast Cancer.<h4>Purpose</h4>To identify potential predictors of response and resistance mechanisms in patients with hormone receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) treated with the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor abemaciclib ± endocrine therapy (ET), baseline and acquired genomic alterations in circulating tumor DNA (ctDNA) were analyzed and associated with clinical outcomes.<h4>Experimental design</h4>MONARCH 3: postmenopausal women with HR+, HER2- ABC and no prior systemic therapy in the advanced setting were randomly assigned to abemaciclib or placebo plus nonsteroidal aromatase inhibitor (NSAI). nextMONARCH: women with HR+, HER2- metastatic breast cancer that progressed on/after prior ET and chemotherapy were randomly assigned to abemaciclib a2024-01-01T00:00:00Z2024 May2026-06-02T01:42:05.76Z2026-04-13T03:12:01.704ZS-EPMC110944243788912010.1158/1078-0432.CCR-22-3573