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William J. Gradishar, MD, FACP, FASCO


ASCO 2024: Prognostic Role of ctDNA in the monarchE Breast Cancer Trial Population

By: Julia Cipriano, MS
Posted: Wednesday, June 12, 2024

The monarchE trial previously demonstrated a sustained invasive disease–free survival benefit in patients who underwent 2 years of adjuvant abemaciclib plus endocrine therapy for hormone receptor–positive, HER2-negative, node-positive, high-risk, early-stage breast cancer, according to Sherene Loi, MMBS, FRACP, PhD, FAHMS, of Peter MacCallum Cancer Centre, Melbourne, Australia, and colleagues. An analysis that investigated the prognostic value of circulating tumor DNA (ctDNA) detection and dynamics in this population was presented during the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract LBA507).

“Detection of ctDNA was relatively infrequent; however, its detection at any time during therapy was adversely prognostic,” the investigators commented. “As compared with patients who had remaining ctDNA positivity, those who had clearance had lower risk of invasive disease–free survival events, but the event risk still remained clinically meaningful in these patients.”

The investigators focused on a subset of the trial population (n = 1,397; abemaciclib plus endocrine therapy: n = 685; endocrine therapy alone: n = 712) enriched for overall invasive disease–free survival events (vs the total population: 31% vs 18%). Of these patients, 910 had provided sufficient plasma samples for whole-exome sequencing; they all reportedly underwent successful ctDNA assay testing.

More than one-quarter of the ctDNA cohort experienced an invasive disease–free survival event (27%; abemaciclib plus endocrine therapy: 23%; endocrine therapy alone: 31%). At baseline, 8% of patients had ctDNA positivity, and the associated invasive disease–free survival event rate was 80%. The investigators observed ctDNA clearance in 3% of the cohort, whereas 5% remained ctDNA-positive and 9% became ctDNA-positive; the associated invasive disease–free survival event rates were 42%, 100%, and 93%, respectively. A total of 87% of the patients with ctDNA positivity at any timepoint (17%) experienced an invasive disease–free survival event vs 15% of those with persistent ctDNA negativity (83%).

Disclosure: For full disclosures of the study authors, visit

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