Clinical Significance of PIK3CA and ESR1 Mutations in Circulating Tumor DNA: Analysis from the MONARCH 2 Study of Abemaciclib plus Fulvestrant.

ABSTRACT:

Purpose

PIK3CA and ESR1 mutations have been implicated in resistance to endocrine therapy (ET) in HR+, HER2- advanced breast cancer (ABC). Inhibition of CDK4 and 6 has been hypothesized as a therapeutic strategy to overcome endocrine resistance in patients with PIK3CA- or ESR1-mutant breast cancers. The objective of this exploratory analysis was to assess efficacy of abemaciclib plus fulvestrant in patients with or without PIK3CA or ESR1 mutations in MONARCH 2.

Patients and methods

MONARCH 2 was a global, randomized, double-blind phase III trial of abemaciclib plus fulvestrant in 669 women with HR+, HER2- ABC, which had progressed on ET. Patients were randomized 2:1 to receive abemaciclib plus fulvestrant or placebo plus fulvestrant. Exploratory analyses assessed progression

SUBMITTER: Tolaney SM 

PROVIDER: S-EPMC10234145 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature