Clinical Trials


Innovation of the 1st line strategy optimized as abemaciclib with endocrine therapy based on the ESR1 mutation of ctDNA for HR-positive HER2-negative advanced metastatic breast cancer patients - Multi-institutional phase 2 trial

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To explore the efficacy of a treatment strategy to select an endocrine agent based on assessment of ESR1 mutation status by ctDNA analysis in patients who continue abemaciclib and aromatase inhibitor combination therapy for at least 6 months as first-line treatment for hormone receptor (HR)-positive, HER2-negative advanced metastatic breast cancer.

Hormone receptor-positive, HER2-negative inoperable or recurrent breast cancer

2-year PFS rate from the secondary enrollment (all arms)

Trial Period

Lead Principal Investigator
Tetsuhiro Yoshinami, MD, PhD.
Department of Breast and Endocrine Surgery, Osaka University Hospital

Target Sample Size
Secondary enrollment: 150 patients

Repeated "ctDNA measurements" will be performed for the eligible patients treated with Aromatase inhibitor + abemaciclib combination therapy (AI + ABE) as first-line treatment.
In case of ESR1 mutation detected by "ctDNA measurement", treatment would change.

Protocol treatment overview
1) AI + ABE continued for 3 months after primary registration
2) If no sign of PD is seen on the images after 3 months from the primary registration, secondary registration will be performed.
3) After secondary registration, treatment will be decided based on ESR1 mutation status of ctDNA measurement.
・ ctDNA evaluation period: before secondary registration, 24 weeks, 48 weeks after secondary registration
・In case of ESR1 mutation detected at any point, AI + ABE change to fulvestrant (FUL) + ABE.
・ In case of no ESR1 mutation detected at either point, AI + ABE will be continued.
4) ctDNA measurement will be performed at 24 weeks after start of FUL + ABE.
・In case of ESR1 mutation detected at this point, FUL + ABE will be continued
・In case of no ESR1 mutation detected at this point, FUL will be stopped and AI + ABE will be resumed.

Source of Funding
Eli Lilly Japan K.K.

Conference Presentation

Articles and Publications




COI Disclosure
COI Disclosure_M08_20240307

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