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NCT04975308 · OUTCOME

Percentage of Participants With Investigator-assessed Clinical Benefit Rate (CBR) in the ESR1-Mutation Detected Population (Between Arm A and Arm B)

A Study of Imlunestrant, Investigator's Choice of Endocrine Therapy, and Imlunestrant Plus Abemaciclib in Participants With ER+, HER2- Advanced Breast Cancer · Source last updated 2026-07-22

Results reported by the registry submitting party. Population, time horizon, units and missing values must be read together.

Measure
NUMBER
Unit
Percentage of participants
Interval / dispersion
95% Confidence Interval
Time frame
Randomization until measured progressive disease (up to 28 months)

What was measured

CBR was the best confirmed overall tumor response of stable disease (SD) for greater than or equal to (≥) 24 weeks, CR or PR as defined by RECIST v1.1. CR is a disappearance of all target and non-target lesions and normalization of tumor marker level. PR is an at least 30% decrease in the sum of the diameters of target lesions (taking as reference the baseline sum diameter) without progression of non-target lesions or appearance of new lesions. SD is neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD) for target lesions, no progression of non-target lesions, and no appearance of new lesions. PD is defined as at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum on study and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions.

Analysis population: All participants who were randomly assigned to either arm A or arm B and had ESR1 mutations detected at baseline.

Groups in this outcome

Arm A: Imlunestrant

Participants received Imlunestrant 400 milligrams (mg) orally once daily on days 1 to 28 of a 28-day cycle, until disease progression or a criterion for discontinuation were met.

Arm B: Investigator's Choice of Endocrine Therapy

Participants received the investigator's choice of endocrine therapy, either exemestane 25 mg administered orally once daily on days 1 to 28 of a 28-day cycle, or Fulvestrant 500 mg intramuscularly on days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and beyond, until disease progression or a criterion for discontinuation was met.

Group identifiers and denominators belong to this outcome only. They may differ in another outcome or in safety reporting.

Analysis denominator · Participants

GroupSource count
Arm A: Imlunestrant138
Arm B: Investigator's Choice of Endocrine Therapy118

Reported measurements

Source class 1
Values in Percentage of participants · Interval/dispersion: 95% Confidence Interval
GroupValueSpreadLowerUpperComment
Arm A: Imlunestrant46.4Not reported38.154.7Not reported
Arm B: Investigator's Choice of Endocrine Therapy36.4Not reported27.845.1Not reported
Complete source fields
classes
  1. categories
    1. measurements
      1. group Id
        OG000
        lower Limit
        38.1
        upper Limit
        54.7
        value
        46.4
      2. group Id
        OG001
        lower Limit
        27.8
        upper Limit
        45.1
        value
        36.4
denoms
  1. counts
    1. group Id
      OG000
      value
      138
    2. group Id
      OG001
      value
      118
    units
    Participants
description
CBR was the best confirmed overall tumor response of stable disease (SD) for greater than or equal to (≥) 24 weeks, CR or PR as defined by RECIST v1.1. CR is a disappearance of all target and non-target lesions and normalization of tumor marker level. PR is an at least 30% decrease in the sum of the diameters of target lesions (taking as reference the baseline sum diameter) without progression of non-target lesions or appearance of new lesions. SD is neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD) for target lesions, no progression of non-target lesions, and no appearance of new lesions. PD is defined as at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum on study and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions.
dispersion Type
95% Confidence Interval
groups
  1. description
    Participants received Imlunestrant 400 milligrams (mg) orally once daily on days 1 to 28 of a 28-day cycle, until disease progression or a criterion for discontinuation were met.
    id
    OG000
    title
    Arm A: Imlunestrant
  2. description
    Participants received the investigator's choice of endocrine therapy, either exemestane 25 mg administered orally once daily on days 1 to 28 of a 28-day cycle, or Fulvestrant 500 mg intramuscularly on days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and beyond, until disease progression or a criterion for discontinuation was met.
    id
    OG001
    title
    Arm B: Investigator's Choice of Endocrine Therapy
param Type
NUMBER
population Description
All participants who were randomly assigned to either arm A or arm B and had ESR1 mutations detected at baseline.
reporting Status
POSTED
time Frame
Randomization until measured progressive disease (up to 28 months)
title
Percentage of Participants With Investigator-assessed Clinical Benefit Rate (CBR) in the ESR1-Mutation Detected Population (Between Arm A and Arm B)
type
SECONDARY
unit Of Measure
Percentage of participants

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Preserved source evidence · Not medical advice