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Imlunestrant

Phase 3

Breast Neoplasms | Small molecule | Oncology |Eli Lilly and Company|Last Updated: Aug 21, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedACTIVE_CONTROLLEDDMC
Total Trials3
Total Enrollment9,474

FDA Designations

No designations recorded

Clinical trial landscape

Imlunestrant · 6 trials · 4 indications

Phase 3 2Phase 2 1Phase 1 3
NCT05514054A Study of Imlunestrant Versus Standard Endocrine Therapy in Participants With Early Breast CancerBreast Neoplasms
ACTIVE NOT_RECRUITING8,000 Analytics
NCT04975308A Study of Imlunestrant, Investigator's Choice of Endocrine Therapy, and Imlunestrant Plus Abemaciclib in Participants With ER+, HER2- Advanced Breast CancerBreast Neoplasms
ACTIVE NOT_RECRUITING874 Analytics
PHASE3ACTIVE NOT_RECRUITING
A Study of Imlunestrant Versus Standard Endocrine Therapy in Participants With Early Breast Cancer
Breast NeoplasmsUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
A Study of Imlunestrant, Investigator's Choice of Endocrine Therapy, and Imlunestrant Plus Abemaciclib in Participants With ER+, HER2- Advanced Breast Cancer
Breast NeoplasmsUnlock trial analytics

Study Endpoints

Primary Endpoints

Invasive Disease-Free Survival (IDFS)
Randomization to recurrence or death from any cause (up to 10 years)

IDFS excluding second non-breast primary invasive cancers

Investigator-assessed Progression Free Survival (PFS) (Between Arm A and Arm B)
Randomization to the date of first documented progression of disease or death from any cause (up to 28 months)

PFS was defined as the time from randomization to the date of first documented progression of disease or death from any cause in the absence of disease progression using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria, as assessed by investigator. Progressive disease (PD) was 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. Participants known to be alive and without disease progression were censored at the date of their last adequate tumor assessment per RECIST 1.1 criteria, or date of randomization (whichever is later).

Investigator-assessed PFS (Between Arm C and Arm A)
Randomization to the date of first documented progression of disease or death from any cause (up to 26 months)

PFS was defined as the time from randomization to the date of first documented progression of disease or death from any cause in the absence of disease progression using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria, as assessed by investigator. Progressive disease (PD) was 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. Participants known to be alive and without disease progression were censored at the date of their last adequate tumor assessment per RECIST 1.1 criteria, or date of randomization (whichever is later).

Investigator-assessed PFS in the Estrogen Receptor 1 (ESR1)-Mutation Detected Population (Between Arm A and Arm B)
Randomization to the date of first documented progression of disease or death from any cause (up to 28 months)

PFS was defined as the time from randomization to the date of first documented progression of disease or death from any cause in the absence of disease progression using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 criteria, as assessed by investigator. Progressive disease (PD) was 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. Participants known to be alive and without disease progression were censored at the date of their last adequate tumor assessment per RECIST 1.1 criteria, or date of randomization (whichever is later).

Change from Baseline in Antigen Kiel (Ki-67) Expression
Baseline, Day 29
Rate of Symptomatic Ovarian Cysts
Up to Day 180
Pharmacokinetics (PK): Area Under the Concentration Versus Time Curve From Zero to Infinity (AUC[0-∞]) of Midazolam
Day 1: Predose, 0.25hours (h), 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, 12h and 24h postdose; Day 9: Predose, 0.25h, 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, 12h, 24, 36, 48h postdose

PK: AUC\[0-∞\] of Midazolam

PK: Maximum Observed Concentration (Cmax) of Midazolam
Day 1: Predose, 0.25h, 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, 12h and 24h postdose; Day 9: Predose, 0.25h, 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, 12h, 24, 36, 48h postdose

PK: Cmax of Midazolam

Pharmacokinetics (PK): Area Under the Concentration Versus Time Curve From Zero to Infinity (AUC[0-∞]) of Repaglinide (Cohort 1)
Day 1 and Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 hours post-dose

PK: AUC\[0-∞\] of Repaglinide

PK: Maximum Observed Concentration (Cmax) of Repaglinide (Cohort 1)
Day 1 and Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 hours post-dose

PK: Cmax of Repaglinide

PK: AUC[0-∞] of Omeprazole (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

PK: AUC\[0-∞\] of Omeprazole

PK: Cmax of Omeprazole (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

PK: Cmax of Omeprazole

PK: AUC[0-∞] of Omeprazole Metabolite: 5-hydroxyomeprazole (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

5-hydroxyomeprazole is a major metabolite of omeprazole.

PK: Cmax of Omeprazole Metabolite: 5-hydroxyomeprazole (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

5-hydroxyomeprazole is a major metabolite of omeprazole.

PK: AUC[0-∞] of Dextromethorphan (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

PK: AUC\[0-∞\] of Dextromethorphan

PK: Cmax of Dextromethorphan (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

PK: Cmax of Dextromethorphan

PK: Area Under the Concentration Versus Time Curve (AUC) From Time Zero to Tlast (AUC[0-tlast]) of Dextromethorphan Metabolite: Dextrorphan (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

Dextrorphan is a major metabolite of Dextromethorphan.

PK: Cmax of Dextromethorphan Metabolite: Dextrorphan (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8,12, and 24 h postdose; Day 3: Predose, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, 36, and 48 h postdose

Dextrorphan is a major metabolite of Dextromethorphan.

PK: AUC[0-∞] of Imlunestrant (Cohort 3)
Day 1 and Day 18: Predose, 1, 2, 3, 4, 5, 6 ,8, 12, 24, 36, 48, 72, 96, 120, 144, and 168 h post dose

PK: AUC\[0-∞\] of Imlunestrant

PK: Cmax of Imlunestrant (Cohort 3)
Day 1 and Day 18: Predose, 1, 2, 3, 4, 5, 6 ,8, 12, 24, 36, 48, 72, 96, 120, 144, and 168 h post dose

PK: Cmax of Imlunestrant

PK: AUC[0-∞] of Rosuvastatin (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, and 96 h post dose; Day 10: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, 96, and 120 h post dose

PK: AUC\[0-∞\] of Rosuvastatin

PK: Cmax of Rosuvastatin (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, and 96 h post dose; Day 10: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, 96, and 120 h post dose

PK: Cmax of Rosuvastatin

PK: AUC[0-∞] of Digoxin (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, and 96 h post dose; Day 10: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, 96, and 120 h post dose

PK: AUC\[0-∞\] of Digoxin

PK: Cmax of Digoxin (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, and 96 h post dose; Day 10: Predose, 0.5, 1, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72, 96, and 120 h post dose

PK: Cmax of Digoxin

Pharmacokinetics (PK): Maximum Observed Concentration (Cmax) of Imlunestrant
Day 1 (Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours post dose)

PK: Cmax of Imlunestrant is reported.

PK: Area Under the Concentration-time Curve From 0 to the Last Measurable Concentration (AUC[0-t]) of Imlunestrant
Day 1 (Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours post dose)

AUC(0-t) of Imlunestrant is reported.

Secondary Endpoints

Distant Recurrence-Free Survival (DRFS)
Randomization to Distant Recurrence or Death from Any Cause (up to 10 Years)
Overall Survival (OS)
Randomization to Death from Any Cause (up to 10 Years)
Pharmacokinetics (PK): Steady State Plasma Concentrations of Imlunestrant
Year 1, Month 2 to Month 4
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
ImlunestrantEXPERIMENTALImlunestrant administered orally.
Investigator's Choice of Endocrine TherapyACTIVE_COMPARATORInvestigator's choice of tamoxifen, anastrozole, letrozole, or exemestane administered per local approved label.
Arm A: ImlunestrantEXPERIMENTALParticipants 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 TherapyEXPERIMENTALParticipants 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.
Arm C: Imlunestrant + AbemaciclibEXPERIMENTALParticipants received Imlunestrant 400 mg orally once daily on Days 1 to 28 of a 28-day cycle, plus Abemaciclib 150 mg orally twice daily on Days 1 to 28 of a 28-day cycle, until disease progression or a criterion for discontinuation was met.
Cohort 1 Arm AEXPERIMENTALImlunestrant will be given orally
Cohort 1 Arm B - Imlunestrant + GoserelinEXPERIMENTALImlunestrant will be given orally and goserelin will be given subcutaneously (SC)
Cohort 1 Arm C - TamoxifenACTIVE_COMPARATORTamoxifen will be given orally
Cohort 2 Arm A - ImlunestrantEXPERIMENTALImlunestrant will be given orally
Cohort 2 Arm B - TamoxifenACTIVE_COMPARATORTamoxifen will be given orally
Midazolam + ImlunestrantEXPERIMENTALParticipants received 400 milligram (mg) Imlunestrant (2 × 200 mg) tablets administered once daily (QD) orally for 7 days on Days 3 to 9 and a single dose of 0.5 mg midazolam solution orally on Day 1 and Day 9 as per below dosing sequence: Day 1: 0.5 mg midazolam alone Days 3 to 8: 400 mg imlunestrant QD alone Day 9: 0.5 mg midazolam + 400 mg imlunestrant There was a washout period of 8 days between doses of midazolam.
Imlunestrant + Repaglinide (Cohort 1)EXPERIMENTALParticipants received: Day 1: A single oral dose of 0.5 mg repaglinide administered alone. Day 3: A single oral dose of 800 mg imlunestrant, followed approximately 2 hours later by 0.5 mg repaglinide, both administered orally.
mlunestrant + Omeprazole & Dextromethorphan (Cohort 2)EXPERIMENTALParticipants received: Day 1: A single oral dose of 20 mg omeprazole and 30 mg dextromethorphan, administered in the morning. Day 3: A single oral dose of 800 mg imlunestrant, followed immediately by 20 mg omeprazole and 30 mg dextromethorphan, all administered orally.
Imlunestrant + Quinidine (Cohort 3)EXPERIMENTALParticipants received: Day 1: A single oral dose of 400 mg imlunestrant, administered in the morning. Days 15 to 17 and 19 to 24: Twice-daily oral doses of 200 mg quinidine, administered alone. Day 18: A single oral dose of 400 mg imlunestrant administered in combination with 200 mg quinidine (quinidine was dosed twice on this day as part of the regular regimen).
Imlunestrant + Rosuvastatin & Digoxin (Cohort 4)EXPERIMENTALParticipants received: Day 1: A single oral dose of 10 mg rosuvastatin and 0.25 mg digoxin, administered in the morning. Day 10: A single oral dose of 400 mg imlunestrant, administered in combination with 10 mg rosuvastatin and 0.25 mg digoxin, all administered orally.
Imlunestrant (Normal Hepatic Function)EXPERIMENTALParticipants received a single dose of Imlunestrant 400 milligrams (mg) administered orally on Day 1 in fasted state.
Imlunestrant (Mild Hepatic Impairment)EXPERIMENTALParticipants received a single dose of Imlunestrant 400 mg administered orally on Day 1 in fasted state.
Imlunestrant (Moderate Hepatic Impairment)EXPERIMENTALParticipants received a single dose of Imlunestrant 400 mg administered orally on Day 1 in fasted state.
Imlunestrant (Severe Hepatic Impairment)EXPERIMENTALParticipants received a single dose of Imlunestrant 200 mg administered orally on Day 1 in fasted state.

Interventions

NameTypeDescription
ImlunestrantDRUGAdministered orally.
TamoxifenDRUGAdministered per local approved label.
AnastrozoleDRUGAdministered per local approved label.
LetrozoleDRUGAdministered per local approved label.
ExemestaneDRUGAdministered per local approved label.
FulvestrantDRUGAdministered IM.
AbemaciclibDRUGAdministered orally.
GoserelinDRUGGiven SC
Tamoxifen 20 mgDRUGGiven orally
MidazolamDRUGAdministered orally.
RepaglinideDRUGAdministered orally.
OmeprazoleDRUGAdministered orally.
DextromethorphanDRUGAdministered orally.
QuinidineDRUGAdministered orally.
RosuvastatinDRUGAdministered orally.
DigoxinDRUGAdministered orally.
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites672

Inclusion Criteria: * Have a diagnosis of ER+, HER2- early-stage, resected, invasive breast cancer without evidence of distant metastasis. * Participants must have received at least 24 months but not more than 60 months of any adjuvant ET, from time of adjuvant ET initiation. * Participants may hav...

Countries:United StatesArgentinaAustraliaAustriaBelgiumBrazilCanadaChinaCzechiaFranceGermanyGreeceHong KongHungaryIndiaIrelandIsraelItalyJapanMexicoNetherlandsPolandPortugalRomaniaSingaporeSlovakiaSouth KoreaSpainTaiwanTurkey (Türkiye)United KingdomRussiaUkraine
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Recent Changes (Last 90 Days)

LOWAug 21, 2026NCT07287098lastUpdatePostDate: changed
LOWAug 21, 2026NCT07287098lastUpdatePostDate: changed
LOWAug 6, 2026NCT07287098lastUpdatePostDate: changed
LOWAug 6, 2026NCT07287098lastUpdatePostDate: changed
LOWJul 22, 2026NCT04975308lastUpdatePostDate: changed
LOWJul 22, 2026NCT04975308lastUpdatePostDate: changed
LOWJul 17, 2026NCT07287098lastUpdatePostDate: changed
LOWJul 17, 2026NCT07287098lastUpdatePostDate: changed
LOWJul 7, 2026NCT07287098lastUpdatePostDate: changed
LOWJul 7, 2026NCT07287098lastUpdatePostDate: changed
LOWJun 26, 2026NCT07287098Status: NOT_YET_RECRUITING → RECRUITING
LOWJun 26, 2026NCT07287098Status: NOT_YET_RECRUITING → RECRUITING

Frequently asked questions about Imlunestrant

What is Imlunestrant used for?

Imlunestrant is an investigational small molecule being studied for the treatment of breast cancer, specifically in patients with estrogen receptor-positive (ER+), HER2-negative advanced or early breast cancer. It is also being evaluated in healthy participants and in individuals with hepatic insufficiency. The drug is currently in Phase 3 clinical development.

What does Imlunestrant target?

Imlunestrant targets the estrogen receptor as a selective estrogen receptor degrader (SERD). By degrading the estrogen receptor, it aims to block estrogen signaling that drives the growth of ER+ breast cancer cells. This mechanism is being studied in both advanced and early breast cancer settings.

Who makes Imlunestrant?

Imlunestrant is being developed by Eli Lilly and Company, a pharmaceutical company listed on the New York Stock Exchange under the ticker symbol LLY. The company is conducting multiple clinical trials to evaluate the drug's safety and efficacy in breast cancer and other conditions.

What phase is Imlunestrant in?

Imlunestrant is in Phase 3 clinical development for breast cancer. It is also being studied in earlier-phase trials, including a Phase 1 study in healthy participants and a Phase 2 study in premenopausal women with early breast cancer. The drug is investigational and not yet approved by regulatory authorities.

What clinical trials is Imlunestrant in?

Imlunestrant is being evaluated in several clinical trials. NCT04975308 is a Phase 3 study in ER+, HER2- advanced breast cancer. NCT05514054 is a Phase 3 study in early breast cancer. NCT05444556 is a Phase 1 study in healthy female participants, and NCT07287098 is a Phase 2 study in premenopausal women with early breast cancer.

Is Imlunestrant the same as LY3484356?

Yes, Imlunestrant is also known as LY3484356. Clinical trial records refer to the drug by both names, with LY3484356 serving as the investigational compound identifier used by Eli Lilly and Company in study documentation.