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LY3484356

Phase 1

Breast Cancer | Small molecule | Oncology |Eli Lilly and Company|Last Updated: Jun 22, 2026

Target and mechanism

Molecular targetER
Target classEstrogen Receptor
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

RandomizedCONTROLLED
Total Trials2
Total Enrollment466

FDA Designations

No designations recorded

Clinical trial landscape

LY3484356 · 5 trials · 6 indications

Phase 1 5
NCT05509790A Study of LY3484356 in Chinese Participants With Advanced Breast CancerBreast Neoplasms
ACTIVE NOT_RECRUITING17 Analytics
NCT04991766A Study of [¹⁴C]-LY3484356 in Healthy Female ParticipantsHealthy
COMPLETED16 Analytics
NCT04840888A Study of LY3484356 in Healthy Female ParticipantsHealthy
COMPLETED82 Analytics
NCT04647487A Study of LY3484356 in Women With Breast Cancer Before Having SurgeryBreast Cancer
COMPLETED87 Analytics
NCT04188548A Study of LY3484356 in Participants With Advanced or Metastatic Breast Cancer or Endometrial CancerBreast Cancer
ACTIVE NOT_RECRUITING379 Analytics
PHASE1ACTIVE NOT_RECRUITING
A Study of LY3484356 in Chinese Participants With Advanced Breast Cancer
Breast NeoplasmsUnlock trial analytics
PHASE1COMPLETED
A Study of [¹⁴C]-LY3484356 in Healthy Female Participants
HealthyUnlock trial analytics
PHASE1COMPLETED
A Study of LY3484356 in Healthy Female Participants
HealthyUnlock trial analytics
PHASE1COMPLETED
A Study of LY3484356 in Women With Breast Cancer Before Having Surgery
Breast CancerUnlock trial analytics
PHASE1ACTIVE NOT_RECRUITING
A Study of LY3484356 in Participants With Advanced or Metastatic Breast Cancer or Endometrial Cancer
Breast CancerUnlock trial analytics

Study Endpoints

Primary Endpoints

Pharmacokinetics (PK): Plasma Concentration of LY3484356
Time Frame: Cycle 1, Day 1 through Day 3 and Day 17 through Day 18; Cycle 2 Day 1 (Cycle 1 = 30 days, Cycle 2 = 28 days)

PK: Plasma Concentration of LY3484356

Part 1: Pharmacokinetics (PK): Fecal Excretion of LY3484356 Radioactivity Over Time Expressed as a Percentage of the Total Radioactive Dose Administered
Predose, 24, 48, 72, 96, 120, 144, 168,192, 216, 240, 264, 288 and 312 hours post dose

The percentage of the total radioactive dose administered that was excreted in feces = (amount of radioactive dose recovered in feces / total radioactive dose administered) \* 100.

Part 1: PK: Urinary Excretion of LY3484356 Radioactivity Over Time Expressed as a Percentage of the Total Radioactive Dose Administered
Predose, 24, 48 ,72, 96, 120, 144, 168, 192, 216, 240, 264, 288 and 312 hours post dose

The percentage of the total radioactive dose administered that was excreted in urine = (amount of radioactive dose recovered in urine / total radioactive dose administered) \* 100.

Part 2: Pharmacokinetics (PK): Percent Absolute Bioavailability (F%) of LY3484356
Predose, 5 minutes(min), 15 min, 20 min, 30 min, 45 min, and 1, 2, 3, 4, 6, 8, 10, 12, 24, 48, 72, 96, 120, 144, 168, and 192 hours postdose

PK: Bioavailability is defined as the percentage of a drug which enters the circulation when introduced into the body and so is able to have an active effect. Percent absolute bioavailability, calculated for plasma LY3484356 as "F %= \[AUC (0-∞), LY3484356\] × \[Dose, \[14C\]-LY3484356\] / \[AUC (0-∞), \[14C\]-LY3484356\] × \[Dose, LY3484356\] ×100%'' Higher percent indicates better absorption of drug into the body.

Pharmacokinetics (PK): Area Under the Concentration Versus Time Curve From Zero to Infinity (AUC[0-∞]) of LY3484356 (Cohort 1)
Period 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 hours (h) postdose; Period 2: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 and 96 h postdose

PK: AUC\[0-∞\] of LY3484356

PK: AUC[0-∞] of LY3484356 (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 9: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

PK: AUC\[0-∞\] of LY3484356

PK: AUC[0-∞] of LY3484356 (Cohort 3)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 10: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

PK: AUC\[0-∞\] of LY3484356

PK: AUC[0-∞] of LY3484356 (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 18: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

AUC\[0-∞\] of LY3484356

PK: Time of Maximum Observed Concentration (Tmax) of LY3484356 (Cohort 1)
Period 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 h postdose; Period 2: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 and 96 h postdose

PK: Tmax of LY3484356

PK: Tmax of LY3484356 (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 9: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

PK: Tmax of LY3484356

PK: Tmax of LY3484356 (Cohort 3)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 10: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

PK: Tmax of LY3484356

PK: Tmax of LY3484356 (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 18: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

Tmax of LY3484356

PK: Maximum Observed Concentration (Cmax) of LY3484356 (Cohort 1)
Period 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 h postdose; Period 2: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 48 and 72 and 96 h postdose

Cmax of LY3484356

PK: Cmax of LY3484356 (Cohort 2)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 9: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

Cmax of LY3484356

PK: Cmax of LY3484356 (Cohort 3)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 10: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

Cmax of LY3484356

PK: Cmax of LY3484356 (Cohort 4)
Day 1: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose; Day 18: Predose, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 h postdose

Cmax of LY3484356

Percent Change From Baseline in Estrogen Receptor (ER) Expression
Baseline, Day 15

Tumor tissue collected by biopsy is used to determine ER expression. ER expression is measured by immunohistochemistry (IHC) and quantified by H-score. The H-score was calculated as the sum of multiplying the tumor cell ER staining intensity level 0 to 3 (0=none, 1=low, 2=moderate, 3=high) by the percentage (0 to 100) of cells at each intensity. Total ER H-score ranged from 0 to 300, where a higher score indicated stronger ER expression. Percent change in ER expression was defined as 100\*(ER expression on-treatment - ER expression pre-treatment)/(ER expression pre-treatment). Geometric mean percent change and 90 percent (%) confidence interval for percent change were obtained from a t-test of the log ratio i.e. log(ER expression on-treatment/ER expression pre-treatment).

Number of Participants with Dose Limiting Toxicities (DLTs) and DLT-Equivalent Toxicities
Baseline through Cycle 1 (21/28 Day Cycle)

Number of Participants with DLTs and DLT-Equivalent Toxicities

Secondary Endpoints

2. Percentage of Participants Who Achieve a Best Overall Response (BOR) of Complete Response (CR) or Partial Response (PR): Overall Response Rate (ORR)
Randomization to Disease Progression or Death from Any Cause (Estimated up to 28 months)
Disease Control Rate (DCR): Percentage of Participants With a BOR of Complete Response (CR), Partial Response (PR) or Stable Disease (SD)
Randomization to Disease Progression or Death from Any Cause (Estimated up to 28 months)
Progression-Free Survival (PFS)
Randomization to Disease Progression or Death from Any Cause (Estimated up to 28 months)
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
LY3484356 Dose Level 1EXPERIMENTALAdministered orally.
LY3484356 Dose Level 2EXPERIMENTALAdministered orally.
[¹⁴C]-LY3484356 (Part 1)EXPERIMENTALParticipants received a single oral dose of 400 mg Carbon 14 labelled \[¹⁴C\]-LY3484356 following an overnight fast of at least 10 hours on Day 1.
LY3484356 + [¹⁴C]-LY3484356 (Part 2)EXPERIMENTALParticipants received a single oral dose of 400 mg LY3484356 following an overnight fast of at least 10 hours on Day 1, followed 4 hours later by a single dose of less than 100 microgram (μg) \[¹⁴C\]-LY3484356 (actual ranged from 44.55 to 45.95 μg), as an intravenous (IV) infusion on day 1.
Cohort 1 Sequence 1: 400 mg LY3484356 Fasted/ 400 mg LY3484356 FedEXPERIMENTALParticipants were randomized (1:1) to 1 of 2 treatment sequences; LY3484356 administered as single doses orally with (fed) or without food (fasted) as below: Period 1: Single dose of 400 mg LY3484356 in the fasted state. Period 2: Single dose of 400 mg LY3484356 in the fed state. There was a washout period of 4 days between doses of LY3484356
Cohort 1 Sequence 2: 400 mg LY3484356 Fed/ 400 mg LY3484356 FastedEXPERIMENTALParticipants were randomized (1:1) to 1 of 2 treatment sequences; LY3484356 administered as single doses orally with (fed) or without food (fasted) as below: Period 1: Single dose of 400 mg LY3484356 in the fed state. Period 2: Single dose of 400 mg LY3484356 in the fasted state. There was a washout period of 4 days between doses of LY3484356.
Cohort 2: LY3484356 + OmeprazoleEXPERIMENTALParticipants received single dose of LY3484356 and a single dose of omeprazole alone and in combination administered orally as below: Day 1: 400 mg LY3484356 alone Days 5 to 8: 40 mg omeprazole alone once daily Day 9: 400 mg LY3484356 + 40 mg omeprazole once There was a washout period of 8 days between doses of LY3484356.
Cohort 3: LY3484356 + ItraconazoleEXPERIMENTALParticipants received single dose of LY3484356 and a single dose of Itraconazole alone and in combination administered orally as below: Day 1: 200 mg LY3484356 alone Days 5 to 9: 200 mg itraconazole alone (twice on Day 5 \[dose separated by approximately 12 hours\], then once daily on Days 6 through 9) Day 10: 200 mg LY3484356 + 200 mg itraconazole once (coadministered with the morning dose) Days 11 to 16: 200 mg itraconazole alone once daily. There was a washout period of 9 days between doses of LY3484356.
Cohort 4: LY3484356 + CarbamazepineEXPERIMENTALParticipants received single dose of LY3484356 and a single dose of carbamazepine alone and in combination administered orally as below: Day 1: 400 mg LY3484356 alone Days 6 to 8: 100 mg carbamazepine BID alone Days 9 to 11: 200 mg carbamazepine BID alone Days 12 to 17: 300 mg carbamazepine BID alone Day 18: 300 mg carbamazepine BID + 400 mg LY3484356 (coadministered with morning dose) Days 19 to 22: 300 mg carbamazepine BID alone Day 23: 300 mg carbamazepine alone (morning dose only). There was a washout period of 17 days between doses of LY3484356.
Cohort 5: Carbamazepine + MidazolamEXPERIMENTALParticipants received single dose of Carbamazepine and a single dose of midazolam alone and in combination administered orally as below: Day 1: 1.2 mg midazolam alone Days 2 to 4: 100 mg carbamazepine BID alone Days 5 to 7: 200 mg carbamazepine BID alone Days 8 to 10: 300 mg carbamazepine BID alone Day 11: 300 mg carbamazepine BID + 1.2 mg midazolam (coadministered with morning dose) Days 12 to 13: 300 mg carbamazepine BID alone Day 14: 300 mg carbamazepine BID + 1.2 mg midazolam (coadministered with morning dose).
200 milligrams (mg) LY3484356EXPERIMENTALParticipants received 200 mg LY3484356 administered orally once daily for 15 days
400 mg LY3484356EXPERIMENTALParticipants received 400 mg LY3484356 administered orally once daily for 15 days
800 mg LY3484356EXPERIMENTALParticipants received 800 mg LY3484356 administered orally once daily for 15 days
Dose Escalation LY3484356EXPERIMENTALLY3484356 given orally.
Part A: Dose Expansion: LY3484356 + Abemaciclib +/- AIEXPERIMENTALLY3484356 and abemaciclib given orally in combination with or without Aromatase Inhibitor (AI) of physician's choice (Anastrozole, Exemestane, or Letrozole) administered orally.
Part B: Dose Expansion: Cohort E3: LY3484356EXPERIMENTALLY3484356 given orally.
Part B: Dose Expansion: Cohort E4: LY3484356 + EverolimusEXPERIMENTALLY3484356 and everolimus given orally.
Part B: Dose Expansion: Cohort E5: LY3484356 + AlpelisibEXPERIMENTALLY3484356 and alpelisib given orally.
Part C:Dose Expansion: LY3484356 + Trastuzumab +/- AbemaciclibEXPERIMENTALLY3484356 administered orally in combination with trastuzumab intravenously with or without Abemaciclib.
Part D: Dose Expansion: LY3484356 +/- AbemaciclibEXPERIMENTALLY3484356 and Abemaciclib given orally with trastuzumab administered intravenously.
Part E: Dose Expansion: LY3484356 + Trastuzumab + PertuzumabEXPERIMENTALLY3484356 administered orally in combination with trastuzumab and pertuzumab administered intravenously.

Interventions

NameTypeDescription
LY3484356DRUGAdministered orally.
[¹⁴C]-LY3484356DRUGAdministered orally.
[¹⁴C]-LY3484356 (IV)DRUGAdministered IV.
OmeprazoleDRUGAdministered orally.
ItraconazoleDRUGAdministered orally.
CarbamazepineDRUGAdministered orally.
MidazolamDRUGAdministered orally.
AbemaciclibDRUGAdministered orally
EverolimusDRUGAdministered orally
AlpelisibDRUGAdministered orally
TrastuzumabDRUGAdministered intravenously
Aromatase Inhibitor (AI)DRUGAnastrozole or Exemestane or Letrozole administered orally (physician choice)
PertuzumabDRUGAdministered intravenously
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites4

Inclusion Criteria: * Native Chinese participants must be of an acceptable age to provide informed consent * Have locally advanced (not amenable to curative treatment by surgery) or metastatic disease and be an appropriate candidate for experimental therapy in the judgment of the investigator, afte...

Countries:ChinaUnited StatesBelgiumFranceGermanySpainUnited KingdomAustraliaJapanSouth KoreaTaiwan
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Competitive Landscape -Breast Cancer 402 trials

Top 20 of 92 competitors

CompanyTickerTrialsLead PhaseDrugs
AstraZeneca PLCAZN47PHASE3Fulvestrant, Capivasertib
Merck & Co., Inc.MRK12PHASE3Pembrolizumab, Paclitaxel, Doxorubicin, Epirubicin, Cyclophosphamide
Eli Lilly and CompanyLLY27PHASE3Abemaciclib, Standard Adjuvant Endocrine Therapy
BioNTech SE Sponsored ADRBNTX7PHASE3DB-1303/BNT323, T-DM1
Gilead Sciences, Inc.GILD13PHASE3Sacituzumab Govitecan-hziy, Eribulin, Capecitabine Product, Gemcitabine, Vinorelbine
Novartis AG Sponsored ADRNVS30PHASE3Ribociclib
Pfizer Inc.PFE34PHASE3ARV-471, Fulvestrant
BeOne Medicines Ltd. Sponsored ADRONC5PHASE3BGB-43395, Letrozole, Abemaciclib, Palbociclib, Ribociclib
Olema Pharmaceuticals, Inc.OLMA5PHASE3Palazestrant, Fulvestrant, Anastrozole, Letrozole, Exemestane
Jazz Pharmaceuticals Public Limited CompanyJAZZ3PHASE3Zanidatamab, Trastuzumab, Eribulin, Vinorelbine, Gemcitabine
Celcuity Inc.CELC3PHASE3Gedatolisib, Palbociclib, Fulvestrant, Alpelisib
Relay Therapeutics, Inc.RLAY2PHASE3Zovegalisib, Capivasertib, Fulvestrant
GSK plc Sponsored ADRGSK2PHASE3Niraparib
Greenwich LifeSciences, Inc.GLSI1PHASE3GLSI-100
Bristol-Myers Squibb CompanyBMY5PHASE2Iza-bren, Nab-paclitaxel, Paclitaxel, Capecitabine, Carboplatin
BriaCell Therapeutics CorpBCTX2PHASE3SV-BR-1-GM, Cyclophosphamide, Interferon infiltration of the inoculation site, Retifanlimab, Treatment of Physician's Choice
Incyte CorporationINCY4PHASE2Ruxolitinib, Capecitabine, Regorafenib
Natera, Inc.NTRA3PHASE2Discontinuation of the anti-HER2 maintenance therapy
Puma Biotechnology, Inc.PBYI3PHASE2Neratinib, Loperamide, Colesevelam
Atossa Therapeutics, Inc.ATOS1PHASE2endoxifen, goserelin
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Recent Changes (Last 90 Days)

HIGHJun 22, 2026NCT04188548Enrollment: 500 → 379
HIGHJun 22, 2026NCT04188548Enrollment: 500 → 379

Frequently asked questions about LY3484356

What is LY3484356 used for?

LY3484356 is an investigational small molecule being studied for the treatment of breast cancer, including advanced and metastatic breast cancer, as well as endometrial cancer. It is also being evaluated in healthy female participants for research purposes. The drug is currently in Phase 1 clinical development.

What does LY3484356 target?

LY3484356 targets the estrogen receptor (ER). As an estrogen receptor-targeting agent, it is being investigated for its potential role in treating hormone-related cancers such as breast cancer. The drug is designed to interact with this receptor, which is a key driver in certain types of breast cancer.

Who makes LY3484356?

LY3484356 is being developed by Eli Lilly and Company, a pharmaceutical company listed on the stock exchange under the ticker symbol LLY. The company is conducting clinical trials to evaluate the safety and efficacy of this investigational drug in patients with breast cancer and other conditions.

What phase is LY3484356 in?

LY3484356 is in Phase 1 clinical development. It is an investigational drug, meaning it has not yet been approved by regulatory authorities. The ongoing Phase 1 trials are designed to assess the drug's safety, tolerability, and preliminary efficacy in participants with breast cancer and healthy volunteers.

What clinical trials is LY3484356 in?

LY3484356 is being studied in several Phase 1 clinical trials. NCT04188548 is an active trial in participants with advanced or metastatic breast cancer or endometrial cancer. NCT04647487 is a completed trial in women with breast cancer before surgery. NCT04840888 and NCT04991766 are completed trials in healthy female participants.

Is LY3484356 the same as imlunestrant?

LY3484356 is also known as imlunestrant. This alternative name is used in some clinical and research contexts. The drug is being developed by Eli Lilly and Company for the treatment of breast cancer and other conditions. Both names refer to the same investigational compound.