A Study of LY3484356 in Chinese Participants With Advanced Breast Cancer

Study Overview
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Brief Summary
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This is a study of LY3484356 in Chinese participants with advanced breast cancer. Participants must have breast cancer that is estrogen receptor positive (ER+), HER2 negative (HER2-). The purpose of this study is to measure how much LY3484356 gets into the bloodstream and how long it takes the body to remove it. The safety and effectiveness of LY3484356 will also be studied. Participation could last up to 28 months.

Official Title
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A Phase 1 Study of LY3484356 in Chinese Patients With Estrogen Receptor Positive, HER2 Negative Locally Advanced or Metastatic Breast Cancer

Conditions
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Breast Neoplasms

Intervention / Treatment
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* Drug: LY3484356


Participation Criteria
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Eligibility Criteria
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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, after available standard therapies have ceased to provide clinical benefit Have a diagnosis of ER+, HER2- breast cancer Female participants have postmenopausal status due either surgical/natural menopause or ovarian suppression If postmenopausal status is due to ovarian suppression, participants must have a negative serum pregnancy test and agree to use highly effective, medically approved precautions to prevent pregnancy Have a performance status less than or equal to (≤)1 on the Eastern Cooperative Oncology Group (ECOG) scale Have adequate organ function Must be able to swallow capsules/tablets Exclusion Criteria: Have symptomatic central nervous system (CNS) metastasis and/or carcinomatous meningitis Have a serious concomitant systemic disorder Human immunodeficiency virus (HIV) positive patients are excluded unless they are well controlled on highly active antiretroviral therapy with no evidence of autoimmune deficiency syndrome-defining opportunistic infections within the last 2 years, and cluster of differentiation 4 (CD4) count greater than (>)350 cells/microliter (μL) Active hepatitis B or C virus infection Severe renal impairment, interstitial lung disease, severe dyspnea at rest or requiring oxygen therapy, history of major surgical resection involving the stomach or small bowel, preexisting Crohn's disease or ulcerative colitis or a preexisting chronic condition resulting in clinically significant diarrhea Have visceral crisis Have a serious cardiac condition Have an acute leukemia or other relevant cancers Females who are pregnant or lactating Known allergic reaction against any of the components of the study drug

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: LY3484356 Dose Level 1<br>Administered orally. | Drug: LY3484356<br>* Administered orally.<br>|
| Experimental: LY3484356 Dose Level 2<br>Administered orally. | Drug: LY3484356<br>* Administered orally.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pharmacokinetics (PK): Plasma Concentration of LY3484356 | 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) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 2. Percentage of Participants Who Achieve a Best Overall Response (BOR) of Complete Response (CR) or Partial Response (PR): Overall Response Rate (ORR) | 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) | DCR | Randomization to Disease Progression or Death from Any Cause (Estimated up to 28 months) | 
| Progression-Free Survival (PFS) | PFS | Randomization to Disease Progression or Death from Any Cause (Estimated up to 28 months) |