A Study of LY3295668 Erbumine in Participants With Breast Cancer That Has Spread to Other Parts of the Body

A Phase 1b Study of Aurora A Kinase Inhibitor LY3295668 Erbumine in Monotherapy and Combination Therapy in Patients With Metastatic Breast Cancer Post CDK4/6 Inhibitor and Endocrine Therapy

The reason for this study is to determine the recommended phase 2 dose of the study drug LY3295668 erbumine in participants with breast cancer that has spread to other parts of the body.

Inclusion Criteria:

• Participant must have hormone receptor positive and HER2 negative metastatic breast cancer
• Participant must have progressed on at least 1 line of endocrine therapy and 1 cyclin dependent kinase (CDK)4/6 inhibitor
• Participant must be able and willing to undergo mandatory tumor biopsy
• Participant must have normal organ function
• Participant must be able to swallow capsules

Exclusion Criteria:

• Participant must not have had prior chemotherapy for mBC. Chemotherapy in the adjuvant/neoadjuvant setting is permitted
• Participant must not be currently enrolled in a clinical study
• Participant must not have another serious medical condition
• Participant must not have previously received an aurora kinase inhibitor