A Study of E7090 as Monotherapy and in Combination With Other Anticancer Agents in Participants With Estrogen Receptor Positive (ER+) and Human Epidermal Growth Receptor 2 Negative (HER2-) Recurrent/Metastatic Breast Cancer

Inclusion criteria

Common to Part 1, 2 and 3

• Participants who provided written voluntary informed consent for participation in the study.
• Female participants who are age >=18 years at the time of informed consent.
• Post-menopausal or pre/peri-menopausal participants who have been continuously on concurrently given a luteinizing hormone-releasing hormone (LHRH) agonist since before the start of study treatment and is planned to continue this treatment during the study.
• Participants with histologically confirmed diagnosis of progressive/recurrent or metastatic, ER+, HER2 negative breast cancer.
• Participants who received prior CDK4/6 inhibitor treatment.
• Participants with Performance Status (PS) score of 0-1 established by Eastern Cooperative Oncology Group (ECOG).
• Part 1 and Part 2: Participants with at least one accessible lesion for biopsy and who agree to undergo a biopsy of accessible lesion prior to study treatment (if archived tissues collected after CDK4/6 inhibitor treatment is not available) and on Day 1 of Cycle 3.

(Part 3) participants must agree to undergo a biopsy at screening if no archival tissue is available (tissue collection must be after CDK4/6 inhibitor treatment and prior to study treatment). A biopsy on Day 1 of Cycle 3 is not mandatory.

• Participants who agree to provide archival or fresh tumor tissue collected after CDK4/6 inhibitor treatment.
• Part 2 only: Participants with positive protein expression of fibroblast growth factor receptor 1 (FGFR) and/or FGFR2, with which tumor was collected after CDK4/6 inhibitor treatment at the central laboratory.

Exclusion criteria

• Participants with brain or subdural metastases, unless they have completed local therapy and have discontinued the use of corticosteroids for this indication for at least 4 weeks before starting treatment in this study. Any signs (example. radiologic) or symptoms of brain metastases must be stable for at least 4 weeks before starting study treatment.
• (Part 1 and Part 2) Participant who have received 2 or more regimen of chemotherapy for the treatment of advanced or metastatic lesions.
• (Part 3) Participant who have received 1 or more regimens of chemotherapy or antibody-drug conjugate therapy for the treatment of advanced or metastatic lesions.
• Participant with inflammatory breast cancer.
• Participant with bilateral breast cancer of different histologic types. Participants who have bilateral breast cancers that are both ER+ and HER2- may be enrolled in the study.
• Participant who have history of active malignancy within the past 24 months prior to the first dose of study drugs.
• Participants with clinically significant cardiovascular impairment.
• Presence of a progressive central nervous system (CNS) disease, including degenerative CNS diseases and progressive tumors.
• Concomitant active infection requiring systemic treatment.
• Participants who test positive for human immunodeficiency virus (HIV antibody), or positive for hepatitis B surface (HBs antigen) or hepatitis C (HCV antibody and RNA).
• Participants with following ocular disorders:

• Current evidence of Grade 2 or higher corneal disorder.
• Current evidence of active retinopathy (example. age-related macular degeneration, central serous chorioretinal disease, retinal tear)
• Participants who received prior treatment with an FGFR inhibitor.
• Females who are pregnant or breastfeeding.
• Part 1 only: Participants with T-score less than (<) -2.5 by dual-energy X-ray absorptiometry (DXA) scan.
• Part 3 only: Participants who received 3 or more prior lines of endocrine therapy in advanced/metastatic setting.