Fisetin to Improve Physical Function in Stage I-III Breast Cancer Survivors

Inclusion Criteria:

• Women who are postmenopausal at the start of study treatment.

Postmenopausal status will be established as follows:

• Women aged: >= 60 years OR

• Women aged < 60 years AND one of the following conditions is met:

• They have not had any menstrual periods for at least 12 months in the absenceof exogenous hormonal treatments, chemotherapy, and/or tamoxifen AND have serumestradiol and follicle-stimulating hormone (FSH) levels confirmed as beingwithin the standard laboratory reference range for postmenopausal females.

• They have documented irreversible bilateral oophorectomy.

• They are receiving ovarian suppression with their breast cancer endocrinetherapy

• Women with a diagnosis of early-stage breast cancer (Stage I-III) treatedwith neo/adjuvant chemotherapy within 12 months of starting studytreatment

• No evidence of active/recurrent breast cancer or other serious chronicillnesses

• Have evidence of frail health, defined as a diminished 6-minute walkdistance (< 400m) at baseline

• Platelets > 60,000/mm^3

• White blood cell count > 2,000/mm^3

• Absolute neutrophil count > 500/mm^3

• Hemoglobin >= 8.0 g/dL

• Total bilirubin =< 3.0 X upper limit of normal (ULN)

• Aspartate aminotransferase (AST) =< 4.0 x ULN

• Alanine aminotransferase (ALT) =< 4.0 x ULN

• Estimated glomerular filtration rate (eGFR) of >= 30mL/min/1.73m^2 per theModification of Diet in Renal Disease (MDRD) calculation

• Ability to understand and the willingness to sign a written informedconsent document

Exclusion Criteria:

• Cancer-directed chemotherapy, biological therapy, or immunotherapy within 30 daysprior to the start of study treatment. Exceptions include: trastuzumab, pertuzumab,pembrolizumab, tamoxifen, and aromatase inhibitors

• Surgery and/or radiation within the last 30 days of starting study treatment (Exception: invasive non- major procedures such as an outpatient biopsy)

• Subjects taking medications that are considered prohibited.

• Exception: Subjects taking any of the medications listed in under "Temporarymedication adjustment required" may participate if they are otherwise eligibleAND the medication can be safely withheld (from immediately before the 1ststudy agent administration until at least 10 hours after the last study agentadministration, for each dosing interval)

• On herbal and natural medications with possible senolytic properties (i.e.,curcumin, kava kava, St. John's wort) and are unable or unwilling to hold itsadministration 2 days prior to and during study treatment dosing. Exceptions includecannabidiol (CBD), vitamins, probiotics, and fish oil. Other herbal and naturalmedications may be permitted or prohibited per clinician discretion

• Subjects taking potentially senolytic agents within the last year: fisetin,quercetin, luteolin, dasatinib or imatinib (or other tyrosine kinase inhibitors),piperlongumine, or navitoclax

• Subjects on therapeutic doses of anticoagulants (e.g., warfarin, heparin, lowmolecular weight heparin, factor Xa inhibitors, etc.)

• Issues with tolerating oral medication (such as but not limited to, inability toswallow pills (g-tubes not allowed), malabsorption issues, ongoing nausea orvomiting during screening, history of Crohn's, gastric bypass/reduction, or celiacdisease)

• Any other condition that would, in the Investigator's judgment, contraindicate thepatient's participation in the clinical study due to safety concerns with clinicalstudy procedures

• Currently participating in another intervention research study seeking to improvefunctional status, alleviate frailty, muscle strength, exhaustion/fatigue, orcognitive function