Tesetaxel Plus Reduced Dose of Capecitabine vs. Capecitabine in HER2 Negative, HR Positive, LA/MBC

Inclusion Criteria:

   1. Female or male patients at least 18 years of age

   2. Histologically or cytologically confirmed breast cancer

   3. HER2 negative disease based on local testing: American Society of Clinical
   Oncology/College of American Pathologists (ASCO/CAP) guidelines should be utilized for
   assessing HER2 status

   4. HR (estrogen receptor [ER] and/or progesterone receptor [PgR]) positive disease based
   on local testing: ASCO/CAP guidelines should be utilized for assessing HR status

   5. Measurable disease per RECIST 1.1 or bone-only disease with lytic component

      - Patients with bone-only metastatic cancer must have a lytic or mixed
      lytic-blastic lesion that can be accurately assessed by computerized tomography
      (CT) or magnetic resonance imaging (MRI). Patients with bone-only disease without
      a lytic component (ie, blastic-only metastasis) are not eligible.

      - Known metastases to the CNS are permitted but not required. The following
      criteria apply:

         - Patients must be neurologically stable and either off corticosteroids or
         currently treated with a maximum daily dose of 4 mg of dexamethasone (or
         equivalent), with no increase in corticosteroid dose within 7 days prior to
         randomization

         - Patients with a history of CNS metastases but with no current evidence of
         CNS lesions following local therapy are eligible

         - Patients may have CNS metastases that are stable or progressing
         radiologically

         - Patients with current evidence of leptomeningeal disease are not eligible

         - Patients may have untreated brain metastases or previously treated brain
         metastases, as long as no immediate local CNS-directed therapy is indicated

         - Any prior whole brain radiation therapy must have been completed > 14 days
         prior to the date of randomization

         - Prior stereotactic brain radiosurgery is permitted

         - CNS surgical resection must have been completed > 28 days prior to the date
         of randomization; patient must have complete recovery from surgery

   6. Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2

   7. Prior therapy (at least one completed dose) with a taxane-containing regimen in the
   neoadjuvant or adjuvant setting

   8. Prior therapy with an anthracycline-containing regimen in the neoadjuvant, adjuvant,
   or metastatic setting, where indicated by local regulation or Investigator judgment.

   9. Prior endocrine therapy with or without a CDK 4/6 inhibitor unless endocrine therapy
   is not indicated (ie, short relapse-free interval while on adjuvant endocrine therapy
   [endocrine resistance]; rapidly progressing disease/visceral crisis; or endocrine
   intolerance). Any targeted therapies approved for HER2 negative, HR positive LA/MBC,
   including everolimus, are permitted as prior therapy. There is no limit to the number
   of prior endocrine therapies.

10. Documented disease recurrence or disease progression of: (a) locally advanced disease
   that is not considered curable by surgery and/or radiation; or (b) metastatic disease.

11. Adequate hematologic, hepatic and renal function, as evidenced by:

      - Absolute neutrophil count (ANC) ≥ 1,500/μL without colony-stimulating factor
      support

      - Platelet count ≥ 100,000/μL

      - Hemoglobin ≥ 10 g/dL without need for hematopoietic growth factor or transfusion
      support

      - Total bilirubin < 1.5 × upper limit of normal (ULN); does not apply to patients
      with Gilbert's syndrome

      - Alanine aminotransferase (ALT) < 3 × ULN unless hepatic metastases are present,
      then < 5 × ULN

      - Aspartate aminotransferase (AST) < 3 × ULN unless hepatic metastases are present,
      then < 5 × ULN

      - Alkaline phosphatase < 2.5 × ULN unless hepatic metastases are present, then < 5
      × ULN

      - Calculated creatinine clearance ≥ 50 mL/min (by Cockcroft-Gault formula or local
      standard)

      - Serum albumin ≥ 3.0 g/dL

      - Prothrombin time (PT) < 1.5 × ULN or international normalized ratio (INR) < 1.3,
      and partial thromboplastin time (PTT) < 1.5 × ULN, unless the patient is on a
      therapeutic anticoagulant

12. Complete recovery to baseline or Grade 1 per National Cancer Institute (NCI) CTCAE
   version 5.0 from adverse effects of prior surgery, radiotherapy, endocrine therapy and
   other therapy, as applicable, with the exception of Grade 2 alopecia from prior
   chemotherapy

13. Ability to swallow an oral solid-dosage form of medication

14. A negative serum pregnancy test within 7 days prior to the first dose of Study
   treatment in women of childbearing potential (ie, all women except those who are post
   menopause for ≥ 1 year or who have a history of hysterectomy or surgical
   sterilization)

15. Women of childbearing potential must use an effective, non-hormonal form of
   contraception from Screening throughout the Treatment Phase and until 70 days after
   the last dose of study treatment

   • Acceptable methods include: copper intrauterine devices or double barrier methods,
   including male/female condoms with spermicide and use of contraceptive sponge,
   cervical cap, or diaphragm

16. Male patients must use an effective, non-hormonal form of contraception from screening
   throughout the treatment phase and until 130 days after last dose of study treatment

   • Acceptable methods include male/female condoms with spermicide, or vasectomy with
   medical confirmation of surgical success

17. Written informed consent and authorization to use and disclose health information

18. Ability to comprehend and comply with the requirements of the study

Exclusion Criteria:

   1. Two or more prior chemotherapy regimens for advanced disease

   2. Prior treatment with a taxane in the metastatic setting

   3. Prior treatment with capecitabine at any dose

   4. Current evidence of leptomeningeal disease

   5. Other cancer that required therapy within the preceding 5 years other than adequately
   treated: (a) non-melanoma skin cancer or in situ cancer; or (b) following approval by
   the Medical Monitor, other cancer that has a very low risk of interfering with the
   safety or efficacy endpoints of the study

   6. Known human immunodeficiency virus infection, unless well controlled. Patients who are
   on an adequate antiviral regimen with no evidence of active infection are considered
   well controlled.

   7. Active hepatitis B or active hepatitis C infection

   8. Other severe acute or chronic medical or psychiatric condition or laboratory
   abnormality that may increase the risk associated with study participation or
   investigational product administration or may interfere with the interpretation of
   study results and, in the judgment of the Investigator, would make the patient
   inappropriate for entry into this study

   9. Presence of neuropathy > Grade 1 per NCI CTCAE version 5.0

10. History of hypersensitivity to taxanes; hypersensitivity to the solvent does not
   preclude patient participation in this study

11. Anticancer treatment, including endocrine therapy, radiotherapy (except stereotactic
   brain radiosurgery), chemotherapy, biologic therapy, or therapy in an investigational
   clinical study, ≤ 14 days prior to the date of randomization

12. Major surgery ≤ 28 days prior to the date of randomization; patient must have complete
   recovery from surgery

13. Less than 2 weeks or 5 plasma half-lives (whichever is greater) since last use of a
   medication or ingestion of an agent, beverage or food that is a known clinically
   relevant strong inhibitor or known clinically relevant inducer of the cytochrome P450
   (CYP) 3A pathway (patients should discontinue taking any regularly taken medication
   that is a strong inhibitor or inducer of the CYP3A pathway)

14. History of hypersensitivity or unexpected reactions to capecitabine, other
   fluoropyrimidine agents or any of their ingredients

15. Known dihydropyrimidine dehydrogenase (DPD) deficiency. Testing for DPD deficiency
   must be performed where required by local regulations, using a validated method that
   is approved by local health authorities.

16. Pregnant or breastfeeding

17. If, in the opinion of the Investigator, the patient is deemed unwilling or unable to
   comply with the requirements of the study

18. Treatment with brivudine, sorivudine or its chemically-related analogs ≤ 28 days prior
   to the date of randomization