An International, Multi-Center, Open-Label, Randomized, Phase III Trial of Sacituzumab Govitecan versus Treatment of Physician Choice in Patients with Metastatic Triple-Negative Breast Cancer Who Received at Least Two Prior Treatments

The primary objective of this study is to compare the efficacy of sacituzumab govitecan to
the treatment of physician's choice (TPC) as measured by independently-reviewed Independent
Review Committee (IRC) progression-free survival (PFS) in participants with locally advanced
or metastatic triple-negative breast cancer (TNBC) previously treated with at least two
systemic chemotherapy regimens for unresectable, locally advanced or metastatic disease, and
without brain metastasis at baseline.

Key Inclusion Criteria:

- Histologically or cytologically confirmed TNBC based on the most recent analyzed
biopsy or other pathology specimen. Triple negative is defined as <1% expression for
estrogen receptor (ER) and progesterone receptor (PR) and negative for human epidermal
growth factor receptor 2 (HER2) by in-situ hybridization.

- Refractory to or relapsed after at least two prior standard therapeutic regimens for
advanced/metastatic TNBC.

- Prior exposure to a taxane in localized or advanced/metastatic setting.

- Eligible for one of the chemotherapy options listed as TPC (eribulin, capecitabine,
gemcitabine, or vinorelbine) as per investigator assessment.

- Eastern Cooperative Oncology Group (ECOG) performance score of 0 or 1.

- Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) as
per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). Bone-only
disease is not permitted.

- At least 2 weeks beyond prior anti-cancer treatment (chemotherapy, endocrine therapy,
radiotherapy, and/or major surgery), and recovered from all acute toxicities to Grade
1 or less (except alopecia and peripheral neuropathy).

- At least 2 weeks beyond high dose systemic corticosteroids (however, low dose
corticosteroids < 20 mg prednisone or equivalent daily are permitted provided the dose
is stable for 4 weeks).

- Adequate hematology without ongoing transfusional support (hemoglobin > 9 g/dL,
absolute neutrophil count (ANC) > 1,500 per mm^3, platelets > 100,000 per mm^3).

- Adequate renal and hepatic function (creatinine clearance [CrCL] > 60 mL/min,
bilirubin ≤ 1.5 institutional upper limit of normal [IULN], aspartate aminotransferase
[AST] and alanine aminotransferase [ALT] ≤ 2.5 x IULN or ≤ 5 x IULN if known liver
metastases and serum albumin ≥3 g/dL).

- Recovered from all toxicities to Grade 1 or less by National Cancer Institute common
terminology criteria for adverse events (NCI CTCAE) v4.03 (except alopecia or
peripheral neuropathy that may be Grade 2 or less) at the time of randomization.
Participants with Grade 2 neuropathy are eligible but may not receive vinorelbine as
TPC.

- Participants with treated, non-progressive brain metastases, off high-dose steroids
(>20 mg prednisone or equivalent) for at least 4 weeks can be enrolled in the trial.

Key Exclusion Criteria:

- Women who are pregnant or lactating.

- Women of childbearing potential or fertile men unwilling to use effective
contraception during study and up to three months after treatment discontinuation in
women of child-bearing potential and six months in males post last study drug.

- Participants with Gilbert's disease.

- Participants with non-melanoma skin cancer or carcinoma in situ of the cervix are
eligible, while participants with other prior malignancies must have had at least a
3-year disease-free interval.

- Participants known to be human immunodeficiency (HIV) positive, hepatitis B positive,
or hepatitis C positive.

- Infection requiring antibiotic use within one week of randomization.

- Other concurrent medical or psychiatric conditions that, in the Investigator's
opinion, may be likely to confound study interpretation or prevent completion of study
procedures and follow-up examinations.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.