Phase 3 Study of Sacituzumab Govitecan (IMMU-132) Versus Treatment of Physician's Choice (TPC) in subjects with Hormonal Receptor-Positive (HR+) Human Epidermal Growth Factor Receptor2(HER2)Negative Metastatic Breast Cancer(MBC) who have failed at least two prior chemotherapy regimens

The primary objective of this study is to assess and compare the efficacy and safety of
sacituzumab govitecan-hzi versus treatment of physician's choice (TPC) in participants with
hormonal receptor-positive (HR+) human epidermal growth factor receptor 2 (HER2-) negative
metastatic breast cancer (MBC).

Key Inclusion Criteria:

- Documented evidence of hormone receptor-positive human epidermal growth factor
receptor 2 negative (HER2-negative) (hormonal receptor-positive (HR+)/HER2-)
metastatic breast cancer (MBC) confirmed.

- Refractory to or relapsed after at least 2, and no more than 4, prior systemic
chemotherapy regimens for metastatic disease:

- At least 1 taxane in any setting.

- At least 1 prior anticancer hormonal treatment in any setting.

- At least 1 cyclin-dependent kinase inhibitor 4/6 in any setting.

- Eligible for one of the chemotherapy options listed in the TPC arm.

- Documented disease progression after the most recent therapy.

- Adequate bone marrow function (hemoglobin ≥ 9 g/dL, absolute neutrophil count (ANC) ≥
1,500 per mm^3, platelets ≥ 100,000 per mm^3).

- Adequate renal function: calculated creatinine clearance ≥ 30 mL/minute according to
the Cockcroft and Gault formula .

- Adequate liver function (bilirubin ≤ 1.5 institutional upper limit of normal (IULN),
or ≤ 3 IULN for individuals with documented Gilbert's syndrome, aspartate
aminotransferase (AST) and Alanine aminotransferase (ALT) ≤ 2.5 x IULN (in the case of
liver metastases ≤ 5.0 x IULN)).

- Females must not be lactating or pregnant at Screening or Baseline (as documented by a
negative beta human chorionic gonadotropin (ß-hCG)).

Key Exclusion Criteria:

- Previous treatment with topoisomerase 1 Inhibitors as a free form or as other
formulations.

- History of significant cardiovascular disease or clinically significant
electrocardiogram (ECG) abnormality.

- Active serious infection requiring antibiotics.

- Any medical or other condition which, in the opinion of the Investigator, causes the
individual to be medically unfit to receive sacituzumab govitecan or unsuitable for
any reason.

- Locally advanced MBC (stage IIIc) in individuals who are candidates for curative
intent therapy at the time of study enrollment.

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