A Phase II Study to Explore the Safety, Tolerability, and Preliminary Antitumor Activity of Sitravatinib Plus Tislelizumab or Combination With Nab-paclitaxel in Patients With Locally Recurrent or Metastatic Triple Negative Breast Cancer (TNBC)

The purpose of this study is to assess the efficacy and safety of sitravatinib plus tislelizumab or combination with nab-paclitaxel in locally recurrent or metastatic triple-negative breast cancer (TNBC) patients.

This is a prospective, single-center, three cohorts, phase II clinical trial in locally recurrent or metastatic triple-negative breast cancer(TNBC) patients. Subjects will be divided into three cohorts by different treatment combination. Cohort A \& Cohort B aim to explore the two dosages of sitravatinib in combination with tislelizumab in TNBC with prior ≤ 3 treatment line. Cohort A patients will receive 70mg sitravatinib (QD PO) in combination with 200mg tislelizumab (Q3W IV); Cohort B patients will receive 100mg sitravatinib (QD PO) in combination with 200mg tislelizumab (Q3W IV). Cohort C aims to explore the sitravatinib (QD PO) plus 200mg tislelizumab (Q3W IV) and 100 mg/m2 nab-paclitaxel (D1, D8 Q3W IV) in TNBC previously untreated for metastatic setting or recurred/metastasized after surgery. Subjects in the three cohorts will be treated until disease progression, intolerable toxicity, informed consent withdrawn, or investigators-determined medication termination. Drug efficacy and safety data will be collected.

Eligibility Criteria:
Inclusion Criteria:

* Able to provide written informed consent and can understand and agree to comply with the requirements of the study and the schedule of assessments
* Age ≥ 18 years on the day of signing the ICF (or the legal age of consent in the jurisdiction in which the study is taking place)
* Histologically confirmed diagnosis of TNBC characterized by estrogen-receptor negative (ER-), progesterone receptor negative (PR-) and human epidermal growth factor-2 receptor negative (HER2-);
* ≤ 3 prior lines of systemic therapy
* For patients refractory/resistant to anti-PD-1/PD-L1 antibodies, there should be no anti-PD-1/PD-L1 treatment-related toxicity from prior therapies
* Previously untreated for metastatic setting or recurred/metastasized after surgery for locally recurrent or metastatic breast cancer (cohort C), and the time from previous neo-/adjuvant therapy to recurrence met the following requirements: ≥ 6 months interval between the end of neo-/adjuvant paclitaxel-based treatment and the onset of recurrence/metastasis; ≥ 6 months interval between the end of neo-/adjuvant anti-angiogenic treatment and the onset of recurrence/metastasis; ≥ 6 months interval between the end of neo-/adjuvant immunotherapy and recurrence/metastasis
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
* Adequate organ function
* Females of childbearing potential must be willing to use a highly effective method of birth control for the duration of the study, and ≥ 120 days after the last dose of study drug(s), and have a negative serum pregnancy test ≤ 7 days of first dose of study drug(s)
* Nonsterile males must be willing to use a highly effective method of birth control for the duration of the study and for ≥ 120 days after the last dose of study drug(s)

Exclusion Criteria:

* Active leptomeningeal disease or uncontrolled brain metastasis
* Active autoimmune diseases or history of autoimmune diseases that may relapse
* Any active malignancy ≤ 2 years
* Severe chronic or active infections (including tuberculosis infection, etc) requiring systemic antibacterial, antifungal, or antiviral therapy within 14 days prior to first dose of study drug(s)
* History of interstitial lung disease, noninfectious pneumonitis or uncontrolled diseases including pulmonary fibrosis, acute lung diseases, etc
* Known history of human immunodeficiency virus (HIV) infection
* Untreated chronic hepatitis B or chronic hepatitis B virus (HBV) carriers
* Any major surgical procedure requiring general anesthesia ≤ 28 days before the first dose of study drug(s)
* Prior allogeneic stem cell transplantation or organ transplantation
* Inadequately controlled hypertension (defined as systolic blood pressure \> 150 mmHg and/or diastolic blood pressure \> 100 mmHg)
* Bleeding or thrombotic disorders or use of anticoagulants such as warfarin or similar agents requiring therapeutic international normalized ratio (INR) monitoring
* Any systemic chemotherapy within 28 days of the first dose of study drug(s) or hormone therapy, targeted therapy, or any investigational therapies Toxicities (as a result of prior anticancer therapy) that have not recovered to baseline or stabilized, except for AEs not considered a likely safety risk (eg, alopecia, neuropathy, and specific laboratory abnormalities)
* Inability to swallow capsules or disease significantly affecting gastrointestinal function
* Pregnant or breastfeeding woman NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.