P2 Clinical Efficacy & Safety Study of V-111 Monotherapy & Sacituzumab Govitecan-hziy/V-111 Combo Therapy for mTNBC .

Stage 1: This is a safety run-in portion of the study for the combination therapy. Three subjects will be enrolled into Stage 1 of the study to receive sacituzumab govitecan-hziy for injection + sabizabulin 32 mg. Dosing with sabizabulin should be within 1 hour prior to initiation of the sacituzumab govitecan-hziy infusion. Safety will be assessed for 21 days. Samples for assessment of pharmacokinetics of sacutizumab (in the Control Treated Group and TS Combination Group), and sabizabulin (in the Sabizabulin Treated Group and TS Combination Group) will be collected on Day 1 (prior to dosing and within 1 hour after the sacituzumab govitecan-hziy infusion has been completed in Stage 1 and Stage 2, Cycle 1 only), Day 3 (prior to dosing with sabizabulin, Stage 1, Cycle 1 only), and Day 8 (prior to dosing and within 1 hour after the sacituzumab govitecan-hziy infusion has been completed in Stage 1 and Stage 2, Cycle 1 only). The primary objective of Stage 1 is to demonstrate an acceptable safety profile of the combination therapy regimen that is planned for Stage 2 of the protocol. If an acceptable safety profile and no unacceptable drug related adverse event is observed in Stage 1, then Stage 2 will be initiated as designed. If an unacceptable drug related adverse event is observed in one patient in the combination treatment group in Stage 1, then an additional 3 patients will be enrolled to the combination treatment arm. If 2 out of 3 or 2 out of 6 patients experience an unacceptable drug related adverse event in Stage 1, then the combination treatment regimen will not be dosed in Stage 2 of this protocol. Stage 2: This study is a multicenter, randomized, open-label, three treatment-arm, efficacy and safety study. Subjects will be randomized to the three treatment arms. Patients will be randomized in a 1:1:1 fashion to the sacituzumab govitecan-hziy monotherapy, sabizabulin monotherapy, and the sacituzumab govitecan-hziy/sabizabulin combination therapy treatment arms. Subjects in the Sabizabulin Treated Group and sacituzumab govitecan-hziy/sabizabulin Combination Group will receive sabizabulin 32 mg per day orally until radiographic progression (blinded independent central read) in observed. Subjects in the Control Treated Group and in the sacituzumab govitecan-hziy/sabizabulin Combination Group will receive sacituzumab govitecan-hziy using the dose and dosing regimen defined in the FDA approved prescribing information for the treatment of mTNBC until radiographic progression in observed. The primary efficacy endpoint of the study will be the median rPFS. Subjects will continue study treatment until disease progression confirmed by blinded independent central reader (BICR) is observed. A follow up visit will occur approximately 30 days after last dose of study drug.