A Study to Evaluate the Efficacy and Toxicities of PLX038, in Patients With Locally Advanced or Metastatic Triple-negative Breast Cancer

This is an open label, multi-centric phase II study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and efficacy of PLX038 in locally-advanced or metastatic TNBC. Patient must have received prior therapy (administered in the neoadjuvant, adjuvant and/or metastatic setting) with chemotherapy by an anthracycline, taxane and sacituzumab-govitecan (unless not medically appropriate or contraindicated for the patient) and received a minimum of two prior cytotoxic chemotherapy regimens for locally advanced or metastatic breast cancer. Patients will be treated at a dose of 1730mg/m2 IV infusion on Day 1 of each cycle Q3W (every 21 days, 1 cycle = 1 injection). All included patients will receive PLX038 as single agent as long as study is ongoing or until progression of disease, unacceptable toxicity, patient withdrawal of consent, Investigator decision, lost to follow-up, death, patient non-compliance, or study termination by Sponsor. Tumor assessments must be performed according to the RECIST V1.1 criteria at inclusion and every 8 weeks (± 7 days) from inclusion until documented disease progression, withdrawal of consent, or death. Radiographic measurements must be performed to the RECIST specifications.