• Age ≥ 18 years old

• Female

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

• Histological diagnosis of carcinoma of the breast, according to AJCC 8th edition that is estrogen receptor negative (ER-), progesterone receptor negative (PR-) and HER2- negative according to local testing on the most recent tumor sample examined before signing consent form to participate in the study.

∙ ER-negative and PR-negative are defined as having an immunohistochemistry (IHC) \< 10%

‣ HER2 negative is defined as per the 2018 American Society of Clinical Oncology (ASCO) - College of American Pathologists (CAP) guidelines, indeed as having an IHC of 0 or 1+ without ISH OR IHC 2+ and ISH non-amplified with ratio less than 2.0 and if reported, average HER2 copy number \< 4 signals/cells OR ISH non-amplified with ratio less than 2.0 and if reported, average HER2 copy number \< 4 signals/cells \[without IHC\]; Note: a IHC of 3+ is always considered HER2 positive, independently of the ISH result.

• Cohort A (early setting): patients will be enrolled regardless of their tumor PD-L1 status.

• Cohort B (metastatic setting): patients will be enrolled regardless of their tumor PD-L1 status but participants with PD-L1 negative tumor status (i.e.\<1% defined by Immunohistochemistry with Ventana SP142) will be capped at 40%. i.e.\<1% defined by immunohistochemistry with Ventana SP142) will be capped at 40%.

• Agreement to perform new study-related biopsies and blood sampling as described in the study schedule of activity.

• Tumor considered as accessible by biopsy, according to the investigator. Fine-needle aspiration, brushing, cell pellet from pleural effusion, bone metastases, and lavage samples are not acceptable. Tumor tissue from bone metastases is not acceptable.

• For female of childbearing potential (WCBP): negative serum or urinary pregnancy test within 2 weeks prior to first dose of study administration.

• Women of childbearing potential must agree to use one highly effective method of contraception during the screening period, during the course of the study and at least 12 months after the last administration of study treatment (see appendix 7) .

• Adequate bone marrow function as defined below:

• Absolute neutrophil count ≥1500/μL, i.e., 1.5x109/L Hemoglobin ≥ 9.0 g/dL Platelets ≥100000/μL, i.e., 100x109/L

⁃ Adequate liver function as defined below:

⁃ Serum total bilirubin ≤ 1.5 x ULN. In case of known Gilbert's syndrome ≤ 3 x UNL is allowed AST ≤ 3.0 x ULN, ALT ≤ 3.0 x ULN

⁃ Adequate renal function as defined below:

⁃ Creatinine ≤ 1.5 x UNL and eGFR≥40ml/min/1.73m²

⁃ Adequate coagulant function as defined below:

⁃ International Normalized Ratio (INR) ≤ 1.5 x ULN

⁃ Completion of all necessary screening procedures within 28 days prior to inclusion

⁃ Signed Informed Consent form (ICF) obtained prior to any study related procedure

⁃ Patients must be covered by a health insurance system

⁃ For tumor stage T1c, nodal stage N1-3, by at least one radiographic or clinical measurement.

⁃ For tumor stage T2-4, nodal stage N0-3, by at least one radiographic or clinical measurement.

⁃ Multifocal, multicentric unilateral or bilateral breast adenocarcinoma tumors are allowed provided that all foci are ER-/PR-/HER2- according to local testing.

⁃ Left ventricular ejection fraction (LVEF) ≥ 50%.

⁃ No prior line of chemotherapy / or systemic therapy for metastatic disease (patients with known germline BRCA1 or BRCA2 mutations may have been treated with one prior line of therapy with PARP inhibitor).

⁃ Radiation therapy for metastatic disease is permitted. There is no required washout period for radiation therapy. Patients should be recovered from the effects of radiation.

⁃ Prior chemotherapy in the neoadjuvant or adjuvant setting is allowable if treatment was completed 12 months prior to inclusion.

⁃ Patients with documented liver metastases: AST and ALT Patients with documented liver metastases: AST and ALT less than 5 x ULN

⁃ Have a life expectancy of at least 3 months.