This trial is a translational, open-label, monocentric and prospective cohort study of participants with breast cancer aiming to create a combined ESPRESSO (= organelle properties) phenotype and spatial proteomics data collection encompassing four cohorts:

• TN eBC = cohort A,
• HER2+ eBC = cohort B,
• Luminal eBC = cohort C,
• dnMBC = cohort D. In total 1050 participants will be enrolled in the study. Laboratory analysis (including ESPRESSO technique) will be conducted on the biological specimen collected during this study.

The primary objective is to describe the amount of fatty acids accumulated in lipid droplets, within the four cohorts. As a secondary objective, the analysis will expand to other organelles like lysosomal acidity and nuclear organization.

The study is due to last 9 years (4 years of recruitment and 5 years of study participation)

The study targets participants with early breast cancer (eBC) or de novo metastatic breast cancer (dnMBC) who will be treated within a standard of care procedure or a clinical trial.

Following informed consent form signature, participants will be included in the study protocol and will be assigned in one of four cohorts, depending on the immunohistochemical subtype of tumor.

Patients will be enrolled concomitantly in each cohort, with the following recruitment goals:

• Cohort A (N = 300 patients): Triple Negative eBC (TN eBC)
• Cohort B (N = 300 patients): HER2+ eBC (HR+ or HR-)
• Cohort C (N = 300 patients): Luminal eBC (Luminal A or B)
• Cohorte D (N = 150 patients): dnMBC of any subtype (TN, HER2+ or Luminal).

After the cancer treatment completion, the participants will remain in the study for a follow-up period (study participation will be 5 years maximum since baseline).

In this study, anti-cancer procedures or treatments, whatever they are, will not be under investigation; they will be performed, administrated and dosed according to the standard of care or according to the study protocol (if participation in a clinical trial).

For each included participant, biological specimen (fresh tumor sample, blood samples, ascite or pleural fluids if applicable) will be collected. Depending on participant's cohort and treatment strategy (i.e. eBC with indication of neoadjuvant treatment or not, dnMBC with indication of surgical treatment or not), samples will be collected at different times points.

• Inclusion Criteria:

  1. Patient (women or men) with histologically documented breast cancer
  2. Early Breast Cancer (eBC) or de novo metastatic BC (dnMBC), regardless the immunohistochemical subtype: Triple Negative BC (ER-negative [<10%], PR-negative [<10%] and HER2-negative [i.e. null, ultra-low or low] BC); HER2-positive BC: HER2 overexpression score 3+ or ERBB2 amplification whatever ER/PR expression and proliferation level; Luminal A-like BC: low to moderately proliferative (Ki67<20%) ER-positive (≥ 10%) PR-positive (≥ 20%) BC and low proliferative (Ki67< 14%) ER-positive PR-negative (< 20%) BC; Luminal B-like BC: highly proliferative (Ki67≥ 20%) ER-positive, PR-positive BC or moderately proliferative (14% ≤ Ki67< 20%) ER-positive PR-negative (<20%) BC
  3. Age ≥ 18 years at the time of study entry
  4. Patient followed within a standard of care procedure or clinical trial
  5. ECOG performance status ≤ 2
  6. Breast cancer treatment not yet started
  7. Patient able to participate and willing to give informed consent prior performance of any study-related procedures and to comply with the study protocol
  8. Patient affiliated to a Social Health Insurance in France.

• Exclusion Criteria:

  1. Known history of positive test for Hepatitis B virus or Hepatitis C virus or Immunodeficiency Virus (HIV) or Hanta virus.
  2. Abnormal coagulation contraindicating biopsy
  3. Previous or on going treatment for the breast cancer
  4. Bone metastases when this is the only site of biopsiable disease for dnMBC patients
  5. Any condition contraindicated with blood sampling procedures required by the protocol (including Hemoglobin < 8g/dl)
  6. Patients with known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer
  7. Patient pregnant, or breast-feeding
  8. Any psychological, familial, geographic or social situation, according to the judgment of investigator, potentially preventing the provision of informed consent or compliance to study procedure.
  9. Patient who has forfeited his/her freedom by administrative or legal award or who is under guardianship.