Multicenter, retrospective and prospective, cohort, observational study evaluating the clinical efficacy and tolerability of Eribulin as second-line treatment in accordance with the indications authorized by AIFA in patients with triple negative advanced breast cancer in a real world setting.

The study, multicenter, retrospective and prospective, cohort, observational, describes the modalities of treatment with Eribulin as a second line therapy for triple negative breast cancer and "clinical outcomes" in a population real-world, evaluating any differences with the results obtained in clinical trials. Therapeutic sequences will also be evaluated with the aim of providing a photograph of the choices made in clinical practice in this historical moment characterized by rapid evolution of new molecules available to clinicians.

A total of at least 200 patients with triple negative advanced breast cancer treated with Eribulin as second line will be enrolled in the retrospective or prospective cohort. Enrollment period will last 2 years.

Pseudoanonymized data will be collected in a electroctronic database (RedCap Cloud); here the list of the main variables collected:

• Patient Registration
• Demography
• Pregnancy test
• Past history and habits of the patient
• Previous antineoplastic therapy
• Anamnesis close to entering the study
• Vital signs and ECOG performance status (WHO)
• Blood chemistry tests
• RECIST 1.1 Baseline and re-evaluations
• 12 Lead ECG evaluation
• Eribulin cycles
• Adverse events
• Previous and concomitant medications
• End of study

The retrospective analysis of the choices made in clinical practice and the benefits obtained from the second therapeutic lines could provide important data to favor the definition of prospective randomized studies, and guide the clinician towards a better therapeutic path.

Inclusion Criteria:

• Performance status according to ECOG equal to 0-2
• Locally advanced or triple negative metastatic breast cancer (HR- and HER2-) confirmed histologically
• Progressing after first-line chemotherapy for advanced disease
• Previous anthracyclines and taxanes therapy (in an adjuvant, neoadjuvant or metastatic), unless the patient is ineligible to receive such treatments
• Treatment with Eribulin mesylate since 2017, in accordance with AIFA indications
• Adequate haematological, renal and hepatic function, as per clinical practice
• Written informed consent

Exclusion Criteria:

• Breast cancer HER2 + or HR +
• Treatment with Eribulin in the context of clinical studies
• Patients unsuitable for treatment with Eribulin
• Diagnosis of other malignancies in the two years prior to enrollment, with one exception of adequately treated localized basal cell or squamous cell carcinomas of the skin o cervical carcinomas undergoing curative treatment

Patients with metastatic triple negative breast cancer