PROVIDENCE - Prospective Non-interventional Study (NIS) to Examine Patient-reported Outcomes and Real-world Clinical Data in Patients With HER2-positive or HER2-low Unresectable or Metastatic Breast Cancer Treated With Trastuzumab Deruxtecan

This is a prospective non-interventional, multicenter study observing patient reported outcomes as well as real-world efficacy and safety of trastuzumab deruxtecan (T-DXd) in patients with documented Human epidermal growth factor receptor 2 (HER2)-positive unresectable or metastatic breast cancer (BC) and in patients with documented HER2-low unresectable or metastatic BC receiving T-DXd in line with the applicable summary of product characteristics (SmPC) within routine clinical practice in Germany. In addition, patients will be informed about use of digital healthcare application (DiGA).

Eligible participants will be those patients with documented HER2-positive unresectable or metastatic BC receiving T-DXd treatment or patients with documented HER2-low unresectable or metastatic BC receiving T DXd treatment in line with the applicable summary of product characteristics (SmPC) within routine clinical practice.

All diagnostic and treatment procedures including visit frequency are at the discretion of the treating physician and not defined by the protocol. T-DXd treatment is considered as a selection criteria. Patients will be informed about use of digital healthcare application (DiGA).

Approximately 800 eligible participants will be enrolled which includes 400 patients in the HER2-positive cohort and 400 patients in the HER2-low cohort.

Eligibility Criteria:
Inclusion Criteria:

1. Adults ≥ 18 years old
2. Patients (irrespective of sex and gender) with pathologically documented breast cancer that:

   * is unresectable or metastatic
   * has confirmed HER2+ or HER2-low tumor status by local pathology
   * was previously treated with one or more anti-HER2 directed therapy if the tumor is HER2+ OR
   * was previously treated with prior chemotherapy in the metastatic setting or developed disease recurrence during or within 6 months of completing adjuvant chemotherapy if the tumor is HER2-low.
3. Has documented radiologic progression (during or after most recent treatment)
4. Patient is eligible for T-DXd treatment in line with the specifications mentioned in the ENHERTU® SmPC and is scheduled for T-DXd treatment \*
5. Patient is able to read and understand either German or English
6. Signed written informed consent

   * The prescription of the medicinal product is clearly separated from the decision to include the patient in this NIS.

Exclusion Criteria:

1. Start of T-DXd treatment for more than 30 days before enrolment (eCRF registration date)
2. Known hypersensitivity to T-DXd or any of the excipients of the drug
3. Pregnancy or breast feeding
4. Current or planned participation in an interventional clinical trial
5. Current or planned systemic treatment of any tumor other than unresectable or metastatic BC

Patients who have never received any T-DXd dose will be discontinued from the study and will be considered as a late screening failure, no further documentation besides reason and date of discontinuation is needed.