The DESTINY-Breast RESPOND study was terminated early due to start-up delays and slow enrolment, despite extensive mitigation. Operational challenges alone prevent study continuation and were not related to any product or patient safety concerns.

This study will collect real-world clinical and patient reported outcomes (PRO) and diary data from eligible patients with documented Human Epidermal Growth Factor Receptor 2 (HER2+) [globally] or HER2-low [North America only] in routine clinical practice.

This is a multi-center, observational prospective study that will characterize the demographic and clinical characteristics, treatment patterns, effectiveness, tolerability and its management, and patient experience of Trastuzumab Deruxtecan (T-DXd) in a real-world setting. This study is planned to be conducted in several countries and aims to enroll approximately 750 patients eligible patients with HER2+ unresectable and/or metastatic breast cancer (mBC) who has received a prior anti HER2 based regimen in the metastatic setting or in the neoadjuvant or adjuvant setting and has developed disease recurrence during or within 6 months of completing therapy. Approximately 250 eligible patients with HER2-low unresectable and/or mBC who have received a prior chemotherapy in the metastatic setting or developed disease recurrence during or within 6 months of completing adjuvant chemotherapy will be enrolled into the study in North America only.

The planned duration of patient recruitment is approximately 18 months for HER2+ and approximately 12 months for HER2 low.

Inclusion Criteria:

• Patients ≥18 years of age at time of consent.
• Histological or cytological confirmed diagnosis of unresectable and/or mBC.
• Documented HER2 status via a validated method.
• Adult patients with unresectable or metastatic HER2+ breast cancer who have received a prior anti-HER2-based regimen in the metastatic setting or in the neoadjuvant or adjuvant setting and developed disease recurrence during or within 6 months of completing therapy.

Or

Adult patients with unresectable or metastatic HER2 low (IHC 1+ or IHC 2+/ISH-) breast cancer who have received a prior chemotherapy in the metastatic setting or developed disease recurrence during or within 6 months of completing adjuvant chemotherapy.

• Decision to newly initiate monotherapy T-DXd per standard of care.
• Capable of providing informed consent and completing questionnaires.

Exclusion Criteria:

• Pregnancy or breastfeeding.
• History of other primary malignancies in 2 years prior to unresectable and/or mBC diagnosis.
• Patients who at time of data collection for this study are participating in or have participated in an interventional study that remains blinded.

Patients with HER2+ and HER2-low unresectable and/or mBC who are prescribed T-DXd for 2L or earlier metastatic treatment per standard of care.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool. Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.