The human epidermal growth factor receptor 2 (HER2)-enriched intrinsic subtype represents up to 75% of all HER2-positive hormone receptor (HR)-negative breast cancer (BC). Optimizing HER2-targeting therapy in this population might allow the omission of anthracycline-based chemotherapy, which is associated with potentially severe toxicities. DECRESCENDO (NCT04675827) is a large, multicenter, single-arm phase II trial in patients with HR-negative, HER2-positive, node-negative early BC evaluating a neoadjuvant pertuzumab and trastuzumab fixed-dose combination administered subcutaneously plus taxane-based chemotherapy followed by adjuvant treatment, adapted according to response to neoadjuvant therapy. The primary end point is the 3-year recurrence-free survival rate in patients with ‘HER2-enriched’ tumors and a pathological complete response. This flexible care substudy offers adjuvant treatment administration outside the hospital to some patients.