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.
Keywords: HER2-enriched; HER2-positive; breast cancer; de-escalation; neoadjuvant; treatment optimization.
Breast cancer is the most frequent cancer type among women worldwide. Different types of breast cancer exist, defined by the type of proteins on the tumor cell surface: HER2-positive: overproduction of human epidermal growth factor receptor 2 (HER2); Hormone receptor-positive: overproduction of the estrogen and/or progesterone hormone receptors. In the past 30 years, effective anti-HER2 drugs have been developed. However, they are often combined with chemotherapy, which can cause serious side effects (also called toxicities). HER2-positive tumors, which are also hormone receptor-negative, respond better to HER2-targeting drugs with less toxicity than chemotherapy. The DECRESCENDO trial aims to test treating HER2-positive, hormone receptor-negative patients (with a maximum breast cancer tumor size of 5 cm, without swollen lymph nodes) with pertuzumab + trastuzumab. The combination therapy would be given presurgery to reduce the tumor size as much as possible first (known as neoadjuvant therapy). The intensity of the patient's chemotherapy would be reduced with only one chemotherapy drug instead of standard three to four drugs. Patients that respond well will require less intense treatment after their surgery. Tissue from the tumors will be tested to see if any of the HER2-positive tumors belong to a subtype known as ‘HER2-enriched’ – this subtype is predicted to be more responsive to the trastuzumab and pertuzumab combination therapy. In a separate study of the DECRESCENDO trial, patients with good responses to neoadjuvant therapy and no safety concerns may continue their postsurgery treatment outside the hospital, such as at home.