What this Trial Is About

Triple-negative breast cancer (TNBC) is a group of tumors that occurs mainly in young, premenopausal women and accounts for 10-20% of breast cancers. Over the past decade, the incidence of women diagnosed with early-stage TNBC has significantly increased due to the widespread use of screening mammography. Treatment of patients with localized TNBC mainly involves surgery and (neo)adjuvant chemotherapy with or without radiotherapy. However, the benefit of chemotherapy may be controversial in patients with early-stage TNBC defined by small size and absence of lymph node involvement, and with significant tumor lymphocyte infiltration. The ETNA study is a phase II trial designed to evaluate a chemotherapy de-escalation strategy in patients with TNBC T1b/c N0M0 and stromal TILs (sTILs) ≥ 30%. ETNA comprises two cohorts defined according to the level of TILs and the age of patients. Patients aged \> 40 years with 30% ≤ sTILs \< 50% and those aged ≤ 40 years with 30% ≤ sTILs \< 75% will be included in the cohort 1 and will receive adjuvant pembrolizumab 200 mg every three weeks for 9 cycles and Paclitaxel 80 mg/m² weekly for 12 cycles. Patients aged \> 40 years with sTILs ≥ 50% and those aged ≤ 40 years with sTILs ≥ 75% will be included in cohort 2 and will not receive adjuvant treatment, they will undergo standard surveillance every six months.

Pembrolizumab and Chemotherapy Treatment or no Treatment Guided by the Level of TILs in Resected Early-stage TNBC