Circulating Tumor Cells and Treatment De-escalation After Neoadjuvant Therapy for HER2 Positive Breast Cancer

Circulating Tumor Cells and Adjuvant Treatment De-escalation After Neoadjuvant Therapy With Trastuzumab and Pertuzumab for HER2 Positive Early Breast Cancer

Phase II unicentric randomized trial which will include early HER2 positive breast cancer patients, candidate to neoadjuvant therapy with trastuzumab and pertuzumab. Circulating tumor cells will be collected at neoadjuvant therapy baseline.

Patients with pathological complete response will be randomized in 1:1 ratio for adjuvant trastuzumab (arm A) versus trastuzumab + pertuzumab (arm B) in a two factorial design: group A, with HER2 positive CTCs and group B, with HER2 negative/absent CTCs.

Patients with HER2 positive breast cancer (hormone receptors positive or negative), which are candidate to neoadjuvant therapy with pertuzumab and trastuzumab will be included.

Blood samples will be collected at baseline (before neoadjuvant start) for the analysis of CTCs and its positivity for HER2 by IHC and ISH.

Patients with pathological complete response will be included in the randomization phase of the study. There will be 2 cohorts: HER2 positive CTCs at baseline and HER2 negative/absent CTCs at baseline. In each cohort, patients will be randomized in 1:1 ratio for adjuvant trastuzumab versus adjuvant trastuzumab + pertuzumab

Inclusion Criteria:

• HER2 positive breast cancer (hormone receptors positive or negative)
• Stage I to III
• Indication for neoadjuvant therapy with chemo (any regimen) + trastuzumab + pertuzumab
• Breast surgery after neoadjuvant therapy
• Preserved coagnition
• ECOG 0-3
• For the randomization phase: pathological complete response (ypT0/ypTis and ypN0)
• Agreement on participation and signature of de ICF

Exclusion Criteria:

• Contradindication for trastuzumab or pertuzumab
• Adjuvant chemotherapy. Hormone therapy is allowed
• Second primary tumor < 5 years, with an exception for treated non-melanoma skin cancer, and in situ cervical cancer