Neoadjuvant Treatment for HER2 Positive Breast Cancer

Standard Neoadjuvant Regimens

The American College of Surgeons considers neoadjuvant chemotherapy with dual HER2 blockade (pertuzumab-trastuzumab) as standard for high-risk patients (tumors ≥2 cm and/or positive lymph nodes) 1, 2
The standard regimen includes docetaxel or paclitaxel combined with carboplatin, trastuzumab, and pertuzumab, demonstrating high rates of pathological complete response (pCR) 3, 4
The NeoSphere study showed that the combination of pertuzumab-trastuzumab with docetaxel resulted in a pCR rate of 45.8%, significantly higher than the combination of trastuzumab with docetaxel (29%) 3, 4

The KRISTINE study evaluated de-escalation with T-DM1 (trastuzumab emtansine) plus pertuzumab versus conventional chemotherapy (docetaxel and carboplatin) plus pertuzumab-trastuzumab 1
The T-DM1-based regimen produced a significantly lower pCR rate (44.4% versus 55.7%, p=0.016) 1
After 3 years of follow-up, the risk of event-free survival (EFS) events was higher with T-DM1 plus pertuzumab (HR 2.61; 95% CI 1.36-4.98), driven by pre-surgical locoregional progression events (15 versus 0) 1

For patients with cardiac concerns, anthracycline-free regimens (docetaxel/carboplatin) with trastuzumab are recommended, with lower rates of cardiac dysfunction compared to anthracycline-containing regimens 5, 6
The WSG-ADAPT study evaluated T-DM1 ± endocrine therapy for 12 weeks, with pCR rates of approximately 41%, but long-term efficacy results showed no differences in disease-free survival/overall survival 1
The PHERGain study evaluated the possibility of omitting chemotherapy in PET responders after 2 cycles of pertuzumab-trastuzumab ± endocrine therapy, with a pCR rate of 37.9% in PET responders without chemotherapy 5

The complete withdrawal of taxanes (docetaxel or paclitaxel) from the neoadjuvant regimen is not recommended as a standard approach for HER2-positive patients 1, 2
De-escalation strategies should only be considered in clinical trials or for selected patients with low risk of recurrence 1, 5
The assessment of pathological complete response after neoadjuvant therapy is crucial to determine subsequent adjuvant treatment, especially to consider T-DM1 in patients with residual disease 2, 7

The National Comprehensive Cancer Network (NCCN) recommends TCHP (docetaxel, carboplatin, trastuzumab, pertuzumab) as a preferred neoadjuvant regimen for high-risk HER2+ early breast cancer, based on multiple guideline endorsements and clinical trial data 8
TCHP achieved pathological complete response (pCR) rates of 66.2% in the TRYPHAENA trial, the highest among three pertuzumab-containing regimens tested 9, 10

The FDA granted accelerated approval for pertuzumab combined with trastuzumab and docetaxel, based on significantly improved pCR rates in the NeoSphere and TRYPHAENA trials 9, 10
The NCCN lists TCHP as a "preferred regimen" for neoadjuvant treatment of stage II-III HER2-positive breast cancer 8

If pathological complete response (pCR) is achieved, complete 1 year total of trastuzumab-based therapy (18 cycles total including neoadjuvant period) 8
Continue pertuzumab plus trastuzumab if node-positive at initial diagnosis (category 1 recommendation) 8

AC followed by paclitaxel plus trastuzumab and pertuzumab (sequential anthracycline-taxane approach) is an alternative regimen to consider 8

Avoid concurrent trastuzumab/pertuzumab with anthracyclines due to significant cardiac toxicity risk 8
Do not omit pertuzumab in high-risk patients, as dual HER2 blockade is superior to single-agent trastuzumab 10