A Retrospective, Single-Center Study Comparing Neoadjuvant ACTHP vs. DCbHP in HER2-Positive Early Breast Cancer Patients.

Background: Neoadjuvant systemic therapy is the preferred treatment approach for stage II-III HER2-positive breast cancer (BC). Real-life data comparing regimens with or without anthracyclines combined with two HER2 drugs is lacking. We compared the efficacy and toxicity of two commonly used regimens.

Methods: Retrospective data were collected on patients newly diagnosed with clinical stage II-III HER2-positive BC and treated at Sheba Medical Center, Israel, between September 2017 and June 2022 with either neoadjuvant DCbHP (docetaxel, carboplatin, trastuzumab, pertuzumab) or ACTHP (doxorubicin, cyclophosphamide, paclitaxel trastuzumab pertuzumab). PCR (pathological complete response) (ypT0/isN0) was evaluated in both cohorts and according to HER2 immunohistochemistry (IHC) staining (3+ or 2+ and fluorescence in situ hybridization [FISH] positive), estrogen receptor (ER), tumor size and nodal status. The toxicity indices evaluated were reductions in left ventricle ejection fraction (LVEF), dose reductions, hospitalizations and febrile neutropenia.

Results: Here, 106 received ACTHP and 73 received DCbHP. Median age at diagnosis, ER status, HER2 IHC (2+/FISH pos or 3+) and nodal status were balanced. PCR occurred in 63.1% of patients, 67.0% and 57.5% in the ACTHP and DCbHP groups, respectively (p = 0.129). In patients with HER2 3+ IHC, pCR rates were significantly better with the ACTHP regimen than with DCbHP (83% vs. 62.9%, p < 0.039). No difference was observed among patients with HER2 +2 IHC FISH pos. Symptomatic LVEF decrease was observed in seven patients (6.6%) receiving ACTHP vs. none (0%) receiving DCbHP (p < 0.001).

Conclusions: PCR rates were similar overall between ACTHP and DCbHP; however, in the HER2 3+ subgroup, ACTHP demonstrated increased efficacy. DCbHP was significantly less cardiotoxic.