Efficacy, cardiotoxicity and factors affecting pathologic complete response of neoadjuvant chemotherapy with anthracycline-containing verses anthracycline-free regimens plus dual HER2 blockade for HER2-positive early-stage breast cancer: a retrospective study.

Background: The aim of this study was to compare the efficacy, cardiotoxicity and factors affecting pathologic complete response (pCR) of neoadjuvant chemotherapy (NACT) regimen TCbHP (docetaxel/nab-paclitaxel, carboplatin, trastuzumab and pertuzumab) and AC-THP (doxorubicin, cyclophosphamide followed by docetaxel/nab-paclitaxel, trastuzumab and pertuzumab) for human epidermal growth factor receptor 2-positive (HER2+) early-stage breast cancer at a retrospective cohort.

Methods: This retrospective study included the patients with HER2+ early-stage breast cancer who received NACT with the regimen TCbHP or AC-THP and then underwent surgery from 2019 to 2022. pCR rate and breast-conserving rate were calculated to evaluate the efficacy of the regimens. Left ventricular ejection fraction (LVEF) from echocardiograms and abnormal electrocardiographs (ECGs) were collected to evaluate the cardiotoxicity of the two regimens. Association between the characteristics of the breast cancer lesions by magnetic resonance imaging (MRI) and the pCR rate were also explored.

Results: A total of 159 patients were enrolled, including 48 patients in the AC-THP group and 111 patients in the TCbHP group. The pCR rate of the TCbHP group 64.0% (71/111) was significantly higher than that of for the the AC-THP group 37.5% (18/48) (P=0.002). Estrogen receptor (ER) status (P=0.011, OR: 0.437, 95% CI: 0.231-0.829), progesterone receptor (PR) status (P=0.001, OR: 0.309, 95% CI: 0.157-0.608) and IHC HER2 status (P=0.003, OR: 7.167, 95% CI: 1.970-26.076) were significantly correlated with the pCR rate. LVEF decreased at 6 and 12 months after treatment in the AC-THP group (P=0.024 and 0.040), which only decreased after 6 months of treatment in the TCbHP group (P=0.048). Post-NACT MRI characteristics including mass features (P<0.001) and enhancement type (P<0.001) were significantly associated with pCR rate.

Conclusions: Early-stage HER2+ breast cancer treated with the TCbHP regimen has a higher pCR rate than the AC-THP group. The TCbHP regimen appears to have lower cardiotoxicity than the AC-THP regimen in terms of LVEF. Mass features and enhancement type at post-NACT MRI significantly associated with the pCR rate of breast cancer patients.