Neoadjuvant Trastuzumab and Pertuzumab in Combination with Standard Chemotherapy for HER2-Positive Early Breast Cancer: Real-World Practice in Cuba

Purpose: Dual HER2 blockade chemotherapy is the standard of care for localized HER2+ breast cancer (BC). However, despite the efficacy of neoadjuvant therapy, relapses occurring in around 10% of patients highlight the need to improve its clinical approach. Therefore, this study aimed to evaluate the effectiveness/safety of neoadjuvant therapy with subcutaneous (SC) trastuzumab- pertuzumab chemotherapy (real world) to extend the evidence, which comes mainly from clinical trials (selected population; intravenous [IV] trastuzumab).

Materials and methods: A prospective, longitudinal, observational study in a Cuban hospital.

Population: women aged ≥18 years with histologically confirmed HER2+ early-stage BC (2017-2021) eligible for neoadjuvant treatment (IV pertuzumab, SC trastuzumab, taxane-based chemotherapy). The aim was to determine the pathological complete response (pCR) rate to this scheme, its safety, and the impact of patient's characteristics on the outcomes.

Results: Eighty-seven women were included: n=29 (DPT [docetaxel-IV pertuzumab- SC trastuzumab 600 mg; 4 cycles]); n=58 (ddAC-DPT [dose-dense anthracycline-based scheme+DPT]; 8 cycles). The median age was 57 years (range 30-83), ECOG 0: 97%. Time from diagnosis to treatment (median) was 28 days. The overall pCR rate was 62.1% (55.2%, DPT; 66.5%, ddAC-DPT; p =0.351); HR+, 47.7% vs. HR-, 76.7% (p=0.006). There were no statistically significant differences based on nodal status, stage, or Ki-67 levels. Overall, 94.2% of patients experienced ≥1 adverse event related to treatment, all of them grade 1-3 and more common with ddAC-DPT. The main cause of treatment delays (n=19; ddAC-DPT, 16; DPT, 3) was treatment-related toxicities.

Conclusion: Neoadjuvant trastuzumab (SC) and pertuzumab plus chemotherapy for HER2+ early-stage BC showed benefits in a real-life setting, with an acceptable safety profile.