Abstract 9P
Background
The treatment landscape for early-stage triple-negative breast cancer (TNBC) has witnessed notable advancements with the incorporation of platinum-based chemotherapies, such as carboplatin, and immune checkpoint inhibitors, namely pembrolizumab, into neoadjuvant systemic therapy (NST). Nevertheless, the impact of these regimens on axillary response, particularly with regard to the possibility of surgical de-escalation, remains underexplored.
Methods
This study retrospectively examined non-metastatic TNBC patients who received NST followed by surgical resection at Gangnam Severance Hospital between 2007 and 2024. Patients were excluded if they had recurrent or bilateral breast cancer, did not complete the neoadjuvant pembrolizumab regimen, or were enrolled in surgical de-escalation trials. The eligible patients were divided into three groups; cohort 1 (anthracycline, cyclophosphamide, and taxane [AC-T]), cohort 2 (AC-T with carboplatin [AC-TC]), and cohort 3 (AC-TC with pembrolizumab). Pathologic responses were assessed in surgical specimens, including overall pathologic complete response (pCR), breast pCR, axillary pCR, and axillary pCR in initially clinical node-positive (cN+) patients. The chi-square test was employed for the analysis of rates.
Results
The study included 419 patients: 201 in cohort 1 (158 cN+), 116 in cohort 2 (94 cN+), and 102 in cohort 3 (85 cN+). The overall pCR rates were 35.8%, 56.9%, and 66.7% in each cohorts respectively, indicating a significant increase from AC-T to AC-TC (p<0.001). Breast pCR rates were 40.3%, 59.5%, and 66.7%, showing a significant improvement from AC-T to AC-TC (p=0.001). Axillary pCR rates were 75.6%, 82.8%, and 85.3%, with no significant differences observed. Among cN+ patients, the axillary pCR rates were 69.6%, 80.9%, and 83.5%, with a statistically significant increase from AC-T to AC-TC (p=0.049).
Conclusions
Adding carboplatin to NST significantly improved axillary pCR rates in cN+ TNBC patients, while pembrolizumab does not significantly alter axillary response. Further research is needed to understand the effect of pembrolizumab on breast pCR and to consolidate existing data.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.