Population-based study results support the use of the neoadjuvant chemotherapy + pertuzumab + trastuzumab biosimilar SB3 treatment regimen in the real-world setting, with responses comparable with those achieved in clinical trials.
A randomized phase 3 trial demonstrated the similarity of the trastuzumab biosimilar SB3 to its reference trastuzumab plus neoadjuvant chemotherapy in terms of pathologic complete response (pCR) in patients with human epidermal growth factor receptor 2 (HER2)-positive, early or locally advanced breast cancer.1 To evaluate the efficacy of the combination of neoadjuvant chemotherapy with pertuzumab + SB3, an investigator-initiated study was conducted by the Danish Breast Cancer Group (DBCG) in patients with HER2-positive, early breast cancer in the real-world setting2; the results of this study were reported at the American Society of Clinical Oncology 2020 Annual Meeting.
Consecutive patients in the DBCG database were identified who were diagnosed with unilateral early, HER2-positive breast cancer and treated with neoadjuvant chemotherapy in combination with pertuzumab + SB3 from September 1, 2018, to August 31, 2019.2 The primary outcome measure was pCR, which was defined as absence of residual invasive tumor in the breast and axillary lymph nodes.2
A total of 215 patients were identified who received neoadjuvant chemotherapy + pertuzumab + SB3.2 In the study cohort, the median age was 54.8 years (range, 24-81 years); neoadjuvant chemotherapy predominantly consisted of cyclophosphamide + epirubicin followed by paclitaxel, or other chemotherapy followed by paclitaxel.2
Overall, 68% of patients with node-positive disease prior to receiving the neoadjuvant chemotherapy + pertuzumab + SB3 treatment regimen achieved node-negative status after completing the regimen.2 Following the neoadjuvant combination treatment regimen, 56% of patients achieved a pCR. Correlative analyses by demographic and pre-neoadjuvant chemotherapy pathoanatomical factors showed that pCR was significantly related to low estrogen receptor status and high malignancy grade but not to clinical nodal status and tumor size. A trend toward a correlation was seen between pCR rate and small tumor size (pre-neoadjuvant chemotherapy) and high HER2/Cep17 ratio.2
The findings from this population-based study indicate that the neoadjuvant chemotherapy + pertuzumab + SB3 treatment regimen may yield a pCR rate in the real-world setting that is comparable with those previously reported from clinical trials.3
1. Pivot X, et al. J Clin Oncol. 2018;36:968-974.
2. Andersson M, et al. ASCO 2020. Abstract 577.
3. Chen S, et al. BMC Cancer. 2019;19:973.