Abstract P1-11-20: Trastuzumab (HLX02) plus Pertuzumab as Dual-target Neoadjuvant Therapy for HER2-positive Breast Cancer: A Real-World Study
Authors: Liu Yin , Zuo Wen-Jia , Wang Ruo-Xi , Wang Zhong-Hua , Shao Zhi-Ming 
Published: March 2023

Background: The effect of neoadjuvant therapy on tumor downstaging and breast-conserving during surgery is well documented. Pathologic complete response (pCR) after neoadjuvant treatment was associated with long-term survival. HLX02 (Zercepac®), a biosimilar of trastuzumab, showed the same efficacy, safety, and immunogenicity as the reference drug in human epidermal growth factor receptor-2 (HER2)-positive patients. Despite this, real-world evidence of its effectiveness when combined with pertuzumab in neoadjuvant treatment of HER-2 positive breast cancer still lacks.

Methods: In this retrospective real-world study, women with confirmed invasive HER2-positive breast cancer who have received chemotherapy plus HLX02 and pertuzumab (Perjeta®) as neoadjuvant therapy were enrolled. Patients must be over 18 years old, have an Eastern Cooperative Oncology Group performance status score of 0 or 1, and have a baseline left ventricular ejection fraction of ≥ 55%. Patients without pathological assessment after neoadjuvant therapy were excluded. Pathologic complete response (pCR) was defined as no residual invasive tumors in mammary glands and axillary lymph nodes. Clinical response was assessed using RECIST1.1. To investigate the factors associated with pCR, univariate and multivariate logistic regression (forward stepwise) analyses were conducted.

Results: A total of 85 patients were enrolled in this study, and 55 patients (64.71%) achieved pCR after neoadjuvant therapy. There were 84 (98.82%) patients with partial response (PR), one (1.18%) patient with stable disease (SD). According to the univariable analysis, when compared to those with a tumor diameter ≤ 5 cm, patients with a tumor diameter &gt; 5 cm at baseline showed a lower pCR rate (odds ratio [OR] = 0.286; 95% confidence interval [CI]: 0.108-0.758, P = 0.01). Patients with preoperative PR positivity &gt; 10% showed lower pCR rate than those with preoperative PR positivity &lt; 1% (OR = 0.115, 95% CI 0.036-0.372, P = 0.02). Besides, pCR was more common in patients with preoperative hormone receptor (HR)-negative than in those with preoperative HR-positive (ER or PR positivity &gt; 10%) (OR = 4.452, 95% CI 1.679-11.804, P &lt; 0.01). Multivariable analyses showed that patients with tumor diameter &gt; 5 cm had a lower pCR rate than those with tumor diameter ≤ 5cm (OR = 0.213; 95% CI 0.070-0.644, P = 0.01). Patients with preoperative HR-negative tumors were more likely to achieve pCR than those with preoperative HR-positive tumors (OR =5.649, 95% CI 1.927-16.556, P &lt; 0.01) (Table 1). The treatment were well tolerated by patients, and no additional adverse events were reported.

Conclusion: According to this real-world study, HLX02 in combination with pertuzumab as neoadjuvant therapy for HER2-positive breast cancer patients showed a similar pCR rate to that of dual-target neoadjuvant therapy reported in previous clinical trials. The treatment showed an encouraging effectiveness, and may become a novel neoadjuvant option for patients with HER2-positive breast cancer.

The study was supported by the Natural Science Foundation of Shanghai (21ZR1414700).

Table 1. Logistic regression for pCR.

Citation Format: Yin Liu, Wen-Jia Zuo, Ruo-Xi Wang, Zhong-Hua Wang, Zhi-Ming Shao. Trastuzumab (HLX02) plus Pertuzumab as Dual-target Neoadjuvant Therapy for HER2-positive Breast Cancer: A Real-World Study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-11-20.