First-Line Treatment of HER2-Positive Metastatic Breast Cancer With Dual Blockade Including Biosimilar Trastuzumab (SB3): Population-Based Real-World Data From the DBCG

Abstract

Purpose: Dual blockade with trastuzumab and pertuzumab in combination with chemotherapy is the recommended first-line therapy for human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (mBC). The purpose of this retrospective study is to examine the clinical outcomes of the trastuzumab biosimilar SB3 in first-line dual blockade treatment using real-world data of patients with HER-positive mBC. Methods: In Denmark, all women with breast cancer are registered in the database of the Danish Breast Cancer Group (DBCG). From this prospective observational registry, we extracted information on primary diagnosis and treatment of all women with HER2-positive mBC who received first-line treatment with SB3 and pertuzumab from September 1, 2018, to February 29, 2020. Retrospectively collected data from the DBCG database included information concerning treatment start, end, and reason for discontinuation. The primary endpoints for the study were overall survival (OS) and progression-free survival (PFS). Results: The study included 117 women who received first-line treatment with SB3 and pertuzumab for their HER2-positive mBC. The study population had a mean age of 60 years. A total of 71 patients (61%) had recurrent disease and 46 patients (39%) presented with de novo mBC. The median follow-up was 11.1 and 15.4 months for PFS and OS, respectively. At 12 months, OS was 84% (95% confidence interval [CI], 78-91), whereas the median OS was not reached. The median PFS was 12.7 months (95% CI, 11.1-16.2). Median time on treatment was 8.7 months (95% CI, 7.6-11.4); 36 patients (31%) were still on treatment at end of study. Conclusions: This retrospective real-world, nationwide study demonstrated comparable median PFS to the historical data of using reference trastuzumab and pertuzumab as first-line dual blockade.

Trastuzumab Biosimilar ABP 980 Plus Pertuzumab and Docetaxel in the Therapy of Metastatic Breast Cancer: Real World Experiences from the National Research Institute of Oncology in Warsaw

“…Patients with HER2-positive, HR-positive breast cancer also prevailed in other studies, but the percentage of those patients was lower (47-70%), which could translate into a higher ORR. A significant percentage of patients in our study had previously received systemic therapy for early breast cancer (55.7%), while in other studies, except for the Chinese study [28] and the SB3 evaluation study [29], this group of patients usually did not exceed 50% (27.8%-48%). These differences in the structure of the patient group also could potentially translate into slightly poorer therapy outcomes, as well as potentially higher rates of cardiotoxic complications.…”

“…The median PFS achieved in these studies ranged between 14.5 and 27.8 months [24][25][26][27][28]. Equivalent results were also presented in a study evaluating a trastuzumab biosimilar (SB3); the mPFS obtained in this study was 12.7 months [29]. Table 5 shows a comparison of the results of the most frequently quoted studies evaluating the efficacy and safety of PTH therapy.…”

Epidemiology trends and progress in breast cancer survival: earlier diagnosis, new therapeutics

“…Conversely, survival remained substantially unchanged for patients with triple-negative or HR+/HER2-negative MBC [ 63 ]. Similarly, population-based studies from Canada, Denmark, Sweden and Australia showed that median OS, for patients receiving double anti-HER2 blockade, rose from 21.8 during 2006–2014 to 39.2 months during 2012–2017, compared to 14 months for patients diagnosed during 1985–2000 who did not receive trastuzumab [ 64 – 67 ].…”

Evaluation of clinical and pathological responses of HER-2 positive locally advanced breast cancer patients after neoadjuvant therapy and surgery

“…Dual HER-2 blockade has become the accepted neoadjuvant approach for HER2-positive breast cancer 10,11 . However, there are still incidences of drug resistance following therapy 12 .…”