Abstract PS10-50: Patterns of use of a trastuzumab biosimilar (ABP 980) in patients with HER2+ breast cancer treated in clinical practice in Europe: An interim analysis from an observational chart review study (GARDENIA)

Background: Over recent years, therapeutic biosimilars have started to be licensed as oncology treatments in both palliative and potentially curative settings, but little is known about their uptake and usage in routine clinical practice. ABP 980 is a trastuzumab biosimilar that is licensed in Europe and the USA for the treatment of HER2+ early or metastatic breast cancer and metastatic gastric cancer. This European real-world study aimed to describe patterns of ABP 980 usage in clinical practice in patients with breast cancer. Methods: This descriptive observational chart review study included consecutive patients aged ≥18 years with HER2+ breast cancer (any disease stage or treatment phase) who were receiving or had previously received ABP 980 and had medical charts available for data extraction. Patients were followed up from ABP 980 initiation to withdrawal of consent, death, loss to follow up, entry into an interventional trial, or study end (12 months after last patient enrolled). Follow-up data from ABP 980 initiation to enrolment were retrospectively collected; data after enrolment were prospectively collected. Data were extracted into electronic case report forms quarterly. The primary objective is to describe patient demographics and disease characteristics by treatment phase and prior trastuzumab exposure and communication with patients about biosimilar use is an exploratory objective. Other exploratory endpoints are ABP 980 safety (including cardiac dysfunction, infusion-related reactions and other adverse events of interest) and efficacy (both to be assessed in the final analysis). This planned interim analysis was performed approximately 6 months after the first patient enrolled and provides baseline data on patient characteristics. Results: At the time of analysis, 135 women were included from five countries (Poland n=42; Italy n=38; the Netherlands n=32; France n=21; Spain n=2). Patients were mostly recruited from hospital-based sites (61%), including a mixture of academic/non-academic and publicly/privately funded centers. A policy on biosimilar use was documented in 28% of sites and 36% of patients were informed they were starting a biosimilar, with the brand mentioned to 34% of patients. Mean (standard deviation [SD]) age at ABP 980 initiation was 58.3 (11.5) years and mean (SD) time from ABP 980 initiation to enrolment was 7.3 (4.8) months. At ABP 980 initiation, 22%, 27%, 13% and 28% of patients had Stage I, II, III or IV disease, respectively. Overall, 68% of patients had estrogen/progesterone receptor-positive tumors and all patients with known ECOG performance status (n=73) had a score of 0 or 1. ABP 980 usage was approximately equally distributed across neoadjuvant (39%), adjuvant (30%), and metastatic settings (30%). Of the patients receiving treatment for metastatic disease (n=41), most received ABP 980 as their 1st- (56%) or 2nd- (20%) line treatment. Overall, 40% of patients had switched to ABP 980 from another trastuzumab product. Of these 54 patients, 44% switched from the intravenous form of originator trastuzumab and 15% switched from the subcutaneous form. Most of those switching from subcutaneous originator trastuzumab to ABP 980 were being treated for metastatic disease (7/8 patients). Conclusions: These interim results report usage patterns of the trastuzumab biosimilar ABP 980 in Europe. There was uptake across a mixture of institution types and breast cancer treatment settings, including those with curative potential, and 40% of patients switched to ABP 980 from another trastuzumab product. Recruitment to this study is ongoing. Citation Format: Joanna Kufel-Grabowska, Tevy San, Antonio Bernardo, Luigi Cavanna, Isaura Fernandez Perez, Grazyna Suchodolska, Jane Hippenmeyer, Priya Gokani, Mark Lillie, Cesar A. Rodriguez. Patterns of use of a trastuzumab biosimilar (ABP 980) in patients with HER2+ breast cancer treated in clinical practice in Europe: An interim analysis from an observational chart review study (GARDENIA) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-50.