Abstract P2-13-30: First interim analysis from ELEANOR: A multi-national, prospective, non-interventional study (NIS) in patients with human epidermal growth factor receptor positive (HER2+) early breast cancer observing real-life extended adjuvant treatment with neratinib

Abstract Background: Recent advances in (post-)/(neo)adjuvant treatment for HER2+ breast cancer have led to a major reduction in recurrence risk; still a relevant percentage of patients relapses over time, predominantly presenting with distant recurrence. Neratinib is registered in Europe as extended adjuvant treatment for adult patients with HER2+, HR+ early-stage breast cancer (eBC), who completed adjuvant trastuzumab-based therapy less than one year ago. In the ExteNET study, neratinib improved the 5-year iDFS absolute-rate by 5.1% versus placebo in this population (90.8% vs. 85.7%; HR 0.58 [95% CI 0.41-0.82]), mainly by prolonging time to development of distant metastases. According to explorative (post-hoc) analyses from ExteNET, the effect might be even more pronounced in patients with non-pCR after neoadjuvant trastuzumab treatment and/or in patients with completion of neratinib therapy (i.e. ≥11 months of neratinib treatment). Diarrhea, the most common grade 3 adverse event (neratinib: 39% without primary diarrhea prophylaxis, median cumulative duration 5 days; placebo: 1%; no grade 4 events) can generally be managed through adequate prophylaxis and treatment management. ELEANOR is the first international NIS to investigate real-world use of neratinib and its treatment management in eBC patients in Germany, Austria and Switzerland. Methods: The primary objective of this ongoing NIS is to investigate the rate of patients being adherent to neratinib treatment (i.e. neratinib intake for ≥75% of treatment days). Secondary objectives include detailed patient and disease characteristics, details on prior trastuzumab-based therapies (including pertuzumab and T-DM1), neratinib doses, dose modifications and neratinib treatment management, relapses, safety/tolerability, and quality of life (QoL), among others. 300 adult female patients with HER2+/HR+ eBC are planned in accordance with the SmPC specifications (planned end of documentation: 2023). CANKADO, an application developed to support patient/physician communication, is an integral part of the NIS. Different CANKADO modules can be used optionally, including QoL documentation (EQ-5D-5L- and diarrhea-specific questionnaires) and continuous documentation of health status and symptoms. Results: Between July 2020 and July 2021, 141 patients have been enrolled; patient enrollment is ongoing. The first pre-planned interim analysis will be performed after the 100th patient has been observed for 3 months (data cut July 2021). Here, we will present baseline demographic and tumor characteristics for the first 100 patients, as well as prior trastuzumab-based treatments and first safety and tolerability data of real-world neratinib use. Conclusion: The results of the first interim analysis present a preliminary snapshot of the current treatment landscape and real-life neratinib use in Germany and Austria. The ELEANOR NIS should help to understand adherence to neratinib treatment and use of extended adjuvant HER2-targeted therapy in the current treatment landscape focussing on treatment management after different pre-therapies. The study is funded by Pierre Fabre Pharma GmbH (Freiburg, Germany), Pierre Fabre Pharma Austria (Wels, Austria) and Pierre Fabre Pharma AG (Allschwil, Switzerland). Citation Format: Diana Lüftner, Rupert Bartsch, Urs Breitenstein, Marija Balic, Christian Jackisch, Volkmar Müller, Gabriel Rinnerthaler, Marcus Schmidt, Michael Schwitter, Khalil Zaman, Denise Wrobel, Dagmar Guth, Jürgen Terhaag, Matthias Zaiss, Timo Schinköthe, Nadia Harbeck. First interim analysis from ELEANOR: A multi-national, prospective, non-interventional study (NIS) in patients with human epidermal growth factor receptor positive (HER2+) early breast cancer observing real-life extended adjuvant treatment with neratinib [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-30.