Abstract P5-20-03: Impact of prior adjuvant trastuzumab (aT) on clinical characteristics, patterns of recurrence and outcome in 2863 patients with Her2 positive (HER2+) metastatic breast cancer (MBC)- Results from the French ESME UNICANCER program

Background: The management of HER2+ BC has changed dramatically with the introduction and widespread use of HER2-targeted therapies, especially in the adjuvant setting. However, there is relatively limited real-world information on the impact of adjuvant Trastuzumab (aT) on patterns of recurrence and outcome of HER2+ MBC. Methods: In 2014, the 18 French Cancer Centers launched the Epidemiological Strategy and Medical Economics (ESME) program to provide real-world data on MBC patients (pts). All pts who started a 1st-line treatment for MBC between 01-Jan-2008 and 31-Dec-2014 were included. We examined clinical characteristics and outcomes (overall survival [OS] and time to next treatment [TNT]) in patients with HER2+ MBC pretreated with trastuzumab in the adjuvant setting (aT) compared with trastuzumab-naïve patients (nT) and patients with de novo HER2+ MBC (dn). Multivariate analyses adjusted for baseline demographic, prognostic factors and year of diagnosis (prior or after 2005, when aT was approved and widely administered in France for early HER2+ breast cancer). Results: Among the 15170 pts of the ESME database, 2863 (19%) were HER2+: 1093 pts (38%) had de novo and 1765 pts (62%) recurrent MBC; 63% were Hormone Receptor (HR) +; 54%, 25% and 21% had respectively 1, 2, or > 2 metastatic sites (68% visceral and 12% brain). Median time to 1st metastasis was 43.4 months (m) (95% CI: 24.6-84.4): 54 m in HR+ and 30 m in HR-. Among pts with recurrent MBC, 55% (995) had received aT. As 1st-line therapy for MBC, 90 % of pts received HER2-targeted agents (73% T-based). With a median follow-up of 46 m, median OS is 45 m (95% CI: 42.5-48). OS is significantly higher in de novo compared to recurrent MBC: 54 m (95% CI: 50.2-60.4) vs. 38.4 m (95% CI: 36.7-41.9), (p < 0.0001). Among pts with recurrent cancers, median OS is inferior in pts who had received aT, as compared to those who had not: 33.4 m (95% CI: 29.6-36.7) vs. 49.5 m (95% CI: 44.3-56.8), (p < 0.0001). Statistically significant differences persist after adjustment for age at MBC, disease-free interval, metastatic sites and RH status in the multivariate model (HR=1.45, 95% CI: 1.26-1.67) but not after adjustment for year of diagnosis (prior or after 2005) (HR=0.90, 95% CI: 0.70-1.15). Conclusions: These large-scale real-world data in patients with HER2+ MBC provide evidence that the survival outcome remain similar in patients with failure of adjuvant trastuzumab compared with trastuzumab-naïve patients after adjustment for year of diagnosis. De novo HER2+ MBC pts have the best outcomes. Data on clinical characteristics of metastasis and time to next treatment for the three subgroups will be presented at the meeting. Citation Format: Saghatchian M, Carton M, Piot I, Pérol D, Pistilli B, Brain E, Ghouadni A, Ricci F, Vanlemmens L, Loeb A, Levy C, Goncalves A, Dalenc F, Lefeuvre-Plesse C, Campone M, Jaffre A, Gourgou S, Cailliot C, Robain M, Dieras V. Impact of prior adjuvant trastuzumab (aT) on clinical characteristics, patterns of recurrence and outcome in 2863 patients with Her2 positive (HER2+) metastatic breast cancer (MBC)- Results from the French ESME UNICANCER program [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-03.