Abstract PS7-08: Characteristics of HR+/HER2- patients with recurrent disease from a prospective registry of unresectable locally advanced or metastatic breast cancer: GEICAM/2014-03 (RegistEM)
Authors: Alvarez Isabel , Guerrero- Zotano Angel , López-Tarruella Sara , Martínez Purificación , Mori Marta , Falo Catalina , Antolin Silvia , Rodríguez Cesar A. , Margeli Mireia , Garau Isabel , Tibau Ariadna , Moreno Diana , Cruz Josefina , Echarri M. Jose , Lao Juan , Rodríguez-Lescure Alvaro , Miralles Juan Jose , Bezares Susana , Rojo Federico , Jara Carlos 
Published: February 2021

Background: There is limited prospective data for advanced breast cancer (ABC) patients (pts), unresectable locally or metastatic, treated as per clinical practice. RegistEM, an academic study conducted by a non-profit collaborative group, will provide epidemiological, pathological and clinical data as per routine practice, including treatments for different disease settings, collected from pts’ medical records. Understanding the real distribution of BC subtypes is the primary objective. This is a non-interventional cohort study that will enroll approximately 1,867 pts with advanced disease diagnosed from January 2016 to December 2019, either after recurrence or as first diagnosis (de novo), in 38 Spanish sites representative of the whole country geography and whose investigators are GEICAM members. Biological samples (primary and/or metastatic tumor tissue, and blood) collection is part of study procedures. Methods: In this analysis we describe the characteristics of 229 pts with HR+/HER2- BC documented in a metastatic tumor lesion after disease recurrence and who received adjuvant endocrine therapy (ET). This subpopulation has been identify as an interesting group from a clinical perspective for detailed analysis. Three subgroups of pts have been considered for this analysis based on their disease-free interval (DFI) since the diagnosis of early disease: &lt;36 months (mo), ≥36 mo to &lt;60 mo, and ≥60 mo. Results: This subset of pts makes up 13.7% (n=229) of the whole population currently registered (n=1,672). The distribution of pts on &lt;36 mo, ≥36 mo to &lt;60 mo, and ≥60 mo DFI subgroups was 15.3%, 16.6% and 68.1%, respectively, with &gt;50% pts recurring at ≥84 mo and only 1.3% pts at ≤12 mo. Most pts were Caucasian (99.1%) and female (99.6%), and at ABC diagnosis, 75.5% were postmenopausal and their median age was 59 years (33-88); median age was higher in pts with DFI ≥60 mo. Family history of BC and/or ovarian cancer was reported in 31.4% pts, with a slightly higher percentage in pts with DFI &lt;36 mo; an hereditary-risk genetic test was performed in 11.4% pts in total and BRCA2 gene mutation (n=6) was the only one reported. Bone (59%), liver (33.2%), lung (23.1%) and lymph nodes (21.8%) were the most frequent sites of metastases. Visceral disease was present in 63.3% pts and 76% pts had ≤2 locations. Liver involvement was more frequent in pts with DFI &lt;36. The most frequent 1st-line therapies were ET/biological therapy (BT) (46.7%) and ET (28.8%). The most common ET/BT regimens were aromatase inhibitor (AI)/cyclin-dependent kinase 4/6 inhibitor (CDKi) (48.6%) and fulvestrant (FUL)/CDKi (28.0%); AIs (67.3%) and FUL (31.0%) were also the most common drugs for ET ( as monotherapy). A 2nd-line therapy was reported in 52.4% pts. The median time to progression (TTP) to 1st-line therapy was 11.4 mo (1.2-37.0), being similar in pts with DFI &lt;36 mo and ≥36 mo to &lt;60 mo (around 7 mo), and higher in pts with DFI ≥60 mo (13.2 mo). The most frequent 2nd-line therapies were ET/BT (33.3%) (FUL/CDKi 42.5%, AI/CDKi 30%), chemotherapy as monotherapy (29.2%) (capecitabine 51.7%, taxanes 20.7%, eribulin 13.8%) and ET (19.2%) (FUL 54.5%, AI 36.4%). Median duration of 2nd-line therapy was 5.7 mo (0.03-37.2) and disease progression was reported in 56.7% pts. Most frequent 1st-/2nd-line therapies between DFI subgroups were similar in type but not in frequency. 3rd-line therapy has been reported in 25.8% of 229 pts. Conclusions: In pts with HR+/HER2- ABC due to disease recurrence, &gt;50% pts recurred at ≥84 mo. Bone is the most frequent metastatic location in all DFI subgroups. The most common 1st- and 2nd-line therapies were the ET/BT combination, with AI/CDKi and FUL/CDKi, respectively. The median TTP to 1st-line therapy was superior in pts with DFI ≥60 mo.

Citation Format: Isabel Alvarez, Angel Guerrero- Zotano, Sara López-Tarruella, Purificación Martínez, Marta Mori, Catalina Falo, Silvia Antolin, Cesar A. Rodríguez, Mireia Margeli, Isabel Garau, Ariadna Tibau, Diana Moreno, Josefina Cruz, M. Jose Echarri, Juan Lao, Alvaro Rodríguez-Lescure, Juan Jose Miralles, Susana Bezares, Federico Rojo, Carlos Jara. Characteristics of HR+/HER2- patients with recurrent disease from a prospective registry of unresectable locally advanced or metastatic breast cancer: GEICAM/2014-03 (RegistEM) [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 PS7-08.