Abstract P4-07-45: Treatment strategies for advanced triple negative breast cancer patients as per routine clinical practice: analysis from the observational study GEICAM/2014-03 (RegistEM)
Authors: Novoa Silvia Antolin , Rodríguez César A , Cruz Josefina , López-Tarruella Sara , Tibau Ariadna , Adrover Encarna , Miguel Ana , Margelí Mireia , Martínez Purificación , Hernández María , Antón Antonio , Rodríguez-Lescure Álvaro , Falo Catalina , Álvarez Isabel , Malón Diego , Andrés Raquel , Alonso-Romero José L , Gómez César , Illaramendi J. José , Campo Ruth , Miralles Juan José , Bezares Susana , Rojo Federico , Guerrero-Zotano Angel 
Published: March 2023

Abstract
Background: Triple negative breast cancer (TNBC) is well known for its more aggressive course and poorer prognosis compared to other BC subtypes. RegistEM study provides real world data to understand the distribution of BC subtypes in the advanced setting, being its primary objective. Biological samples collection is part of its procedures. This is a non-interventional cohort study and 1,907 patients (pts) have been enrolled up to now (females and males) with advanced BC (ABC), diagnosed from Jan-2016 to Dec-2019, either after recurrence or as first BC diagnosis, in 38 Spanish sites. These pts will be followed for at least 5 years.
Methods: In the current analysis (cut-off date 08/April/2022, database ongoing), we describe characteristics, treatment patterns and outcomes, including comparison between recurrent and de novo disease, of 157 pts with advanced TNBC included in the RegistEM study. Those pts represent the 10% of pts available in the database at the cut-off date and with ABC diagnosis up to December 2018 (n=1559). The BC clinical subtypes were histologically confirmed on the most recent tumor lesion (metastatic [M] or primary BC) before starting with the 1st-line therapy.
Results: At first ABC diagnosis, 73% pts had recurrent early BC (EBC), 26% de novo MBC and 1% unresectable locally ABC (ULABC). Median age was 57 years (range 30-88), all pts were women, 98% Caucasian and 65% postmenopausal. Family history of BC and/or ovarian cancer was reported in 37% pts, and a hereditary-risk genetic test was performed in 59 of 147 pts. Germline BRCA1/2 and TP53 were the most frequently mutated genes, 21% (6/28) and 47% (8/17) pts, respectively. Visceral involvement was present in 69% pts (similar between recurrent EBC and de novo ABC, although brain metastases were only present in the recurrent EBC group), and ≤ 2 metastatic locations in 59%. In 61% (70/115) pts with recurrent EBC, the subtype was assessed in metastatic lesions, and 39 pts of them also had TN subtype in primary BC. In terms of the most frequent therapies by line: 1) 1st-line: chemotherapy (CT) (60%) and CT/biological therapy (BT) (39%). Of the 87 pts with CT alone, monotherapy was the preferred option in 57% pts (capecitabine 25%, taxanes 16%, and eribulin or vinorelbine, 5% each). Bevacizumab was the most frequent BT (79%) combined with CT (single agent in 56% pts, mostly taxanes and capecitabine). Progressive disease (PD) was reported in 85% pts (similar in pts with both recurrent and de novo MBC or ULABC); 2) 2nd-line: CT (79%) (monotherapy capecitabine, eribulin, taxanes) and CT/BT (17%) (CT-containing bevacizumab 82%). Progression was reported in 92% pts; 3) 3rd-line: CT (90%) (eribulin 33%, platinum-based 25%) and CT/BT (9%) (CT-containing bevacizumab 67%). Progression was reported in 88% pts. At database cut-off date, death was reported in 133 (85%) pts, mainly because of PD. Overall survival (OS) was similar between both groups, recurrent and de novo MBC.
Conclusion: In this population of Spanish TNBC pts with ABC, three quarters had recurrent disease. De novo ABC pts had a higher proportion of non-visceral metastases, with absence of brain involvement at the first diagnosis. Single-agent CT and CT plus bevacizumab were the most frequent therapies, and OS was similar between recurrent and de novo MBC pts, although numerically higher in the later group.

Citation Format: Silvia Antolin Novoa, César A Rodríguez, Josefina Cruz, Sara López-Tarruella, Ariadna Tibau, Encarna Adrover, Ana Miguel, Mireia Margelí, Purificación Martínez, María Hernández, Antonio Antón, Álvaro Rodríguez-Lescure, Catalina Falo, Isabel Álvarez, Diego Malón, Raquel Andrés, José L Alonso-Romero, César Gómez, J. José Illaramendi, Ruth Campo, Juan José Miralles, Susana Bezares, Federico Rojo, Angel Guerrero-Zotano. Treatment strategies for advanced triple negative breast cancer patients as per routine clinical practice: analysis from the observational study GEICAM/2014-03 (RegistEM) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-45.