Abstract P1-14-04: Outcomes in patients (pts) with metastatic triple-negative breast cancer (mTNBC) treated in second line (2L) in the US real-world setting
Authors: Luhn P , O'Hear C , Ton TG , Hsieh A , Yi J , Chang C-W , Funke R , Kurian A 
Published: May 2019

Abstract
Background: mTNBC represents an area of high unmet need, yet studies assessing real-world outcomes in pts treated in 2L are limited. We describe treatment patterns and outcomes in mTNBC pts receiving 2L treatment primarily in community cancer care clinics in the USA.
Methods: Pts aged ≥18 y with a confirmed diagnosis of mTNBC between 1 Jan 2011 and 28 Feb 2017 and who received 2L therapy were identified from the Flatiron Health electronic health record-derived database. Overall survival (OS) and time to next treatment (TTNT) were assessed as primary outcomes using Kaplan–Meier methods in both the overall population and subgroups of pts receiving the most commonly used agents (capecitabine, taxane, gemcitabine).
Results: Most of the 623 pts analyzed were White (62.9%) and received care in community clinics (94.9%). The most commonly used previous first-line (1L) regimens in this 2L pt population were: capecitabine (14.0%), cyclophosphamide/doxorubicin (11.6%), carboplatin/gemcitabine (9.3%), paclitaxel (7.1%), and nab-paclitaxel (7.1%); the remaining 51.0% of pts received 95 different 1L regimens. The most common 2L treatments were monotherapy regimens: capecitabine (10.9%), paclitaxel (9.3%), eribulin (9.0%), nab-paclitaxel (8.2%), and gemcitabine (7.7%); the remaining 54.9% of pts received 120 different 2L regimens. Selected demographic, clinical, and treatment characteristics and outcomes after median follow-up of 8.5 (interquartile range [IQR] 4.5–15.7) mo are shown below.
No. of pts (%)All pts (n=623)Selected subgroups by agent-containing regimen* Capecitabine (n=101)Taxane (n=222)Gemcitabine (n=111)Median age at initial metastatic diagnosis, y (IQR)58 (50–68)60 (53–67)58 (50–68)61 (51–70)Recurrent458 (73.5)81 (80.2)130 (58.6)93 (83.8)TFI &gt;12 mo†104 (47.1)18 (43.9)21 (42.9)23 (57.5)TFI ≤12 mo†117 (52.9)23 (56.1)28 (57.1)17 (42.5)TFI missing237408153De novo164 (26.3)20 (19.8)92 (41.4)18 (16.2)Missing1 (0.2)000Median time from 1L to start of 2L, mo (IQR)3.7 (2.1–6.4)4.2 (2.6–7.5)2.5 (1.8–4.3)4.1 (2.1–7.1)ECOG PS ≥2 at start of 2L57 (9.1)13 (12.9)15 (6.8)16 (14.4)CNS/brain metastases at start of 2L80 (12.8)14 (13.9)21 (9.5)16 (14.4)Median TTNT‡, mo (95% CI)4.5 (4.1–5.0)4.1 (3.5–5.0)5.5 (4.4–6.2)4.1 (3.1–4.8)Median OS‡, mo (95% CI)10.2 (8.9–11.1)10.0 (8.0–13.5)12.4 (10.6–15.0)8.3 (6.9–9.6)1-y OS‡, % (95% CI)42.3 (38.2–46.4)43.6 (33.3–53.8)51.9 (45.2–58.7)29.3 (20.1–38.6)TFI=treatment-free interval. *Any regimen containing each agent (monotherapy or combination); subgroups not mutually exclusive. †Defined as the interval between last (neo)adjuvant therapy and metastatic diagnosis; percentages calculated using pts with recurrent disease and non-missing TFI as the denominator. ‡From start of 2L
Conclusions: There was no clear 2L treatment standard used for mTNBC and median OS was short (10.2 mo overall). Notably, pts receiving 2L gemcitabine- vs taxane-containing therapy experienced shorter median OS and lower 1-y OS rates, although imbalances in prior therapy, disease biology, and demographic and prognostic factors between these subgroups may have contributed to the observed differences. 2L treatment for mTNBC remains an area of high unmet medical need.
Citation Format: Luhn P, O'Hear C, Ton TG, Hsieh A, Yi J, Chang C-W, Funke R, Kurian A. Outcomes in patients (pts) with metastatic triple-negative breast cancer (mTNBC) treated in second line (2L) in the US real-world setting [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-14-04.