Abstract P1-19-26: Characteristics of MBC patients receiving first line treatments in the US real-world setting in the era of CDK4/6 inhibitors
Authors: Brufsky Adam , Chen Connie , Mardekian Jack , Liu Xianchen , McRoy Lynn , Torres Mylin 
Published: March 2020

Background: In the 4 years since Palbociclib approval, oral CDK4/6 inhibitors in combination with endocrine therapy (CKD4/6 + ET) have become a standard of care for HR+/HER2- advanced/metastatic breast cancer (MBC). We conducted this analysis to understand treatment patterns in HR+/HER2- MBC pts in the 1st line setting and associated patient (pt) characteristics in routine US clinical practice. Methods: A retrospective analysis was conducted of eligible HR+HER- MBC pts within the Flatiron Health longitudinal database treated in the 1st line setting between August 2015 and August 31st, 2018. Three patient groups were evaluated: those treated with CDK4/6 + ET, chemotherapy alone (Chx), or ET monotherapy (ET). Pt demographics and tumor characteristics were described. The impact of time, starting 6 months after FDA approval of the 1st CDK 4/6 inhibitor Palbociclib was evaluated. Changes in treatment initiation by year were evaluated by treatment category. Results: Among the 3950 meeting eligibility criteria, 1370 pts received CDK+ET, 786 Chx, and 1794 ET alone. Median overall follow-up was 13.2 months. Payor coverage was relatively similar across groups. The table presents demographic and clinical pt characteristics. More Chx pts had visceral metastasis, higher mean number of sites of metastases, and fewer patients &gt;75 years of age. ET pts were older and more likely to have bone only disease. The proportion of pts receiving an CDK + ET combination as 1st line treatment increased from 22% in 2015 to 49% in 2018. Conclusions: Treatment patterns have evolved over time with CDK combination therapy representing the 1st line of tx for nearly half of all patients in the final year available for analysis. Variations in pt clinical characteristics exist across treatment groups. Further evaluation is needed to determine if pt outcomes could be optimized with the use of CDK4/6 in patients receiving Chx or ET monotherapy in the first line setting. Funding: Pfizer

CDK + ETChxET(N=1370)(N=786)(N=1794)Mean age (SD), 64.0 (11.5) 60.2 (12.0)67.9 (12.5) Age &gt; 75261 (19.1)97 (12.3)631 (35.2)Caucasian N (%)903 (65.9)467 (59.4)1169 (65.2)Prescribing year N (%) 2015125 (22.3)124 (22.1)311 (55.5)2016424 (29.5)305 (21.2)709 (49.3)2017478 (38.3)252 (20.2)517 (41.5)2018343 (48.7)105 (14.9)257 (36.5)Stage IV at initial diagnosis456 (33.3)286 (36.4)516 (28.8)Metastasis N (%) Bone only418 (30.5)82 (10.4)602 (33.6)Bone1108 (80.9)535 (68.1)1389 (77.4)Visceral692 (50.5)541 (68.8)823 (45.9)Liver351 (25.6)326 (41.5)409 (22.8)Lung494 (36.1)351 (44.7)572 (31.9)Brain77 (5.6)113 (14.4)130 (7.2)Distant Lymph Node411 (30.0)320 (40.7)440 (24.5)0 or 1 metastasis site586 (42.8)225 (28.6)875 (48.8)&gt;=2 metastasis sites784 (57.2)561 (71.4)919 (51.2)

Citation Format: Adam Brufsky, Connie Chen, Jack Mardekian, Xianchen Liu, Lynn McRoy, Mylin Torres. Characteristics of MBC patients receiving first line treatments in the US real-world setting in the era of CDK4/6 inhibitors [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-26.