Treatment patterns among patients with advanced/recurrent endometrial cancer in the United States.

291 Background: Among patients (pts) with endometrial cancer (EC), response rates for platinum-based regimens in the first-line (1L) setting range from 40% to 62% in clinical trials. This study describes patient characteristics, treatment patterns, time to next treatment (TTNT), and overall survival (OS) among pts with advanced/recurrent EC treated with a platinum-based regimen in a real-world setting in the US. Methods: This retrospective study used Optum Clinformatics Extended Data Mart de-identified databases from January 1, 2007, to December 31, 2019. Adult pts with advanced/recurrent EC who initiated a 1L platinum-based regimen and subsequently initiated second-line (2L) antineoplastic therapy were identified. Prior to initiation of 1L, a 12-month washout period of continuous enrollment without use of antineoplastic agents (except hormonal agents) was imposed. Kaplan-Meier (KM) rates were used to report TTNT and OS from 2L, third line (3L), and fourth line (4L), separately. Results: A total of 1878 pts with advanced/recurrent EC initiated 2L therapy following a platinum-based regimen in 1L. Among them, 739 (39.4%) pts initiated 3L and 330 (17.6%) initiated 4L or later (4L+) therapy. Median pt age was 68.0 years. More pts received platinum-based regimens (56.4%) in 2L than other options (Table). Few pts (3.3%) received immunotherapy. Among pts receiving 3L, a similar percentage of pts were treated with platinum-based (33.2%) and other chemotherapy regimens (33.8%); few pts received immunotherapy (3.0%). Among pts receiving 4L+, the most frequent treatment option was other chemotherapy (46.1%). Median TTNT was 17.7, 10.6, and 8.4 months for 2L, 3L, and 4L pts, respectively. KM rates of OS following initiation of 2L therapy at 1, 2, 3, and 4 years were 68.4%, 49.6%, 41.3%, and 33.6%, respectively, with a median OS of 23.5 months. Conclusions: Among pts with advanced/recurrent EC treated with platinum-based therapy in 1L, platinum-based regimens remain prevalent treatment choices in later lines of therapy. In this study, immunotherapy was used infrequently in 2L, 3L, and 4L+. The median TTNT decreased in later lines of therapy. This study highlights a critical need for novel, more effective treatment options in later lines of therapy to optimize outcomes among pts with advanced/recurrent EC.[Table: see text]