Recent trends in US real-world first-line (1L) treatment patterns for patients with locally advanced or metastatic urothelial carcinoma (la/mUC).

e16556 Background: Recent advances in a rapidly evolving la/mUC treatment (tx) landscape have provided more life-prolonging tx options. Real-world data are needed to understand the impact on tx patterns of recently approved tx, such as avelumab 1L maintenance, nivolumab + gemcitabine/cisplatin (gem/cis) for cis-eligible patients (pts), and enfortumab vedotin + pembrolizumab (EV+P) for pts with la/mUC, regardless of cis eligibility. Here, we describe current real-world uptake of novel tx for 1L la/mUC in US clinical practice and trends over time. Methods: A retrospective, observational study was conducted using the nationwide Flatiron Health electronic health record–derived deidentified database. Eligible pts were adults with la/mUC diagnosed between Jan 2017 and Jun 2024, followed until death or end of data availability in Sep 2024. Rates of 1L tx and tx patterns were assessed for the overall period, and trends over time (Jan 2017-Mar 2020, Apr 2020-Mar 2023, and Apr 2023 onward) were described. Results: Of 7459 pts diagnosed with la/mUC who met eligibility criteria, 5751 (77.1%) received 1L tx. Slight increases in 1L tx rate were seen over the 3 time periods (73.9%, 78.7%, and 81.7%, respectively). In the overall study period, the most common 1L tx regimens were platinum-based chemo with or without avelumab maintenance (40.9%) and PD-(L)1 monotherapy (37.9%). From Apr 2023 to Sep 2024, EV+P was the most common 1L regimen (Table). In the most recent period, 43% of pts remained on 1L tx at study end. Conclusions: These data show an evolution of 1L la/mUC tx patterns over time, including increasing rates of 1L tx, possibly due to recent approvals of life-prolonging tx, and a marked reduction in use of PD-(L)1 monotherapy and chemo following approvals for EV+P. Despite recent advances, a notable proportion continue to use other 1L tx. Further research is needed to evaluate the real-world impact on clinical outcomes. 1L tx, n (%) Overall (N=5751) Jan 2017-Mar 2020 (n=2350) Apr 2020-Mar 2023 (n=2466) Apr 2023-Sep 2024 (n=935) EV+P a 333 (5.8) 1 (0.0) 9 (0.4) 323 (34.5) PD-(L)1 monotherapy 2179 (37.9) 947 (40.3) 996 (40.4) 236 (25.2) Cis+gem or MVAC w/ avelumab maintenance b 198 (3.4) 11 (0.5) 157 (6.4) 30 (3.2) Cis+gem or MVAC w/out avelumab maintenance 1111 (19.3) 581 (24.7) 418 (17.0) 112 (12.0) Nivolumab+cis+gem c 6 (0.1) 1 (0.0) 1 (0.0) 4 (0.4) Carbo+gem w/ avelumab maintenance b 183 (3.2) 5 (0.2) 151 (6.1) 27 (2.9) Carbo+gem w/out avelumab maintenance 864 (15.0) 445 (18.9) 364 (14.8 55 (5.9) Other 877 (15.2) 359 (15.3) 370 (15.0) 148 (15.8) carbo, carboplatin; MVAC, methotrexate, vinblastine sulfate, doxorubicin hydrochloride, and cisplatin. a Accelerated FDA approval in 1L for cis-ineligible pts: Apr 2023; FDA approval in 1L for all pts with la/mUC: Dec 2023. b FDA approval: Jun 2020. c FDA approval: Mar 2024.