Lin, Yi‐An

Background: Historically, the standard of care for advanced biliary tract cancers (aBTCs) was gemcitabine plus cisplatin (GemCis). Immunotherapy plus GemCis is now recommended as a first-line treatment for aBTCs. Whether patients can tolerate eight cycles of GemCis in clinical practice, as per the Advanced Biliary Cancer (ABC)-02 study, remains to be assessed. We performed a retrospective observational cohort study to assess real-world treatment patterns and overall survival (OS) in patients with de novo or recurrent aBTCs treated with first-line gemcitabine-based chemotherapy in the United States. Methods: This retrospective observational cohort study used Optum’s de-identified Market Clarity Data (Market Clarity). Adults diagnosed with de novo or recurrent aBTCs in the United States who began first-line gemcitabine-based chemotherapy from January 2016–March 2022 were identified and followed from index until death, the end of continuous enrolment, or the end of study period. Treatment patterns and OS were assessed. Results: Overall, 559 patients were included (de novo, n = 462; recurrent, n = 97). GemCis was the most common first-line therapy received (de novo: 73.8%; recurrent: 57.7%). Most patients received approximately five cycles of GemCis; median (95% CI) time to discontinuation was 4.6 (4.3–5.1) months. Most patients died over the follow-up period (de novo: 70.3%; recurrent: 62.9%). Median OS (95% CI) was 14.2 (12.1–16.1) months (de novo) and 18.5 (15.6–26.9) months (recurrent). Conclusions: GemCis was the most common first-line therapy received during the study period; most patients were unable to receive eight cycles of GemCis. Survival was limited over the follow-up period, highlighting the need for new treatments for aBTCs. Future studies are warranted to understand the real-world impact of first-line immunotherapy plus GemCis for patients with aBTCs.

454 Background: Biliary tract cancers (BTC) are often diagnosed at advanced stages (aBTC) when prognosis is poor. In the Phase 3 TOPAZ-1 study (NCT03875235), durvalumab plus gemcitabine and cisplatin (GemCis) significantly improved overall survival versus placebo plus GemCis. To better understand the context of the TOPAZ-1 trial results in the US, we looked at first-line (1L) treatment patterns in participants with aBTC treated with GemCis and other gemcitabine (Gem)-based chemotherapy (CT) regimens. Methods: This retrospective observational cohort study used linked electronic health records and medical and pharmacy claims data from the Optum Market Clarity Database. Adults diagnosed with de novo or recurrent aBTC, who initiated 1L Gem-based CT between January 2016 and March 2022, were identified and followed from the index date (defined as the first administration of Gem-based CT on or after initial BTC diagnosis date) until death, end of continuous enrollment, or end of study period, whichever occurred first. Variables including patient demographics, clinical characteristics, and treatment patterns were described. Results: A total of 580 patients were included in the analysis with either de novo aBTC (n=481, 82.9%) or recurrent aBTC (n=99, 17.1%) with median follow-up time of 10.4 (interquartile range: 6.4, 17.5) and 12.0 (interquartile range: 6.3, 21.9) months, respectively. Mean (SD) age was 64.6 (11.2) and 66.8 (10.4) years, with 45.7% and 54.5% male in the de novo and recurrent aBTC groups, respectively. Most patients were white (77.6%). The most frequent site of primary tumor diagnosis was single-site intrahepatic (overall 62.8%, de novo 66.7%, recurrent 43.4%). In the 12 months prior to index date, 38.5% of patients had biliary obstruction, 30.2% had biliary stents, 29.3% had jaundice, and 17.1% had nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. Common comorbidities included cardiovascular disease (50.9%), obesity (46.8%), and diabetes (35.2%). The most common 1L CT was GemCis followed by Gem for both the de novo (n=355, 73.8% and n=36, 7.5%) and recurrent groups (n=58, 58.6% and n=26, 26.3%), respectively. Approximately half of participants (50.9%) switched to a new line of treatment, 33.3% discontinued 1L CT, and 15.9% remained on 1L CT at last follow-up. Most frequent 2L treatments included fluorouracil/oxaliplatin (36.9%) and capecitabine (14.2%). Further analysis will characterize outcomes and regimen duration. Conclusions: Findings from this retrospective study showed that the most common 1L therapies were GemCis and Gem among both de novo and recurrent patients with aBTC. These results provide insight into aBTC treatment practices and may help inform treatment decisions.