1687PReal-world outcomes of patients with locally advanced or metastatic epithelioid sarcoma

Abstract Background Limited data are available on effectiveness and safety of systemic therapies for treatment of advanced (unresectable and/or metastatic) epithelioid sarcoma (ES). This natural history study collected real-world (rw) data on outcomes of ES patients (pts) receiving at least first-line (1L) or 2 or more lines (2L+) of systemic therapies. Methods Retrospective chart review was conducted in pts with advanced ES who initiated systemic therapy between 2000-2017 at 5 US cancer centers. Due to unavailability of RECIST assessment, rw overall response rate (rwORR) was assessed by review of radiology reports. rw disease control rate (rwDCR) was defined as percent of pts with response of any duration or stable disease ≥32 wks. Median rw duration of response (rwDOR), rw progression-free survival (rwPFS) and overall survival (OS) were estimated from start of therapy by Kaplan-Meier method. The index date for time-to-event endpoints was the start of first-line treatment. Adverse events (AEs) resulting in treatment modification, discontinuation, hospitalization, permanent sequelae or death, were abstracted. Results Of 74 eligible pts, 53 (71.6%) were male, and 63 (85.1%) had metastatic ES. INI1/BAF47 was not expressed in 90.2% of 41 tumors tested. Mean age at advanced ES diagnosis was 36.4 years. Anthracycline-based (54.1%) and gemcitabine-based (24.3%) regimens were most common in 1L. Median (range) number of lines of therapy received was 2 (1-7). 1L rwORR was 14.9%, rwDCR was 20.3%, rwDOR was 14.5 wks, and median OS was 66.3 wks. The table shows 1L and 2L+ results. Over 50% of pts had an AE; most frequently febrile neutropenia (13.5%), pain (9.5%), anemia, dyspnea, fever, thrombocytopenia and transaminitis (5.4% each). Conclusions Currently available systemic therapies are not specific for advanced ES, have a limited response durability and low tolerability. This is the largest US-based rw study that provides benchmarking treatment efficacy and safety data for development of standard of care therapies for ES. Table:1687P Real-world outcomes by line of therapy1L N = 742L+ N = 46rwORR (95% CI), %14.9 (7.7-25.0)9.4 (4.4-17.1)Median rwDOR (95% CI), wks14.5 (9.1-22.6)19.6 (3.1-24.3)rwDCR (95% CI), %20.3 (11.8-31.2)19.8 (12.4-29.2)Median rwPFS (95% CI), wks11.0 (7.3-29.9)26.0 (13.9-32.0)Median OS (95% CI), wks66.3 (49.6-94.1)43.3 (33.6-78.3) Legal entity responsible for the study Epizyme, Inc. Funding Epizyme, Inc. Disclosure M.M. Gounder: Advisory / Consult