Real-world response rates and clinical outcomes of patients treated with first-line (1L) platinum-based chemotherapy (PBC) in advanced urothelial cancer (aUC).

Abstract

4567 Background: Standard of care has been established as 1L PBC followed by avelumab 1L maintenance (1LM) in eligible pts based on the JAVELIN Bladder 100 trial (NCT02603432) which showed that avelumab 1LM significantly prolonged overall and progression-free survival (OS, PFS) in pts with aUC with no disease progression after 1L PBC. Contemporary and robust real-world (rw) data are limited in pts treated with 1L PBC; however, because response status to PBC determines avelumab 1LM eligibility, it is critical to understand rwR rates. This study aimed to assess current rwR rates and rw outcomes in pts treated with 1L PBC. It also sought to understand avelumab 1LM eligibility and its early utilization since FDA approval on June 30, 2020. Methods: A non-interventional, retrospective cohort study of pts with aUC in the US was conducted using data from Flatiron Health’s electronic health record database. Pts were included if they were diagnosed with aUC between Jan 1, 2017, and Sep 30, 2021, received 1L PBC, did not have a progression event and had an observed rwR (complete response [rwCR]/partial response [rwPR]) or stable disease (rwSD) during 1L. Pt characteristics and rw outcomes were described based on response type (rwCR/PR, rwSD); rwPFS and rwOS were measured from time of 1L PBC initiation using the Kaplan-Meier method. Results: 1,245 pts with aUC received 1L PBC and had rwR data available during study period. Of these, 80% (n=998) may have been eligible to receive avelumab 1LM (rwCR/PR: 60%, rwSD: 20%). Key characteristics and outcomes by rwR are summarized. During the study period that occurred after FDA approval of avelumab 1LM, 435 pts discontinued 1L PBC, 78% (n=339) of these pts had observed rwCR/PR/SD during 1L PBC, and 29% (n=97) of maintenance eligible pts received avelumab 1LM. Follow-up time for avelumab 1LM treated pts was short (median 7.5 months from initiation of 1LM) and outcomes were immature at the end of the study period. Conclusions: In this rw study, a large proportion of pts with aUC treated with 1L PBC had rwR or rwSD (≈80%) and may have been eligible for avelumab 1LM, which is the standard of care supported by international guidelines. RwR rate appears slightly higher compared to historic data, and may reflect better general patient care, as shown in recent large phase 3 trials (NCT02853305, NCT02516241, NCT02807636). Early uptake of avelumab 1LM was observed, and future studies with longer follow-up may demonstrate increased utilization and allow assessment of potential impact on outcomes. [Table: see text]