Baseline characteristics from a retrospective, observational, US-based, multicenter, real-world (RW) study of avelumab first-line maintenance (1LM) in locally advanced/metastatic urothelial carcinoma (la/mUC) (PATRIOT-II).

Abstract

465 Background: The JAVELIN Bladder 100 clinical trial demonstrated a significant overall survival and progression-free survival benefit with avelumab 1LM + best supportive care (BSC) vs BSC alone for la/mUC not progressing on platinum-based chemotherapy (PBC). PATRIOT-II aims to describe RW data for avelumab 1LM treatment (tx) of patients (pts) with la/mUC. Methods: PATRIOT-II collected data from pts with la/mUC treated in 37 geographically dispersed oncology practices/communities and academic centers in the US. Pts who initiated avelumab 1LM following PBC were retrospectively enrolled and will be followed up via medical record review for 52 weeks post avelumab 1LM initiation. This analysis focused on pt characteristics and tx data from la/mUC diagnosis through the PBC period and at avelumab 1LM initiation. Disease and PBC tx characteristics, as well as response to PBC, were assessed. All analyses were descriptive. Results: A total of 160 pts were enrolled (Table), 118 (74%) were white, non-Hispanic, 16 (10%), were Black, Asian, or Hispanic, and the rest unknown; 102 (64%) were current or former smokers. 77 (48%) were tested for PD-L1 via various assays, with 44 (57%) of those tumor samples reported as positive. 1L PBC was cisplatin-based in 100 (63%) of pts and carboplatin-based in 60 (38%). Pts received a median of 4 PBC cycles (interquartile range [IQR], 3-6) for a median of 13 weeks (IQR, 10-17). 31 (19%) discontinued PBC due to unacceptable side effects/toxicity. Best observed response was complete response in 21 (13%), partial response in 109 (68%), and stable disease in 17 (11%), with the remainder unknown. Median time to first imaging was 10 weeks (IQR, 5-14) after PBC initiation. 23 (14%) were hospitalized while receiving PBC, and 25 (16%) were seen in the emergency department. Pts proceeded to avelumab 1LM at a median of 4 weeks (IQR, 3-6) following PBC completion. Avelumab was administered at 800 mg every 2 weeks in 130 (81%), 10 mg/kg in 15 (9%), <800 mg in 8 (5%), and >800 mg in 7 (4%) pts. Conclusions: This ‘RW’ study offers valuable insights into characteristics and outcomes of pts with la/mUC treated in the US. Baseline factors, tx patterns and response to PBC were consistent with usual therapy paradigms in the 1L induction setting. Ongoing trials are evaluating the optimal number of PBC cycles and predictive biomarkers. Limitations include the retrospective nature, lack of randomization and central review, potential selection and confounding biases. [Table: see text]