Real-world use, dose intensity, and adherence to enfortumab vedotin (EV) in locally advanced or metastatic urothelial cancer (la/mUC).

Abstract

e16567 Background: EV, the first antibody drug conjugate approved for la/mUC, received accelerated approval in the US in 2019 as later-line therapy (post-immunotherapy and platinum-chemotherapy) and regular approval in 2021 with label expansion to include earlier-line therapy (cisplatin-ineligible, ≥1 prior therapy). Because EV delivery per current labelling (1.25 mg/kg, D1, 8, 15 of a 28D cycle) may differ from routine practice, we examined real-world EV use, dose intensity and adherence across 280 US cancer clinics. Methods: This descriptive post-marketing retrospective cohort study used the Flatiron Health longitudinal database derived from EHR records of US patients with la/mUC initiating EV on or after December 19, 2019. We summarized EV use, including but not limited to: % cisplatin-ineligible, and median duration of use and number of cycles administered. We computed metrics of dose intensity: average treatment rate (mean number of treatments per patient-month), dosing frequency (mean number of treatments per cycle), dose (mean dose, mg/kg), and % change in dose (mg) from baseline (difference in dose between last recorded treatment in last cycle and first recorded treatment in first cycle). Finally, we measured treatment adherence, defined as % of cycles across all patients where a patient had > 2 treatments per 28D cycle. Results: Among patients with la/mUC, we identified 416 EV users (mean [SD] age 71 [9] years, 27.4% female, 24.8% non-white, 70.2% prior smokers, 17.5% ECOG 2+, 81.5% from community sites). EV use, dose intensity, and adherence are shown (table). Most were cisplatin-ineligible (55%). Average dosing frequency (2.4 [0.5] treatments per cycle) and dose (1.1 [0.2] mg/kg) were lower than label indication guidelines; 58.8% received > 2 treatments per 28D cycle. Conclusions: Among la/mUC patients treated with EV in contemporary practice, treatment frequency and dosing were lower than recommended in the product labelling. Further research is required to understand clinical factors and outcomes associated with the differences observed. [Table: see text]