Background: It is well established that the monitoring and evaluation of PROs in cancer patients has a positive impact in both quality of life and overall survival.¹ In parallel, the widespread use of electronic devices such as smart phones in the general population have increased significantly over recent years,² representing a unique opportunity to operationalize ePROs. However, there is uncertainty about the feasibility and applicability of these technologies in certain patient population such as prostate cancer (PC) patients. PRO-WAVE1 aims to determine the acceptability and engagement of the Wave Health patient app and healthcare provider portal, enhanced for PC patients. Specific endpoints include measuring longitudinal use of varying ePROs to impact care management, patient health literacy, and ability to identify and manage emerging risks. Methods: The study is underway across eight sites in Spain. Patient ePRO engagement is being evaluated through the administration of 19 ePRO questionnaires over the course of 13 weeks, including: health-related QoL (FACT-P); health literacy (CHLT-30-Dkspa); and weekly reviews of symptoms (WSR). Compliance rates per patient and per cohort will be reported at assessment time-points and for the entire study period. Secondary objectives evaluated include engagement with Wave Health App; changes in HRQoL; changes in health literacy; and the perceived value of the platform by patients and HCPs. Results: 98 patients were enrolled in the study. Patient cohort representation included: 44.9% mHSPC, 36.7% mCRPC, and 18.3% nmPC. Of the 98 patients, 84 successfully became active in the study and participated (85.7% acceptance). As of September 20, 2023, among the completed patients (N=46), the compliance rate for the ePRO questionnaires was 93.7%. During their participation, these patients used the app for an average of 12.2 weeks, and approximately two-thirds (67.4%) used the app for all 13 weeks. Weekly “usefulness” ratings among the HCPS averaged 3.6 (scale: 1 “not at all useful” to 5 “very useful”). Conclusions: Study results exceeded expectations for patient acceptability and engagement with the app; as well as perceived usefulness of the portal among HCPs – suggesting the platform as an impactful tool for patients working with HCPs to manage treatment journeys. A larger study using a comparator arm will help further evaluate the impact on costs and clinical outcomes. 1. Basch E., JAMA 2017. 2. Statista, 2023.