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 [Basch E., JAMA 2017]. In parallel, the widespread use of electronic devices such as smart phones in the general population have increased significantly over recent years [Statista, 2023], 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, engagement and satisfaction of the Wave Health patient app and healthcare provider portal, enhanced for PC patients. Methods: 98 patients across 8 sites in Spain enrolled in the study, and 82 of those patients actively engaged with the Wave Health App over a 13-week period. Each week, patients completed validated ePRO questionnaires (generating 93.3% compliance) consisting of: a weekly symptom review (WSR), FACT-P and CHLT-30-Dkspa. A report summary of the patients’ WSR was generated for care team view in the Wave Health Connect platform – specifically to conduct weekly check ins on patients. Further, an optional in-app feedback survey was administered once patients completed the study to measure overall app satisfaction, information usefulness, reduction in anxiety, and effectiveness of communication with medical teams. Results: In addition to unusually high compliance and perceived usefulness, there was a particularly high response rate for an optional end of study survey (78%), whereby 64 patients who completed the feedback survey reported remarkable experiences, including: 90% reported being satisfied with the app to track their activities and keep their medical team informed; 95% of patients described the information provided by Wave Health as “useful"; 6 in 10 patients indicated that using Wave Health helped them feel less anxious about their treatment experience; 75% of patients reported that Wave Health helped them track their health and keep their medical team informed. Correspondingly, patients without a caregiver rated the platform higher than those with a caregiver across all areas (information useful/relevancy, communication with care team, likeliness to recommend and overall satisfaction). Additionally, 90% of HCPs positively perceived the platform’s impact on the quality of communication with patients. Conclusions: The high levels of patient compliance, satisfaction, perceived usefulness, and anxiety reduction associated with the app, along with the high HCP perceived usefulness of the portal, underscore the opportunity to enable better treatment management between HCPs and patients - particularly for those without caregivers. A larger study with a comparator arm will help further evaluate impact on costs and clinical outcomes.