e23190 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 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: Patients across eight sites in Spain engaged with the Wave Health App over a 13-week period. Each week, patients completed a validated weekly symptom review (WSR) assessing 16 Prostate cancer-specific symptoms, including severity and/or frequency of each; as well as a health-related QoL (FACT-P) and health literacy survey (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, including verifying patient completion; evaluating report content; indicating plans for follow up per patient; and rating their perceived value of the platform. Results: 98 patients were enrolled in the study – of which 82 actively participated in the study (84% acceptance). The compliance rate for the ePRO questionnaires was 93.3%, while during their participation, patients used the app for an average of 12.2 weeks, and approximately two-thirds (67.4%) used the app for all 13 weeks. Patient satisfaction with the platform was 93%, with 100% of respondents feeling the information provided in the app was relevant to their personal experience. Correspondingly, almost all HCPs (98%) rated the platform as useful – with the majority willing to recommend it to their peers and future patients; 90% of HCPs positively perceived the platform’s impact on the quality of communication with patients. 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.