Abstract Introduction: Advances in technology and internet capability have provided an opportunity for efficient collection of Patient Reported Outcomes (PRO) during medical treatment. Here we describe the development and implementation of a system for monitoring patient reported adverse events (AEs) and quality of life (QoL) using electronic PRO (ePRO) instruments for patients enrolled on the Investigation of Serial studies to Predict Your Therapeutic Response with Imaging And moLecular analysis (I-SPY 2 TRIAL), a phase II adaptive platform clinical trial for locally advanced breast cancer. Methods: We designed an ePRO system to increase the accuracy of patient-reported QoL and AE data collection with the intent to act on symptoms in real time. Using the OpenClinica electronic data capture system, we developed rules-based logic to build automated ePRO surveys, customized to the I-SPY 2 treatment schedule. Weekly surveys contained a maximum of 126 validated, branching logic questions from the Patient Reported Outcomes Measurement Information System (PROMIS®) Health Measures and the National Cancer Institute’s Patient Reported Outcomes - Common Terminology Criteria for Adverse Events (PRO-CTCAE™) instruments. We piloted ePROs at the University of California, San Francisco (UCSF) to evaluate compatibility with a variety of I-SPY 2 patient scenarios (e.g., dose delays). We then staggered rollout of the ePRO system to 22 I-SPY 2 sites to ensure technological feasibility. In order to improve accuracy of data collection, we utilized real-time tracking and developed a Clinical Research Coordinator (CRC) training manual, which integrated workflow diagrams with technical solutions. CRCs were trained using remote video sessions. Results: The UCSF ePRO pilot began in September of 2020. Over 9-months, we accrued 43 I-SPY 2 patients (average age of 43.8 years), whose interactions with the ePRO system informed design improvements. Of the patients who received a baseline ePRO survey, the completion rate was 75.9% (average age of 44.2 years). This represents an increase from the 15-20% baseline completion rate for the 360 UCSF I-SPY 2 patients who received paper-based PRO surveys between May 2012 - January 2019. As of June 2021, the ePRO system was operational at all 22 I-SPY 2 sites. The UCSF pilot revealed that engagement with patients at critical timepoints improved survey completion. CRCs facilitated patient participation by sending instructional emails and communicating with patients weekly. We tracked data completeness using a Patient Tracking report, which displayed each patient’s survey completion history. This real-time tool enabled CRCs to identify patients who had not completed ePRO surveys prior to their visit, so they could be provided a tablet computer to complete the survey in the clinic. After introducing tablets into the workflow at UCSF, patient completion of the baseline survey increased from 75.9% to 80%. Conclusion: The transition from paper to electronic QOL and AE data collection improves the ability of patients to complete PRO surveys, but the process must also be optimized and integrated into clinical workflow and trial conduct. In the future, we will present additional results highlighting the feasibility of multilingual ePRO integration into I-SPY 2. ePRO also provides a new opportunity for data analysis, as well as the potential to reduce high grade toxicity through early intervention. It will allow us to assess QoL and AE data by drug regimen, site, provider, and study treatment. The creation of clinician-facing reports also enables access to patient responses in real-time. By implementing ePRO within I-SPY 2, we not only increase efficiency and accuracy of patient-reported data collection, but also improve quality of care and patient safety. Citation Format: Anna Northrop, Anika Christofferson, Michelle Melisko, Laura Sit, Ebunoluwa Olunuga, Ananya Mittal, Adi Goldman, Thelma Brown, Diane Heditsian, Bev Parker, Susie Brain, Carol Simmons, Alessandra Taboada, Kathryn J Ruddy, Tina Hieken, Mara Piltin, Kiri Cook, Carolina Salvador, Candace Mainor, Anosheh Afghahi, Sarah Tevis, Anne Blaes, Irene Kang, Susan Melin, Laura Esserman, Adam Asare, Dawn L Hershman, Amrita Basu. Improving patient-reported outcome data capture for clinical research: ePRO in ISPY 2, a phase 2 breast cancer study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-12-02.