Abstract RF1-05: Utilization of ePROs and smart pill bottles to improve adherence to adjuvant endocrine therapy in early-stage breast cancer

Abstract Background: Non-adherence to adjuvant endocrine therapy (ET) remains a significant clinical challenge. Technologies such as smart devices, electronic messaging, and telehealth offer new approaches to improving adherence. We hypothesized that more frequent monitoring with either electronic medical record (EMR) surveys to assess patient-reported outcomes (ePROs) or smart pill bottles would improve adjuvant ET adherence. Methods: In this phase II, multi-site within a single institution, randomized control investigator-initiated clinical trial, 285 patients receiving adjuvant ET within the first four years of an early stage breast cancer diagnosis were randomly assigned (1:1:1) to either A) standard of care monitoring (SOC) with visits every 3 months, B) SOC plus electronic surveys every 3 weeks, or C) SOC plus an interactive smart pill bottle to assess real-time adherence to ET for 12 months. Data indicating non-adherence, desire to stop ET, or severe toxicity triggered research staff follow-up and in-office or telehealth visits. The primary endpoint was ET adherence, defined as prescriptions filled to cover ≥80% of ET doses plus either self-reported ingesting ≥80% of doses (Arm A and B) or smart pill bottle dispense data (Arm C). 95 patients per arm provided 80% power to detect a difference between 65% adherence in the control arm and 85% adherence in each intervention arm with a significance level of 0.025. Secondary analyses included the effects of year of ET (year 1-4), age (≥50 vs <50 years old), baseline ET agent (aromatase inhibitors vs tamoxifen), and race (Black or African American vs White). Results: A total of 285 patients were randomized (96 to SOC, 94 to SOC + ePROs, and 95 to SOC + smart pill bottle). Features including age, ethnicity, stage, baseline ET agent, and year of ET were well-balanced between arms. 173 patients required additional follow-up beyond SOC monitoring, most commonly due to severe/very severe side effects (n=119). At 6 months, adherence on each arm was 70.8%, 61.7%, and 82.1% respectively; at 12 months, adherence was 53.1%, 45.7%, and 69.5%, statistically worse across all arms (OR 0.49; 95% CI 0.40-0.60, p<0.001). Compared to Arm A, the use of the smart pill bottle (Arm C) was associated with a significant improvement in adherence (OR 1.97; 95% CI 1.10-3.51, p=0.022), whereas the addition of ePRO monitoring (Arm B) resulted in a numerically worse but statistically insignificant decrease in adherence (OR 0.69; 95% CI 0.40-1.20, p=0.187). In secondary analysis, no difference in adherence was seen when stratified for year of ET (p=0.062), age (OR 1.29, CI 0.71-2.35, p=0.396), baseline ET agent (OR 1.39, CI 0.71-2.73, p=0.340), or race (OR 0.98, CI 0.57-1.71, p=0.952). Conclusion: The use of smart pill bottles nearly doubled the odds of adhering to adjuvant ET compared to standard of care monitoring, suggesting benefit from adoption of this novel technology. Citation Format: S. A. Manobianco, A. Lopez, D. P. Silver, A. P. Scarpaci, R. J. Jaslow, S. Bhattacharya, F. M. Fellin, P. Suresh, A. M. Zibelli, J. Rodriguez, K. C. Degen, S. A. Patel, A. R. MacKenzie, P. Anne, S. B. Rudoler, N. L. Simone, I. Chervoneva, M. Abu-Khalaf. Utilization of ePROs and smart pill bottles to improve adherence to adjuvant endocrine therapy in early-stage breast cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr RF1-05.