PS5-09-26: Digital health adherence companion study for tetrathiomolybdate (TM) plus capecitabine in triple-negative breast cancer

Abstract Background: Copper depletion therapy with oral tetrathiomolybdate (TM) is designed to complement standard adjuvant therapy for high risk for relapse triple negative breast cancer (TNBC) by overcoming TNBC resistance mechanisms. The dosing of TM requires an induction and maintenance phase with subsequent monitoring of ceruloplasmin and absolute neutrophil counts (ANC). Several studies have reported on adherence rates for oral anticancer medications, with prior breast cancer trials having adherence rates of 78% across all cycles. Diaries and paper logs are subject to manipulation and errors for medications where dosing schedules are frequently modified, while microelectric event monitoring systems are not feasible in real-word practice beyond clinical trials. This trial in progress aims to evaluate whether a digital mobile application can improve adherence to TM for patients with high risk for relapse TNBC. Methods: The mobile application (TM Dosing Logger) is being evaluated as part of an open-label, non-randomized, dose escalation (phase 1b) and randomized phase 2 study in patients with high risk for relapse TNBC after completion of neoadjuvant chemo-immunotherapy and surgery. Patients will receive TM with capecitabine and pembrolizumab in 20 mg capsule increments, with daily doses up to 180 mg during the induction phase (first 6 months) and 100 mg during the maintenance phase (subsequent 30 months) in 28-day cycles. Doses are divided into capsules taken between one and three times daily. The mobile app will be offered to all patients taking TM utilizing an opt out function. Patients without a smartphone or tablet will receive paper logs. The mobile app contains three parts: a study calendar to view a real-time dosing schedule, surveys to log each dose taken, and reminder notifications to improve adherence. The dosing schedule is adjusted remotely in REDCap based on patient-specific ceruloplasmin levels and ANC and syncs with the mobile app. Real-time dose adjustments can also be made. Study participants may select notification times that match when they plan to take each dose, and study coordinators will be notified if a patient misses three consecutive doses. Surveys are locked after each calendar day to prevent data manipulation or incorrect data entry. Mobile app patient enrollment began in December 2024 as part of the Phase 1b study. Usability of the mobile app for daily use and patient satisfaction will be assessed with the mHealth App Usability Questionnaire at two and four weeks after study start date. Adherence will be measured as number of doses logged within 24 hours of scheduled time for each cycle and across entire three-year study period. Adherence rates will be compared with patients using paper logs and prior reported data using linear mixed models. A multivariate regression analysis will be used to evaluate predictors of adherence. Clinical Trial Information: NCT06134375 Citation Format: A. Suresh, N. Kornhauser, R. M. Lavoie, L. J. Sinks, C. A. Seymour, M. V. Cobham, A. E. Gaughan-Maher, N. Chan, L. T. Vahdat. Digital health adherence companion study for tetrathiomolybdate (TM) plus capecitabine in triple-negative 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 PS5-09-26.