Abstract C064: Feasibility of an interventional clinical trial addressing prostate cancer disparities in Black men by decentralization (DCT): A potential solution to disparities in clinical trial participation

Abstract Introduction: This ongoing study investigates the impact of vitamin D deficiency on the immune response to prostate cancer (CaP) in Black patients and its potential contribution to CaP disparities. The study also evaluates differences in immune function, including p53 and CaP associated antibody levels, in Black men with localized versus metastatic CaP. Methodology: Eligible patients with a history of localized or metastatic CaP are enrolled following informed consent (in person or remote). At baseline, blood is collected for calcium and vitamin D3 levels, and for immune testing. Patients who participate in the screening portion of the trial and are found to have vitamin D3 levels <30 ng/mL are prescribed oral vitamin D3 (2000 IU daily) and asked to record adherence in a medication diary. Follow-up includes a 4-week check-in and end-of-treatment labs at 8 weeks for calcium, vitamin D3 levels, and immune re-testing. Virtual consults occur after baseline and at 8 weeks. Quality of life is measured at baseline and EOT follow-up using the CDC HRQOL–4. The study began accruing patients in December 2021. In an attempt to accelerate patient accrual, the protocol was amended to become one of Mayo Clinic’s first fully decentralized clinical trials. Newly integrated components included at-home and community-based blood collection (outside of Mayo Clinic southern sites) and continued virtual engagement. These changes were designed to reduce barriers linked to social determinants of health (SDOH) and expand participation among medically underserved populations. This is a report on the impact of clinical trial DCT. Results: From December 2021 to September 2023 (pre-DCT), 24 patients were enrolled from 66 patients who participated in the screening portion for the trial (mean accrual: 1.09/month; SD: 1.15). Following the DCT amendment, enrollment rose to 102 patients from 213 screened (mean: 4.86/month; SD: 3.12) through June 2025. Of 126 enrolled patients, 119 (94.4%) returned medication diaries, with only 6 non-returns occurring post-DCT. QOL measures were completed by approximately 75% of participants. Importantly, 90 of 126 participants (71%) were enrolled from outside Jacksonville, FL or Scottsdale/Phoenix, AZ, indicating successful national expansion. A total of 111 patients failed the screening due to baseline vitamin D levels >30 ng/ml. The total number of protocol deviations increased post-DCT (60 from 10/23–6/25 vs. 14 from 12/21–9/23), there was no change in the number of protocol deviations per enrolled patients. Minor documentation and study timeline deviations were the most common in both periods. Conclusions: The successful implementation of a fully decentralized model was associated with a marked increase in the accrual of underserved patients and allows the completion of critical clinical trials that address important cancer care disparities without impacting protocol integrity. Clinical trial DCT can potentially reduce SDOH-related barriers and improve representation of underserved populations in research. Citation Format: Sandra Casanova Leyva, Kim M. Barbel Johnson, Tufia Haddad, Lydia Mercado, Trevanne Matthews Hew, Cassandra Moore, Gerardo Colon-Otero, Devina Joshi, Roselyn Heduvor. Feasibility of an interventional clinical trial addressing prostate cancer disparities in Black men by decentralization (DCT): A potential solution to disparities in clinical trial participation [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr C064.