Abstract Financial toxicity has been associated with adverse outcomes for patients with cancer. Out-of-pocket (OOP) costs contribute to the high financial toxicity (FT) experienced by patients with cancer. Cancer clinical trial (CCT) participants face significant extra OOP expenses presenting a barrier to participation and retention. To address FT in CCTs, the Lazarex Foundation created the Improving Patient Access to Cancer Clinical Trials (IMPACT) Program, a financial reimbursement program (FRP) for OOP travel and lodging costs associated with therapeutic CCT participation. Our study aimed to quantify the FT experienced by patients in CCTs and understand their experience to determine the barriers and facilitators of enrolling in the Lazarex IMPACT Program. Patients enrolled in a CCT were referred to the IMPACT team to determine eligibility. Patients were eligible for IMPACT if they were active on a therapeutic CCT and their household income was less than 700% of the most recent HHS federal poverty guidelines. Patients who enrolled in the program were invited to participate in a brief semi-structured interview via telephone call. We used grounded theory techniques of analysis to identify themes of barriers and facilitators to enrollment in the Lazarex IMPACT program at our cancer center. Table 1 shows the emerging themes from the interviews as barriers and facilitators of enrolling in IMPACT. As a part of the interview process, patients also completed the COST-FACIT questionnaire, a patent reported outcomes measure to evaluate the degree of FT associated with cancer. COST scores in our cohort (n=39) ranged from 14-39.6, mean=27.12, median=27.5; SD=7.96. Following enrollment in the program, patients on average had COST scores indicating low degrees of financial distress. Taken altogether, our results have the potential to inform the development of FRPs for patients with cancer to facilitate their participation in CCTs. Table 1. Emerging themes from grounded analysis of semi-structured interviews and their frequency Barrier to enrolling in FRP program. No. of Participants Facilitator of enrolling in FRP program No. of Participants Patients wanted to be made aware of program earlier in their CCT timeline 4 Enrollment process was easy and straightforward 17 Patients made aware of program after their CCT started 3 IMPACT team contacted patients to offer program 13 CCT Team unaware of program availability 3 Patients learned about the program through their CCT team 8 Patients reported difficulty with technology access and literacy 3 Patients reported sufficient technology access and literacy 4 Patients reported hesitancy sharing financial information 2 Cancer foundation was timely and helpful in enrollment process 2 Patients reported difficulty navigating vast resources at cancer center 1 Cancer Center social workers provided connection to program 1 Citation Format: Elizabeth Ramos, Vivian Nguyen, Ashley Santaniello, Dana Dornsife, Robert G. Johnson, Paul E. Wileyto, Robert H. Vonderheide, Carmen E. Guerra. Addressing financial toxicity in cancer clinical trial participation: Barriers and facilitators of enrolling in a reimbursement program for out-of-pocket travel costs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4825.