Change in financial toxicity during early-phase cancer clinical trial (EP-CT) participation.

11119 Background: The high costs of care (financial toxicity) represent a pressing concern in oncology. Little is known about the financial toxicity experienced by EP-CT participants. We sought to describe changes in financial toxicity during EP-CTs and assess associations of change in toxicity with patient characteristics, additional patient-reported outcomes (PROs), and trial reimbursement structure. Methods: We prospectively enrolled adults participating in EP-CTs from 4/2021 – 1/2023. We administered surveys at baseline (between enrollment and Day 1 of trial) and monthly during trial participation. We assessed financial toxicity using the COST tool, graded as low (≥26) and high (0–25) toxicity. We also surveyed baseline hope (Hope Herth Index), quality of life (QOL; FACT-G) and symptom burden (psychological: PHQ-4; physical: ESAS). We calculated within-patient changes in COST score and conducted linear mixed models, controlling for baseline COST score, to determine associations of change in financial toxicity with patient characteristics, baseline PROs, and trial reimbursement structure (using a factor x time interaction term). Results: Of 221 eligible patients, we enrolled 205 (median age = 63. 3 years range 32. 8-88. 6, 57. 1% female). Most common tumors were GI (34. 6%) and breast (20. 0%). At trial start, 35. 0% of patients reported high financial toxicity, 40. 5% at 1 month, 33. 6% at 2 months, 25. 5% at 6 months, and 40. 0% at 1 year. Within-patient COST score worsened over time (B=-0. 20, p=0. 059), although this change did not reach significance. We found no patient characteristics that significantly correlated with change in COST score, including age (B=-0. 005, p=0. 602), sex (B=-0. 097, p=0. 667), GI cancer (B=-0. 11, p=0. 118), annual income >60, 000 (B=-0. 10, p=0. 306), and current employment (B=-0. 34, p=0. 121). Higher baseline QOL was associated with increased COST score (financial wellbeing, while on trial (B=0. 012, p=0. 011) ; there was no significant association with other baseline PROs. Most patients (64. 4%) enrolled on trials that offered reimbursement for study costs. Of those offering reimbursement, 40. 1% had all research-specific costs reimbursed. There was no significant association between change in COST score and presence of any reimbursement (B=0. 12, p=0. 614) or presence of full reimbursement (B=-0. 072, p=0. 784). Conclusions: In this cohort of EP-CT participants, over one-third reported high rates of financial toxicity, which appeared relatively stable over time on trial. We did not identify any demographic factors associated with risk of worsening toxicity but did find that high baseline QOL may be protective. Trial reimbursement did not lead to improvement in financial wellbeing. Findings demonstrate that EP-CT participation may not place excess financial burden on at-risk patients and highlight the need to monitor for financial toxicity across all trial participants.