Abstract No. 264 First-line Yttrium-90 Transarterial Radioembolization for Intrahepatic Cholangiocarcinoma

To assess the safety, efficacy, and outcomes of first-line resin based Yttrium-90 (Y90) radioembolization in intrahepatic cholangiocarcinoma (iCCA). Retrospective, institutional review board–approved study of 28 iCCA patients treated with resin based Y90 from 2015 to 2022 with single compartment MIRD model. Exclusion criteria were extra-hepatic disease, dosimetry using the BSA method, bilobar disease, vascular invasion, or ECOG ≥ 2. 24 patients (86%) received Y90 as first-line therapy, 3 (11%) were performed secondary to chemotherapy, and 1 (3%) after ablation. Primary outcomes were overall survival (OS) and progression-free survival (PFS). Secondary outcomes were adverse events in 3 months, local response at 3 and 6 months using RECIST 1.1, and downstaging to resection. Extensive necrosis was defined as >90% of nonviable tumor on pathology. Survival was analyzed using Kaplan-Meier curves and reported as median with 95% CI. Continuous variables are reported as median with interquartile range, and categorical variables as numbers with percentages. For 28 patients (median age 70 years 64-76), 16 males [57%), the median tumor size was 6.9 cm (4.6-8.7). 7 (25%) had multifocal tumor. Median prescribed dose was 180 Gy (125-200). Objective response rate and disease control rates were 42% and 92% at 3 months, and 58% and 89% at 6 months, respectively. Resection occurred in 10/24 (42%) first-line Y90 patients, compared to 0/4 when Y90 was performed secondary (p=0.11). Extensive necrosis was seen in 5/9 (56%). Median OS was 22 months (95% CI: 15 - NA) and median PFS was 6 months (95% CI: 4 - 18). PFS was 13 months (95% CI: 5 - NA) after first-line Y90 compared to 3 months (95% CI: 2 - NA) for subsequent Y90 (p=0.02). For patients treated with first-line Y90 alone (n=8) versus first-line Y90 plus chemotherapy (n=16), there was no difference in OS (18 months 4 - NA vs. 22 months 14 - NA, p = 0.96) or PFS (13 months 2 - NA vs. 6.3 months 5 - NA, p = 0.06). Self-limiting grade 3 clinical adverse events were seen in 7/28 patients (25%). No Grade 4 adverse events were seen. First-line Y90 for iCCA has better PFS compared to Y90 following chemotherapy. The OS and PFS were similar for first-line Y90 alone and first-line Y90 with chemotherapy.