76 - Outcomes of Transarterial Radioembolization as Salvage Liver-directed Therapy in Patients with Poor Response to First-line Bland or Chemoembolization for Neuroendocrine Liver Metastases

Purpose: To assess the safety and efficacy of salvage transarterial radioembolization (TARE) in patients with neuroendocrine liver metastases (NELM) who fail first-line liver-directed therapy (LDT) with bland transarterial embolization (TAE) or chemoembolization (TACE).

Materials and Methods: Retrospective review identified 18 patients (10 male, 8 female, median age 61y; range, 36-82) who failed treatment with TAE/TACE, defined as hepatic progression within < 12 months of treatment, and subsequently underwent TARE between 2011 and 2023. Demographic, clinical, treatment, and adverse event data were recorded and analyzed. Hepatic progression-free survival (hPFS) and overall survival (OS) were calculated by Kaplan-Meier analysis and compared using log-rank test.

Results: NET primary site was pancreas in 61% (n=11), small bowel in 11% (n=2), and other/unknown in 29% (n=5). Tumor grade was grade 1 in 6% (n=1), grade 2 in 78% (n=14), grade 3 in 6% (n=1), and unknown in 2 patients (10%). Ten patients (56%) had liver-dominant disease and eight (44%) had liver-only metastases. Three patients (16%) underwent TAE and 15 (84%) underwent TACE as first line LDT. The median number of TAE/TACE sessions was 2 (range: 1–4). Median hPFS after TAE/TACE was 4.2 months (95% CI 2.5-7.2 months). Mean interval time between radiologic progression after TAE/TACE and the first TARE session was 82 days (range, 27–281). A total of 31 TARE sessions were conducted, 27 (87%) of which were lobar, 3(10%) sub-lobar, and 1 (3%) segmental. The median total radiation dose delivered was 52.7 mCi (range: 26.1-87.4). Median hPFS after TARE was 13.8 months (95% CI 5.6-58.2 months) which was significantly longer compared to TACE (log-rank p < 0.001; HR 0.20, 95% CI 0.08–0.50, p < 0.001). The median OS after TARE was 17 months ( 95% CI 5.8-31.7 months). The most common adverse events were fatigue (14; 78%), nausea/vomiting (11; 61%), abdominal pain (9; 50%), and opiod-induced constipation (7; 39%), all of which were CTCAE Grade 2. Hepatic encephalopathy and radioembolization induced liver disease (REILD) occurred in one (6%) and two (11%) patients, respectively. There was one instance of radioembolization induced chronic hepatotoxicity (RECHT).

Conclusion: TARE is a safe and effective salvage treatment for treatment of NELMs in those with short-term progression after TAE/TACE, suggesting that patients who fail TAE/TACE should immediately be considered for TARE if LDT remains indicated.