3010 - Concurrent Radiation and Immunotherapy for Unresectable Hepatocellular Carcinoma with Portal Vein Thrombus

N. Krishnamurthy¹, D. R. Cherry², C. Rodriguez-Russo¹, and M. Buckstein²; ¹Icahn School of Medicine at Mount Sinai, New York, NY, ²Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, NY

Purpose/Objective(s): While immunotherapy has been established as the standard of care for hepatocellular carcinoma (HCC) Barcelona Clinic for Liver Cancer (BCLC) class C patients, outcomes for patients with portal vein thrombus (PVT) remain poor. In IMBrave 150, median overall survival (OS) for Vp4 was only 7.6 months. This study evaluates the benefit of radiation therapy (RT) in addition to immunotherapy for patients with PVT. Materials/

Methods: A retrospective chart screen was performed to identify patients with HCC with PVT treated with definitive radiation therapy with concurrent (defined as within 6 weeks) immunotherapy. Patients were excluded if they received palliative radiation therapy. Kaplan Meier survival analysis was performed to assess progression free survival (PFS) and overall survival (OS). Cox proportional hazards modeling was employed for each covariate using R software version 4.3.3.
Results: Sixty-two patients met inclusion criteria from 2016 to 2023. Median follow up was 18.9 months. Median age was 64 years with 53 (85.8%) male and 9 (14.5%) female patients. 38 (61%) were Child-Turcott-Pugh (CTP) score A, 22 (36%) score B, and 2 (3%) score C. 29 (47%) were Vp3 and 28 (45%) were Vp4. 38 (61%) patients were treated with SBRT (median dose 4000 cGy) and 24 (39%) patients were treated with fractionated RT (median dose 4500 cGy in 15 fractions). 34 (55%) were treated with nivolumab, 15 (24%) atezolizumab-bevacizumab, 2 (3%) atezolizumab only, 1(2%) nivolumab and ipilimumab, 3 (5%) with durvalumab, and 7 (11%) with pembrolizumab. The median PFS for all patients was 3.70 months (range 0.2-66.7). The median OS was 7.70 months (0.7-67.4). There was no significant difference in PFS or OS for patients that received single-agent immunotherapy with radiation vs. multi-agent immunotherapy (atezolizumab-bevacizumab) with radiation. When selecting for only CTP score A patients (N=38), the median PFS was 5.3 months (0.2-66.7), and median OS was 10.2 months (0.7-67.4). Patients with a CTP score of A versus B/C had a significantly increased PFS (HR 2.1275, p=0.016) and OS (HR 3.078, p = 0.002). On multivariate analysis, prior or concurrent Y90, age, sex, ethnicity, non-alcoholic steatohepatitis, alcohol use, autoimmune hepatitis, any prior therapy, and VP class did not significantly affect PFS or OS.
Conclusion: The addition of radiation to immunotherapy appears to improve outcomes for advanced PVT patients with HCC. Particularly for patients with CTP A liver function that would be eligible for clinical trials, addition of radiation possibly improves OS beyond reported outcomes. This appears to be true even with single-agent immunotherapy. Prospective studies are needed to verify these results.