Safety and Effectiveness of Yttrium-90 Radioembolization around the Time of Immune Checkpoint Inhibitors for Unresectable Hepatic Metastases.

Purpose: To assess the safety and effectiveness of yttrium-90 radioembolization and checkpoint inhibitor immunotherapy within a short interval for the treatment of unresectable hepatic metastases.

Materials And Methods: This single-institution retrospective study included 22 patients (12 men; median age, 65 y ± 11) with unresectable hepatic metastases and preserved functional status (Eastern Cooperative Oncology Group performance status 0/1) who received immunotherapy and radioembolization within a 15-month period (median, 63.5 d; interquartile range, 19.7-178.2 d) from February 2013 to March 2018. Primary malignancies were uveal melanoma (12 of 22; 54.5%), soft tissue sarcoma (3; 13.6%), cutaneous melanoma (3; 14%), and others (4; 18.2%). Studies were reviewed to March 2019 to assess Common Terminology Criteria for Adverse Events grade 3/4 toxicities, disease progression, and death.

Results: There were no grade 4 toxicities within 6 mo of radioembolization. Grade 3 hepatobiliary toxicities occurred in 3 patients (13.6%) within 6 months, 2 from rapid disease progression and 1 from a biliary stricture. Two patients (9.1%) experienced clinical toxicities, including grade 4 colitis at 6 months and hepatic abscess at 3 months. Median overall survival (OS) from first radioembolization was 20 mo (95% confidence interval [CI], 12.5-27.5 mo), and median OS from first immunotherapy was 23 months (95% CI, 15.9-30.1 mo). Within the uveal melanoma subgroup, the median OS from first radioembolization was 17.0 months (95% CI, 14.2-19.8 mo). Median time to progression was 7.8 months (95% CI, 3.3-12.2 mo), and median progression-free survival was 7.8 mo (95% CI, 3.1-12.4 mo).

Conclusions: Checkpoint immunotherapy around the time of radioembolization is safe, with a low incidence of toxicity independent of primary malignancy.