Safety and Efficacy of ¹⁶⁶Ho Radioembolization in Hepatocellular Carcinoma: The HEPAR Primary Study

The safety and efficacy of ¹⁶⁶Ho radioembolization was first determined in the HEPAR and HEPAR II studies, which, however, excluded patients with hepatocellular carcinoma (HCC). The aim of this prospective clinical early phase II study was to establish the toxicity profile of ¹⁶⁶Ho radioembolization in patients with measurable, liver-dominant HCC; Barcelona clinic liver cancer stage B or C; a Child–Pugh score of no more than B7; and an Eastern Cooperative Oncology Group performance status of 0–1 without curative treatment options. Methods: The primary endpoint was a rate of unacceptable toxicity defined as grade 3 hyperbilirubinemia (Common Terminology Cancer Adverse Events, version 4.03) in combination with a low albumin or ascites level in the absence of disease progression or treatment-related serious adverse events. Secondary endpoints included overall toxicity, response, survival, change in α-fetoprotein, and quality of life. Thirty-one patients with Barcelona clinic liver cancer stage B (71%) or C (29%) HCC were included, mostly multifocal (87%) or bilobar (55%) disease. Results: Common grade 1 or 2 clinical toxicity included fatigue (71%), back pain (55%), ascites (32%), dyspnea (23%), nausea (23%), and abdominal pain (23%), with no more than 10% grade 3–5 toxicity. Grade 3 laboratory toxicity (>10%) included an aspartate transaminase and g-glutamyltransferase increase (16%), hyperglycemia (19%), and lymphopenia (29%). Treatment-related unacceptable toxicity occurred in 3 of 31 patients. At 3 mo, 54% of target lesions showed a complete or partial response according to modified RECIST. Median overall survival was 14.9 mo (95% CI, 10.4–24.9 mo). No significant changes in quality of life or pain were observed. Conclusion: The safety of ¹⁶⁶Ho radioembolization was confirmed in HCC, with less than 10% unacceptable toxicity. Efficacy data support further evaluation.