Yttrium-90 Radioembolization for the Treatment of Solitary, Unresectable Hepatocellular Carcinoma: The LEGACY Study.

Locoregional therapies, including yttrium-90 (90 Y) radioembolization, play an important role in the treatment of unresectable hepatocellular carcinoma (HCC). The aim of the LEGACY study was to evaluate objective response rate (ORR) and duration of response (DoR) in patients with solitary unresectable HCC treated with 90 Y glass microspheres. LEGACY is a multi-center, single-arm, retrospective study conducted at 3 sites that included all eligible, consecutive HCC patients treated with radioembolization between 2014-2017. Eligibility criteria included: solitary HCC ≤8 cm, Child-Pugh A cirrhosis, and ECOG performance status 0-1. Primary endpoints were ORR and DoR based on mRECIST in the treated area (localized mRECIST) as evaluated by blinded, independent, central review (BICR). Radioembolization was performed with intent of ablative-level dosimetry in a selective fashion when possible. Overall survival (OS) was evaluated using Kaplan-Meier (KM) and multivariate Cox proportional hazards. Among the 162 patients included, 60.5% were ECOG 0; the median tumor size was 2.7 cm (range: 1-8) according to BICR. Radioembolization served as neoadjuvant therapy for transplantation or resection in 21.0% (34/162) and 6.8% (11/162) of patients, respectively, and as primary treatment for all others. Median follow-up time was 29.9 months by reverse KM. ORR (best response) was 88.3% (CI:82.4-92.4), with 62.2%(CI:54.1-69.8) exhibiting a DoR ≥6 months. Three-year OS was 86.6% for all patients and 92.8% for those neoadjuvant patients resected or transplanted. Conclusion: In this multi-center study of radioembolization, clinical meaningful response rates and prolonged DoR were observed in the treatment of unresectable, solitary HCC ≤8 cm.