Cure can be achieved by conversion to microwave ablation following atezolizumab-bevacizumab therapy in unresectable hepatocellular carcinoma

Abstract

Backgrounds/aims: Atezolizumab/bevacizumab is the recommended first-line systemic therapy for unresectable hepatocellular carcinoma (uHCC) and may facilitate curative conversion through resection and locoregional therapies. However, there have been very few reports on curative conversion using microwave ablation (MWA). This study aimed to determine the curative conversion rate with MWA using atezolizumab-bevacizumab as the first-line treatment in patients with uHCC, and to compare the characteristics and survival of patients with and without curative conversion.

Methods: Consecutive patients with uHCC who were started on atezolizumab-bevacizumab from May 2021 to December 2023 in a single tertiary center were included. Objective response rate (ORR) and disease control rate (DCR) were based on the Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 and modified RECIST (mRECIST) criteria.

Results: Twenty consecutive patients with uHCC (60% advanced-stage) were included, 90% exceeding the up-to-7 criteria. The ORR and DCR were 35% and 60%, 35% and 55% using RECIST and mRECIST, respectively. Five patients (25%) underwent successful curative conversion with MWA (four advanced and one intermediate stage) despite a median HCC size of 6.1 cm (range, 2.4-7.3). Two of these patients were tumor and drug-free 132-133 weeks from the 1st atezolizumab-bevacizumab dose. Patients who underwent curative conversion had significantly longer survival than those who did not (P=0.024). Other factors associated with survival were male sex, Child-Pugh class A, and an objective response.

Conclusions: Despite the relatively large tumor size, successful curative conversion with MWA was achieved with first-line atezolizumab-bevacizumab in uHCC. However, data from prospective multicenter trials are required to determine whether this strategy is universally applicable.

Keywords: Combination; Immune checkpoint inhibitors; Locoregional therapy; Microwave ablation; Tyrosine kinase inhibitors.

Figure 1.

Swimmer’s plot of selected baseline characteristics and outcomes of all patients. Progression refers to progressive disease while on atezolizumab-bevacizumab while recurrence means new HCC occurring after curative conversion. HCC, hepatocellular carcinoma; TACE, transarterial chemoembolization; NAFLD, nonalcoholic fatty liver disease; LEN, lenvatinib; PEM, pembrolizumab; BCLC, Barcelona Clinic Liver Cancer; MWA, microwave ablation; VT, venous thrombosis; Mets, extrahepatic metastasis; CPC, Child-Pugh classification.

Figure 2.

Selected cross-sectional imaging of patient 1. (A) Pre-treatment images showing a 13.6 cm HCC. (B) Partial response after TACE and atezolizumab-bevacizumab. (C) Complete response after curative conversion with MWA with good surrounding ablation zone. HCC, hepatocellular carcinoma; TACE, transarterial chemoembolization; MWA, microwave ablation.

Figure 3.

Selected cross-sectional imaging of patient 2. (A) Arterial phase CT showing a 10.5 cm HCC with satellite nodules. (B) Portal venous phase showing segmental thrombosis (black arrow). (C) Arterial phase MRI showing partial response after atezolizumabbevacizumab with (D) portal phase showing disappearance of the portal vein thrombosis. (E) Complete response after MWA curative conversion showing pre-existing hyperdensity due to ablation-induced hemorrhage in the plain film and (F) absence of enhancement in the arterial phase. CT, computed tomography; HCC, hepatocellular carcinoma; MRI, magnetic resonance imaging.

Figure 4.

Comparison of overall survival between HCC patients (A) with and without curative conversion with MWA, (B) with and without ORR (RECIST) at 12 weeks, and (C) with and without ORR (mRECIST) at 12 weeks. ORR, objective response rate; wk, weeks; RECIST, Response Evaluation Criteria In Solid Tumors; mRECIST, modified RECIST; SD, stable disease; PD, progressive disease; HCC, hepatocellular carcinoma; MWA, microwave ablation.