# Conversion therapy for advanced hepatocellular carcinoma following complete response to transarterial radioembolization combined with atezolizumab and bevacizumab

## TL;DR

This paper reports three cases where combining radioembolization with immunotherapy allowed advanced liver cancer patients to undergo surgery, even with low radiation doses.

## Contribution

Demonstrates a potential synergistic effect of combining radioembolization and immunotherapy for surgical conversion in advanced HCC.

## Key findings

- All three patients achieved complete pathological response and underwent surgical resection after combined treatment.
- Tumors received subtherapeutic radiation doses, suggesting a synergistic or abscopal effect.
- The combination therapy enabled conversion to surgery in patients with advanced HCC features.

## Abstract

The current Barcelona Clinic Liver Cancer (BCLC) classification recommends systemic treatment with atezolizumab and bevacizumab as the first-line therapy for advanced hepatocellular carcinoma (HCC). Recent studies suggest that combining systemic immunotherapy with locoregional treatments, such as transarterial radioembolization (TARE), may enhance immune responses and improve overall treatment outcomes. This article presents a case series of three patients with advanced hepatocellular carcinoma who were treated with transarterial radioembolization followed by atezolizumab and bevacizumab achieving conversion to surgical resection.

Between June 2020 and April 2024, three patients with advanced HCC were treated with TARE followed by atezolizumab and bevacizumab. The cohort included: Patient 1: A 59-year-old female, with noncirrhotic liver, with a 12 cm tumor and a 1.5 cm satellite lesion located in the liver, with hepatic vein and inferior vena cava (IVC) tumor thrombosis (Vv3 Japanese classification) and a small lung metastasis. Patient 2: A 63-year-old male with chronic hepatitis C (CHV), presenting with a 10 cm tumor and portal vein tumor thrombosis (Vp4 Japanese classification). Patient 3: A 50-year-old male, with non-cirrhotic liver, with a 17 cm tumor with portal vein and IVC tumor thrombosis (Vp3, Vv3 Japanese classification).

The combined treatment approach enabled surgical resection in all three patients, each achieving a complete pathological response. Interestingly, follow-up dosimetric analysis showed that all tumors had received a subtherapeutic absorbed radiation doses.

In selected patients, combining transarterial radioembolization with systemic immunotherapy may enable conversion to surgical resection in advanced hepatocellular carcinoma, even with subthreshold tumor radiation doses, highlighting a potential synergistic and abscopal effect between locoregional and systemic therapies.