According to Global Cancer Statistics 2022, primary liver cancer (PLC), which remains the third most lethal cancer among all malignant tumors, accounts for 7.8% of all cancer - related deaths, with hepatocellular carcinoma (HCC) making up 75 - 85% of PLC cases (1). Although traditional treatment methods such as hepatectomy, liver transplantation, transcatheter arterial chemoembolization (TACE), radiofrequency ablation (RFA) and microwave ablation (MWA) have been widely used, due to the high heterogeneity and immune escape mechanisms of HCC, a single treatment modality often fails to achieve a durable treatment effect. Moreover, it is important to recognize that the rate of local tumor progression in HCC remains high when relying on a single treatment modality such as surgery, ablation, or TACE. This underscores the necessity for a multimodal and personalized approach in HCC management to enhance patient outcomes and reduce the risk of tumor recurrence and progression (2, 3). TACE is primarily used for HCC cases that are considered inoperable or for patients who are not suitable candidates for surgical resection. Nevertheless, TACE alone often exhibits limited tumor necrosis and is prone to recurrence in residual lesions (4). The combination of TACE and ablation has demonstrated a synergistic effect, leading to more extensive tumor necrosis and improved survival rates compared to monotherapy (5–8). A retrospective study conducted at our institution demonstrated that the 5-year recurrence rate in patients treated with a combination of TACE and ablation was still as high as 80% (9). It is therefore necessary to optimize the current routine treatment of HCC and explore new treatment strategies.

As a novel tumor immunotherapy approach, oncolytic adenovirus H101 can specifically infect and kill tumor cells and simultaneously activate the host’s anti-tumor immune response. H101 induces the immunogenic death of tumor cells through virus replication and tumor cell lysis, thereby enhancing the body’s anti-tumor immune response (10, 11). Previous studies have shown that H101 has demonstrated good preclinical and clinical effects in the treatment of various solid tumors (12–14). In addition, H101 was approved for market release by the China National Medical Products Administration (NMPA) in 2005, some studies have further confirmed that H101 combined with TACE improves the prognosis of patients with HCC (15–17). However, there are currently no relevant literature reports on the treatment of transarterial embolization (TAE) combined with H101 in sequence with thermal ablation. Therefore, in this study, a retrospective analysis was conducted to evaluate the efficacy and safety of H101 combined with TAE in sequence with thermal ablation in the treatment of HCC. The primary endpoints examined in this analysis were the tumor recurrence, progression, and overall survival (OS) status of the patients.

TACE combined with ablation therapy has been reported in many studies to reduce the recurrence rate of patients and improve their prognosis (5, 7, 20). However, according to the early retrospective study reports from our center, the 5-year recurrence rate of TACE combined with ablation still remains as high as 80% (9). Although oncolytic viruses have been reported in many tumors, most of the reports are about the direct injection of H101 into the tumor body (13, 14, 21). In addition, there are very few reports on the efficacy of TACE combined with oncolytic viruses for HCC at present. Whether the chemotherapeutic drugs during hepatic artery embolization affect H101 remains to be further verified. In this study, TAE combined with H101 can avoid the influence of chemotherapeutic drugs on the efficacy of H101. In addition, research has confirmed that oncolytic viruses can enhance anti-tumor immunity and induce pyroptosis of vascular endothelial cells to inhibit tumor growth (12). Ablation therapy can also promote the release of tumor antigens and stimulate the immune response in the body (22). The sequential thermal ablation treatment of TAE combined with H101 is reported for the first time. This combined therapy offers a novel therapeutic strategy for the treatment of HCC.

Although more than 41.8% of patients in this study were non-treatment-naïve, the median 3-year OS for early and intermediate-stage HCC remained higher than those reported in the literature. According to the literature, the median survival time from recurrence to death for patients with HCC undergoing surgical resection is reported to be 21 months (23). Additionally, a study with a slightly larger sample size, involving 497 patients with recurrent HCC, developed a prognostic model to predict survival after recurrence (SAR), demonstrating a median SAR of 41.2 months (24). For patients classified as having intermediate-stage HCC according to the BCLC staging system, this study indicates that the 3-year OS rate is 70%, which similar to the results of our previous retrospective study (9). On one hand, it is believed that the combination of TAE and ablation can improve patient prognosis. On the other hand, in the study, only 4 out of 23 patients had AFP levels greater than 400 ng/ml. Elevated serum AFP levels are associated with poor prognosis in HCC patients (25). This also suggests that H101 may have a better effect on HCC patients who are AFP-negative. The favorable outcomes observed in patients with tumors ≤ 3 cm or AFP-negative status in this study are merely retrospective correlations, and a causal relationship has not been established. These outcomes may be related to confounding factors such as lower tumor burden and more indolent biological behavior in such patients, requiring further verification through prospective studies. Regrettably, the tumor progression rate in this study remains high, with 1-year PFS rates for HCC patients at 56.4%. This is consistent with the majority of literature reports and represents a challenge in the treatment of HCC (26). For example, Yun et al. reported that the cumulative 1-year recurrence rate of patients with early-stage HCC after TACE was 43.9%, while Wang et al. reported that the cumulative 1-, 3-, and 5-year recurrence rates of patients with early-stage HCC after TACE combined locoregional ablation were 26.0% (142/547), 57.8% (316/547), and 68.2% (373/547), respectively (27, 28). However, this does not mean that H101 is of no significance in the treatment of HCC. The reasons are analyzed as follows: First, in this study, nearly 41.8% of the patients had previously undergone surgical resection or multiple TACE or ablation treatments. In addition, 4 patients had undergone transjugular intrahepatic portosystemic shunt (TIPS) treatment due to gastrointestinal bleeding. Although most patients had Child-Pugh class A liver function, this was largely achieved through pharmacological intervention. These patients had undergone multiple treatments, suggesting that they might be at high risk for recurrence or progression. Second, the majority of patients exhibit good compliance; among the patients, 69.1% (38/55) have hepatitis B, which implies that these patients require long-term antiviral treatment and regular follow-ups to monitor viral load and liver function. Third, after ablation, patients are required to attend follow-ups at our hospital for three consecutive months, which allows for the early detection of any new lesions. For patients with BCLC stage B, the median PFS time in this study was 12.1 months. Zhang et al. reported that the median PFS time of patients after transarterial chemoembolization - microwave ablation (TACE-MWA) was also 10 months (29). However, all the patients included in their study were treatment-naive. In contrast, in this study, only 61% (14/23) of the patients with BCLC stage B were treatment-naive, while the remaining patients had received multiple previous local treatments, including surgery, ablation, and TACE. This indirectly indicates that for patients with BCLC stage B, the combination treatment of H101 with TAE and ablation is superior to TACE - MWA in therapeutic efficacy, but further research is needed to confirm this. Additionally, in the present study, all six patients (10.9%) with BCLC stage 0 disease presented with individual clinical factors precluding standard curative therapy: three exhibited severe cirrhosis, for whom the combined modality approach was selected to mitigate procedure-related hemorrhagic risk during ablation; and three had tumors critically abutting major vasculature or biliary structures at the hepatic hilum, where achieving an adequate ablative margin with stand-alone ablation was not feasible. In this cohort, we employed a sequential regimen of H101 combined with TAE followed by thermal ablation. This therapeutic strategy was designed to leverage the synergistic oncolytic, embolic, and ablative effects, thereby reducing procedural invasiveness while enhancing local tumor control.

The characteristics of cirrhosis are diffuse liver fibrosis and the replacement of normal liver structures with regenerated liver nodules, which have been proven to be positively correlated with liver cancer (30). The findings of this study consistently indicate that patients with cirrhosis have a 3.020 times higher risk of progression compared to those without cirrhosis. Moreover, tumor-related factors have been reported to be risk factors for recurrence after curative treatment in patients with early- stage HCC, such as tumor size, number of tumors, and pathological type (28). In this study, we found that the number of tumors and the maximum tumor diameter were risk factors for tumor progression. Furthermore, multivariate analysis showed that only the maximum tumor diameter was an independent prognostic factor for disease progression in HCC patients after H101 combined with TAE sequential thermal ablation. Our results suggest that HCC patients with a maximum tumor diameter of ≤ 3 cm are more likely to benefit from H101 combined with TAE sequential thermal ablation therapy.

In terms of safety, this study did not identify any serious adverse events (SAEs) caused by the injection of H101. The most common complication associated with H101 was fever that was consistent with the reports in the literature (14, 31). However, upon reviewing medical records, we found that such fever typically does not persist beyond 24 hours. Notably, this fever differs from that caused by TAE-induced post-embolization syndrome or infection secondary to tumor necrosis. The primary distinction lies in the timing of onset, as the latter usually occurs more than 24 hours after the procedure. However, strictly speaking, due to the lack of a control group in this study, and the fact that fever and abnormal transaminase levels can also occur after TAE, a randomized controlled study would be better able to distinguish between the two.

This study has several limitations. Firstly, it is a single-center, small-sample retrospective study, introduces multiple potential biases including selection bias, information bias, and confounding factors. Secondly, due to the lack of control group, it is difficult to distinguish whether the observed treatment effects result from H101, TAE, thermal ablation, or their synergistic combination. Therefore, the results of this study need to be further verified through prospective studies. Thirdly, this study included some non-treatment-naïve patients who had received other treatments before the start of the study, which made the interpretation of the research results more complex. Furthermore, univariate and multivariate analyses did not identify variables with a significant impact on OS, possibly due to the small sample size. Based on this, we are conducting a prospective randomized controlled trial (ChiCTR2300067319), using traditional TACE combined with ablation therapy as the control group, to investigate whether the combination of H101 and TAE sequential ablation therapy can reduce the recurrence of HCC and provide stronger treatment outcomes, thereby identifying the population that may respond effectively to H101 immunotherapy.

HI01 combined with TAE followed by sequential thermal ablation is safe and effective in the treatment of HCC. In observational analyses, this therapeutic approach is associated with more favorable outcomes in patients with a maximum tumor diameter of ≤ 3 cm, AFP, or in BCLC stage B. This approach provides a new local treatment option for HCC. However, due to the limited number of current studies, future research with larger sample sizes and higher levels of evidence is needed to confirm these findings.