Transarterial injection of recombinant human type-5 adenovirus H101 in combination with transarterial chemoembolization (TACE) improves overall and progressive-free survival in unresectable hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide [1]. Less than 20 % of patients with HCC are eligible for potentially curative liver transplantation or surgical resection [2]. Worldwide, transhepatic arterial chemoembolization (TACE) is regarded as the best palliative treatment for unresectable HCC and has been shown to provide a clinical survival benefit [2], albeit with poor prognosis [3] suggesting that additional strategies are needed to improve patient prognosis.

Gene therapy, especially oncolytic viral therapy, is a promising treatment for liver tumors and is being increasingly used in the clinic with favorable results [4]. H101 is a recombinant human type-5 adenovirus (Ad5) in which the gene encoding the 55 kDa E1B protein responsible for p53-binding and inactivation has been deleted to confer p53-selective replication of oncolytic viruses inducing accumulation of p53 leading to direct and selective cytotoxicity in tumor cells during replication [5]. The H101 virus produced by Shanghai Sunway Biotech also contains a deletion of a 78.3–85.8 μm gene segment in the E3 region. The E3 region is responsible for the inhibition of host immunity, which enhances virus replication and spread in tumor cells [6].

Previous studies evaluating the safety of H101 as a direct injection [7] or transarterial infusion combined with TACE [8, 9], but the result were insufficient because of the small patient numbers (10,27,1), moreover, without a control group. While this large sample-sized study has enrolled 87 patients treated by H101 with a control group(n = 88), aimed to demonstrate the effect for unresectable HCCs. In the current study, treatment-related tumor response, overall survival(OS) and progression free survival (PFS) rates between H101 plus TACE and TACE alone were compared as the primary endpoints. The secondary endpoint included an assessment of treatment-related adverse events (AEs).

Patient demographics and clinical characteristics were similar between the groups and are shown in Table 1. From April 2012 to April 2013, 187 patients with unresectable HCC were treated with TACE plus H101 met the inclusion criteria (H101 group) (Additional file 1: Figure S1) . In the same period, 88 patients with unresectable HCC underwent conventional TACE alone met the inclusion criteria (control group).

Tumor response is shown in Table 2 significant difference was noted in tumor response between the two groups (Table 2). Furthermore, subgroup analysis according to treatment response showed that the number of each response type was significantly different between the groups (Table 2). In general, patients in the H101 group responded better to treatment compared with those who received TACE alone.

The majority of the patients (90.2 %) tested positive for hepatitis B virus (HBV) and some patients received anti-HBV agents that could potentially confound the beneficial effects of H101 as antiviral agents. To determine the effect of anti-HBV treatment on H101, patients were stratified by anti-HBV therapy administration. As shown in Table 2B, there was no significant difference in treatment response between the two subgroups.

Significant positive correlations have been reported between lipiodol accumulation observed on CT images and necrosis in resected tumors examined after TACE, and, therefore, intratumor lipiodol accumulation is regarded as an indicator of necrosis [14, 15]. The degree of lipiodol retention for all patients is presented in Table 3. There were significant differences in lipiodol accumulation between the two treatment groups (P = 0.002).

Blood samples for laboratory analysis were collected before and 1–2 days after TACE for each patient (Table 4). There were no significant differences in clinical parameters between the two groups with the exception of a significant increase in white blood cell count in the H101 group compared with the control group (P = 0.001). Post-treatment AEs are shown in Table 4 Fever was significantly higher in the H101 group compared with the control group (P = 0.023). No grade 4 clinical toxicity or procedure-related deaths (30 days) due to liver failure were experienced in either group. There were no major complications or grade 3–4 liver toxicities within the first post-treatment month. The overall frequency of treatment-emergent AEs was not significantly different between the groups (P = 0.263).

The median OS time during follow-up was 12.8 months (mean ± SD: 12.95 ± 8.36 months) in the H101 group and 11.6 months (mean ± SD: 12.87 ± 8.28 months) in the control group. 24 patients (27.6 %) in the H101 group and 41 (46.6 %) in the control group expired. The causes of death included liver disease progression (46/65, 70.8 %), upper gastrointestinal hemorrhage (7/65, 10.8 %), encephalopathy (7/65, 10.8 %), and peritonitis and pneumonia (6/65, 9.2 %). There were no treatment-related deaths. The cumulative OS rates at 1 and 2 years were significantly different and were 69 and 60 % in the H101 group, respectively, 60 and 44 % in the control group, respectively (P = 0.046, Fig. 1). Univariate analysis by Cox-regression revealed 6 prognostic factors affecting OS: Child-Pugh grade (grade A vs. grade B, P = 0.007), total bilirubin (<20 vs. ≥20 U/L, P = 0.003), BCLC(Barcelona Clinic Liver Cancer )stage (P = 0.001), tumor number (≤3 vs. >3, P < 0.001), tumor size (≤5 cm vs. >5 cm, P = 0.028), and H101 (P = 0.042). Multivariate analysis by cox-regression revealed that AFP (P = 0.004), CHILD PUGH grade (P = 0.018), BCLC stage(P = 0.002), Platelet count (PLT)(P = 0.011), the number of tumors (P = 0.018), tumor size(P = 0.010)and H101 (P = 0.048) were independent prognostic factors of OS.

After the first post-treatment review, all 175 patients were assigned as CR, PR, SD, or PD according to mRECIST criteria. In total, 142 patients in both groups (H101: 74; control: 68) were judged as CR, PR, or SD. During follow-up, progression free survival was observed in these 142 patients. The median time to progression for the H101 and control groups were significantly different at 10.49 and 9.72 months, respectively (P = 0.044, Fig. 2).

In univariate analysis by cox-regression, 3 prognostic factors affecting tumor progression were identified: tumor number (P = 0.002), tumor size (P = 0.041), and treatment modality (H101; P = 0.036; Table 5). Multivariate analysis identified 4 prognostic factors as independent predictors of progression: the number of tumors (P = 0.001), tumor size (P = 0.041), Child-Pugh grade (P = 0.050) and treatment modality (H101) (P = 0.017, Table 5).

The main purpose of this study was to compare the outcomes of patients with late stage HCC treated with two different methods of chemoembolization: a conventional method with commonly used protocols, and one using H101 virus. The data revealed that transcatheter therapy with H101 provided a significant tumor response and survival advantage over treatment with conventional chemoembolization (TACE alone) in patients with unresectable HCC.

H101 is an E1B-55 K-/E3B-deleted adenovirus [16], which has been used as an anticancer agent with the goal of restricting replication to p53-mutated neoplasm, sparing p53 wild-type human tissues. Preclinical studies have confirmed the anticancer activity of the H101 virus [17]. Clinical studies demonstrated the tolerability and anti-tumor efficacy of this agent as a monotherapy in patients with head and neck cancer [18, 19]. Different studies have compared the efficacy and safety of multiple routes of H101 administration in patients with HCC or liver tumors including hepatic arterial administration [20, 21],intravenous injection, and ultrasound-guided intratumoral injection [7, 22, 23]. Overall, H101 was safe when administered intratumorally, intraperitoneally, intraarterially, or intravenously at doses up to 3 × 10¹¹ pfu [8, 24].

In this study, a significant difference in response rate was noted between the H101 and control groups. Radiologically, tumor response as determined by mRECIST was shown as obvious volume shrinkage and large areas of necrosis in tumor. The response rate of the control group was similar to that reported in previous studies of our department [25]. In the H101 group, greater improvements were seen especially with regard to CR and PD which may suggest more complete necrosis in the tumor and less lost-control. The mechanism behind the increased efficacy of H101 is not clear but may suggested as follows: 1)H101 is a p53-mutated specific agent, and up to 30–50 % [26] HCCs were found mutated or lost of p53. 2) Pei et al. [27] showed that HCC cells expressed high levels of inhibitor of apoptosis proteins, and were resistant to tumor necrosis factor (TNF)-related apoptosis while E1B-55 K-deleted oncolytic adenovirus showed partial antitumoural efficacy in the BEL7404 xenograft tumour model. 3)H101 has synergistic effect while combined with chemotherapy, and the enhanced antitumor effect was demonstrated in Hep3B (p53-null) and HepG2 (p53-wt) in vitro and in vivo [28].

The OS and PFS rate was significantly different between the two treatment modalities, and results from cox-regression showed H101 were the independent prognostic factor for these late stage HCC patients. These results coordinate with the response advantage of H101, demonstrate the survival advantage for HCCs. However, as generally accepted, beside tumor burden, overall survival in unresectable HCCs is affected by multiple reasons. First, OS in patients with HCC is greatly affected by the degree of liver dysfunction, and patients with Child-Pugh B liver function usually have poor survival regardless of the treatment regimen [29]. In many cases, liver function did not reflect the tumor response and in some patients liver function actually worsened with tumor shrinkage. In this study, most patients had a liver function status graded as Child-Pugh A(88 %), 21 Child-Pugh B cases were nearly even in the two groups(10:11), the bias to overall survival was insignificant. Second, TACE was the initial treatment for these patients, most of whom received subsequent treatments including resection, ablation, repeated TACE, and systemic therapies, or best supportive care. As our previous prospective clinical trial demonstrated, subsequent treatments can influence OS, especially for patients with large and multiple HCC at diagnosis; surgical resection for patients who responded well to TACE significantly prolonged survival, when compared to those who refused surgery [30]. In this study, patients whose tumor was downstaged were offered radical treatment including 36 patients for surgical resection and 29 for local ablation, most of which was CR, PR and some of SD, but without PD patient. These subsequent treatments most likely improved OS, which would enhance the advantage of tumor response.

More than 80 % of patients with HCC in Asia are hepatitis B virus positive, and most are receiving anti-viral therapy [31]. This could confound the results of any evaluation of H101 because it is a recombinant adenovirus and anti-viral therapy has the potential to prevent H101 replication. However, to the best of our knowledge, this has not been previously investigated. The most employed anti-viral agents for hepatitis B in our patients were lamivudine (35.5 %), adefovir dipivoxil (14.7 %), and entecavir (42.3 %). There are no reported studies demonstrating any potential interaction of these agents with adenovirus. Moreover, stratification of our patient data to those receiving anti-viral therapy or not, did not reveal any significant effect of antiviral therapy on H101 efficacy in terms of tumor response or OS and PFS.

Other than efficacy, safety and adverse events are important aspects to consider in patients undergoing viral therapy. The first case of a patient dying as a result of gene therapy was reported in 1999 by Marshall [32]. The patient, a relatively fit 18-year-old male with an inherited enzyme deficiency, received a dose of 4 × 10¹³ pfu of a replication-deficient adenovirus expressing the ornithine transcarbamylase gene. Less than 24 h later, he experienced hyperammonemia, acute respiratory distress syndrome, disseminated intravascular coagulation, and suffered multiorgan system failure. He died 4 days later, which questioned the safety of adenovirus for gene therapy [33, 34]. However, subsequent studies have found no mortality associated with adenoviral vector therapy and any complications are usually mild and reversible [8, 35], suggesting that the case reported by Marshall et al., may be a sporadic case of accidental death. In this study, no patients died and all AEs were reversible. The complication rates between H101 group and TACE alone (control) group were similar. Child-Pugh class A and B patients did not experience any major complications after treatment with H101, but did experience liver failure after treatment, but there was no statistically significant difference in liver toxicity at 1–2 months between the treatment groups. Increases in liver enzymes and total bilirubin levels and decreases in serum albumin levels were mild and not significantly different between the treatment groups. However, frequent high fever (P = 0.023) and an increase in the white blood cell count (P = 0.001) were apparent in the H101 group, which might be explained by the immune activation. Previous studies have noted an increase in inflammatory cytokine generation and fever after hepatic arterial infusion of adenovirus [36]. Interestingly, Lu et al., [36] found that during H101 injection, the efficacy was significantly higher in those who had fever than that in those who did not, suggesting that virus infection may activate the host immune system and the elevated cell-mediated immunity may play a role in the tumor regression. In this study, subgroup analysis based on fever did not reveal any differences between fever and treatment efficacy (OS, P = 0.109; PFS, P = 0.221).

This study has several limitations including its retrospective nature. As a case-controlled study, the survival benefit demonstrated must be considered preliminary and further prospective, randomized-controlled, long-term studies are needed to confirm our results.

Transcatheter H101 therapy in combination with TACE for patients with unresectable HCC may provide a survival(OS and PFS) and tumor response advantage over treatment with conventional TACE alone.