Development of a radiofrequency ablation platform in a clinically relevant murine model of hepatocellular cancer

Interventional oncology and immunotherapy: current status and future perspectives

Interventional oncology has become an important part of multidisciplinary cancer treatment following the development of interventional radiology. Tumors can release antigens, activate immunity, and cause an abscopal effect after interventional therapy. However, the activated immune response is limited and involves a complex process. New methods to solve the problems were developed following the advent of immunotherapy. The combination therapies enhanced the antitumor immune response and improved patient outcomes with good application prospects. In this review, we have summarized the interventional therapies used to improve immune efficacy and discussed the advancements in combining interventional therapy and immunotherapy.

Suppression of the transforming growth factor-β signaling pathway produces a synergistic effect of combination therapy with programmed death receptor 1 blockade and radiofrequency ablation against hepatic carcinoma in mice

Primary liver cancer (PLC) significantly affects the health of patients globally owing to its high morbidity and low survival rate. Radiofrequency ablation (RFA) has recently been introduced for the clinical treatment of PLC. However, significant immunosuppressive effects are induced by RFA, which limits its application. This study aimed to explore the potential of combination therapy with RFA by investigating the effects of siRNAs against programmed death receptor 1 (PD-1) and transforming growth factor-β (TGF-β) on the antitumor effect induced by RFA. We observed that compared with si-NC, cell viability was reduced, apoptosis rate was elevated, release of inflammatory factors and percentage of CD3+CD8+ cells were increased, and the PI3K/AKT/mTOR pathway was repressed in the co-culture of RFA-treated H22 cells and CD8+ T cells by transfection with si-PD-1 and si-TGF-β; these effects were further enhanced by co-transfection with si-PD-1 and si-TGF-β. Additionally, in H22 cell xenograft-bearing mice treated with RFA, compared with the si-NC group, repressed tumor growth, prolonged survival, increased production of inflammatory factors and expression of CD3 and CD8 in tumor tissues, and downregulation of the PI3K/AKT/mTOR pathway were observed in the si-PD-1 and si-TGF-β groups; these effects were further enhanced in the si-PD-1 + si-TGF-β group. Taken together, our data revealed that suppression of the TGF-β signaling pathway produced a synergistic antitumor effect of combination therapy with PD-1 blockade and RFA against PLC. [Figure: see text].

Nanoliposome C6-Ceramide in combination with anti-CTLA4 antibody improves anti-tumor immunity in hepatocellular cancer

Combination therapy represents an effective therapeutic approach to overcome hepatocellular cancer (HCC) resistance to immune checkpoint blockade (ICB). Based upon previous work demonstrating that nanoliposome C6‐ceramide (LipC6) not only induces HCC apoptosis but also prevents HCC‐induced immune tolerance, we now investigate the potential of LipC6 in combination with ICB in HCC treatment. We generated orthotopic HCC‐bearing mice, which have typical features in common with human patients, and then treated them with LipC6 in combination with the antibodies (Abs) for programmed cell death protein 1 (PD‐1) or cytotoxic T‐lymphocyte antigen 4 (CTLA4). The tumor growth was monitored by magnetic resonance imaging (MRI) and the intrahepatic immune profiles were checked by flow cytometry in response to the treatments. Realtime PCR (qPCR) was used to detect the expression of target genes. The results show that LipC6 in combination with anti‐CTLA4 Ab, but not anti‐PD‐1 Ab, significantly slowed tumor growth, enhanced tumor‐infiltrating CD8⁺ T cells, and suppressed tumor‐resident CD4⁺CD25⁺FoxP3⁺ Tregs. Further molecular investigation indicates that the combinational treatment suppressed transcriptional factor Krüppel‐like Factor 2 (KLF2), forkhead box protein P3 (FoxP3), and CTLA4. Our studies suggest that LipC6 in combination with anti‐CTLA4 Ab represents a novel therapeutic approach with significant potential in activating anti‐HCC immune response and suppressing HCC growth.

Synergizing sunitinib and radiofrequency ablation to treat hepatocellular cancer by triggering the antitumor immune response

BACKGROUND

Minimally invasive radiofrequency ablation (RFA) is used as a first-line treatment option for hepatocellular cancer (HCC) with the weaknesses of incomplete ablation, tumor recurrence, and inferior outcomes. To overcome this limitation, we proposed to develop sunitinib-RFA integrated therapy with a potential of activating anti-HCC immune response.

METHODS

Using our unique murine model, we developed a novel RFA platform with a modified human cardiac RF generator. Therapeutic efficacy of sunitinib-RFA combined treatment in HCC was tested in this platform. Tumor progression was monitored by MRI; tumor necrosis and apoptosis were detected by H&E and terminal deoxynucleotidyl transferase dUTP nick end labeling; immune reaction was defined by flow cytometry; and signaling molecules were examined with real-time PCR (qPCR), western blot, and immunohistochemical staining.

RESULTS

A significantly reduced tumor growth and extended lift span were observed in the mice receiving combined treatment with RFA and sunitinib. This combined treatment significantly increased the frequency of CD8+ T cell, memory CD8+ T cell, and dendritic cells (DCs); decreased the frequency of regulatory T cells; and activated tumor-specific antigen (TSA) immune response in tumor microenvironment. We found that RFA caused PD-1 upregulation in tumor-infiltrated T cells by boosting hepatocyte growth factor (HGF) expression, which was suppressed by sunitinib treatment. We have also demonstrated that sunitinib suppressed VEGF's effect in enhancing PD-L1 expression in DCs and attenuated heat-sink effect. The results indicate that RFA induced tumor destruction and release of in situ TSAs which can activate a tumoricidal immune response in sunitinib-treated mice, significantly improving anti-HCC therapeutic efficacy.

CONCLUSIONS

Sunitinib enables RFA-released in situ TSA to ignite an effective anti-tumor immune response by suppressing HGF and VEGF signaling pathways. Sunitinib-RFA as a synergistic therapeutic approach significantly suppresses HCC growth.

A new compound Trichomicin exerts antitumor activity through STAT3 signaling inhibition

Trichomicin, a novel small-molecule compound isolated from the fungus Trichoderma harzianum and identified as new structure compound, exhibited antitumor activities in various human cancer cell lines and reversed drug resistance activity in the multidrug-resistant cancer cell line KBV. The underlying cellular and molecular mechanism was illuminated. Trichomicin can significantly induce cancer cell apoptosis and reduced IL-6 expression and phosphorylation of STAT3 were found in response to Trichomicin treatment. The blockade of IL-6 mediated JAK-STAT3 signaling pathway by Trichomicin was confirmed using reporter gene system. As a promising antitumor-activity compound, Trichomicin is presented in this study.

An Oncogenic Hepatocyte-Induced Orthotopic Mouse Model of Hepatocellular Cancer Arising in the Setting of Hepatic Inflammation and Fibrosis

The absence of a clinically relevant animal model addressing the typical immune characteristics of hepatocellular cancer (HCC) has significantly impeded elucidation of the underlying mechanisms and development of innovative immunotherapeutic strategies. To develop an ideal animal model recapitulating human HCC, immunocompetent male C57BL/6J mice first receive a carbon tetrachloride (CCl4) injection to induce liver fibrosis, then receive histologically-normal oncogenic hepatocytes from young male SV40 T antigen (TAg)-transgenic mice (MTD2) by intra-splenic (ISPL) inoculation. Androgen generated in recipient male mice at puberty initiates TAg expression under control of a liver-specific promoter. As a result, the transferred hepatocytes become cancer cells and form tumor masses in the setting of liver fibrosis/cirrhosis. This novel model mimics human HCC initiation and progression in the context of liver fibrosis/cirrhosis and reflects the most typical features of human HCC including immune dysfunction.

Disruption of oncogenic liver-intestine cadherin (CDH17) drives apoptotic pancreatic cancer death

Liver-intestine cadherin (CDH17) has been known to function as a tumor stimulator and diagnostic marker for almost two decades. However, its function in highly malignant pancreatic cancer (PC) has yet to be elucidated. Using different strategies including siRNA, shRNA, and CRISPR technology, we successfully induced knockdown and knockout of CDH17 in Panc02-H7 cells and established the corresponding stable cell lines. With these cells, we demonstrated that loss of CDH17 function not only suppressed Panc02-H7 cell growth in vitro but also significantly slowed orthotopic tumor growth in vivo, resulting in the significant life extension. In vitro studies demonstrated that impairing CDH17 inhibited cell proliferation, colony formation, and motility by mechanistically modulating pro- and anti-apoptosis events in PC cells, as CDH17 suppression obviously increased expression of Bad, cytochrome C, cleaved caspase 3, and cleaved PARP, and reduced expression of Bcl-2, Survivin, and pAkt. In vivo studies showed CDH17 knockout resulted in apoptotic PC tumor death through activating caspase-3 activity. Taken together, CDH17 functions as an oncogenic molecule critical to PC growth by regulating tumor apoptosis signaling pathways and CDH17 could be targeted to develop an anti-PC therapeutic approach.

Development of inCVAX, In situ Cancer Vaccine, and Its Immune Response in Mice with Hepatocellular Cancer

Manipulation of immune system toward the rejection of established cancers has become the standard of care in some patients. Here we propose the development of an in situ autologous cancer vaccine, inCVAX, for the treatment of hepatocellular cancer (HCC). inCVAX is based on the induction of local immunogenic cancer cell death combined with local dendritic cell stimulation by intratumoral injection of the immune-activator N-dihydro-galacto-chitosan (GC). In a first set of experiments, cellular and molecular studies were performed to investigate the effect of inCVAX on immune activation in a murine model of HCC that we previously developed. Once large tumors were formed in mice, the tumor is surgically exposed and a laser fiber was inserted into the center of an individual tumor mass. Using a 10 mm diffuser tip, laser irradiation of 1.5 W was applied to heat the tumor at different durations (6-10 min) to assess tolerability of photothermal application at different temperatures. The laser application was followed by immediate injection of GC, and each mouse received one laser treatment and one GC injection. ELISA was used to assess the level of cytokines; immunohistochemical staining was conducted to analyze the effect of inCVAX on immune cell tumor-filtration and expression of tumor-specific antigens (TSAs) and tumor-associated antigens (TAAs). Results indicate that survival correlated to thermal exposure. At lower temperatures the photothermal effect was sufficient to induce tumor necrosis, but without obvious complication to the mice, although at these temperatures the treatment didn’t alter the level of TSAs and TAAs, so further optimization is suggested. Nevertheless, in response to the inCVAX treatment, cytotoxic cytokine IFN-γ was significantly increased, but suppressive cytokine TGF-β was dramatically reduced. Furthermore, inCVAX prompted tumor infiltration of CD3⁺, CD4⁺, and CD8⁺ T cells; but modulated macrophage subsets differently. In conclusion, while the protocol needs further optimization, it would appear that inCVAX for the treatment of HCC activates an immune response in tumor-bearing mice, which in turn may have potential for the treatment of HCC.