Quantitative MRI for Assessment of Treatment Outcomes in a Rabbit VX2 Hepatic Tumor Model

Advances in experimental animal models of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor with insidious early symptoms, easy metastasis, postoperative recurrence, poor drug efficacy, and a high drug resistance rate when surgery is missed, leading to a low 5-year survival rate. Research on the pathogenesis and drugs is particularly important for clinical treatment. Animal models are crucial for basic research, which is conducive to studying pathogenesis and drug screening more conveniently and effectively. An appropriate animal model can better reflect disease occurrence and development, and the process of anti-tumor immune response in the human body. This review summarizes the classification, characteristics, and advances in experimental animal models of HCC to provide a reference for researchers on model selection.

Multifunctional nanoplatforms application in the transcatheter chemoembolization against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has the sixth-highest new incidence and fourth-highest mortality worldwide. Transarterial chemoembolization (TACE) is one of the primary treatment strategies for unresectable HCC. However, the therapeutic effect is still unsatisfactory due to the insufficient distribution of antineoplastic drugs in tumor tissues and the worsened post-embolization tumor microenvironment (TME, e.g., hypoxia and reduced pH). Recently, using nanomaterials as a drug delivery platform for TACE therapy of HCC has been a research hotspot. With the development of nanotechnology, multifunctional nanoplatforms have been developed to embolize the tumor vasculature, creating conditions for improving the distribution and bioavailability of drugs in tumor tissues. Currently, the researchers are focusing on functionalizing nanomaterials to achieve high drug loading efficacy, thorough vascular embolization, tumor targeting, controlled sustained release of drugs, and real-time imaging in the TACE process to facilitate precise embolization and enable therapeutic procedures follow-up imaging of tumor lesions. Herein, we summarized the recent advances and applications of functionalized nanomaterials based on TACE against HCC, believing that developing these functionalized nanoplatforms may be a promising approach for improving the TACE therapeutic effect of HCC.

Experimental study of camptothecin combined with drug-eluting bead transarterial chemoembolization in the rabbit VX2 liver tumor model

Drug-eluting bead transarterial chemoembolization (DEB-TACE) has been widely used in the treatment of liver cancer; however, the utilization rate of chemotherapeutic drugs after embolization is low. Chemotherapy resistance mediated by high nuclear factor E2-related factor 2 (NRF2) expression limits DEB-TACE efficacy. Camptothecin (CPT), an NRF2 inhibitor, exerts chemosensitizing effects. We designed a controlled experiment to determine the efficacy and feasibility of DEB-TACE combined with CPT for the treatment of rabbit VX2 hepatoma. DEB-TACE activated NRF2 expression in the tumor region. NRF2 activation could be inhibited by the combined use of CPT. After DEB-TACE alone, the tumor necrosis was incomplete, there were still highly active tumor residues, and the apparent diffusion coefficient (ADC) value, which was negatively correlated with tumor activity observed by magnetic resonance imaging, remained low. After DEB-TACE combined with CPT, the relative necrosis of the tumor was more complete, the ADC value was higher, and the ADC change was greater. The single application of CPT did not result in evident liver function and physical burden to the rabbits. The combined use of CPT and DEB-TACE did not significantly increase DEB-TACE imaging of liver function and body. In conclusion, CPT can also inhibit high NRF2 expression after DEB-TACE treatment. Combining CPT with DEB-TACE can improve the sensitivity of DEB-TACE in the treatment of VX2 tumors, improve the therapeutic effect, and has no evident toxic and side effects. This study explored the methods for enhancing the efficacy of DEB-TACE in liver cancer from a new perspective and performed model experiments, which provided a theoretical basis for future clinical treatment.

Imaging Diagnosis of Primary Liver Cancer Using Magnetic Resonance Dilated Weighted Imaging and the Treatment Effect of Sorafenib

Objective

This work explores the application value of dilated weighted imaging (DWI) in the diagnosis of primary liver cancer (PLC) and the effect of sorafenib in the treatment of PLC.

Methods

88 patients with PLC who were treated in The First Affiliated Hospital of Northwest University from March 2019 to March 2021 were selected and randomly rolled into an experimental group and a control group, with 44 cases in each group. Patients in both groups were treated with transcatheter arterial chemoembolization (TACE), and the patients in the experimental group were treated with oral sorafenib on the basis of TACE. The indicators of complications, short-term efficacy (STE), and long-term efficacy (LTE) of the two groups were observed. All patients received DWI and magnetic resonance (MR) plain scan. The diagnostic accuracy and misdiagnosis rate of the two methods in diagnosing the PLC were compared.

Results

The accuracy, specificity, and sensitivity of MR plain scan were 68%, 88%, and 89%, respectively, while those of DWI were 96%, 95%, and 94.2%, respectively. It indicated that the accuracy, specificity, and sensitivity of DWI in diagnosing lesions were better than those of MR plain scan, especially the diagnostic accuracy (P < 0.05). The objective response rate (ORR) and disease control rate (DCR) of the STE in the experimental group were 30% and 97%, respectively, and those in the control group were 6% and 54.5%, respectively. The experimental group's mean progression-free survival (mPFS) and mean overall survival (mOS) were 12 and 25 months, respectively, while the control group's were 8 and 19 months, respectively. It was concluded that the mPFS and mOS of patients receiving TACE combined with oral sorafenib were much higher than those receiving TACE only (P < 0.05).

Conclusion

DWI and TACE combined with sorafenib had high application value in the diagnosis and treatment of PLC.

Rabbit VX2 Liver Tumor Model: A Review of Clinical, Biology, Histology, and Tumor Microenvironment Characteristics

The rabbit VX2 is a large animal model of cancer used for decades by interventional radiologists to demonstrate the efficacy of various locoregional treatments against liver tumors. What do we know about this tumor in the new era of targeted therapy and immune-oncology? The present paper describes the current knowledge on the clinics, biology, histopathology, and tumor microenvironment of VX2 based on a literature review of 741 publications in the liver and in other organs. It reveals the resemblance with human cancer (anatomy, vascularity, angiogenic profile, drug sensitivity, immune microenvironment), the differences (etiology, growth rate, histology), and the questions still poorly explored (serum and tissue biomarkers, genomic alterations, immune checkpoint inhibitors efficacy).

Oxygen-Challenge Blood Oxygen Level-Dependent Magnetic Resonance Imaging for Evaluation of Early Change of Hepatocellular Carcinoma to Chemoembolization: A Feasibility Study

RATIONALE AND OBJECTIVES

To investigate the feasibility of oxygen-challenge blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) at 3T for evaluating the early change of blood oxygenation before and after transcatheter arterial embolization (TACE) in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Thirty HCC patients with cirrhosis (HCC group, n = 30) and 30 healthy volunteers (control group, n = 30) were included in this study. Patients in the HCC group underwent BOLD before and 1 month after TACE. Oxygen was administered via a mask. Differences between pre- and post-O₂ T₂* values were evaluated using a pairwise t-test. Analysis of variance was performed to assess the statistical differences in the T₂* values measured in HCC group pre-TACE and post-TACE and in healthy volunteers.

RESULTS

In the HCC group, the pre- and post-O₂ T₂* values of the cancerous area before TACE were 26.03 ± 3.30 and 26.84 ± 3.42 msec, respectively, and both decreased significantly to 8.67 ± 1.76 and 8.82 ± 1.80 msec, respectively, at 1 month after TACE (p < 0.001). The respective pre- and post-O₂ T₂* values of the noncancerous area increased significantly from 14.96 ± 2.32 and 15.33 ± 2.28 msec at baseline to 16.38 ± 2.22 and 16.89 ± 2.24 msec at 1 month after TACE (p < 0.001). No significant response to BOLD was observed in the control group (p = 0.059).

CONCLUSION

Oxygen-challenge BOLD MRI is feasible to assess post-TACE changes in HCC patients.

Native T1 Mapping Magnetic Resonance Imaging as a Quantitative Biomarker for Characterization of the Extracellular Matrix in a Rabbit Hepatic Cancer Model

To characterize the tumor extracellular matrix (ECM) using native T1 mapping magnetic resonance imaging (MRI) in an experimental hepatic cancer model, a total of 27 female New Zealand white rabbits with hepatic VX2 tumors were examined by MRI at different time points following tumor implantation (day 14, 21, 28). A steady-state precession readout single-shot MOLLI sequence was acquired in a 3 T MRI scanner in prone position using a head-neck coil. The tumors were segmented into a central, marginal, and peritumoral region in anatomical images and color-coded T1 maps. In histopathological sections, stained with H&E and Picrosirius red, the regions corresponded to central tumor necrosis and accumulation of viable cells with fibrosis in the tumor periphery. Another region of interest (ROI) was placed in healthy liver tissue. T1 times were correlated with quantitative data of collagen area staining. A two-way repeated-measures ANOVA was used to compare cohorts and tumor regions. Hepatic tumors were successfully induced in all rabbits. T1 mapping demonstrated significant differences between the different tumor regions (F(1.43,34.26) = 106.93, p < 0.001) without interaction effects between time points and regions (F(2.86,34.26) = 0.74, p = 0.53). In vivo T1 times significantly correlated with ex vivo collagen stains (area %), (center: r = 0.78, p < 0.001; margin: r = 0.84, p < 0.001; peritumoral: r = 0.73, p < 0.001). Post hoc tests using Sidak’s correction revealed significant differences in T1 times between all three regions (p < 0.001). Native T1 mapping is feasible and allows the differentiation of tumor regions based on ECM composition in a longitudinal tumor study in an experimental small animal model, making it a potential quantitative biomarker of ECM remodeling and a promising technique for future treatment studies.

Treatment for Liver Tumor Using Combined Transarterial Embolization and Interaarterial Transfecting HIF-1α shRNA in a Rabbit VX2 Model

Background

Hypoxia-inducible factor-1α (HIF-1α) has been selected as therapeutic gene in gene therapy. The aim of this study was to explore the treatment effect of combined transarterial embolization using microsphere treatment (MD) and intraarterial transfecting HIF-1α shRNA on hepatocellular carcinoma (HCC).

Materials and Methods

Rabbit skin fibroblast was transfected with HIF-1α shRNA to evaluate the knocking down efficiency. Sixteen rabbit VX2 liver tumor models were randomly divided into four groups: the control group without any treatment, the MD group, the shRNA group (HIF-1α shRNA transfection by transcatheter intraarterial infusion), and the shRNA+MD group. The necrotic score, mitotic count and expression of HIF-1α, vascular endothelial growth factor (VEGF), CD34 and periodic acid-Schiff (PAS) stain were evaluated at the 14th and 28th day after treatment. The expression of HIF-1α and VEGF of VX2 tumors was also evaluated by real-time polymerase chain reaction on the 28th day.

Results

The expression of HIF-1α-mRNA was lower in HIF-1α shRNA group than the control (p < 0.01). The tumor size was smaller in the shRNA + MD group than the shRNA group and the MD group (p < 0.05) on the 28th day. The growth rate of tumors in the shRNA + MD group was also lower than in other groups. The gene and protein expressions of both HIF-1α and VEGF in the shRNA + MD group were lower than the MD group, shRNA group and control group on the 28th day (p < 0.05). The necrotic score was higher in the shRNA + MD group than the MD group and control group (p < 0.05). The mitotic count and PAS-positive cells in shRNA + MD group were lower and CD34 was higher than the other three groups (p < 0.05).

Conclusion

Compared to therapy with MD or HIF-1α shRNA with transcatheter intraarterial transfection alone, the combined treatment has a better effect on HCC.