The Accumulation and Effects of Liposomal Doxorubicin in Tissues Treated by Radiofrequency Ablation and Irreversible Electroporation in Liver: In Vivo Experimental Study on Porcine Models

Investigation of lethal thresholds of nanosecond pulsed electric field in rabbit VX2 hepatic tumors through finite element analysis and verification with a single-needle bipolar electrode: A prospective strategy employing three-dimensional comparisons

Pulsed electric field has emerged as a promising modality for the solid tumor ablation with the advantage in treatment planning, however, the accurate prediction of the lesion margin requires the determination of the lethal electric field (E) thresholds. Herein we employ the highly repetitive nanosecond pulsed electric field (RnsPEF) to ablate the normal and VX2 tumor-bearing livers of rabbits. The ultrasound-guided surgery is operated using the conventional double- and newly devised single-needle bipolar electrodes. Finite element analysis is also introduced to simulate the E distribution in the practical treatments. Two- and three-dimensional investigations are performed on the image measurements and reconstructed calcification models on micro-CT, respectively. Specially, an algorithm considering the model surface, volume and shape is employed to compare the similarities between the simulative and experimental models. Blood vessel injury, temperature and synergistic efficacy with doxorubicin (DOX) are also investigated. According to the three-dimensional calculation, the overall E threshold is 4536.4 ± 618.2 V/cm and the single-needle bipolar electrode is verified to be effective in tissue ablation. Vessels are well preserved and the increment of temperature is limited. Synergy of RnsPEF and DOX shows increased apoptosis and improved long-term tumor survival. Our study presents a prospective strategy for the evaluation of the lethal E threshold, which can be considered to guide the future clinical treatment planning for RnsPEF.

Can two-step ablation combined with chemotherapeutic liposomes achieve better outcome than traditional RF ablation? A solid tumor animal study

Objectives: To determine whether two-step ablation using sequential low and high temperature heating can achieve improved outcomes in animal tumor models when combined with chemotherapeutic liposomes (LP). Materials and methods: Balb/c mice bearing 4T1 tumor received paclitaxel-loaded liposomes followed 24 h later by either traditional RFA (70 °C, 5 min) or a low temperature RFA (45 °C, 5 min), or two-step RFA (45 °C 2 min + 70 °C 3 min). Intratumoral drug accumulation and bio-distribution in major organs were evaluated. Periablational drug penetration was evaluated by pathologic staining and the intratumoral interstitial fluid pressure (IFP) was measured directly. For long-term outcomes, mice bearing 4T1 or H22 tumors were randomized into five groups (n = 8 per group): control (no treatment), RFA alone, LP + RFA (45 °C), LP + RFA (70 °C) and LP + RFA (45 + 70 °C). End-point survivals were compared among the different groups. Results: The greater intratumoral drug accumulation (3.35 ± 0.32 vs. 3.79 ± 0.29 × 10⁸ phot/cm²/s at 24 h, p = 0.09), deeper periablational drug penetration (45.7 ± 5.0 vs. 1.6 ± 0.5, p < 0.001), and reduced off-target drug deposition in major organs (liver 96.1 ± 31.6 vs. 47.4 ± 1.5 × 10⁶ phot/cm²/s, p < 0.001) were found when combined with RFA (45 °C) compared to drug alone. For long-term outcomes, 4T1 tumor growth rates for LP + two-step RFA (45 + 70 °C) were significantly slower than those of LP + RFA (70 °C), LP + RFA (45 °C), and RFA alone (P < 0.01 for all comparisons). End point survival for LP + RFA (45 + 70 °C) was also longer than that for LP + RFA (70 °C) (median 16 vs. 10 days, p = 0.003) or LP + RFA 45 °C (11 days, p = 0.009) and RFA alone (8.3 days, p < 0.001) in 4T1 tumor models. The intratumoral IFP after RFA (45 °C) was significantly lower than baseline RFA (3.3 ± 0.8 vs. 19.2 ± 3.1 mmHg, p < 0.001), but was not measurable after RFA (70 °C). Conclusions: A two-step ablation combined with chemotherapeutic liposomes can achieve better survival benefit compared to traditional RFA in animal models.

Three-dimensional (3D) liver cell models - a tool for bridging the gap between animal studies and clinical trials when screening liver accumulation and toxicity of nanobiomaterials

Despite the exciting properties and wide-reaching applications of nanobiomaterials (NBMs) in human health and medicine, their translation from bench to bedside is slow, with a predominant issue being liver accumulation and toxicity following systemic administration. In vitro 2D cell-based assays and in vivo testing are the most popular and widely used methods for assessing liver toxicity at pre-clinical stages; however, these fall short in predicting toxicity for NBMs. Focusing on in vitro and in vivo assessment, the accurate prediction of human-specific hepatotoxicity is still a significant challenge to researchers. This review describes the relationship between NBMs and the liver, and the methods for assessing toxicity, focusing on the limitations they bring in the assessment of NBM hepatotoxicity as one of the reasons defining the poor translation for NBMs. We will then present some of the most recent advances towards the development of more biologically relevant in vitro liver methods based on tissue-mimetic 3D cell models and how these could facilitate the translation of NBMs going forward. Finally, we also discuss the low public acceptance and limited uptake of tissue-mimetic 3D models in pre-clinical assessment, despite the demonstrated technical and ethical advantages associated with them.

The combination of endoluminal radiofrequency ablation and metal stent implantation for the treatment of malignant biliary stenosis - Randomized study

PURPOSE

To analyse whether endobiliary radiofrequency ablation prior metal stent insertion in malignant biliary stenosis show improved survival or stent patency.

METHODS

76 patients with histologically proven malignant biliary stenosis have been enrolled in a prospective, randomized study. In control arm, 40 patients underwent self-expandable metal stent insertion. In experimental arm, the endoluminal ablation with a bipolar radiofrequency catheter was performed immediately before stent insertion. A subgroup analysis of cholangiocarcinoma was performed (22 vs 21 patients). The objective of the study was to determine the rate of complications, duration of the stent patency and the survival of patients (Kaplan-Meier analysis).

RESULTS

No major complications related to the stent insertion and the endoluminal ablation were found. The mean primary stent patency was 5.2 (95% CI 0.7-12.8) vs 4.8 months (95% CI 0.8-18.2) months (p = 0.79) in control and experimental group, respectively, in the subgroup analysis with cholangiocarcinoma 4.5 (95% CI 0.8-10.3) and 9.6 (95% CI 5.2-11.2) months (p = 0.029). The median survival since the insertion of the stent was 6.8 (95 %CI 3.0-10.6) vs 5.2 (95 %CI 2.4-7.9) months (p = 0.495) and since the initial drainage 9.8 (95 %CI 6.9-12.7) vs 9.1 (95 %CI 5.4-12.7) months (p = 0.720) in the control and experimental arm.

CONCLUSION

Endobiliary radiofrequency ablation prior metal stent insertion showed increased patency rate only in patients with cholangiocarcinoma, on the other hand, no improvement in survival was demonstrated in this randomized clinical study.