Enhanced efficacy of radiofrequency ablation for hepatocellular carcinoma using a novel vascular disrupting agent, CKD-516

Radiofrequency ablation: mechanisms and clinical applications

Radiofrequency ablation (RFA), a form of thermal ablation, employs localized heat to induce protein denaturation in tissue cells, resulting in cell death. It has emerged as a viable treatment option for patients who are ineligible for surgery in various diseases, particularly liver cancer and other tumor-related conditions. In addition to directly eliminating tumor cells, RFA also induces alterations in the infiltrating cells within the tumor microenvironment (TME), which can significantly impact treatment outcomes. Moreover, incomplete RFA (iRFA) may lead to tumor recurrence and metastasis. The current challenge is to enhance the efficacy of RFA by elucidating its underlying mechanisms. This review discusses the clinical applications of RFA in treating various diseases and the mechanisms that contribute to the survival and invasion of tumor cells following iRFA, including the roles of heat shock proteins, hypoxia, and autophagy. Additionally, we analyze‌ the changes occurring in infiltrating cells within the TME after iRFA. Finally, we provide a comprehensive summary of clinical trials involving RFA in conjunction with other treatment modalities in the field of cancer therapy, aiming to offer novel insights and references for improving the effectiveness of RFA.

A phase 1 dose-escalation and dose-expansion study to assess the safety and efficacy of CKD-516, a novel vascular disrupting agent, in combination with Irinotecan in patients with previously treated metastatic colorectal cancer

Introduction The combination of an anti-angiogenic agent with cytotoxic chemotherapy is a standard treatment strategy for metastatic colorectal cancer. CKD-516 is an oral vascular disrupting agent that was preliminarily shown to be safe and efficacious as a monotherapy in refractory solid cancers. We evaluated the recommended phase 2 dose, safety, and preliminary efficacy of CKD-516 in combination with irinotecan in treatment-refractory metastatic colorectal cancer. Methods This phase 1 dose-escalation and dose-expansion study included patients with treatment-refractory metastatic colorectal cancer. CKD-516 tablets were administered for five consecutive days followed by two days off in combination with intravenous irinotecan (120 mg/m²) administered on day one of each treatment cycle every two weeks. A traditional 3 + 3 dose-escalation design was used. Results In total, 16 and 23 patients were enrolled in the dose-escalation and dose-expansion cohorts, respectively. The most common adverse events included diarrhea (79%), nausea (74%), vomiting (67%), and neutropenia (62%). No dose-limiting toxicity occurred, and the recommended phase 2 dose was determined at CKD-516/irinotecan doses of 11/120 mg/m². No cases of cardiac ischemia, cardiac dysfunction, or thromboembolism were reported. Among the 34 patients with available tumor response assessments, one patient achieved partial response (3%) and 26 patients achieved stable disease (76%). The median progression-free survival and overall survival were 4.1 and 11.6 months, respectively. Conclusion This phase 1 study showed that the combination of oral CKD-516 and irinotecan is safe and tolerable in metastatic, treatment-refractory colorectal patients and showed favorable efficacy outcomes. Further studies to confirm these preliminary findings are warranted. Trial registration number NCT03076957 (Registered at March 10, 2017).

Tract ablation after radiofrequency ablation to prevent viable tumor cell adhesion to the needle electrode

PURPOSE

To evaluate whether the additive needle tract ablation (TA) can reduce adherent cells on the needle tract after radiofrequency ablation (RFA) in a preclinical HCC mouse model.

METHODS

Hep3B-Luc cells were engrafted in the Balb/c-nude mice. Nineteen mice were randomly assigned into three groups: the needle only group (needle placement only without performing RFA), the RFA only group (needle placement with active RFA treatment), and the RFA-TA group (needle placement with active RFA treatment and additive tract ablation). The 17-gauge needle with a 10-mm active tip was used. After RFA and TA, the viability of adherent tumor cells on the RFA needle was evaluated with bioluminescence imaging (BLI) and live-cell counting.

RESULTS

We observed that RFA-TA group had the lowest BLI values compared with other groups (needle only group, 11.2 ± 6.4 million; RFA only group, 13.6 ± 9.1 million; RFA-TA group, 1.11 ± 0.8 million, p = 0.001). Live cell counting with acridine orange/propidium iodide staining also confirmed that the counted viable cell numbers in RFA-TA group were lowest compared to the other groups (needle only group, 14.8 ± 4.5; RFA only group, 643.8 ± 131.9; RFA-TA group, 1.5 ± 0.9, p < 0.001).

CONCLUSIONS

The additive tract ablation can significantly reduce the number of viable tumor cells adherent to the RFA needle, which can prevent needle tract seeding after RFA procedure.

Test-retest repeatability of ultrasonographic shear wave elastography in a rat liver fibrosis model: toward a quantitative biomarker for preclinical trials

PURPOSE

This study evaluated the test-retest repeatability and measurement variability of ultrasonographic shear wave elastography (SWE) for liver stiffness in a rat liver fibrosis model.

METHODS

In 31 Sprague-Dawley rats divided into three groups (high-dose, low-dose, and control), liver fibrosis was induced by intraperitoneal administration of thioacetamide for 8 weeks. A dedicated radiographer performed SWE to measure liver stiffness in kilopascals in two sessions at a 3-day interval. We calculated correlations between liver stiffness and histopathologic results, measurement variability in each session using coefficients of variation (CoVs) and interquartile/median (IQR/M), and test-retest repeatability between both sessions using the repeatability coefficient.

RESULTS

Different levels of liver fibrosis in each group were successfully induced in the animal model. The mean liver stiffness values were 8.88±1.48 kPa in the control group, 11.62±1.70 kPa in the low-dose group, and 11.91±1.73 kPa in the high-dose group. The correlation between collagen areas and liver stiffness values was moderate (r=0.6). In all groups, the second session yielded lower CoVs (i.e., more reliable results) for liver stiffness than the first session, suggesting a training effect for the operator. The mean IQR/M values were also lower in the second session than in the first session, which had four outliers (0.21 vs. 0.12, P<0.001). The test-retest repeatability coefficient was 3.75 kPa and decreased to 2.82 kPa after removing the four outliers.

CONCLUSION

The use of ultrasonographic SWE was confirmed to be feasible and repeatable for evaluating liver fibrosis in preclinical trials. Operator training might reduce variability in liver stiffness measurements.

Involvement of ER stress and reactive oxygen species generation in anti-cancer effect of CKD-516 for lung cancer

PURPOSE

CKD-516 (Valecobulin), a vascular-disrupting agent, inhibits microtubule elongation. We evaluated the effect of CKD-516 on lung cancer cells and the underlying molecular mechanisms.

METHODS

The effects of S516, an active metabolite of CKD-516, were evaluated in HUVECs and three lung cancer cell lines and by a microtubule polymerization assay. Tubulin cross-linking was used to identify the binding site of S516 on tubulin, and Western blotting was performed to identify the intracellular pathways leading to cell death. Subcutaneous lung cancer xenograft models were used to assess the in vivo effect of CKD-516 on tumor growth.

RESULTS

S516 targeted the colchicine binding site on β-tubulin. In lung cancer cells, S516 increased endoplasmic reticulum (ER) stress and induced reactive oxygen species (ROS) generation by mitochondria and the ER. In addition, CKD-516 monotherapy strongly inhibited the growth of lung cancer xenograft tumors and exerted a synergistic effect with carboplatin.

CONCLUSION

The findings suggest that CKD-516 exerts an anticancer effect in company with inducing ER stress and ROS production via microtubule disruption in lung cancer cells. CKD-516 may thus have therapeutic potential for lung cancer.