Combined Radiofrequency Ablation and Double Anti-Angiogenic Protein Therapy to Increase Coagulation Efficacy: An Experimental Study in a Murine Renal Carcinoma Model

Objective: To evaluate whether suppression of tumor microvasculature by double anti-angiogenic protein (DAAP) treatment could increase the extent of radiofrequency ablation (RFA)-induced coagulation in a murine renal cell carcinoma model. Materials and Methods: Renal cell carcinoma cell lines were implanted subcutaneously into 10 nude mice. Four mice received adenoviral DAAP treatment and 6 mice received sterile 0.9% saline solution as DAAP-untreated group. The effect of DAAP was evaluated according to the vascularity by contrast-enhanced ultrasound (CEUS) using microbubbles. Four DAAP-treated mice and 4 DAAP-untreated mice were then treated with RFA, resulting in 3 groups: no-therapy (n = 2), RFA only (n = 4), and RFA combined with DAAP treatment (n = 4). Immediately after RFA, the size of coagulation necrosis and mitochondrial enzyme activity were compared between the groups using analysis of variance (ANOVA) and post hoc test. Results: The contrast enhancement ratio for tumor vascularization on CEUS was significantly lower in the DAAP treated group than in DAAP-untreated group ($30.2{\pm}9.9%$ vs. $77.4{\pm}17.3%$; p = 0.021). After RFA, the mean coagulation diameter was 0 mm for no-therapy group, $6.7{\pm}0.7mm$ for the RFA only group and $8.5{\pm}0.4mm$ for the RFA with DAAP group (ANOVA, p < 0.001). The area of viable mitochondria within the tumor was $27.9{\pm}3.9%$ in no-therapy group, $10.3{\pm}4.5%$ in the RFA only group, and $2.1{\pm}0.7%$ in the RFA with DAAP group (ANOVA, p < 0.001). Conclusion: Our results suggest the potential value of combining RFA with anti-angiogenic therapy.