Does doxorubicin survive thermal ablation? Results of an ex vivo bench top study.

PURPOSE We aimed to test the hypothesis that doxorubicin (DOX) survives thermal ablative heating in an ex vivo model of combined transarterial chemoembolization (TACE) and thermal ablation. METHODS Fresh porcine psoas major muscle (3 samples, 15×10×3 cm) was submerged in aqueous DOX solution (60 µg/mL, 0.1 M) for 24 hours to passively saturate tissue. DOX-infused tissue was then dried and treated with microwave ablation (MWA) using a 2.45 GHz antenna at 65 W for 2, 5, and 10 minutes. Ablations were repeated in triplicate (9 total). Tissue was then sampled at both ablated and unablated control sites, and DOX concentration was quantified via ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), with samples analyzed in triplicate. Tissue DOX levels in ablation and control groups were compared using one-way ANOVA. RESULTS Homogeneous DOX uptake into porcine tissue was evident in all three samples. Mean DOX concentration in unablated tissue was 8.0±2.2 µg/mL. MWA was technically successful in all 9 procedures (100%), with tissue heating to 95-100°C. Mean tissue DOX concentration showed progressive reduction with increasing ablation time, measuring 6.7±1.3, 4.9±0.9, and 4.8±1.3 µg/mL in MWA-treated tissue after 2, 5, and 10 minutes, respectively. Differences in tissue DOX levels between unablated tissue and MWA groups were statistically significant (P < 0.001). CONCLUSION Contrary to the initial hypothesis, tissue DOX concentration progressively decreased after MWA of longer ablation times. These results suggest that TACE followed by ablation may result in lower intratumoral DOX than would otherwise be anticipated for TACE alone.