Clinical-grade Doxorubicin encapsulated low temperature sensitive liposomes (LTSLs) were combined with a clinical magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) platform to investigate in-vivo image-guided drug delivery. Plasma pharmacokinetics were determined in 3 rabbits. Fifteen rabbits with Vx2 tumors within superficial thigh muscle were randomly assigned into three treatment groups: 1) free doxorubicin, 2) LTSL and 3) LTSL+MR-HIFU. For the LTSL+MR-HIFU group, mild hyperthermia (40–41°C) was applied to the tumors using an MR-HIFU system. Image-guided non-invasive hyperthermia was applied for a total of 30 min, completed within 1 hour after LTSL infusion. High-pressure liquid chromatography (HPLC) analysis of the harvested tumor and organ/tissue homogenates was performed to determine doxorubicin concentration. Fluorescence microscopy was performed to determine doxorubicin spatial distribution in the tumors. Sonication of Vx2 tumors resulted in accurate (mean=40.5±0.1°C) and spatially homogenous (SD=1.0°C) temperature control in the target region. LTSL+MR-HIFU resulted in significantly higher tumor doxorubicin concentrations (7.6- and 3.4-fold greater compared to free doxorubicin and LTSL respectively, p<0.05, Newman-Keuls). This improved tumor concentration was achieved despite heating <25% of the tumor volume. Free doxorubicin and LTSL treatments appeared to deliver more drug in the tumor periphery as compared to the tumor core. In contrast, LTSL+MR-HIFU treatment suggested an improved distribution with doxorubicin found in both the tumor periphery and core. Doxorubicin bio-distribution in non-tumor organs/tissues was fairly similar between treatment groups. This technique has potential for clinical translation as an image-guided method to deliver drug to a solid tumor.

Purpose:To evaluate the influence of subtotal radiofrequency (RF) ablation on a tumor-specific immune response in a murine tumor model and to explore the role of intratumoral dendritic cells (ITDCs) in mediating this effect. Materials and Methods:Animal work was performed according to an approved protocol and in compliance with the National Cancer Institute Animal Care and Use Committee guidelines and regulations. A murine urothelial carcinoma (MB49) model expressing the male minor histocompatibility (HY) antigen was inoculated subcutaneously in female mice. Fourteen days later, splenic T cells were analyzed with enzymelinked immunosorbent spot for HY immune response (n ϭ 57). In subsequent experiments, mice were randomized into control (n ϭ 7), RF ablation, ITDC (n ϭ 9), and RF ablation ϩ ITDC (n ϭ 9) groups and monitored for tumor growth. Eleven days after treatment, tumors were harvested for histologic and immunohistochemical analysis. Animals demonstrating complete tumor regression were rechallenged in the contralateral flank. Results:Animals treated with subtotal RF ablation showed significant increases in tumor-specific class I and II responses to HY antigens and tumor regression. RF ablation, ITDC, and combined groups demonstrated similar levels of antigenpresenting cell infiltration; all groups demonstrated greater levels of infiltration compared with untreated controls. ITDC injection also resulted in tumor regression. However, combination therapy did not enhance tumor regression when compared with either treatment alone. Rechallenged mice in RF ablation, ITDC, and combination groups demonstrated significant tumor growth inhibition compared with controls. Conclusion:Subtotal RF ablation treatment results in enhanced systemic antitumor T-cell immune responses and tumor regression that is associated with increased dendritic cell infiltration. ITDC injection mimics the RF ablation effect but does not increase immune responses when injected immediately after RF ablation.

Purpose The objective of this study was to determine local doxorubicin levels surrounding radiopaque drug-eluting beads (DEB) in normal swine liver and kidney following transcatheter arterial chemoembolization (TACE). The influence of bead size (70–150µm or 100–300µm) was compared with regard to tissue penetration and spatial distribution of the bead as well as eventual drug coverage (i.e., amount of tissue exposed to drug). Materials and Methods Radiopaque DEBs were synthesized by suspension polymerization followed by incorporation of iodized oil and doxorubicin. Chemoembolization of swine liver and kidney was performed under fluoroscopic guidance. Three dimensional tissue penetration of image-able DEB was investigated ex vivo with microCT. Drug penetration from the bead surface and drug coverage was evaluated with epi-fluorescence microscopy while cellular localization of doxorubicin was evaluated with confocal microscopy. Necrosis was evaluated with H&E. Results MicroCT demonstrated that 70–150µm DEB were present in more distal arteries and located in a more frequent and homogeneous spatial distribution. Tissue penetration of doxorubicin from the bead appeared similar (~300µm) for both DEBs with a maximum tissue drug concentration at 1hr coinciding with nuclear localization of doxorubicin. The greater spatial frequency of the 70–150µm DEBs resulted in ~2-fold improved drug coverage in kidney. Cellular death is predominantly observed around the DEBs beginning at 8 hr but increased at 24 and 168 hrs. Conclusions Smaller DEBs penetrated further into targeted tissue (macroscopic) with a higher spatial density, resulting in greater and more uniform drug coverage (microscopic) in swine.