MP61-08 PHOTOTHERMAL ABLATION OF BLADDER CANCER USING PHOSPHATIDYLSERINE TARGETED CARBON NANOTUBES

Abstract

INTRODUCTION AND OBJECTIVES: Use of ablative therapy has the potential to treat bladder cancer resistant to BCG and chemotherapy. However, early efforts with photodynamic therapy and intravenous application of the photosensitizer resulted in significant complications. We have combined Annexin V targeting of phosphatidylserine on tumor surface with single-walled carbon nanotubes (SWNTs) to target bladder tumor cells and treat with near infrared (NIR) light for thermal ablation of tumor in the preclinical setting. METHODS: In vitro studies were conducted on mouse bladder cancer (MB49) and human bladder cancer (J82) cell lines. The dissociation constant for AV binding strength was determined. The specific binding results were confirmed with fluorescence microscopy. Quantitative analysis of the number of cell surface bound AVs was conducted for each cell line. Alamar blue preand post-cell viability assays were conducted to determine the cytotoxic effects of NIR and SWNT-AVs alone as well as a combined approach on both bladder cancer lines. In vivo studies were conducted to determine the biodistribution of intravesically delivered SWNT-AVs in MB49 orthotropic models. FT-Raman analysis was conducted to determine SWNT-AV accumulation in harvested organs. An in vivo NIR tolerance test followed by H&E staining was conducted with a 360 radiating fiber to confirm minimized non-specific tissue damage. A therapeutic efficacy study combining SWNT-AVs and NIR was performed. RESULTS: In vitro binding studies confirmed a strong binding affinity of AV to MB49 (Kd 1⁄4 4.14 1.28 nM) and J82 (Kd 1⁄4 0.38 0.20 nM) cells. Subtoxic levels of docetaxel increased the number of bound AVs per MB49 cell but had no effect on the J82 cells. Inducing SWNT-AV heating due to NIR confirmed significant cancer cell death as compared to untreated controls for both cell lines. The in vitro tests provided statistically significant validation for the potential of this targeted ablation therapy. In vivo testing on C57BL-6 mice was conducted to confirm the efficacy of this treatment even further. A biodistribution study followed by FT-Raman analysis verified no non-specific accumulation of SWNT-AVs in various organs. NIR power tolerance tests confirmed that no healthy tissue damage occurred at 50 J/cm2. In vivo data will also be presented for the effect of SWNT-AV and NIR combination therapy on MB49 mouse bladder cancer. CONCLUSIONS: SWNT-AVs have proven to preferentially target bladder cancer cells and in conjunction with NIR cause significant cytotoxicity in vitro. The results of this study show promise for NIR thermally heated SWNT-AVs as a viable therapeutic option for recurrent bladder cancers.