Abstract A02: Photodynamic therapy in combination with immunotherapy enhances the long-term cure of bladder cancer in tumored mice

Abstract

Abstract Introduction and Objectives: To investigate the utility of combination approach for treating bladder cancer, mice bearing UMUC3 (human transitional cell carcinoma) and T24 (human urinary bladder) tumors were treated with HPPH (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a)-PDT alone and in combination with BCG. The HPPH, a multifunctional agent, was selected as a photosensitizer because of its higher tumor avidity, improved fluorescence imaging ability, and limited skin phototoxicity than Photofrin, a current clinical standard. Methods: Imaging: IVIS/Spectrum: A noninvasive in vivo, continuous wave fluorescence imaging apparatus used to assess the localization and distribution of the PS at variable time points. In vivo efficacy studies using UMUC3 and T24 tumors in SCID mice with PS HPPH in combination with BCG. Results: Imaging: Tumor uptake in UMUC3 and T24 tumors using IVIS Imaging. PS HPPH showed high tumor uptake and significant difference in their pharmacokinetic profiles in UMUC3 and T24 tumors implanted in SCID mice: The SCID mice bearing either UMUC3 or T24 tumors (4-5 mm size) were injected with the PS HPPH. The tumored mice (3 mice/group) at a dose of 0.47 u-mol/kg) and imaged at variable time points. The uptake of tumor, liver, and skin was measured by IVIS system and interesting pharmacokinetic profiles of the PS were observed. The optimal tumors uptake in UMUC3 and T24 were at 24 hours and 8-12 hours, respectively. In vivo efficacy studies: PS (HPPH) in combination with BCG shows enhanced PDT efficacy CR (Cures) Day 30 = 14/22 = 63.6% and RG (Re-Growth) 6/22 = 36.4% in bladder tumors (UMUC3). To investigate the utility of combination treatment approach for treating bladder cancer, mice bearing UMUC3 tumors were injected intravenously with HPPH (0.47 u-mol/kg) and the tumors were exposed to laser light (135 J/cm2, 75 mW/cm2) at 24 h post-injection. One hour after the PDT treatment, BCG was injected (1-1.5 × 106 CFU), SQ weekly x 3 doses, and at day 30 the results are very encouraging. Conclusions: The HPPH showed higher in vivo uptake (determined by fluorescence) in UMUC3 and T24 bladder cancer tumors with significant differences in the two tumor types. The treatment of HPPH-PDT in combination with BCG using SCID mice bearing UMUC3 tumors showed enhanced long-term tumor cure. Before initiating this approach to human phase I clinical trial, further studies are under way. Source of funding: Roswell Park Alliance Foundation. Citation Format: Farukh Durrani, Ahmed Aly, Khurshid Guru, Ravindra Pandey. Photodynamic therapy in combination with immunotherapy enhances the long-term cure of bladder cancer in tumored mice [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr A02.