Leveraging combination histotripsy tumor ablation and N-dihydrogalactochitosan immunostimulation to advance osteosarcoma therapy - PROJECT SUMMARY: Despite aggressive definitive treatment of osteosarcoma (OS), survival expectations for human and canine OS have not improved in decades due to refractory metastatic disease. The poor immune responsiveness of osteosarcoma to immunomodulating therapies contributes to the persistence of metastatic disease development. Novel therapeutic paradigms to activate this “cold” tumor microenvironment and induce an effective anti-tumor immune response in OS are direly needed. To fulfill this need, our research team proposes a combination therapy approach using 2 highly novel modalities – histotripsy tumor ablation and N-dihydrogalactochitosan (GC) to treat OS. Histotripsy is a non-thermal, non- invasive and non-ionizing tumor ablation technique that utilizes high intensity focused ultrasound waves to mechanically disintegrate tissue. Histotripsy releases non heat-denatured tumor antigens, which can potentially induce a more robust anti-tumor immune response. GC is a semisynthetic derivative of chitin with demonstrated ability as an immunostimulant that enhances the anti-tumor effects of various ablation modalities across different cancer types. Despite the exciting potential of histotripsy and GC to synergistically induce an effective anti-tumor response, combining both therapies to treat OS has not been reported. Thus, this multidisciplinary proposal will evaluate combining histotripsy tumor ablation with GC as an innovative immunomodulatory strategy for treating osteosarcoma using a unique comparative oncology study that incorporates murine preclinical models and pet dogs with spontaneous appendicular osteosarcoma. The overall objective of our proposed study is to evaluate local and systemic immune responses in OS after combining histotripsy tumor ablation with intratumoral injection of GC. Our overall hypothesis is histotripsy-GC treatment of OS induces effective and durable intratumoral and systemic anti- tumor immune responses. We will test this hypothesis with the following aims: Aim 1: Characterize the immunomodulatory responses to and effects on metastasis of histotripsy-GC treatment of OS in a murine heterotopic syngeneic tumor model. We hypothesize that histotripsy-GC treatment of OS heightens the intratumoral and systemic immune activation profiles, induces an abscopal effect, and reduces metastatic burden. Aim 2: Evaluate the feasibility of histotripsy-GC treatment of OS in dogs with appendicular OS, and the effects of treatment on the immune profile of the OS TME and on progression-free survival. We hypothesize that histotripsy-GC treatment of canine appendicular OS does not result in major adverse events, stimulates increased intratumoral immune cell infiltration, upregulation of intratumoral and lymph node immune activation gene profiles, and achieves increased PFS compared to standard-of-care therapy. Significance: These data will inform subsequent studies that generate clinically relevant data to design future human clinical trials for histotripsy-GC therapy in OS.
