Search

Background: Osteosarcoma (OS) is the most frequently occurring malignant bone tumor in humans, primarily affecting children and adolescents. Significant advancements in treatment options for OS have not occurred in the last several decades, and the prognosis remains grim with only a 70% rate of 5-year survival. The objective of this study was to investigate the focused ultrasound technique of histotripsy as a novel, noninvasive treatment option for OS. Methods: We utilized a heterotopic OS murine model to establish the feasibility of ablating OS tumors with histotripsy in a preclinical setting. We investigated the local immune response within the tumor microenvironment (TME) via immune cell phenotyping and gene expression analysis. Findings: We established the feasibility of ablating heterotopic OS tumors with ablation characterized microscopically by loss of cellular architecture in targeted regions of tumors. We observed greater populations of macrophages and dendritic cells within treated tumors and the upregulation of immune activating genes 72 h after histotripsy ablation. Interpretation: This study was the first to investigate histotripsy ablation for OS in a preclinical murine model, with results suggesting local immunomodulation within the TME. Our results support the continued investigation of histotripsy as a novel noninvasive treatment option for OS patients to improve clinical outcomes and patient prognosis.

Purpose Feline soft tissue sarcoma (STS) and injection site sarcoma (fISS) are rapidly growing tumors with low metastatic potential, but locally aggressive behavior. Histotripsy is a non-invasive focused ultrasound therapy using controlled acoustic cavitation to mechanically disintegrate tissue. In this study, we investigated the in vivo safety and feasibility of histotripsy to treat fISS using a custom 1 MHz transducer. Materials and Methods Three cats with naturally-occurring STS were treated with histotripsy before surgical removal of the tumor 3 to 6 days later. Gross and histological analyses were used to characterize the ablation efficacy of the treatment, and routine immunohistochemistry and batched cytokine analysis were used to investigate the acute immunological effects of histotripsy. Results Results showed that histotripsy ablation was achievable and well-tolerated in all three cats. Precise cavitation bubble clouds were generated in all patients, and hematoxylin & eosin stained tissues revealed ablative damage in targeted regions. Immunohistochemical results identified an increase in IBA-1 positive cells in treated tissues, and no significant changes in cytokine concentrations were identified post-treatment. Conclusions Overall, the results of this study demonstrate the safety and feasibility of histotripsy to target and ablate superficial feline STS and fISS tumors and guide the clinical development of histotripsy devices for this application.

Pancreatic tumors can be resistant to drug penetration due to high interstitial fluid pressure, dense stroma, and disarrayed vasculature. Ultrasound-induced cavitation is an emerging technology that may overcome many of these limitations. Low-intensity ultrasound, coupled with co-administered cavitation nuclei consisting of gas-stabilizing sub-micron scale SonoTran Particles, is effective at increasing therapeutic antibody delivery to xenograft flank tumors in mouse models. Here, we sought to evaluate the effectiveness of this approach in situ using a large animal model that mimics human pancreatic cancer patients. Immunocompromised pigs were surgically engrafted with human Panc-1 pancreatic ductal adenocarcinoma (PDAC) tumors in targeted regions of the pancreas. These tumors were found to recapitulate many features of human PDAC tumors. Animals were intravenously injected with the common cancer therapeutics Cetuximab, gemcitabine, and paclitaxel, followed by infusion with SonoTran Particles. Select tumors in each animal were targeted with focused ultrasound to induce cavitation. Cavitation increased the intra-tumor concentrations of Cetuximab, gemcitabine, and paclitaxel by 477%, 148%, and 193%, respectively, compared to tumors that were not targeted with ultrasound in the same animals. Together, these data show that ultrasound-mediated cavitation, when delivered in combination with gas-entrapping particles, improves therapeutic delivery in pancreatic tumors under clinically relevant conditions.

Objective: Osteosarcoma (OS) is a devastating primary bone tumor in dogs and humans with limited non-surgical treatment options. As the first completely non-invasive and non-thermal ablation technique, histotripsy has the potential to significantly improve the standard of care for patients with primary bone tumors. Introduction: Standard of care treatment for primary appendicular OS involves surgical resection via either limb amputation or limb-salvage surgery for suitable candidates. Biological similarities between canine and human OS make the dog an informative comparative oncology research model to advance treatment options for primary OS. Evaluating histotripsy for ablating spontaneous canine primary OS will build a foundation upon which histotripsy can be translated clinically into a standard of care therapy for canine and human OS. Methods: Five dogs with suspected spontaneous OS were treated with a 500 kHz histotripsy system guided by real-time ultrasound image guidance. Spherical ablation volumes within each tumor (1.25-3 cm in diameter) were treated with single cycle histotripsy pulses applied at a pulse repetition frequency of 500 Hz and a dose of 500 pulses/point. Results: Tumor ablation was successfully identified grossly and histologically within the targeted treatment regions of all subjects. Histotripsy treatments were well-tolerated amongst all patients with no significant clinical adverse effects. Conclusion & Significance: Histotripsy safely and effectively ablated the targeted treatment volumes in all subjects, demonstrating its potential to serve as a non-invasive treatment modality for primary bone tumors.

Osteosarcoma (OS) is a malignant bone tumor treated by limb amputation or limb salvage surgeries and chemotherapy. Histotripsy is a non-thermal, non-invasive focused ultrasound therapy using controlled acoustic cavitation to mechanically disintegrate tissue. Recent ex vivo and in vivo pilot studies have demonstrated the ability of histotripsy for ablating OS but were limited in scope. This study expands on these initial findings to more fully characterize the effects of histotripsy for bone tumors, particularly in tumors with different compositions. A prototype 500 kHz histotripsy system was used to treat ten dogs with suspected OS at an intermediate treatment dose of 1000 pulses per location. One day after histotripsy, treated tumors were resected via limb amputation, and radiologic and histopathologic analyses were conducted to determine the effects of histotripsy for each patient. The results of this study demonstrated that histotripsy ablation is safe and feasible in canine patients with spontaneous OS, while offering new insights into the characteristics of the achieved ablation zone. More extensive tissue destruction was observed after histotripsy compared to that in previous reports, and radiographic changes in tumor size and contrast uptake following histotripsy were reported for the first time. Overall, this study significantly expands our understanding of histotripsy bone tumor ablation and informs future studies for this application.

Introduction: Histotripsy is a non-invasive focused ultrasound therapy that uses controlled acoustic cavitation to mechanically disintegrate tissue. To date, there are no reports investigating histotripsy for the treatment of soft tissue sarcoma (STS). Objective: This study aimed to investigate the in vivo feasibility of ablating STS with histotripsy and to characterize the impact of partial histotripsy ablation on the acute immunologic response in canine patients with spontaneous STS. Methods: A custom 500 kHz histotripsy system was used to treat ten dogs with naturally occurring STS. Four to six days after histotripsy, tumors were surgically resected. Safety was determined by monitoring vital signs during treatment and post-treatment physical examinations, routine lab work, and owners’ reports. Ablation was characterized using radiologic and histopathologic analyses. Systemic immunological impact was evaluated by measuring changes in cytokine concentrations, and tumor microenvironment changes were evaluated by characterizing changes in infiltration with tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) using multiplex immunohistochemistry and differential gene expression. Results: Results showed histotripsy ablation was achievable and well-tolerated in all ten dogs. Immunological results showed histotripsy induced pro-inflammatory changes in the tumor microenvironment. Conclusion & Significance: Overall, this study demonstrates histotripsy's potential as a precise, non-invasive treatment for STS.

Purpose: To investigate the safety, feasibility, and outcomes of High-Intensity Focused Ultrasound (HIFU) for the treatment of solid tumors in a spontaneous canine cancer model. Methods: Dogs diagnosed with subcutaneous solid tumors were recruited, staged and pretreatment biopsies were obtained. A single HIFU treatment was delivered to result in partial tumor ablation using a commercially available HIFU unit. Tumors were resected 3-6 days post HIFU and samples obtained for histopathology and immunohistochemistry. Total RNA was isolated from paired pre and post treated FFPE tumor samples, and quantitative gene expression analysis was performed using the nCounter Canine IO Panel. Results: A total of 20 dogs diagnosed with solid tumors were recruited and treated in the study. Tumors treated included Soft Tissue Sarcoma (n = 15), Mast Cell Tumor (n = 3), Osteosarcoma (n = 1), and Thyroid Carcinoma (n = 1). HIFU was well tolerated with only 1 dog experiencing a clinically significant adverse event. Pathology confirmed the presence of complete tissue ablation at the HIFU targeted site and immunohistochemistry indicated immune cell infiltration at the treated/untreated tumor border. Quantitative gene expression analysis indicated that 28 genes associated with T-cell activation were differentially expressed post-HIFU. Conclusions: HIFU appears to be safe and feasible for the treatment of subcutaneous canine solid tumors, resulting in ablation of the targeted tissue. HIFU induced immunostimulatory changes, highlighting the canine cancer patient as an attractive model for studying the effects of focal ablation therapies on the tumor microenvironment.

La Crosse virus (LACV) is the leading cause of pediatric viral encephalitis in North America, and is an important public health pathogen. Historically, studies involving LACV pathogenesis have focused on lineage I strains, but no former work has explored the pathogenesis between or within lineages. Given the absence of LACV disease in endemic regions where a robust entomological risk exists, we hypothesize that some LACV strains are attenuated and demonstrate reduced neuroinvasiveness. Herein, we compared four viral strains representing all three lineages to determine differences in neurovirulence or neuroinvasiveness using three murine models. A representative strain from lineage I was shown to be the most lethal, causing >50% mortality in each of the three mouse studies. However, other strains only presented excessive mortality (>50%) within the suckling mouse neurovirulence model. Neurovirulence was comparable among strains, but viruses differed in their neuroinvasive capacities. Our studies also showed that viruses within lineage III vary in pathogenesis with contemporaneous strains, showing reduced neuroinvasiveness compared to an ancestral strain from the same U.S. state (i.e., Connecticut). These findings demonstrate that LACV strains differ markedly in pathogenesis, and that strain selection is important for assessing vaccine and therapeutic efficacies.

Vaccination remains critical for viral disease outbreak prevention and control, but conventional vaccine development typically involves trade-offs between safety and immunogenicity. We used a recently discovered insect-specific flavivirus as a vector in order to develop an exceptionally safe, flavivirus vaccine candidate with single-dose efficacy. To evaluate the safety and efficacy of this platform, we created a chimeric Zika virus (ZIKV) vaccine candidate, designated Aripo/Zika virus (ARPV/ZIKV). ZIKV has caused immense economic and public health impacts throughout the Americas and remains a significant public health threat. ARPV/ZIKV vaccination showed exceptional safety due to ARPV/ZIKV’s inherent vertebrate host-restriction. ARPV/ZIKV showed no evidence of replication or translation in vitro and showed no hematological, histological or pathogenic effects in vivo. A single-dose immunization with ARPV/ZIKV induced rapid and robust neutralizing antibody and cellular responses, which offered complete protection against ZIKV-induced morbidity, mortality and in utero transmission in immune-competent and -compromised murine models. Splenocytes derived from vaccinated mice demonstrated significant CD4+ and CD8+ responses and significant cytokine production post-antigen exposure. Altogether, our results further support that chimeric insect-specific flaviviruses are a promising strategy to restrict flavivirus emergence via vaccine development.