A Multi-centre, Single Arm, Non-randomized, Prospective European Trial to Evaluate the Safety and Efficacy of the HistoSonics System in the Treatment of Primary and Metastatic Liver Cancers (#HOPE4LIVER)

Precision oncology: The role of minimally-invasive ablation therapy in the management of solid organ tumors

Solid organ tumors present a significant healthcare challenge, both economically and logistically, due to their high incidence and treatment complexity. In 2023, out of the 1.9 million new cancer cases in the United States, over 73% were solid organ tumors. Ablative therapies offer minimally invasive solutions for malignant tissue destruction in situ, often with reduced cost and morbidity compared to surgical resection. This review examines the current Food and Drug Administration-approved locoregional ablative therapies (radiofrequency, microwave, cryogenic, high-intensity focused ultrasound, histotripsy) and their evolving role in cancer care. Data were collected through a comprehensive survey of the PubMed-indexed literature on tumor ablation techniques, their clinical indications, and outcomes. Over time, emerging clinical data will help establish these therapies as the standard of care in solid organ tumor treatment, supported by improved long-term outcomes and progression-free survival.

Revolutionizing cardiovascular care: the power of histotripsy

Histotripsy, an innovative ultrasonic technique, is poised to transform the landscape of cardiovascular disease management. This review explores the multifaceted applications of histotripsy across various domains of cardiovascular medicine. In thrombolysis, histotripsy presents a non-invasive, drug-free, and precise method for recanalizing blood vessels obstructed by clots, minimizing the risk of vessel damage and embolism. Additionally, histotripsy showcases its potential in congenital heart defect management, offering a promising alternative to invasive procedures by creating intracardiac communications noninvasively. For patients with calcified aortic stenosis, histotripsy demonstrates its effectiveness in softening calcified bioprosthetic valves, potentially revolutionizing valve interventions. In the realm of arrhythmias, histotripsy could play an important role in scar-based ventricular tachycardia ablation, eliminating channel-like isthmuses of slowly conducting myocardium. Histotripsy`s potential applications also extend to structural heart interventions, enabling the safe sectioning of basal chordae and potentially addressing mitral regurgitation. Furthermore, it showcases its versatility by safely generating ventricular septal defects, providing a non-invasive means of creating intracardiac communications in neonates with congenital heart disease. Yet, most supporting studies are in-vitro or animal studies and there are possible challenges in translating experimental data on cardiac histotripsy to the clinical level. As histotripsy continues to evolve and mature, its remarkable potential in cardiovascular disease management holds promise for improving patient outcomes and reducing the burden of invasive procedures in the field of cardiology.

Histotripsy-A Novel and Intriguing Technique of Liver Ablation

This article discusses the use of histotripsy as a noninvasive method for tumor ablation that involves mechanical destruction of tissues without the generation of heat, resulting in accurate and precise treatment without surrounding tissue damage.

The Role of Surgery in "Oligometastatic" Pancreas Cancer

The majority of patients diagnosed with pancreatic cancer already have metastatic disease at the time of presentation, which results in a 5-year survival rate of only 13%. However, multiagent chemotherapy regimens can stabilize the disease in select patients with limited metastatic disease. For such patients, a combination of curative-intent therapy and systemic therapy may potentially enhance outcomes compared to using systemic therapy alone. Of note, the evidence supporting this approach is primarily derived from retrospective studies and may carry a significant selection bias. Looking ahead, ongoing prospective trials are exploring the efficacy of curative-intent therapy in managing oligometastatic pancreatic cancer and the implementation of treatment strategies based on specific biomarkers. The emergence of these trials, coupled with the development of less invasive therapeutic modalities, provides hope for patients with oligometastatic pancreatic cancer.

Oncologic Outcomes after Percutaneous Ablation for Colorectal Liver Metastases: An Updated Comprehensive Review

Colorectal cancer is a major cause of cancer-related mortality, with liver metastases occurring in over a third of patients, and is correlated with poor prognosis. Despite surgical resection being the primary treatment option, only about 20% of patients qualify for surgery. Current guidelines recommend thermal ablation either alone or combined with surgery to treat limited hepatic metastases, provided that all visible disease can be effectively eradicated. Several ablation modalities, including radiofrequency ablation, microwave ablation, cryoablation, irreversible electroporation and histotripsy, are part of the percutaneous ablation armamentarium. Thermal ablation, including radiofrequency, microwave ablation and cryoablation, can offer local tumor control rates comparable to limited resection for selected tumors that can be ablated with margins. This review aims to encapsulate the current clinical evidence regarding the efficacy and oncologic outcomes after percutaneous ablation for the treatment of colorectal liver metastatic disease.

The #HOPE4LIVER Single-Arm Pivotal Trial for Histotripsy of Primary and Metastatic Liver Tumors

Background Histotripsy is a nonthermal, nonionizing, noninvasive, focused US technique that relies on cavitation for mechanical tissue breakdown at the focal point. Preclinical data have shown its safety and technical success in the ablation of liver tumors. Purpose To evaluate the safety and technical success of histotripsy in destroying primary or metastatic liver tumors. Materials and Methods The parallel United States and European Union and England #HOPE4LIVER trials were prospective, multicenter, single-arm studies. Eligible patients were recruited at 14 sites in Europe and the United States from January 2021 to July 2022. Up to three tumors smaller than 3 cm in size could be treated. CT or MRI and clinic visits were performed at 1 week or less preprocedure, at index-procedure, 36 hours or less postprocedure, and 30 days postprocedure. There were co-primary end points of technical success of tumor treatment and absence of procedure-related major complications within 30 days, with performance goals of greater than 70% and less than 25%, respectively. A two-sided 95% Wilson score CI was derived for each end point. Results Forty-four participants (21 from the United States, 23 from the European Union or England; 22 female participants, 22 male participants; mean age, 64 years ± 12 [SD]) with 49 tumors were enrolled and treated. Eighteen participants (41%) had hepatocellular carcinoma and 26 (59%) had non-hepatocellular carcinoma liver metastases. The maximum pretreatment tumor diameter was 1.5 cm ± 0.6 and the maximum post-histotripsy treatment zone diameter was 3.6 cm ± 1.4. Technical success was observed in 42 of 44 treated tumors (95%; 95% CI: 84, 100) and procedure-related major complications were reported in three of 44 participants (7%; 95% CI: 2, 18), both meeting the performance goal. Conclusion The #HOPE4LIVER trials met the co-primary end-point performance goals for technical success and the absence of procedure-related major complications, supporting early clinical adoption. Clinical trial registration nos. NCT04572633, NCT04573881 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Nezami and Georgiades in this issue.

Therapeutic ultrasound transducer technology and monitoring techniques: a review with clinical examples

The exponential growth of therapeutic ultrasound applications demonstrates the power of the technology to leverage the combinations of transducer technology and treatment monitoring techniques to effectively control the preferred bioeffect to elicit the desired clinical effect.Objective: This review provides an overview of the most commonly used bioeffects in therapeutic ultrasound and describes existing transducer technologies and monitoring techniques to ensure treatment safety and efficacy.Methods and materials: Literature reviews were conducted to identify key choices that essential in terms of transducer design, treatment parameters and procedure monitoring for therapeutic ultrasound applications. Effective combinations of these options are illustrated through descriptions of several clinical indications, including uterine fibroids, prostate disease, liver cancer, and brain cancer, that have been successful in leveraging therapeutic ultrasound to provide effective patient treatments.Results: Despite technological constraints, there are multiple ways to achieve a desired bioeffect with therapeutic ultrasound in a target tissue. Visualizations of the interplay of monitoring modality, bioeffect, and applied acoustic parameters are presented that demonstrate the interconnectedness of the field of therapeutic ultrasound. While the clinical indications explored in this review are at different points in the clinical evaluation path, based on the ever expanding research being conducted in preclinical realms, it is clear that additional clinical applications of therapeutic ultrasound that utilize a myriad of bioeffects will continue to grow and improve in the coming years.Conclusions: Therapeutic ultrasound will continue to improve in the next decades as the combination of transducer technology and treatment monitoring techniques will continue to evolve and be translated in clinical settings, leading to more personalized and efficient therapeutic ultrasound mediated therapies.

Interventional Oncology: 2024 Update

Interventional Oncology (IO) stands at the forefront of transformative cancer care, leveraging advanced imaging technologies and innovative interventions. This narrative review explores recent developments within IO, highlighting its potential impact facilitated by artificial intelligence (AI), personalized medicine and imaging innovations. The integration of AI in IO holds promise for accelerating tumour detection and characterization, guiding treatment strategies and refining predictive models. Imaging modalities, including functional MRI, PET and cone beam CT are reshaping imaging and precision. Navigation, fusion imaging, augmented reality and robotics have the potential to revolutionize procedural guidance and offer unparalleled accuracy. New developments are observed in embolization and ablative therapies. The pivotal role of genomics in treatment planning, targeted therapies and biomarkers for treatment response prediction underscore the personalization of IO. Quality of life assessment, minimizing side effects and long-term survivorship care emphasize patient-centred outcomes after IO treatment. The evolving landscape of IO training programs, simulation technologies and workforce competence ensures the field's adaptability. Despite barriers to adoption, synergy between interventional radiologists' proficiency and technological advancements hold promise in cancer care.

Histotripsy - hype or hope? Review of innovation and future implications

BACKGROUND

Histotripsy is a novel, ultrasound-based ablative technique that was recently approved by the Food and Drug Administration for hepatic targets. It has several promising additional theoretical applications that need to be further investigated. Its basis as a nonthermal cavitational technology presents a unique advantage over existing thermal ablation techniques in maximizing local effects while minimizing adjacent tissue destruction. This review discusses the technical basis and current preclinical and clinical data surrounding histotripsy.

METHODS

This was a comprehensive review of the literature surrounding histotripsy and the clinical landscape of existing ablative techniques using the PubMed database. A technical summary of histotripsy's physics and cellular effect was described. Moreover, data from recent clinical trials, including Hope4Liver, and future implications regarding its application in various benign and malignant conditions were discussed.

RESULTS

Preclinical data demonstrated the efficacy of histotripsy ablation in various organ systems with minimal tissue destruction when examined at the histologic level. The first prospective clinical trial involving histotripsy in hepatocellular carcinoma and liver metastases, Hope4Liver, demonstrated a primary efficacy of 95.5% with minimal complications (6.8%). This efficacy was replicated in similar trials involving the treatment of benign prostatic hypertrophy.

DISCUSSION

In addition to the noninvasive ability to ablate lesions in the liver, histotripsy offers additional therapeutic potential. Early data suggest a potential complementary therapeutic effect when combining histotripsy with existing immunologic therapies because of the technology's theoretical ability to sensitize tumors to adaptive immunity. As with most novel therapies, the effect of histotripsy on the oncologic therapeutic landscape remains uncertain.

Image-Guided Ablation of Renal Masses: Challenges to Produce High-Quality Evidence and Future Directions

Image-guided ablation (IGA) is a rapidly developing field in interventional oncology. There is some evidence suggesting IGA's non-inferiority compared with partial or radical nephrectomy for the treatment of small renal masses (SRM). However, these are mostly limited to retrospective cohort studies. This review article outlines the evidence comparing IGA to partial nephrectomy by collating the different survival measures and evaluates the challenges of producing clinical trials and high-quality evidence. The main challenges are due to the heterogeneity of SRM, patient selection bias, unstandardized endpoint and outcomes, and the lack of global practice standards. Despite the evidence thus far demonstrating that IGA stands as a non-inferior treatment modality for SRMs, exhibiting favorable short- and long-term outcomes, further robust research is needed to integrate ablation techniques into routine clinical practice with a multidisciplinary approach. There is emerging evidence that suggests randomized controlled trial in SRMs is possible, and technologies such as histotripsy as well as artificial intelligence are used in IGA.

Investigating cell death responses associated with histotripsy ablation of canine osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most frequently occurring primary bone tumor in dogs and people and innovative treatment options are profoundly needed. Histotripsy is an emerging tumor ablation modality, and it is essential for the clinical translation of histotripsy to gain knowledge about the outcome of nonablated tumor cells that could remain postablation. The objective of this study was to characterize the cell death genetic signature and proliferation response of canine OS cells post a near complete histotripsy ablation (96% ± 1.5) and to evaluate genetic cell death signatures associated with histotripsy ablation and OS in vivo.

METHODS

In the current study, we ablated three canine OS cell lines with a histotripsy dose that resulted in near complete ablation to allow for a viable tumor cell population for downstream analyses. To assess the in vivo cell death genetic signature, we characterized cell death genetic signature in histotripsy-ablated canine OS tumors collected 24-h postablation.

RESULTS

Differential gene expression changes observed in the 4% viable D17 and D418 cells, and histotripsy-ablated OS tumor samples, but not in Abrams cells, were associated with immunogenic cell death (ICD). The 4% viable OS cells demonstrated significantly reduced proliferation, compared to control OS cells, in vitro.

CONCLUSION

Histotripsy ablation of OS cell lines leads to direct and potentially indirect cell death as evident by, reduced proliferation in remaining viable OS cells and cell death genetic signatures suggestive of ICD both in vitro and in vivo.

New Insights on Liver-Directed Therapies in Hepatocellular Carcinoma

The incidence of hepatocellular carcinoma (HCC) has been increasing over the past decades, but improvements in systemic and locoregional therapies is increasing survival. Current locoregional treatment options include ablation, transarterial chemoembolization (TACE), transarterial radioembolization (TARE), and stereotactic body radiotherapy (SBRT). There is ongoing research regarding the combination of systemic and local therapies to maximize treatment effect as well as in new non-invasive, image-guided techniques such as histotripsy. There is also active research in optimizing the delivery of therapy to tumors via nanostructures and viral-vector-mediated gene therapies. In many cases, patients require a combination of therapies to achieve tumor control and prolong survival. This article provides an overview of the most common liver-directed therapies for HCC as well as insight into more recent advances in personalized medicine and emerging techniques.

Percutaneous treatment of renal tumours

Image-guided ablation is an accepted treatment option in the management of renal cell carcinoma. Percutaneous renal ablation offers the possibility of minimally invasive treatment while attempting to preserve renal function. Over the past several years there have been advances in tools and techniques that have improved procedure safety and patient outcomes. This article provides an updated comprehensive review of percutaneous ablation in the management of renal cell carcinoma.

Liver-Directed Therapy for Neuroendocrine Tumor Metastases in the Era of Peptide Receptor Radionuclide Therapy

OPINION STATEMENT

The treatment of neuroendocrine neoplasm (NEN) liver metastases involves a multidisciplinary approach that includes liver-directed therapies (LDT) and systemic treatments, such as peptide receptor radionuclide therapy (PRRT). LDT has demonstrated efficacy in rapidly reducing tumor bulk, improving symptoms, and delaying disease progression. Interventional radiologists should be consulted prior to switching therapy for patients with progressive or symptomatic neuroendocrine tumor liver metastases. Long-term follow-up data on the safety of Yttrium-90 radioembolization before and after PRRT remain limited. Therefore, a more conservative approach may be to preferentially employ transarterial embolization (TAE) or transarterial chemoembolization (TACE) for patients' somatostatin receptor-avid disease who may be future candidates for PRRT. Notable exceptions where radioembolization may be a preferred treatment strategy may be patients with history of biliary tract instrumentation, asymmetric unilobar disease distribution, and rapidly progressive diffuse liver involvement. Selection of local treatment modality, sequencing, and combination of LDT with systemic therapy require further investigation.

A review of the development of histotripsy for extremity tumor ablation with a canine comparative oncology model to inform human treatments

Cancer is a devasting disease resulting in millions of deaths worldwide in both humans and companion animals, including dogs. Treatment of cancer is complex and challenging and therefore often multifaceted, as in the case of osteosarcoma (OS) and soft tissue sarcoma (STS). OS predominantly involves the appendicular skeleton and STS commonly develops in the extremities, resulting in treatment challenges due to the need to balance wide-margin resections to achieve local oncological control against the functional outcomes for the patient. To achieve wide tumor resection, invasive limb salvage surgery is often required, and the patient is at risk for numerous complications which can ultimately lead to impaired limb function and mobility. The advent of tumor ablation techniques offers the exciting potential of developing noninvasive or minimally invasive treatment options for extremity tumors. One promising innovative tumor ablation technique with strong potential to serve as a noninvasive limb salvage treatment for extremity tumor patients is histotripsy. Histotripsy is a novel, noninvasive, non-thermal, and non-ionizing focused ultrasound technique which uses controlled acoustic cavitation to mechanically disintegrate tissue with high precision. In this review, we present the ongoing development of histotripsy as a non-surgical alternative for extremity tumors and highlight the value of spontaneously occurring OS and STS in the pet dog as a comparative oncology research model to advance this field of histotripsy research.

The use of histotripsy as intratumoral immunotherapy beyond tissue ablation-the rationale for exploring the immune effects of histotripsy

Mechanical high-intensity focused ultrasound (M-HIFU), which includes histotripsy, is a non-ionizing, non-thermal ablation technology that can be delivered by noninvasive methods. Because acoustic cavitation is the primary mechanism of tissue disruption, histotripsy is distinct from the conventional HIFU techniques resulting in hyperthermia and thermal injury. Phase I human trials have shown the initial safety and efficacy of histotripsy in treating patients with malignant liver tumors. In addition to tissue ablation, a promising benefit of M-HIFU has been stimulating a local and systemic antitumor immune response in preclinical models and potentially in the Phase I trial. Preclinical studies combining systemic immune therapies appear promising, but clinical studies of combinations have been complicated by systemic toxicities. Consequently, combining M-HIFU with systemic immunotherapy has been demonstrated in preclinical models and may be testing in future clinical studies. An additional alternative is to combine intratumoral M-HIFU and immunotherapy using microcatheter-placed devices to deliver both M-HIFU and immunotherapy intratumorally. The promise of M-HIFU as a component of anti-cancer therapy is promising, but as forms of HIFU are tested in preclinical and clinical studies, investigators should report not only the parameters of the energy delivered but also details of the preclinical models to enable analysis of the immune responses. Ultimately, as clinical trials continue, clinical responses and immune analysis of patients undergoing M-HIFU including forms of histotripsy will provide opportunities to optimize clinical responses and to optimize application and scheduling of M-HIFU in the context of the multi-modality care of the cancer patient.

Contrast-Enhanced Imaging of Histotripsy Bubble Clouds Using Chirp-Coded Excitation and Volterra Filtering

Histotripsy is a focused ultrasound therapy that ablates tissue via bubble cloud activity. Real-time ultrasound image guidance is used to ensure safe and effective treatment. Plane-wave imaging enables tracking of histotripsy bubble clouds at a high frame rate but lacks adequate contrast. Furthermore, bubble cloud hyperechogenicity is reduced in abdominal targets, making the development of contrast-specific sequences for deep-seated targets an active area of research. Chirp-coded subharmonic imaging was reported previously to enhance histotripsy bubble cloud detection by a modest 4-6 dB compared to the conventional sequence. Incorporating additional steps into the signal processing pipeline could enhance bubble cloud detection and tracking. In this study, we evaluated the feasibility of combining chirp-coded subharmonic imaging with Volterra filtering for enhancing bubble cloud detection in vitro. Chirped imaging pulses were used to track bubble clouds generated in scattering phantoms at a 1-kHz frame rate. Fundamental and subharmonic matched filters were applied to the received radio frequency signals, followed by a tuned Volterra filter to extract bubble-specific signatures. For subharmonic imaging, the application of the quadratic Volterra filter improved the contrast-to-tissue ratio from 5.18 ± 1.29 to 10.90 ± 3.76 dB, relative to the application of the subharmonic matched filter. These findings demonstrate the utility of the Volterra filter for histotripsy image guidance.