A prospective Phase 2a pilot study investigating focal percutaneous irreversible electroporation (IRE) ablation by NanoKnife in patients with localised renal cell carcinoma (RCC) with delayed interval tumour resection (IRENE trial)

[Ablative therapy of small renal masses]

Renal cell cancer is nowadays predominantly diagnosed in early stages due to the widespread use of sectional imaging for unrelated symptoms. Small renal masses (<4 cm) feature a largely indolent biology with a very low risk for metastasis or even a benign biology in up to 30% of the cases. Consequently, there is a need for less invasive therapeutic alternatives to nephron-sparing surgery. Meanwhile, there is a broad portfolio of local ablation techniques to treat small renal tumors. These include the extensively studied radiofrequency ablation and cryoablation techniques as well as newer modalities like microwave ablation and irreversible electroporation as more experimental techniques. Tumor ablation can be performed percutaneously under image guidance or laparoscopically. In particular, the percutaneous approach is a less invasive alternative to nephron-sparing surgery with lower risk for complications. Comparative studies and meta-analyses report a higher risk for local recurrence after renal tumor ablation compared to surgery. However, long-term oncological results after treatment of small renal masses are promising and do not seem to differ from partial nephrectomy. The possibility for salvage therapy in case of recurrence also accounts for this finding. Especially old patients with an increased risk of surgical and anesthesiological complications as well as patients with recurrent and multiple hereditary renal cell carcinomas may benefit from tumor ablation. Tumor biopsy prior to intervention is associated with very low morbidity rates and is oncologically safe. It can help to assess the biology of the renal mass and prevent therapy of benign lesions.

Utilization of Stereotactic Ablative Body Radiation Therapy for Intact Renal Cell Carcinoma: Trends in Treatment and Predictors of Outcome

Purpose

Surgery is the standard-of-care treatment in patients with localized renal cell carcinoma (RCC), offering excellent chance of cure. However, there is a subset of patients who are ineligible for surgery and instead manage with ablative therapies, such as stereotactic ablative body radiation therapy (SABR). We used the National Cancer Database to examine trends in the use of SABR for inoperable RCC and identify any predictors of outcome.

Methods and Materials

We queried the National Cancer Database for patients with unresected RCC between 2004 and 2016 who were treated with SABR. Kaplan-Meier analyses were used to determine overall survival. Multivariable Cox regression was used to identify predictors of survival.

Results

We identified 347 patients meeting eligibility criteria. Median age was 74, and the majority of patients were clinical stage T1-2 (80%) and N0 (97%). The median tumor size was 3.8 cm (interquartile range [IQR], 2.8-5.2 cm). Six percent of patients received systemic therapy. The median dose of SABR was 45 Gy (IQR, 35-54 Gy) in 3 fractions (IQR, 1-5 fractions). The median follow-up was 36 months (IQR, 1-156 months). Predictors of decreased survival were age >74, larger tumors, and N1 or M1 disease. Median survival across the entire cohort was 58 months. Median survival was 92 months, 88 months, 44 months, and 26 months for primary tumors ≤2.5 cm, 2.6-3.5 cm, 3.5-5.0 cm, and >5.0 cm, respectively (P < .0001).

Conclusions

SABR is being increasingly used for renal cell carcinoma across the United States with excellent outcomes in smaller tumors.

Tumor Ablation Enhancement by Combining Radiofrequency Ablation and Irreversible Electroporation: An In Vitro 3D Tumor Study

We hypothesized and demonstrated for the first time that significant tumor ablation enhancement can be achieved by combining radiofrequency ablation (RFA) and irreversible electroporation (IRE) using a 3D cervical cancer cell model. Three RFA (43, 50, and 60 °C for 2 min) and IRE protocols (350, 700, and 1050 V/cm) were used to study the combining effect in the 3D tumor cell model. The in vitro experiment showed that both RFA enhanced IRE and IRE enhanced RFA can lead to a significant increase in the size of the ablation zone compared to IRE and RFA alone. It was also noted that the sequence of applying ablation energy (RFA → RE or IRE → RFA) affected the efficacy of tumor ablation enhancement. The electrical conductivity of 3D tumor was found to be increased after preliminary RFA or IRE treatment. This increase in tumor conductivity may explain the enhancement of tumor ablation. Another explanation might be that there is repeat injury to the transitional zone of the first treatment by the second one. The promising results achieved in the study can provide us useful clues about the treatment of large tumors abutting large vessels or bile ducts.

Available ablation energies to treat cT1 renal cell cancer: emerging technologies

Purpose

An increasing interest in percutaneous ablation of renal tumors has been caused by the increasing incidence of SRMs, the trend toward minimally invasive nephron-sparing treatments and the rapid development of local ablative technologies. In the era of shared decision making, patient preference for non-invasive treatments also leads to an increasing demand for image-guided ablation. Although some guidelines still reserve ablation for poor surgical candidates, indications may soon expand as evidence for the use of the two most validated local ablative techniques, cryoablation (CA) and radiofrequency ablation (RFA), is accumulating. Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades, resulting in some new emerging types of ablations.

Methods

A literature search was conducted to identify original research articles investigating the clinical outcomes of new emerging technologies, percutaneous MWA, percutaneous IRE and SABR, in patients with primary cT1 localized renal cell cancer.

Results

Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades. New emerging technologies such as microwave ablation (MWA), irreversible electroporation (IRE) and stereotactic ablative radiotherapy (SABR) seem to be getting ready for prime time.

Conclusion

This topical paper describes the new emerging technologies for cT1 localized renal cell cancer and investigates how they compare to CA and RFA.

Management of Small Renal Masses

With the ubiquitous use of cross-sectional abdominal imaging in recent years, the incidence of small renal masses (SRMs) has increased, and the evaluation and management of SRMs have become important clinical issues. Diagnosing a mass in the early stages theoretically allows for high rates of cure but simultaneously risks overtreatment. In the past 20 years, surgical treatment of SRMs has transitioned from radical nephrectomy for all renal tumors, regardless of size, to elective partial nephrectomy whenever technically feasible. Additionally, newer approaches, including renal mass biopsy, active surveillance for select patients, and renal mass ablation, have been increasingly used. In this chapter, we review the current evidence-based papers covering aspects of the diagnosis and management of SRMs.

Focused Transhepatic Electroporation Mediated by Hypersaline Infusion through the Portal Vein in Rat Model. Preliminary Results on Differential Conductivity

Background

Spread hepatic tumours are not suitable for treatment either by surgery or conventional ablation methods. The aim of this study was to evaluate feasibility and safety of selectively increasing the healthy hepatic conductivity by the hypersaline infusion (HI) through the portal vein. We hypothesize this will allow simultaneous safe treatment of all nodules by irreversible electroporation (IRE) when applied in a transhepatic fashion.

Material and methods

Sprague Dawley (Group A, n = 10) and Athymic rats with implanted hepatic tumour (Group B, n = 8) were employed. HI was performed (NaCl 20%, 3.8 mL/Kg) by trans-splenic puncture. Deionized serum (40 mL/Kg) and furosemide (2 mL/Kg) were simultaneously infused through the jugular vein to compensate hypernatremia. Changes in conductivity were monitored in the hepatic and tumour tissue. The period in which hepatic conductivity was higher than tumour conductivity was defined as the therapeutic window (TW). Animals were monitored during 1-month follow-up. The animals were sacrificed and selective samples were used for histological analysis.

Results

The overall survival rate was 82.4% after the HI protocol. The mean maximum hepatic conductivity after HI was 2.7 and 3.5 times higher than the baseline value, in group A and B, respectively. The mean maximum hepatic conductivity after HI was 1.4 times higher than tumour tissue in group B creating a TW to implement selective IRE.

Conclusions

HI through the portal vein is safe when the hypersaline overload is compensated with deionized serum and it may provide a TW for focused IRE treatment on tumour nodules.

Irreversible Electroporation: A Novel Ultrasound-guided Modality for Non-thermal Tumor Ablation

Ultrasound-guided tumor ablation techniques have been proven to be highly effective and minimally invasive in the treatment of many diseases. Traditional approaches to ablation include microwave and radiofrequency techniques, cryotherapy, and high-intensity focused ultrasound. However, these methods are prone to heat-sink effects that can diminish the effectiveness of treatment and damage adjacent structures, such as bile ducts, blood vessels, the gallbladder, or bowel. Irreversible electroporation (IRE) is a non-thermal ablation modality that induces cell apoptosis through the application of high-voltage current. IRE is not limited by many of the limitation which affects conventional tumor ablation techniques, and is particularly useful in treating sensitive areas of the body. The article reviews the basics of ultrasound-guided technology, including its clinical applications and effectiveness in the treatment of tumors.

[Focal therapy for small renal masses : Observation, ablation or surgery]

BACKGROUND

The rising incidence of renal cell carcinoma, its more frequent early detection (stage T1a) and the increasing prevalence of chronic renal failure with higher morbidity and shorter life expectancy underscore the need for multimodal focal nephron-sparing therapy.

DISCUSSION

During the past decade, the gold standard shifted from radical to partial nephrectomy. Depending on the surgeon's experience, the patient's constitution and the tumor's location, the intervention can be performed laparoscopically with the corresponding advantages of lower invasiveness. A treatment alternative can be advantageous for selected patients with high morbidity and/or an increased risk of complications associated with anesthesia or surgery. Corresponding risk stratification necessitates previous confirmation of the small renal mass (cT1a) by histological examination of biopsy samples. Active surveillance represents a controlled delay in the initiation of treatment.

RESULTS

Percutaneous radiofrequency ablation (RFA) and laparoscopic cryoablation are currently the most common treatment alternatives, although there are limitations particularly for renal tumors located centrally near the hilum. More recent ablation procedures such as high intensity focused ultrasound (HIFU), irreversible electroporation, microwave ablation, percutaneous stereotactic ablative radiotherapy and high-dose brachytherapy have high potential in some cases but are currently regarded as experimental for the treatment of renal cell carcinoma.

Decision Making: Thermal Ablation Options for Small Renal Masses

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

Irreversible Electroporation for Locally Advanced Pancreatic Cancer: Where Do We Stand in 2017?

Pancreatic adenocarcinoma has a very poor prognosis. Complete surgical resection remains the only current curative treatment. Locally advanced pancreatic cancers are considered as unresectable because of involvement of celiac and/or mesenteric vessels. Irreversible electroporation has recently been introduced to induce permanent cell death by apoptosis. Irreversible electroporation is a nonthermal cell-destruction technique that was claimed to allow destruction of cancerous cells with less damage to surrounding supporting connective tissues with collagenic structure (such as nearby blood vessels, biliary ducts, and nerves) than other types of treatment. Applications on pancreatic adenocarcinoma seem promising, and this article is an up-to-date review of the first results.

Irreversible Electroporation for the Ablation of Renal Cell Carcinoma: A Prospective, Human, In Vivo Study Protocol (IDEAL Phase 2b)

Background

Irreversible electroporation (IRE) is an emerging technique delivering electrical pulses to ablate tissue, with the theoretical advantage to overcome the main shortcomings of conventional thermal ablation. Recent short-term research showed that IRE for the ablation of renal masses is a safe and feasible treatment option. In an ablate and resect design, histopathological analysis 4 weeks after radical nephrectomy demonstrated that IRE-targeted renal tumors were completely covered by ablation zone. In order to develop a validated long-term IRE follow-up study, it is essential to obtain clinical confirmation of the efficacy of this novel technology. Additionally, follow-up after IRE ablation obliges verification of a suitable imaging modality.

Objective

The objectives of this study are the clinical efficacy and safety of IRE ablation of renal masses and to evaluate the use of cross-sectional imaging modalities in the follow-up after IRE in renal tumors. This study conforms to the recommendations of the IDEAL Collaboration and can be categorized as a phase 2B exploration trial.

Methods

In this prospective clinical trial, IRE will be performed in 20 patients aged 18 years and older presenting with a solid enhancing small renal mass (SRM) (≤4 cm) who are candidates for ablation. Magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) will be performed at 1 day pre-IRE, and 1 week post-IRE. Computed tomography (CT), CEUS, and MRI will be performed at 3 months, 6 months, and 12 months post-IRE.

Results

Presently, recruitment of patients has started and the first inclusions are completed. Preliminary results and outcomes are expected in 2018.

Conclusions

To establish the position of IRE ablation for treating renal tumors, a structured stepwise assessment in clinical practice is required. This study will offer fundamental knowledge on the clinical efficacy of IRE ablation for SRMs, potentially positioning IRE as ablative modality for renal tumors and accrediting future research with long-term follow-up.

Trial Registration

Clinicaltrials.gov registration number NCT02828709; https://clinicaltrials.gov/ct2/show/NCT02828709 (archived by WebCite at http://www.webcitation.org/6nmWK7Uu9). Dutch Central Committee on Research Involving Human Subjects NL56935.018.16

Irreversible Electroporation (IRE) in Renal Tumors

Small renal masses (SRMs) have been traditionally managed with surgical resection. Minimally invasive nephron-sparing treatment methods are preferred to avoid harmful consequences of renal insufficiency, with partial nephrectomy (PN) considered the gold standard. With increase in the incidence of the SRMs and evolution of ablative technologies, percutaneous ablation is now considered a viable treatment alternative to surgical resection with comparable oncologic outcomes and better nephron-sparing property. Traditional thermal ablative techniques suffer from unique set of challenges in treating tumors near vessels or critical structures. Irreversible electroporation (IRE), with its non-thermal nature and connective tissue-sparing properties, has shown utility where traditional ablative techniques face challenges. This review presents the role of IRE in renal tumors based on the most relevant published literature on the IRE technology, animal studies, and human experience.

Low temperature plasmas as emerging cancer therapeutics: the state of play and thoughts for the future

The field of plasma medicine has seen substantial advances over the last decade, with applications developed for bacterial sterilisation, wound healing and cancer treatment. Low temperature plasmas (LTPs) are particularly suited for medical purposes since they are operated in the laboratory at atmospheric pressure and room temperature, providing a rich source of reactive oxygen and nitrogen species (RONS). A great deal of research has been conducted into the role of reactive species in both the growth and treatment of cancer, where long-established radio- and chemo-therapies exploit their ability to induce potent cytopathic effects. In addition to producing a plethora of RONS, LTPs can also create strong electroporative fields. From an application perspective, it has been shown that LTPs can be applied precisely to a small target area. On this basis, LTPs have been proposed as a promising future strategy to accurately and effectively control and eradicate tumours. This review aims to evaluate the current state of the literature in the field of plasma oncology and highlight the potential for the use of LTPs in combination therapy. We also present novel data on the effect of LTPs on cancer stem cells, and speculatively outline how LTPs could circumvent treatment resistance encountered with existing therapeutics.

Irreversible Electroporation (IRE): Standardization of Terminology and Reporting Criteria for Analysis and Comparison

BACKGROUND

Irreversible electroporation (IRE) as newer ablation modality has been introduced and its clinical niche is under investigation. At present just one IRE system has been approved for clinical use and is currently commercially available (NanoKnife® system). In 2014, the International Working Group on Image-Guided Tumor Ablation updated the recommendation about standardization of terms and reporting criteria for image-guided tumor ablation. The IRE method is not covered in detail. But the non-thermal IRE method and the NanoKnife System differ fundamentally from established ablations techniques, especially thermal approaches, e.g. radio frequency ablation (RFA).

MATERIAL/METHODS

As numerous publications on IRE with varying terminology exist so far - with numbers continuously increasing - standardized terms and reporting criteria of IRE are needed urgently. The use of standardized terminology may then allow for a better inter-study comparison of the methodology applied as well as results achieved.

RESULTS

Thus, the main objective of this document is to supplement the updated recommendation for image-guided tumor ablation by outlining a standardized set of terminology for the IRE procedure with the NanoKnife Sytem as well as address essential clinical and technical informations that should be provided when reporting on IRE tumor ablation.

CONCLUSIONS

We emphasize that the usage of all above recommended reporting criteria and terms can make IRE ablation reports comparable and provide treatment transparency to assess the current value of IRE and provide further development.

The Past, Present, and Future in Management of Small Renal Masses

Management of small renal masses (SRMs) is currently evolving due to the increased incidence given the ubiquity of cross-sectional imaging. Diagnosing a mass in the early stages theoretically allows for high rates of cure but simultaneously risks overtreatment. New consensus guidelines and treatment modalities are changing frequently. The multitude of information currently available shall be summarized in this review. This summary will detail the historic surgical treatment of renal cell carcinoma with current innovations, the feasibility and utility of biopsy, the efficacy of ablative techniques, active surveillance, and use of biomarkers. We evaluate how technology may be used in approaching the small renal mass in order to decrease morbidity, while keeping rates of overtreatment to a minimum.

First Delayed Resection Findings After Irreversible Electroporation (IRE) of Human Localised Renal Cell Carcinoma (RCC) in the IRENE Pilot Phase 2a Trial

INTRODUCTION

It is postulated that focal IRE affords complete ablation of soft-tissue tumours while protecting the healthy peritumoral tissue. Therefore, IRE may be an interesting option for minimally invasive, kidney-tissue-sparing, non-thermal ablation of renal tumours.

AIM

With this current pilot study ("IRENE trial"), we present the first detailed histopathological data of IRE of human RCC followed by delayed tumour resection. The aim of this interim analysis of the first three patients was to investigate the ablation efficiency of percutaneous image-guided focal IRE in RCC, to assess whether a complete ablation of T1a RCC and tissue preservation with the NanoKnife system is possible and to decide whether the ablation parameters need to be altered.

METHODS

Following resection 4 weeks after percutaneous IRE, the success of ablation and detailed histopathological description were used to check the ablation parameters.

RESULTS

The IRE led to a high degree of damage to the renal tumours (1 central, 2 peripheral; size range 15-17 mm). The postulated homogeneous, isomorphic damage was only partly confirmed. We found a zonal structuring of the ablation zone, negative margins and, enclosed within the ablation zone, very small tumour residues of unclear malignancy.

CONCLUSION

According to these initial, preliminary study results of the first three renal cases, a new zonal distribution of IRE damage was described and the curative intended, renal saving focal ablation of localised RCC below <3 cm by percutaneous IRE by the NanoKnife system appears to be possible, but needs further, systematic evaluation for this treatment method and treatment protocol.