Irreversible Electroporation for Surgical Renal Masses in Solitary Kidneys: Short-Term Interventional and Functional Outcome

Percutaneous irreversible electroporation of renal cell carcinomas in an acquired solitary kidney: A primary study

OBJECTIVE

To evaluate the postoperative complications and prognosis of renal cell carcinoma (RCC) in a solitary kidney after irreversible electroporation (IRE).

MATERIALS AND METHODS

A total of 8 patients with 9 RCCs in a solitary kidney treated with computed tomography (CT)-guided IRE from February 2017 to September 2020 were retrospectively analyzed. Follow-up included contrast-enhanced CT or magnetic resonance imaging examinations at 1 day, 1 week, 1 month, 3 months, 6 months, 12 months, and each year after IRE and the evaluation of the incidence of postoperative complications, renal function changes, local tumor recurrence, and metastasis.

RESULTS

Technical success was achieved in all 8 patients treated with IRE. No serious complications were observed. Recurrence or metastasis occurred in two patients. The renal function and hemoglobin values of the 8 patients before treatment and at the last follow-up showed no significant difference.

CONCLUSION

IRE is a relatively effective, safe, and feasible treatment for RCCs in a solitary kidney, which improved the effective survival and quality of life of these patients.

The Safety and Efficacy of Nanosecond Pulsed Electric Field in Patients With Hepatocellular Carcinoma: A Prospective Phase 1 Clinical Study Protocol

BACKGROUND

Hepatocellular carcinoma (HCC) is a highly aggressive malignancy. Irreversible electroporation (IRE) is an ablative modality that uses high-voltage electrical pulses to permeabilize the cell membrane leading to cell necrosis. Unlike traditional thermal ablation, IRE is hardly affected by the "heat-sink" effect and can prevent damage of the adjacent vital structures. Nanosecond pulsed electric field (nsPEF) is a new IRE technique using ultra-short pulses (nanosecond duration), can not only penetrate the cell membranes, but also act on the organelles. Sufficient preclinical researches have shown that nsPEF can eliminate HCC without damaging vital organs, and elicit potent anti-tumor immune response.

OBJECTIVE

This is the first clinical study to evaluate feasibility, efficacy, and safety of nsPEF for the treatment of HCC, where thermal ablation is unsuitable due to proximity to critical structures.

METHODS AND ANALYSIS

We will conduct an open-labeled, single-arm, prospective, multicenter, and objective performance criteria trial. One hundred and ninety-two patients with HCC, in which the tumor is located immediately (<0.5 cm) adjacent to the portal vein, hepatic veins, bile duct, gastrointestinal tract, or diaphragm, will be enrolled among 4 academic medical centers. The primary outcomes are the rate of complete ablation at 1 month and adverse events. Secondary outcomes include technical success, technique efficacy, nsPEF procedural characteristics, local tumor progression, and local progression-free survival.

ETHICS AND DISSEMINATION

The trial will be conducted according to the ethical principles of the Declaration of Helsinki and has been approved by the ethics committee of all participating centers. The results of this study will be published in peer-reviewed scientific journals and presented at relevant academic conferences.

CONCLUSIONS

This study is the Phase 1 clinical trial to evaluate the efficacy and safety of nsPEF in patients with HCC at high-risk locations where thermal ablation is contra-indicated. The results may expand the options and offer an alternative therapy for HCC.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT04309747.

Irreversible electroporation in renal tumours: A systematic review of safety and early oncological outcomes

We review the safety and early oncological outcomes of irreversible electroporation (IRE), a novel non-thermal ablation technique, in small renal masses (SRMs). Following PROSPERO registration (CRD42020197943), a systematic search of MEDLINE, EMBASE and SCOPUS databases according to PRISMA guidelines was performed. Critical appraisal of the included studies was performed using the Newcastle-Ottawa Scale. Of 224 articles screened, 10 met the inclusion criteria. In total, 83 patients were identified. Except for one cohort study (n = 41), the remaining studies were case series of n < 10. Follow up was <12 months in 7/10 articles (range 3–34 months). About 10/10 articles reported safety outcomes. There were no 30-day mortalities. The most frequently reported adverse events were transient haematuria (11/83) and asymptomatic perirenal haematomas (7/83). About 62/63 patients with reported length of stay were discharged within 24 h. No significant long-term changes in renal function were reported. About 7/10 articles reported oncological outcomes. Only one article assessed histopathological outcomes, whilst the remaining studies used cross-sectional imaging modalities to assess efficacy, recurrence or disease progression. About 4/7 patients with histopathology outcomes, showed complete response (CR). About 43/55 patients with radiological outcomes showed CR. No mortalities were reported due to SRMs. These initial findings support IRE as safe and feasible in managing SRMs. However, results from larger studies with longer follow-up are needed to evaluate oncological outcomes and compare these with other ablation methods.

Irreversible Electroporation for the Treatment of Small Renal Masses: 5-Year Outcomes

Introduction: Irreversible electroporation (IRE) is a nonthermal ablative technology that applies high-voltage short-pulse electrical current to create cellular membrane nanopores and ultimately results in apoptosis. This is thought to overcome thermal limitations of other ablative technologies. We report 5-year oncologic outcomes of percutaneous IRE for small renal masses. Patients and Methods: A single-institution retrospective review of cT1a renal masses treated with IRE from April 2013 to December 2019 was performed. Those with <1 month follow-up were excluded. IRE was performed with the NanoKnife^© System (Angiodynamics, Latham, NY). Renal mass biopsy was obtained before or during ablation in most circumstances; biopsy was excluded in some patients because of concern for IRE probe displacement. Postablation guideline-based surveillance imaging was performed. Initial treatment failure was defined as persistent tumor enhancement on first post-treatment imaging. Survival analysis was performed through the Kaplan-Meier method for effectively treated tumors (SPSS; IBM, Armonk, NY). Results: IRE was used to treat 48 tumors in 47 patients. Twenty-two per 48 tumors (45.8%) were biopsy-confirmed renal cell carcinoma (RCC). No complications ≥ Clavien Grade III occurred and 36 patients (76.6%) were discharged the same day. Initial treatment success rate was 91.7% (n = 44/48); three treatment failures were managed with salvage radiofrequency ablation and one with robotic partial nephrectomy. Median follow-up was 50.4 months (interquartile range 29.0-65.5). The 5-year local recurrence-free survival was 81.4% in biopsy-confirmed RCC patients and 81.0% in all patients. Five-year metastasis-free survival was 93.3% and 97.1%, respectively, and 5-year overall survival was 92.3% and 90.6%, respectively. Five-year cancer-specific survival was 100% for both biopsy-confirmed RCC and all patient groups. Conclusions: IRE has low morbidity, but suboptimal intermediate-term oncologic outcomes compared with conventional thermal ablation techniques for small low-complexity tumors. Use of IRE should be restricted to select cases.

Frailty predicts outcome of partial nephrectomy and guides treatment decision towards active surveillance and tumor ablation

PURPOSE

To examine frailty and comorbidity as predictors of outcome of nephron sparing surgery (NSS) and as decision tools for identifying candidates for active surveillance (AS) or tumor ablation (TA).

METHODS

Frailty and comorbidity were assessed using the modified frailty index of the Canadian Study of Health and Aging (11-CSHA) and the age-adjusted Charlson-Comorbidity Index (aaCCI) as well as albumin and the radiological skeletal-muscle-index (SMI) in a cohort of n = 447 patients with localized renal masses. Renal tumor anatomy was classified according to the RENAL nephrometry system. Regression analyses were performed to assess predictors of surgical outcome of patients undergoing NSS as well as to identify possible influencing factors of patients undergoing alternative therapies (AS/TA).

RESULTS

Overall 409 patient underwent NSS while 38 received AS or TA. Patients undergoing TA/AS were more likely to be frail or comorbid compared to patients undergoing NSS (aaCCI: p < 0.001, 11-CSHA: p < 0.001). Gender and tumor complexity did not vary between patients of different treatment approach. 11-CSHA and aaCCI were identified as independent predictors of major postoperative complications (11-CSHA ≥ 0.27: OR = 3.6, p = 0.001) and hospital re-admission (aaCCI ≥ 6: OR = 4.93, p = 0.003) in the NSS cohort. No impact was found for albumin levels and SMI. An aaCCI > 6 and/or 11-CSHA ≥ 0.27 (OR = 9.19, p < 0.001), a solitary kidney (OR = 5.43, p = 0.005) and hypoalbuminemia (OR = 4.6, p = 0.009), but not tumor complexity, were decisive factors to undergo AS or TA rather than NSS.

CONCLUSION

In patients with localized renal masses, frailty and comorbidity indices can be useful to predict surgical outcome and support decision-making towards AS or TA.

Irreversible electroporation (IRE) in renal cell carcinoma (RCC): a mid-term clinical experience

Objectives

To evaluate the safety and efficacy of CT-guided IRE of clinical T1a (cT1a) renal tumours close to vital structures and to assess factors that may influence the technical success and early oncological durability.

Methods

CT-guided IRE (2015–2020) was prospectively evaluated. Patients’ demographics, technical details/success, Clavien-Dindo (CD) classification of complications (I–V) and oncological outcome were collated. Statistical analysis was performed to determine variables associated with complications. The overall 2- and 3-year cancer-specific (CS), local recurrence-free (LRF) and metastasis-free (MF) survival rates are presented using the Kaplan-Meier curves.

Results

Thirty cT1a RCCs (biopsy-proven/known VHL disease) in 26 patients (age 32–81 years) were treated with IRE. The mean tumour size was 2.5 cm and the median follow-up was 37 months. The primary technical success rate was 73.3%, where 22 RCCs were completely IRE ablated. Seven residual diseases were successfully ablated with cryoablation, achieving an overall technical success rate of 97%. One patient did not have repeat treatment as he died from unexpected stroke at 4-month post-IRE. One patient had CD-III complication with a proximal ureteric injury. Five patients developed > 25% reduction of eGFR immediately post-IRE. All patients have preservation of renal function without the requirement for renal dialysis. The overall 2- and 3-year CS, LRF and MF survival rates are 89%, 96%, 91% and 87%.

Conclusion

CT-guided IRE in cT1a RCC is safe with acceptable complications. The primary technical success rate was suboptimal due to the early operator’s learning curve, and long-term follow-up is required to validate the IRE oncological durability.

Key Points

• Irreversible electroporation should only be considered when surgery or image-guided thermal ablation is not an option for small renal cancer.

• This non-thermal technique is safe in the treatment of small renal cancer and the primary technical success rate was 73.3%.

• This can be used when renal cancer is close to important structure.

A retrospective study of CT-guided percutaneous irreversible electroporation (IRE) ablation: clinical efficacy and safety

Background

To evaluate the clinical efficacy and safety of ablating renal cell carcinoma (RCC) by irreversible electroporation (IRE).

Methods

Fifteen patients (19 lesions) with RCC who underwent IRE were retrospectively reviewed. Seven patients had solitary kidneys. Two lesions were located in the renal hilus. One patient had chronic renal insufficiency. Percutaneous biopsy for histopathology was performed. The best puncture path plan was evaluated before CT-guided IRE. The estimated glomerular filtration rate (eGFR) was compared vs baseline at 1–2 months after the ablation. Contrast-enhanced computed tomography imaging changes were evaluated immediately after IRE. Contrast-enhanced computed tomography/magnetic resonance was performed 1 month, 3 months, 6 months, 12 months and every year thereafter. The complications after treatment were also reviewed.

Results

The success rate of the procedure was 100%. The median tumor size was 2.4 (IQR 1.3–2.9) cm, with an median score of 6 (IQR 5.5–8) per R.E.N.A.L. criteria (radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, and location relative to polar lines). Two cases (3 lesions) were punctured through the liver. In other cases, puncture was performed through the perirenal space. There were no severecomplications in interventional therapy. Transient gross hematuria occurred in 2 patients (centrally located). Self-limiting perinephric hematomas occurred in 1 patient. Needle puncture path metastasis was found in 1 patient 2.5 years after IRE. The subcutaneous metastasis was surgically removed, and there was no evidence of recurrence. There was no significant change in eGFR levels in terms of short- term clinical outcomes (t = 0.348, P = 0.733). At 6 months, all 15 patients with imaging studies available had no evidence of recurrence. At 1 year, 1 patient (1 of 15) was noted to have experienced needle tract metastasis and accepted salvage radiofrequency ablation (RFA) therapy.

Conclusions

IRE appears to be a safe and effective treatment for RCC that may offer a tissue-sparing method and complete ablation as an alternative therapy for RCC.

[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.

Percutaneous irreversible electroporation for the treatment of small renal masses: The first Canadian case series

INTRODUCTION

Irreversible electroporation (IRE) is a novel technology used in the minimally invasive treatment of small solid organ tumours. Currently, there is a paucity of literature studying treatment of small renal masses (SRMs) with IRE. Our pilot study is the first case series in Canada to use IRE in the treatment of SRMs.

METHODS

This retrospective cohort pilot study includes five patients (three females and two males) who presented with a SRM that was deemed not amendable to any other treatment than a radical nephrectomy or IRE. The IRE procedures were carried out by an interventional radiologist in conjunction with a urologist using the Angiodynamics NanoKnife IRE device.

RESULTS

Mean tumour size was 28 mm (range 18-39), with a mean R.E.N.A.L. nephrometry score of 8.4±0.55. Over a mean followup of 22.8 months (range 14-31), four out of the five patients did not have a radiological recurrence. No adverse events were reported after the five IRE procedures. Renal function was stable post-IRE, with no to negligible decreases in estimated glomerular filtration rate detected (range +2 to -13 mL/min/1.73 m²).

CONCLUSIONS

Our pilot study demonstrates that renal percutaneous IRE is safe to use in the context of challenging-to-treat SRMs. Early radiological and renal function outcomes are encouraging, but further study is required to assess oncological success. The small sample size, retrospective nature of the study, relatively short followup, and the lack of routine renal biopsy to confirm malignancy are the major limitations noted.

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.

Developing a Roadmap for Interventional Oncology

Interventional oncology uses image-guided procedures to enhance cancer care. Today, this specialty plays an increasingly critical role in cancer diagnosis (e.g., biopsy), cancer therapy (e.g., ablation or embolization), and cancer symptom palliation (e.g., nephrostomies or biliary drainages). Although the number of procedures and technical capabilities has improved over the last few years, challenges remain. In this article we discuss the need to advance existing procedures, develop new ones, and focus on several operational aspects that will dictate future interventional techniques to enhance cancer care, particularly by accelerating drug development and improving patient outcomes.

IMPLICATIONS FOR PRACTICE

Interventional oncology is vital for cancer diagnosis, therapy, and symptom palliation. This report focuses on current interventional procedures and techniques with a look toward future improvements that will improve cancer care and patient outcomes.

The Role of Ablation and Minimally Invasive Techniques in the Management of Small Renal Masses

CONTEXT

Nephron-sparing approaches are increasingly recommended for incidental small renal masses. Herein, we review the current literature regarding the safety and efficacy of focal therapy, including percutaneous ablation, for small renal masses.

OBJECTIVE

To summarize the application of ablative therapy in the management of small renal masses.

EVIDENCE ACQUISITION

PubMed and Medline database search was performed to look for findings published since 2000 on focal therapy for small renal masses. After literature review, 64 articles were selected and discussed.

EVIDENCE SYNTHESIS

Radiofrequency ablation and cryotherapy are the most widely used procedures with intermediate-term oncological outcome comparable with surgical series. Cost effectiveness seems excellent and side effects appear acceptable. To date, no randomized trial comparing percutaneous focal therapy with standard surgical approach or active surveillance has been performed.

CONCLUSIONS

Focal ablative therapies are now accepted as effective treatment for small renal tumors. For tumors <3cm, oncological effectiveness of ablative therapies is comparable with that of partial nephrectomy. Percutaneous ablation has fewer complications and a better postoperative profile when compared with minimally invasive partial nephrectomy.

PATIENT SUMMARY

Focal ablative therapies are now accepted as effective treatment for small renal tumors. For tumors <3cm, oncological effectiveness of ablative therapies is comparable with that of partial nephrectomy.

Elimination of Purkinje Fibers by Electroporation Reduces Ventricular Fibrillation Vulnerability

Background The Purkinje network appears to play a pivotal role in the triggering as well as maintenance of ventricular fibrillation. Irreversible electroporation ( IRE ) using direct current has shown promise as a nonthermal ablation modality in the heart, but its ability to target and ablate the Purkinje tissue is undefined. Our aim was to investigate the potential for selective ablation of Purkinje/fascicular fibers using IRE . Methods and Results In an ex vivo Langendorff model of canine heart (n=8), direct current was delivered in a unipolar manner at various dosages from 750 to 2500 V, in 10 pulses with a 90-μs duration at a frequency of 1 Hz. The window of ventricular fibrillation vulnerability was assessed before and after delivery of electroporation energy using a shock on T-wave method. IRE consistently eradicated all Purkinje potentials at voltages between 750 and 2500 V (minimum field strength of 250-833 V/cm). The ventricular electrogram amplitude was only minimally reduced by ablation: 0.6±2.3 mV ( P=0.03). In 4 hearts after IRE delivery, ventricular fibrillation could not be reinduced. At baseline, the lower limit of vulnerability to ventricular fibrillation was 1.8±0.4 J, and the upper limit of vulnerability was 19.5±3.0 J. The window of vulnerability was 17.8±2.9 J. Delivery of electroporation energy significantly reduced the window of vulnerability to 5.7±2.9 J ( P=0.0003), with a postablation lower limit of vulnerability=7.3±2.63 J, and the upper limit of vulnerability=18.8±5.2 J. Conclusions Our study highlights that Purkinje tissue can be ablated with IRE without any evidence of underlying myocardial damage.

Cardiac impact of R-wave triggered irreversible electroporation therapy

BACKGROUND

Irreversible electroporation (IRE) is a novel tumor ablative therapy technique, using electric fields to induce apoptosis in target tissues. Whether these electric pulses of high field strength can cause cardiac damage and/or ablation-induced arrhythmias is unclear.

OBJECTIVE

The purpose of this study was to systematically evaluate the safety of electrocardiogram (ECG)-gated IRE with regard to cardiac side effects.

METHODS

In all patients, 12-lead ECG and signal-averaged ECG (SAECG) recordings were performed before and after IRE and 24-hour Holter recording on the day of the IRE procedure. Venous blood samples (N-terminal pro-brain-type natriuretic peptide [NT-proBNP], high-sensitive troponin I [hsTnI]) were obtained before and 4 and 16 hours after the procedure. Patients with abnormal findings were reevaluated after 3 months.

RESULTS

In total, 26 patients with an oncologic indication for IRE (11 females, mean age 62.9 years) were prospectively enrolled. Nine patients (34.6%) showed an increase in hsTnI and 21 patients (80.8%) an increase in NT-proBNP after ablation. Fifteen patients (57%) developed arrhythmias related to the procedure. One patient, in whom hsTnI and NT-proBNP had increased, developed multiple, nonsustained ventricular tachycardia events. In another patient, atrial fibrillation was triggered twice in 2 separate procedures. Twelve patients had clinically benign arrhythmias. SAECG was negative in all patients.

CONCLUSION

Subclinical myocardial injury and nonfatal cardiac arrhythmias can occur in the context of IRE treatment. Although no sustained cardiac injuries could be found at 3-month follow-up, we propose implementation of a cardiac safety algorithm consisting of cardiac biomarkers and ECG monitoring when IRE is conducted.

[Irreversible electroporation (IRE) : A minimally invasive therapeutic option in prostate cancer]

CLINICAL PROBLEM

Prostate cancer is one of the most common malignant diseases in older men. As such, screening and early detection are of crucial importance.

STANDARD TREATMENT

The standard management of prostate cancer includes radical prostatectomy, radiation therapy, or hormonal therapy. These standard therapies yield excellent oncologic results, but also produce significant side effects. In cases of low-risk prostate cancer, these therapies might result in over-treatment; for this reason, active surveillance has been introduced. However, acceptance of this strategy varies between patients.

TREATMENT INNOVATIONS

Irreversible electroporation is a novel non-thermal ablation technique for soft tissues. The ablation mechanism of irreversible electroporation has some theoretical advantages in the treatment of prostate cancer. It allows image-guided focal treatment of malignant prostate tissue and a potential sparing of adjacent structures, thereby theoretically resulting in a marked reduction in treatment-related side effects compared with standard management.

PRACTICAL RECOMMENDATIONS

Although irreversible electroporation is a promising ablation technique, it should only be used in the context of clinical trials to treat prostate cancer due to the current lack of solid evidence for this new technology.