Focal irreversible electroporation for prostate cancer: functional outcomes and short-term oncological control

MRI after focal therapy for prostate cancer: what radiologists must know?

Focal therapy (FT) is a rapidly growing field aiming to minimize the side effects of whole gland treatments in patients with localized prostate cancer and multiparametric MRI plays an important role in patient selection, treatment planning, and post-treatment monitoring. This article reviews the currently available prostate cancer FT techniques, discusses the key imaging findings that affect patient selection and treatment planning, and illustrates the spectrum of expected and abnormal post-treatment MRI findings.

Outcomes of Focal Therapy for Localized Prostate Cancer: A Systematic Review and Meta-analysis of Prospective Studies

BACKGROUND AND OBJECTIVE

Focal therapies (FTs) for localized prostate cancer (PCa) are recommended only within prospective registries or clinical trials. In this systematic review and meta-analysis, we aimed to synthesize data from prospective trials evaluating the efficacy and safety of FTs in patients with clinically localized PCa.

METHODS

Systematic searches of the PubMed, Scopus, and Web of Science databases identified prospective studies reporting oncological outcomes of FTs in treatment-naïve, clinically localized PCa patients. The primary endpoint was biopsy-proven clinically significant PCa (csPCa; International Society of Urological Pathology grade group ≥2) recurrence-free survival (csPCa RFS). The secondary endpoints included RFS, radical/systemic treatment-free survival, and adverse event (AE) rates.

KEY FINDINGS AND LIMITATIONS

Fifty studies including 4615 patients treated with FTs were analyzed; of these 50 studies, 19 were on predominantly intermediate-risk (n = 2800), 16 on mixed low-/intermediate-risk (n = 990), and 15 on low-risk (n = 825) patients. Estimates of 12- and 24-mo csPCa RFS rates were 86% (95% confidence interval [CI] 82-89%) and 81% (95% CI: 74-86%), respectively. In the intermediate-risk subgroup, the 12-mo csPCa RFS rate was 79% (95% CI: 74-83%). Five-year radical and systemic treatment-free survival was 82% (95% CI: 75-88%). The pooled incidence of grade ≥3 AEs was 3% (95% CI: 2-5%). Pad-requiring urinary incontinence increased by 3% (95% CI: 0-6%), with 11% of patients developing new erectile dysfunction (95% CI: 4-18%). The median follow-up of 21 mo (interquartile range 12-34) and the use of surrogate endpoints constitute the major limitations.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The primarily short-term data from prospective studies of FT in clinically localized PCa demonstrate moderate to high cancer control with a favorable safety profile.

Irreversible Electroporation for the Focal Treatment of Prostate Cancer: A Systematic Review

PURPOSE

Irreversible electroporation (IRE) is a promising alternative treatment for low-intermediate-risk localized prostate cancer. In this systematic review we aim to evaluate the safety profile and functional and oncological outcomes of this new technique.

MATERIALS AND METHODS

A systematic review of the literature was performed on PubMed, EMBASE, and Scopus up to 24 August 2023. Nineteen studies were analyzed, including 12 prospective studies and 7 retrospective studies. A total of 1,452 patients underwent IRE as the sole primary treatment modality.

RESULTS

The in-field clinically significant prostate cancer rate was reported between 0%-15.6% in the repeat biopsy. The retreatment rate was reported from 8% to 36.6%. The 3 years failure-free survival was presented between 90%-96.8%. The post-operative pad-free rate ranged between 96.7%-100%. Greater heterogeneity exists considering the change in erectile function. The most common reported complications were urinary tract infection and hematuria. Major complications were rare.

CONCLUSIONS

These results underline that IRE achieves favorable oncological control with an excellent safety profile, in the meantime preserving patients' urinary and erectile function.

Focal therapy for prostate cancer

Traditional treatments for localized prostate cancer include radical prostatectomy or radiation therapy but pose challenges due to treatment related side effects, namely erectile dysfunction and urinary incontinence. In recent years, focal therapy has emerged as a viable treatment option for localized low-intermediate risk prostate cancer in carefully selected patients. Short and medium-term studies show acceptable cancer control outcomes and reduced morbidity when comparing focal therapy to whole gland treatment for prostate cancer, however there is paucity of long-term studies. Here we review focal ablative therapies commonly used, discuss the role of imaging in monitoring treatment, and summarize oncologic outcomes based on studies to date.

Current role of focal therapy in prostate cancer

BACKGROUND

Thanks to the improved accuracy of multiparametric Magnetic Resonance Imaging (mpMRI) to detect and localize the dominant index lesion on prostate cancer (PCa), the concept of minimally invasive focal treatments (FT) has gained popularity. Nevertheless, although high-quality evidence that FT has favorable functional outcomes, definitive proof of its oncological effectiveness compared to standard treatments remains underreported.

OBJECTIVE

This study aims to explore the efficacy, safety, oncologic and functional outcomes of different type of FT for PCa.

EVIDENCE ACQUISITION

A non-systematic literature review was conducted by searching on PubMed "prostate cancer" AND "focal treatment" OR "HIFU" OR "irreversible electroporation" OR "cryoablation" OR "focal laser ablation." Overall, 22 articles published in English literature from 2018 to 2023 describing FT techniques for PCa were included.

EVIDENCE SYNTHESIS

Related to the field ablated, focal therapies include hemiablation (half gland), focal ablation (zonal-base) or targeted therapy (lesion-based). FT modalities can be categorized in thermal and non-thermal energy: thermal energy techniques include high-intensity focused ultrasound (HIFU), cryotherapy, radiofrequency ablation (RFA), and focal laser ablation (FLA). Focal brachytherapy, irreversible electroporation (IRE), and vascular-targeted photodynamic therapy (VTP) are classified as non-thermal ablation. Each focal ablative treatments could be promising alternative to conventional radical therapies to treat PCa in term of mid-term oncologic and functional outcomes, however, limited data are available in comparison with standardized radical treatments. HIFU and Cryo are the most studied techniques and seem to be superior to radical treatments in term of functional outcomes despite associated with higher recurrence and retreatment rate.

CONCLUSIONS

Current evidences of oncologic and functional outcomes of FT are based mainly on retrospective, non-comparative and single center studies. Thus, none of the focal therapies available should be considered safe alternative to standardized treatments in routine practice and should be offered only for well selected PCa patients with low or at least favorable-intermediate risk disease, unfit for radical options.

Personalized Treatment Strategy in "Low-Risk Prostate Cancer Active Surveillance Candidates" Using Irreversible Electroporation: Prospective Evaluation of Feasibility, Morbidity, Functional and Oncological Outcomes

PURPOSE

To evaluate the morbidity, functional and oncological outcome of irreversible electroporation (IRE) as a focal therapy for prostate cancer (PCa) when used in "active surveillance (AS)" candidates refusing standard treatment options.

MATERIALS AND METHODS

IRE was performed under general anaesthesia, and the transurethral catheter was removed one day after intervention in all patients. Pre- and post-interventional voiding parameters (measured by International Prostate Symptom Score Questionnaire [IPSS], uroflowmetry and post-void residue) were compared. Follow-up (FU) was observed over a minimum of six months, including oncological outcome (controlled by multiparametric magnetic resonance imaging, rebiopsy, prostate-specific antigen dynamic as well as the need and type of secondary treatment) and general functional outcome (International Index of Erectile Function Questionnaire, satisfaction of the procedure).

RESULTS

Twenty-four patients refusing AS or standard treatment with a median FU of 18.7 months were included. IPSS showed nine patients with mild, 12 with moderate and two with severe obstructive voiding symptoms pre-intervention (focal IRE). Median IPSS pre-IRE was 9 points, 8.5 (p=0.341) at six months and 10 (p=0.392) after 12 months, respectively. Pre-IRE maximum urinary flow (Qmax) (median: 16.1±8.0 mL/sec) and Qmax after catheter removal (16.2±7.6 mL/sec) did not differ significantly (p=0.904). Thirteen PCa recurrences occurred (54.2%). Out-of-lesion-PCa was found in 12/13 patients (92.3%), while 4/13 patients showed in-lesion-PCa recurrence simultaneously (30.8%). In one patient, there was an in-lesion-PCa recurrence only (7.7%). Six out of 24 patients (25.0%) received a secondary treatment. All patients were satisfied with the IRE procedure.

CONCLUSIONS

Focal IRE underperforms regarding the overall oncological outcome and should not be offered as an equivalent therapy to established curative treatment strategies. Nevertheless, under a strict FU regimen, its lack of significant additional morbidity compared to an active surveillance strategy makes IRE a feasible alternative for low-risk PCa in highly selected patients as a personalised approach.

Trends in focal therapy for localized prostate cancer: a bibliometric analysis from 2014 to 2023

Focal therapy, a minimally invasive strategy for localized prostate cancer, has been widely employed in the targeted treatment of localized prostate cancer in recent years. We analyzed 1312 relevant papers from the last decade using Web of Science Core Collection data. Our analysis covered countries, institutions, journals, authors, keywords, and references to offer a multifaceted perspective on the development of this field. The U.S. led in publications, contributing over half of the top 10 institutions. Emberton, M from University College London was the most published and cited author. "EUROPEAN UROLOGY" was the top journal by impact factor in 2022. Analysis of references and keywords suggests the prevalence of brachytherapy-related research, while high-intensity focused ultrasound (HIFU), cryotherapy, and irreversible electroporation (IRE) are emerging as new research focuses. Consequently, more high-quality evidence is necessary to evaluate the long-term effectiveness and safety of these novel therapeutic methods.

Radiation therapy and IRreversible electroporation for intermediate risk prostate cancer (RTIRE)

INTRODUCTION

Radiation Therapy and IRreversible Electroporation for Intermediate Risk Prostate Cancer (RTIRE) is a phase II clinical trial testing combination of radiation therapy and irreversible electroporation for intermediate risk prostate cancer BACKGROUND: PCa is the most common non-cutaneous cancer in men and the second leading cause of cancer death in men. PCa treatment is associated with long term side effects including urinary, sexual, and bowel dysfunction. Management of PCa is based on risk stratification to prevent its overtreatment and associated treatment-related toxicity. There is increasing interest in novel treatment strategies, such as focal therapy, to minimize treatment associated morbidity. Focal therapy alone has yet to be included in mainstream guidelines, given ongoing concerns with potentially higher risk of recurrence. We hypothesize combining focal therapy with whole gland, reduced dose radiotherapy will provide acceptable oncologic efficacy with minimal treatment associated morbidity. RTIRE is a phase II single institution, investigator-initiated study combining a local ablative technique though local irreversible electroporation (IRE) with MR guided RT (MRgRT) to treat the entire prostate. The goal is to provide excellent oncologic outcomes and minimize treatment related side effects through leveraging benefits of locally ablative therapy with established radiation treatment techniques.

METHODS

A total of 42 men with intermediate risk PCa per NCCN guidelines and focal grade group (GG) 2 or 3, Gleason Score (GS) 3 + 4 or GS 4 + 3, cancer in an MRI target will be enrolled. Patients with MRI visible foci of GG2/GG3 will undergo focal therapy with IRE of this lesion. Following successful focal therapy, patients will then undergo a course of reduced dose, whole gland MRgRT with either 32.5 Gy in 5 Fractions or 22 Gy in 2 fractions. The primary objective of the study is to determine safety. Secondary outcomes include evaluation of oncologic efficacy (as measured by the proportion of patients free of clinically significant cancer as defined as > Grade Group 1 at 1-year follow-up biopsy), imaging characteristics of patients pre and post RTIRE, impact on quality of life (QoL), and PSA kinetics.

DISCUSSION

Combining IRE with a reduced dose radiotherapy may offer a new treatment paradigm for PCa by both reducing treatment effects of full dose radiotherapy and minimizing the risk of recurrence observed with focal therapy.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT05345444. Date of registration: April 25, 2022.

PROTOCOL VERSION

6.0, July 7, 2023.

Irreversible Electroporation (IRE) for Prostate Cancer (PCa) Treatment: The State of the Art

We evaluated the most recent research from 2000 to 2023 in order to deeply investigate the applications of PCa IRE, first exploring its usage with primary intent and then salvage intent. Finally, we discuss the differences with other focal PCa treatments. In the case of primary-intent IRE, the in-field recurrence is quite low (ranges from 0% to 33%). Urinary continence after the treatment remains high (>86%). Due to several different patients in the studies, the preserved potency varied quite a lot (59-100%). Regarding complications, the highest occurrence rates are for those of Grades I and II (20-77% and 0-29%, respectively). Grade III complications represent less than 7%. Regarding the specific oncological outcomes, both PCa-specific survival and overall survival are 100%. Metastasis-free survival is 99.6%. In a long-term study, the Kaplan-Meier FFS rates reported are 91% at 3 years, 84% at 5 years, and 69% at 8 years. In the single study with salvage-intent IRE, the in-field recurrence was 7%. Urinary continence was still high (93%), but preserved potency was significantly lower than primary-intent IRE patients (23%). In addition, Grade III complications were slightly higher (10.8%). In conclusion, in males with localized low-intermediate-risk prostate cancer, IRE had an excellent safety profile and might have positive results for sexual and urinary function.

Irreversible electroporation as a focal therapy for localized prostate cancer: A systematic review

Introduction

Irreversible electroporation (IRE) is a new and promising focal therapy for the treatment of localized prostate cancer. In this systematic review, we summarize the literature on IRE for prostate cancer published over the last decade.

Methods

PubMed and EMBASE were searched with the end date of May 2023 to find relevant publications on prostate cancer ablation using IRE. Original studies with focal IRE as the primary curative treatment which reported on functional or oncological outcomes were included. The bibliography of relevant studies was also scanned to identify suitable articles.

Results

A total of 14 studies reporting on 899 patients treated with IRE for localized prostate cancer were included. Of all the studies reviewed, 77% reported on recurrence within the zone of ablation, and it ranged from 0% to 38.9% for in-field and 3.6% to 28% for out-of-field recurrence. Although, a standardised follow-up protocol was not followed, all the studies employed serial prostate-specific antigen monitoring, a multiparametric magnetic resonance imaging, and a biopsy (6-12 months post-treatment). Across all the studies, 58% reported that the urinary continence returned to the pretreatment levels and 25% reported a minor decrease in the continence from the baseline at 12-months of follow-up. Erections sufficient for intercourse varied from 44% to 75% at the baseline to 55% to 100% at 12-months of follow-up across all the studies.

Conclusion

IRE, as a focal therapy, shows promising results with minimal complications and reasonably effective oncological control, but the data comparing it to the standard of care is still lacking. Future research should focus on randomized definitive comparisons between IRE, radical prostatectomy, and radiation therapy.

Real-Time and Delayed Imaging of Tissue and Effects of Prostate Tissue Ablation

PURPOSE OF REVIEW

Prostate ablation is increasingly being utilized for the management of localized prostate cancer. There are several energy modalities with varying mechanism of actions which are currently used for prostate ablation. Prostate ablations, whether focal or whole gland, are performed under ultrasound and/or MRI guidance for appropriate treatment plan execution and monitoring. A familiarity with different intraoperative imaging findings and expected tissue response to these ablative modalities is paramount. In this review, we discuss the intraoperative, early, and delayed imaging findings in prostate from the effects of prostate ablation.

RECENT FINDINGS

The monitoring of ablation both during and after the therapy became increasingly important due to the precise targeting of the target tissue. Recent findings suggest that real-time imaging techniques such as MRI or ultrasound can provide anatomical and functional information, allowing for precise ablation of the targeted tissue and increasing the effectiveness and precision of prostate cancer treatment. While intraprocedural imaging findings are variable, the follow-up imaging demonstrates similar findings across various energy modalities. MRI and ultrasound are two of the frequently used imaging techniques for intraoperative monitoring and temperature mapping of important surrounding structures. Follow-up imaging can provide valuable information about ablated tissue, including the success of the ablation, presence of residual cancer or recurrence after the ablation. It is critical and helpful to understand the imaging findings during the procedure and at different follow-up time periods to evaluate the procedure and its outcome.

Median 4-year outcomes of salvage irreversible electroporation for localized radio-recurrent prostate cancer

OBJECTIVES

To evaluate the safety, and short to mid-term oncological and quality-of-life (QoL) outcomes of focal irreversible electroporation (IRE) for radio-recurrent prostate cancer (PCa) at a median follow-up of 4 years.

PATIENTS AND METHODS

This was a single-centre series of men with biopsy-proven radio-recurrent PCa treated with IRE between December 2013 and February 2022, with a minimum follow-up of 6 months. Follow-up included magnetic resonance imaging at 6 months, and standard transperineal saturation template biopsies at 12 months. Further biopsies were guided by suspicion on serial imaging or prostate-specific antigen (PSA) levels. Validated questionnaires were used to measure functional outcomes. Significant local recurrence was defined as any International Society of Urological Pathology (ISUP) score ≥ 2 on biopsies. Progression-free survival was defined as no signs of local or systemic disease on either imaging or template biopsies, or according to the Phoenix criteria for biochemical recurrence.

RESULTS

Final analysis was performed on 74 men with radio-recurrent PCa (median age 69 years, median PSA level 5.4 ng/mL, 76% ISUP score 2/3). The median (range) follow-up was 48 (27-68) months. One rectal fistula occurred, and eight patients developed urethral sloughing that resolved with transurethral resection. Among patients who returned questionnaires (30/74, 41%), 93% (28/30) had preserved urinary continence and 23% (7/30) had sustained erectile function at 12-month follow-up. Local control was achieved in 57 patients (77%), who needed no further treatment. Biopsy diagnosed 41(55%) patients received follow up template biopsies, in-field recurrences occurred in 7% (3/41), and out-field recurrences occurred in 15% of patients (6/41). The metastasis-free survival rate was 91% (67/74), with a median (interquartile range) time to metastases of 8 (5-27) months. The Kaplan-Meier estimated 5-year progression-free survival rate was 60%.

CONCLUSIONS

These short- to mid-term safety, oncological and QoL outcome data endorse results from smaller series and show the ability of salvage focal IRE to safely achieve oncological control in patients with radio-recurrent PCa.

Real-World Comparative Safety and Effectiveness of Irreversible Electroporation and High-Intensity Focused Ultrasound for Prostate Cancer Ablation

OBJECTIVES

To assess the comparative safety and effectiveness of 2 prostate cancer treatment ablation modalities: irreversible electroporation (IRE) and high-intensity focused ultrasound (HIFU).  METHODS: Two systematic literature reviews (SLRs) and meta-analyses (MAs) on IRE and HIFU were conducted in accordance with PRISMA guidelines. Searches were conducted in PubMed and EMBASE. Independent reviewers assessed literature eligibility and abstracted safety and effectiveness data. Oncological, safety, functional, and quality of life (QOL) outcomes were examined for each technology. MAs were conducted where data quality and availability allowed, using normal methods and a random/mixed effects model, and quality assessments performed.

RESULTS

Fifty-five publications (n = 22 IRE; n = 33 HIFU) were included in the SLRs, and MAs were conducted on negative in-field post-procedure biopsy, prostate-specific antigen (PSA) level reduction, potency, urinary continence, and AE rate outcomes. MAs revealed that IRE patients had lower mean percent PSA level reductions, higher mean rates of in-field negative post-treatment biopsy, and higher rates of potency maintenance than HIFU patients. Most adverse events (AEs) reported were comparable and minor (Grades I, II), with urinary tract infection, dysuria, hematuria, and incontinence or urgency most frequently reported. The proportion of patients experiencing a severe AE (≥Grade III) ranged from 0 to 8% after IRE and HIFU. Both modalities were associated with positive functional outcomes as well as maintenance of QOL after treatment.

CONCLUSIONS

Both IRE and HIFU were found to produce favorable effectiveness outcomes and have low complication rates while minimally impacting patient urinary and erectile function and maintaining overall QOL. These real-world findings can help guide clinical decision making and improve disease management for patients with prostate cancer.

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Detect Residual Prostate Cancer Following Irreversible Electroporation-A Multicenter Validation Study

BACKGROUND

Accurate monitoring following focal treatment of prostate cancer (PCa) is paramount for timely salvage treatment or retreatment.

OBJECTIVE

To evaluate the diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI) to detect residual PCa in the short-term follow-up of focal treatment with irreversible electroporation (IRE) using transperineal or transrectal template ± targeted biopsies.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective international multicenter study of men with biopsy-proven PCa, treated with focal IRE, and followed by mpMRI (index-test) and template biopsies (reference-test) between February 2013 and January 2021, was conducted.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of mpMRI were calculated for in- and outfield residual disease based on two definitions of significant PCa: University College London (UCL) 1-International Society of Urological Pathology (ISUP) ≥3 or ISUP ≥1 with maximum cancer core length (MCCL) ≥6 mm, and UCL2-ISUP ≥2 or ISUP ≥1 with MCCL ≥4 mm.

RESULTS AND LIMITATIONS

A total of 303 patients from five focal therapy centers were treated with primary IRE. The final analysis was performed on 217 men (median age 67, median prostate-specific antigen 6.2, 81% ISUP 2/3) who underwent both mpMRI and template biopsies. Multiparametric MRI missed 38/57 (67%) positive biopsy locations (UCL1) in 22 patients. Sensitivity, specificity, PPV, and NPV of mpMRI to detect whole gland residual disease (UCL1) were 43.6% (95% confidence interval [CI]: 28-59), 80.9% (95% CI: 75-86), 33.3% (95% CI: 21-47), and 86.7% (95% CI: 81-91), respectively. Based on UCL2, sensitivity, specificity, PPV, and NPV were 35.8% (95% CI: 25-48), 82.0% (95% CI: 75-88), 47.1% (95% CI: 34-61), and 74.1% (95% CI: 67-80), respectively. Limitations are the retrospective nature and short follow-up.

CONCLUSIONS

The diagnostic accuracy of mpMRI to detect residual clinically significant PCa following IRE was low. Follow-up template biopsies should be performed, regardless of mpMRI results.

PATIENT SUMMARY

We investigated the accuracy of magnetic resonance imaging (MRI) to detect residual prostate cancer after treatment with irreversible electroporation. The accuracy of MRI is insufficient, and we emphasize the importance of confirmatory prostate biopsies.

Irreversible electroporation and electrochemotherapy in oncology: State of the art

Thermal tumor ablation techniques including radiofrequency, microwave, LASER, high-intensity focused ultrasound and cryoablation are routinely used to treated liver, kidney, bone, or lung tumors. However, all these techniques are thermal and can therefore be affected by heat sink effect, which can lead to incomplete ablation, and thermal injuries of non-targeted tissues are possible. Under certain conditions, high voltage pulsed electric field can induce formation of pores in the cell membrane. This phenomenon, called electropermeabilization, is also known as "electroporation". Under certain conditions, electroporation can be irreversible, leading to cell death. Irreversible electroporation has demonstrated efficacy for the treatment of liver and prostate cancers, whereas data are scarce regarding pancreatic and renal cancers. During reversible electroporation, transient cell permeability can be used to introduce cytotoxic drugs into tumor cells (commonly bleomycin or cisplatin). Reversible electroporation used in conjunction with cytotoxic drugs shows promise in terms of oncological response, particularly for solid cutaneous and subcutaneous tumors such as melanoma. Irreversible and reversible electroporation are both not thermal ablation techniques and therefore open a new promising horizon for tumor ablation.

Boosting the Immune Response—Combining Local and Immune Therapy for Prostate Cancer Treatment

Due to its slow progression and susceptibility to radical forms of treatment, low-grade PC is associated with high overall survival (OS). With the clinical progression of PC, the therapy is becoming more complex. The immunosuppressive tumor microenvironment (TME) makes PC a difficult target for most immunotherapeutics. Its general immune resistance is established by e.g., immune evasion through Treg cells, synthesis of immunosuppressive mediators, and the defective expression of surface neoantigens. The success of sipuleucel-T in clinical trials initiated several other clinical studies that specifically target the immune escape of tumors and eliminate the immunosuppressive properties of the TME. In the settings of PC treatment, this can be commonly achieved with radiation therapy (RT). In addition, focal therapies usually applied for localized PC, such as high-intensity focused ultrasound (HIFU) therapy, cryotherapy, photodynamic therapy (PDT), and irreversible electroporation (IRE) were shown to boost the anti-cancer response. Nevertheless, the present guidelines restrict their application to the context of a clinical trial or a prospective cohort study. This review explains how RT and focal therapies enhance the immune response. We also provide data supporting the combination of RT and focal treatments with immune therapies.

Extended Focal Ablation of Localized Prostate Cancer With High-Frequency Irreversible Electroporation: A Nonrandomized Controlled Trial

IMPORTANCE

Focal therapy of prostate cancer must balance the oncologic outcome and functional outcome. High-frequency irreversible electroporation (H-FIRE) can destroy cancer cells while selectively preserving surrounding nerves and blood vessels, but no clinical trials have been conducted, to our knowledge.

OBJECTIVE

To evaluate the efficacy and safety of H-FIRE in the treatment of localized prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS

This was a single-group, objective performance criteria, nonrandomized controlled trial. Recruitment began on May 2, 2018, and ended March 27, 2019. The follow-up duration was 6 months. This was a multicenter trial conducted at 4 tertiary teaching hospitals in China. Patients with low or intermediate risk of biochemical recurrence of localized and locally advanced PCa were eligible. Key inclusion criteria were serum prostate-specific antigen (PSA) level less than 20 ng/mL, clinical stage of T2c or less, and Gleason score of 7 or less. Data were analyzed from January 20 to February 20, 2021.

INTERVENTION

H-FIRE ablation of all lesions identified with biopsy.

MAIN OUTCOMES AND MEASURES

The primary end point was 6-month clinically significant PCa (csPCa), which was defined as any biopsy core with Gleason score of greater than or equal to 7, or Gleason score of 6 plus maximum cancer core length of greater than 3 mm or an increase from the original cancer burden. Secondary outcomes were calculated in patients who actually received H-FIRE treatment.

RESULTS

A total of 117 patients (median [IQR] age, 67 [62-73] years) were recruited from 4 centers, and 109 patients (27 [24.8%] low risk and 82 [75.2%] intermediate risk) actually received H-FIRE. Median (IQR) PSA level was 9.0 (6.0-12.7) ng/mL. Among the 100 patients who underwent biopsy at 6 months, the 6-month csPCa rate was 6.0% (95% CI, 2.2%-12.6%; P < .001; 1 in the treatment zone and 5 outside the treatment zone). Superiority criteria vs the historical control of 20% was achieved. PCa was detected in 14 patients, with a Gleason score of 7 in 2 patients and 6 in the remaining 12 patients. At 6 months, median (IQR) PSA level was 1.08 (0.4-3.2) ng/mL, median (IQR) International Prostate Symptom Score was 4.5 (2.0-9.5), and median (IQR) International Index of Erectile Function 5 score was 2.0 (0.5-12.5). Superiority vs the 20% historical control was also met in the subgroup analysis that only included the 57 patients with Gleason score of 7 at baseline (3.5% 6-month csPCa; 95% CI, 0.4%-12.1%).

CONCLUSIONS AND RELEVANCE

The rate of 6-month csPCa with H-FIRE ablation was lower than the historical control using other energy platforms.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03838432.

Transforming Commercial Copper Sulfide into Injectable Hydrogels for Local Photothermal Therapy

Photothermal therapy (PTT) is a promising local therapy playing an increasingly important role in tumor treatment. To maximize PTT efficacy, various near-infrared photoabsorbers have been developed. Among them, metal sulfides have attracted considerable interest due to the advantages of good stability and high photothermal conversion efficiency. However, the existing synthesis methods of metal-sulfide-based photoabsorbers suffer from the drawbacks of complicated procedures, low raw material utilization, and poor universality. Herein, we proposed a flexible, adjustable strategy capable of transforming commercial metal sulfides into injectable hydrogels for local PTT. We took copper sulfide (CuS) as a typical example, which has intense second-window near-infrared absorption (1064 nm), to systematically investigate its in vitro and in vivo characteristics. CuS hydrogel with good syringeability was synthesized by simply dispersing commercial CuS powders as photoabsorbers in alginate-Ca²⁺ hydrogel. This synthesis strategy exhibits the unique merits of an ultra-simple synthesizing process, 100% loading efficiency, good biocompatibility, low cost, outstanding photothermal capacity, and good universality. The in vitro experiments indicated that the hydrogel exhibits favorable photothermal heating ability, and it obviously destroyed tumor cells under 1064 nm laser irradiation. After intratumoral administration in vivo, large-sized CuS particles in the hydrogel highly efficiently accumulated in tumor tissues, and robust local PTT was realized under mild laser irradiation (0.3 W/cm²). The developed strategy for the synthesis of CuS hydrogel provides a novel way to utilize commercial metal sulfides for diverse biological applications.

Focal therapy for prostate cancer with irreversible electroporation: Oncological and functional results of a single institution study

Purpose

Materials and Methods

Results

Conclusions

Detailing Sexual Outcomes After Focal Therapy for Localised Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

Focal therapy has emerged as a promising option to treat well-selected men with localised prostate cancer while preserving healthy prostate tissue and key structures, such as the urethral sphincter and neurovascular bundles. However, how this tissue preservation may translate into improved outcomes, particularly into improved sexual outcomes, is still an active research field.

OBJECTIVE

We conducted a systematic review and meta-analysis of the literature to summarise the existing evidence, in order to provide patients with updated data on what to expect after treatment and help identify gaps in current knowledge that may warrant future research.

EVIDENCE ACQUISITION

A systematic literature search was conducted on Medline, EMBASE, Scopus, and Web of Science. The search strategy was defined using the "litsearchr" function in R based on a preliminary "naïve" search using the following terms on Medline: (("focal therapy" OR "focal treatment") AND ("prostate cancer") AND ("sexual function" OR "erectile function")). A total of 42 studies, comprising 3117 patients treated and 2352 with available sexual outcomes, were included in the qualitative data synthesis and 26 in a random-effect meta-analysis.

EVIDENCE SYNTHESIS

The five-item International Index of Erectile Function (IIEF-5) was the most frequently used questionnaire (30/42 studies), with completion rates ranging from 24% to 100% at 18-24 mo. A decrease was noted at 3 mo (IIEF-5 decrease estimate -3.70 [95% confidence interval -4.43, -2.96]), with improvements at 6 mo (-2.18 [-2.91, -1.46]) and 12 mo (-2.14 [-2.96, -1.32]). Studies in which patients had an altered baseline sexual function were more likely to report a significant and durable postoperative decrease in erectile function scores. The patient-reported outcome questionnaires used were not designed for a diverse population. Functional outcomes were not the primary endpoint and have not been reported consistently in most studies considered.

CONCLUSIONS

Focal therapy led to changes in erectile function in most cases under the significance threshold of the patient-reported outcome questionnaires used. However, patients should be counselled according to their baseline erectile function. More research is warranted to detail aspects other than erectile function, such as ejaculation or orgasm. The early postoperative period appears key to study sexual changes after focal therapy, while only a moderate decrease is expected at 12 mo.

PATIENT SUMMARY

We reviewed the published literature detailing the sexual consequences of focal therapy for localised prostate cancer using patient-reported outcome questionnaires. Patients were likely to describe a significant decrease in their erectile function at 3 mo, with improvements noted at 6 and 12 mo. The results obtained may not be reproducible in a more diverse population, and further research is warranted to better study aspects other than erectile function, such as ejaculation or orgasm.

An Updated Systematic Review on Focal Therapy in Localized Prostate Cancer: What Has Changed over the Past 5 Years?

CONTEXT

Focal therapy is a promising, minimally invasive strategy to selectively treat localized prostate cancer. A previous systematic review indicated that there is growing evidence for favorable functional outcomes, but that oncological effectiveness was yet to be defined.

OBJECTIVE

To assess the effectiveness of focal therapy in patients with localized prostate cancer in terms of functional and oncological outcomes.

EVIDENCE ACQUISITION

PubMed, Embase, and The Cochrane Library were searched for studies between October 2015 and December 31, 2020. In addition, the research stages were acquired according to the Idea, Development, Exploration, Assessment, Long-term study (IDEAL) recommendations. Ongoing studies were identified through clinical trial registries.

EVIDENCE SYNTHESIS

Seventy-two studies were identified exploring eight different sources of energy to deliver focal therapy in 5827 patients. Twenty-seven studies reported on high-intensity focused ultrasound (HIFU), nine studies on irreversible electroporation, 11 on cryoablation, eight on focal laser ablation and focal brachytherapy, seven on photodynamic therapy (PDT), two on radiofrequency ablation, and one on prostatic artery embolization. The majority of studies were prospective development stage 2a studies (n = 35). PDT and HIFU, both in stage 3, showed promising results. Overall, HIFU studies reported a median of 95% pad-free patients and a median of 85% patients with no clinically significant cancer (CSC) in the treated area. For PDT, no changes in continence were reported and a median of 90% of patients were without CSC. Both treatments were well tolerated.

CONCLUSIONS

Over the past 5 yr, focal therapy has been studied for eight different energy sources, mostly in single-arm stage 2 studies. Although a first randomized controlled trial in focal therapy has been performed, more high-quality evaluations are needed, preferably via multicenter randomized controlled trials with long-term follow-up and predefined assessment of oncological and functional outcomes and health-related quality-of-life measures.

PATIENT SUMMARY

Focal treatment (FT) of prostate cancer has potential, considering that it has less impact on continence and potency than radical treatment. Our systematic review indicates that despite the method being studied extensively over the past half decade, the majority of studies remain in an early research stage. The techniques high-intensity focused ultrasound and photodynamic therapy have shown most progression toward advanced research stages and show favorable results. However, more high-quality evidence is required before FT can become available as a standard treatment.

Focal therapy for primary and salvage prostate cancer treatment: a narrative review

Despite innovations in surgical technology and advancements in radiation therapy, radical treatments for clinically localized prostate cancer are associated with significant patient morbidity, including both urinary and sexual dysfunction. This has created a vital need for therapies and management strategies that provide an acceptable degree of oncologic efficacy while mitigating these undesirable side effects. Successful developments in screening approaches and advances in prostate imaging have allowed clinicians to identify, localize, and more precisely target early cancers. This has afforded urologists with an important opportunity to develop and employ focal ablation techniques that selectively destroy tumors while preserving the remainder of the gland, thus avoiding detrimental treatment effects to surrounding sensitive structures. A lack of high-level evidence supporting such an approach had previously hindered widespread adoption of focal treatments, but there are now numerous published clinical trials which have sought to establish benchmarks for safety and efficacy. As the clinical evidence supporting a potential role in prostate cancer treatment begins to accumulate, there has been a growing acceptance of focal therapy in the urologic oncology community. In this narrative review article, we describe the techniques, advantages, and side effect profiles of the most commonly utilized focal ablative techniques and analyze published clinical trial data supporting their evolving role in the prostate cancer treatment paradigm.

Irreversible Electroporation for Prostate Cancer

Although it can be lethal in its advanced stage, prostate cancer can be effectively treated when it is localised. Traditionally, radical prostatectomy (RP) or radiotherapy (RT) were used to treat all men with localised prostate cancer; however, this has significant risks of post-treatment side effects. Focal therapy has emerged as a potential form of treatment that can achieve similar oncological outcomes to radical treatment while preserving functional outcomes and decreasing rates of adverse effects. Irreversible electroporation (IRE) is one such form of focal therapy which utilises pulsatile electrical currents to ablate tissue. This modality of treatment is still in an early research phase, with studies showing that IRE is a safe procedure that can offer good short-term oncological outcomes whilst carrying a lower risk of poor functional outcomes. We believe that based on these results, future well-designed clinical trials are warranted to truly assess its efficacy in treating men with localised prostate cancer.

Cryoablation, high-intensity focused ultrasound, irreversible electroporation, and vascular-targeted photodynamic therapy for prostate cancer: a systemic review and meta-analysis

Cryoablation (CA), high-intensity focused ultrasound (HIFU), irreversible electroporation (IRE), and vascular-targeted photodynamic therapy (VTP) have been evaluated as novel strategies for selected patients with prostate cancer (PCa). We aim to determine the current status of literature regarding the clinical outcomes among these minimally invasive therapies. A systematic search of PubMed, EMBASE, and the Cochrane Library for all English literature published from January 2001 to December 2019 was conducted to identify studies evaluating outcomes of CA, HIFU, IRE or VTP on PCa. Proportionality with 95% confidence intervals (CIs) was performed using STATA version 14.0. 56 studies consisting of 7383 participants were found to report data of interest and fulfilled the inclusion criteria in the final meta-analysis. The pooled proportions of positive biopsy after procedure were 20.0%, 24.3%, 24.2%, and 36.2% in CA, HIFU, IRE and VTP, respectively. The pooled proportions of BRFS were 75.7% for CA and 74.4% for HIFU. The pooled proportions of CSS were 96.1%, 98.2%, and 97.9% for CA, HIFU, and IRE, respectively. The pooled proportions of OS were 92.8% for CA and 85.2% for HIFU. The pooled proportions of FFS were 64.7%, 90.4%, and 76.7% for CA, IRE and VTP, respectively. The pooled proportions of MFS were 92.8% for HIFU and 99.1% for IRE. This meta-analysis shows that CA, HIFU, IRE, and VTP are promising therapies for PCa patients with similar clinical outcomes. However, further larger, well-designed randomized controlled trials are required to confirm this assertion.

A systematic review of irreversible electroporation in localised prostate cancer treatment

Irreversible electroporation is a treatment option used for focal therapy. In this systematic review, we summarise data on irreversible electroporation outcomes in patients with localised prostate cancer. We performed a literature search in 3 databases and included articles with own data on irreversible electroporation results in patients with localised prostate cancer. Primary outcome was procedure efficacy measured as the absence of cancer in the treatment area on the follow-up biopsy. Secondary outcomes were the absence of prostate cancer recurrence in the treatment area on MRI, out-of-field recurrence, complications and functional outcomes (erectile function and micturition). In-field recurrence rate was 0%-39% and out-field 6.4%-24%. In all studies, PSA level decreased: twice lower than baseline after 4 weeks and by 76% after 2 years. Most of the authors noted sexual and urinary toxicity during the first half year after surgery. However, functional outcomes recovered to baseline after 6 months with mild decrease in sexual function. Complication rates after irreversible electroporation were 0%-1% of Clavien-Dindo III and 5%-20% of Clavien-Dindo I-II. Irreversible electroporation has promise oncological outcomes, rate of post-operative complications and minimal-to-no effects on erectile and urinary function. However, medium and long-term data on cancer-specific and recurrence-free survival are still lacking.

Preliminary Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Detect Residual Prostate Cancer Following Focal Therapy with Irreversible Electroporation

BACKGROUND

It is recommended to perform multiparametric magnetic resonance imaging (mpMRI) in the follow-up following focal therapy of prostate cancer (PCa).

OBJECTIVE

To determine the diagnostic accuracy of mpMRI to detect residual PCa following focal therapy with irreversible electroporation.

DESIGN, SETTING, AND PARTICIPANTS

Seventy-six patients with biopsy-proven localized PCa consented for primary irreversible electroporation between February 2013 and March 2016. Final analysis was performed on 50 patients that received follow-up mpMRI at 6 mo, serial prostate-specific antigen (PSA) testing, and transperineal template-mapping biopsies at 12 mo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Outfield regions of interest (ROI) were reported using PI-RADS version 2. A binary outcome (suspicious vs nonsuspicious) was given for the infield ablation zone. Sensitivity, specificity, positive predictive values, and negative predictive values were calculated for different definitions of significant PCa: (1) Gleason ≥4+3 or Gleason ≥3+3 with a maximum cancer core length ≥6mm, (2) Gleason ≥3+4 or Gleason ≥3+3 with a maximum cancer core length ≥4mm, for outfield and infield ROI. Multivariate linear regression analyses evaluated the additional value of nadir PSA.

RESULTS AND LIMITATIONS

Sensitivity, specificity, positive predictive values, and negative predictive values of infield ROI was 43%, 86%, 33%, and 90% for definition 1 and 38%, 86%, 33%, and 88% for definition 2, respectively. For outfield ROI this was 33%, 82%, 20%, and 90% for definition 1 and 38%, 86%, 50%, and 80% for definition 2. PSA had no additional value in predicting residual significant PCa. Limitations include retrospective design, single reader, and low incidence of residual PCa.

CONCLUSIONS

Our preliminary data suggest that mpMRI can rule out high-volume residual PCa. However, follow-up biopsies should still be performed to determine oncological control.

PATIENT SUMMARY

Multiparametric magnetic resonance imaging is able to detect high-volume significant prostate cancer following focal therapy. Prostate biopsies are still required in the follow-up of focal therapy as (low-volume) significant prostate cancer is being missed by multiparametric magnetic resonance imaging.

Focal therapy, time to join the multi-disciplinary team discussion?

Organ preserving management is common place in renal cancer, breast cancer and many other solid organ tumours. Current strategies in managing intermediate risk prostate cancer include either whole gland treatment, in the form of radical radiotherapy or radical prostatectomy, or active surveillance. The former is associated with significant post-treatment functional morbidity, whilst the latter associated with the burden of surveillance activity and patient anxiety. Focal therapy would logically fit as a middle ground for suitable patients in whom treatment would be recommended, but where much better functional outcomes may be possible. Ideally this comes without restricting the successful prevention of harm from the cancer. Historically limitations in developing tissue preserving focal therapy strategies in prostate cancer, were due to inaccuracies in tumour characterisation prior to treatment and during follow up. Consequently for example many patients undergoing an active surveillance strategy were being upgraded and upstaged within a short period. Recently high level evidence supporting the use of MRI and targeted biopsies, in particular the PROMIS and PRECISION trials have strengthened clinician confidence in accurate disease characterisation, thus making focal therapy to become a more feasible management option. With improved diagnostic strategies and the publication of reassuring medium term oncological and functional outcomes after focal therapy for intermediate risk prostate cancer, has the time come to require consideration of focal therapy within our multi-disciplinary team (MDT) meetings and with patients? In this review we will consider patient selection and the evidence for the various focal ablation options as well as the surveillance of these patients after treatment. The forthcoming trials to determine comparative effectiveness will be discussed.

Targeting the cancer lesion, not the whole prostate

Modern cancer treatment aims to conserve as much healthy tissue as possible. This has been challenging in the treatment of prostate cancer due to the difficulty in imaging the gland and concerns over leaving multifocal cancer untreated. With improvements in imaging and understanding of multifocal prostate cancer evidence now shows accurate treatment of just the primary focus of cancer or the index lesion can control progression or recurrence of the disease. Many different energy sources are now available to target the cancer lesion within the prostate with less significant side-effects on urinary and sexual function compared to radical treatment. Evidence shows that men value these functions highly and would even trade years of life in exchange for preserved retention of continence or erectile function. Focal treatment of prostate cancer aims to provide both cancer control and preservation of sexual and urinary functions so that men do not have to make a choice between the two. This is a treatment option that men clearly want and deserve.

Development of a Multi-Pulse Conductivity Model for Liver Tissue Treated With Pulsed Electric Fields

Pulsed electric field treatment modalities typically utilize multiple pulses to permeabilize biological tissue. This electroporation process induces conductivity changes in the tissue, which are indicative of the extent of electroporation. In this study, we characterized the electroporation-induced conductivity changes using all treatment pulses instead of solely the first pulse as in conventional conductivity models. Rabbit liver tissue was employed to study the tissue conductivity changes caused by multiple, 100 μs pulses delivered through flat plate electrodes. Voltage and current data were recorded during treatment and used to calculate the tissue conductivity during the entire pulsing process. Temperature data were also recorded to quantify the contribution of Joule heating to the conductivity according to the tissue temperature coefficient. By fitting all these data to a modified Heaviside function, where the two turning points (E₀, E₁) and the increase factor (A) are the main parameters, we calculated the conductivity as a function of the electric field (E), where the parameters of the Heaviside function (A and E₀) were functions of pulse number (N). With the resulting multi-factor conductivity model, a numerical electroporation simulation can predict the electrical current for multiple pulses more accurately than existing conductivity models. Moreover, the saturating behavior caused by electroporation can be explained by the saturation trends of the increase factor A in this model. The conductivity change induced by electroporation has a significant increase at about the first 30 pulses, then tends to saturate at 0.465 S/m. The proposed conductivity model can simulate the electroporation process more accurately than the conventional conductivity model. The electric field distribution computed using this model is essential for treatment planning in biomedical applications utilizing multiple pulsed electric fields, and the method proposed here, relating the pulse number to the conductivity through the variables in the Heaviside function, may be adapted to investigate the effect of other parameters, like pulse frequency and pulse width, on electroporation.

High-Voltage Electrical Pulses in Oncology: Irreversible Electroporation, Electrochemotherapy, Gene Electrotransfer, Electrofusion, and Electroimmunotherapy

This review summarizes the use of high-voltage electrical pulses (HVEPs) in clinical oncology to treat solid tumors with irreversible electroporation (IRE) and electrochemotherapy (ECT). HVEPs increase the membrane permeability of cells, a phenomenon known as electroporation. Unlike alternative ablative therapies, electroporation does not affect the structural integrity of surrounding tissue, thereby enabling tumors in the vicinity of vital structures to be treated. IRE uses HVEPs to cause cell death by inducing membrane disruption, and it is primarily used as a radical ablative therapy in the treatment of soft-tissue tumors in the liver, kidney, prostate, and pancreas. ECT uses HVEPs to transiently increase membrane permeability, enhancing cellular cytotoxic drug uptake in tumors. IRE and ECT show immunogenic effects that could be augmented when combined with immunomodulatory drugs, a combination therapy the authors term electroimmunotherapy. Additional electroporation-based technologies that may reach clinical importance, such as gene electrotransfer, electrofusion, and electroimmunotherapy, are concisely reviewed. HVEPs represent a substantial advancement in cancer research, and continued improvement and implementation of these presented technologies will require close collaboration between engineers, interventional radiologists, medical oncologists, and immuno-oncologists.

Focal therapy for localized prostate cancer in the era of routine multi-parametric MRI

BACKGROUND

Prostate cancer focal therapy aims to minimize the side-effects of whole gland treatments, such as radical prostatectomy and radiotherapy without compromising oncological efficacy. However, concerns exist regarding the multifocal nature of prostate cancer and the lack of long-term oncological data for this form of treatment. In recent years, the routine adoption of multi-parametric magnetic resonance imaging (mpMRI) of the prostate has improved our ability to select candidates for focal therapy and to accurately deliver this form of prostate cancer treatment.

METHODS

We performed a review of the literature to provide a summary of the oncological and functional outcomes of men receiving primary prostate focal therapy. Furthermore, we discuss the impact of the routine implementation of mpMRI as part of the initial prostate cancer diagnostic pathway on the selection of candidates and delivery of focal therapy. Finally, we summarize knowledge gaps in the field and highlight active clinical trials in this arena.

RESULTS

Primary focal therapy involves the application of one of a number of energies that ablate tissue, such as cryotherapy and high intensity focused ultrasound (HIFU). Success is principally dependent on highly accurate patient selection and disease localization underpinned in large part by the routine integration of pre-biopsy mpMRI. Prospective medium-term follow-up data for primary HIFU and cryotherapy for men with intermediate-risk disease have shown acceptable cancer control with low risk of side effects and complications. Additional research is needed to clearly define an appropriate follow-up approach and to guide the management of in- and out-of-field recurrences. Multiple comparative trials with randomization against standard care are currently underway in men with intermediate- and high-risk prostate cancer.

CONCLUSION

The widespread adoption of prostate mpMRI has led to improved disease localization, enabling the performance of focal therapy as a viable treatment strategy for men with low volume intermediate-risk prostate cancer.

Irreversible Electroporation: Background, Theory, and Review of Recent Developments in Clinical Oncology

Irreversible electroporation (IRE) has established a clinical niche as an alternative to thermal ablation for the eradication of unresectable tumors, particularly those near critical vascular structures. IRE has been used in over 50 independent clinical trials and has shown clinical success when used as a standalone treatment and as a single component within combinatorial treatment paradigms. Recently, many studies evaluating IRE in larger patient cohorts and alongside other novel therapies have been reported. Here, we present the basic principles of reversible electroporation and IRE followed by a review of preclinical and clinical data with a focus on tumors in three organ systems in which IRE has shown great promise: the prostate, pancreas, and liver. Finally, we discuss alternative and future developments, which will likely further advance the use of IRE in the clinic.

Gold nanoshell-localized photothermal ablation of prostate tumors in a clinical pilot device study

Biocompatible gold nanoparticles designed to absorb light at wavelengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer therapy, resulting in cell death and tumor remission in a multitude of preclinical animal models. Here we report the initial results of a clinical trial in which laser-excited gold-silica nanoshells (GSNs) were used in combination with magnetic resonance-ultrasound fusion imaging to focally ablate low-intermediate-grade tumors within the prostate. The overall goal is to provide highly localized regional control of prostate cancer that also results in greatly reduced patient morbidity and improved functional outcomes. This pilot device study reports feasibility and safety data from 16 cases of patients diagnosed with low- or intermediate-risk localized prostate cancer. After GSN infusion and high-precision laser ablation, patients underwent multiparametric MRI of the prostate at 48 to 72 h, followed by postprocedure mpMRI/ultrasound targeted fusion biopsies at 3 and 12 mo, as well as a standard 12-core systematic biopsy at 12 mo. GSN-mediated focal laser ablation was successfully achieved in 94% (15/16) of patients, with no significant difference in International Prostate Symptom Score or Sexual Health Inventory for Men observed after treatment. This treatment protocol appears to be feasible and safe in men with low- or intermediate-risk localized prostate cancer without serious complications or deleterious changes in genitourinary function.

Prostate cancer "super-active surveillance" era opened by vascular targeted photodynamic therapy

The "super-active surveillance" concept denotes any active surveillance optimization that allows longer surveillance periods, with the main intention of avoiding overtreatment, by safely eliminating or postponing radical treatment. Super-active surveillance might add to the oncological control with minimal functional impact and similar quality of life compared to active surveillance, which has proved to be safe in well-selected patients. Vascular targeted photodynamic therapy has pioneering shown to significantly reduce the upgrade on subsequent biopsies, resulting in fewer cases converted to radical therapy, and any energy source can be applied to the super-active surveillance concept allowing more men to consider a tissue-preserving therapy for prostate cancer.

Prostate cancer treatment with Irreversible Electroporation (IRE): Safety, efficacy and clinical experience in 471 treatments

BACKGROUND

Irreversible Electroporation (IRE) is a novel image-guided tissue ablation technology that induces cell death via very short but strong pulsed electric fields. IRE has been shown to have preserving properties towards vessels and nerves and the extracellular matrix. This makes IRE an ideal candidate to treat prostate cancer (PCa) where other treatment modalities frequently unselectively destroy surrounding structures inducing severe side effects like incontinence or impotence. We report the retrospective assessment of 471 IRE treatments in 429 patients of all grades and stages of PCa with 6-year maximum follow-up time.

MATERIAL AND FINDINGS

The patient cohort consisted of low (25), intermediate (88) and high-risk cancers (312). All had multi-parametric magnetic resonance imaging, and 199 men had additional 3D-mapping biopsy for diagnostic work-up prior to IRE. Patients were treated either focally (123), sub-whole-gland (154), whole-gland (134) or for recurrent disease (63) after previous radical prostatectomy, radiation therapy, etc. Adverse effects were mild (19.7%), moderate (3.7%) and severe (1.4%), never life-threatening. Urinary continence was preserved in all cases. IRE-induced erectile dysfunction persisted in 3% of the evaluated cases 12 months post treatment. Mean transient IIEF-5-Score reduction was 33% within 12-month post IRE follow-up and 15% after 12 months. Recurrences within the follow-up period occurred in 10% of the treated men, 23 in or adjacent to the treatment field and 18 outside the treatment field (residuals). Including residuals for worst case analysis, Kaplan Maier estimation on recurrence rate at 5 years resulted in 5.6% (CI95: 1.8-16.93) for Gleason 6, 14.6% (CI95: 8.8-23.7) for Gleason 7 and 39.5% (CI95: 23.5-61.4) for Gleason 8-10.

CONCLUSION

The results indicate comparable efficacy of IRE to standard radical prostatectomy in terms of 5-year recurrence rates and better preservation of urogenital function, proving the safety and suitability of IRE for PCa treatment. The data also shows that IRE, besides focal therapy of early PCa, can also be used for whole-gland ablations, in patients with recurrent PCa, and as a problem-solver for local tumor control in T4-cancers not amenable to surgery and radiation therapy anymore.

Use of the IDEAL framework in the urological literature: where are we in 2018?

OBJECTIVES

To assess uptake and application of the IDEAL principles in original surgical procedure- or device-related clinical research studies, as well as its reported relevance as characterized by secondary publications, editorials and reviews.

MATERIALS AND METHODS

IDEAL (Idea, Development, Exploration, Assessment, Long-term study) is a framework that provides stage-specific guidance for surgical innovation and represented a major advance towards raising evidential standards. We performed a comprehensive literature search of all urology-related publications citing one or more of seven key publications on IDEAL in The Lancet and BMJ using multiple databases up to 31 December 2017.

RESULTS

We identified a total of 150 urology-related manuscripts citing IDEAL, of which 83 (55.3%) were original research and 67 (44.7%) were secondary publications. Among the original research articles, 40 (48.2%) did not explicitly apply IDEAL principles or were not surgical innovation studies. The IDEAL phases of the 43 (51.8%) remaining original research studies were IDEAL, in nine (20.9%), 27 (62.8%), four (9.3%), 0 (0%), and three publications (7.0%), respectively. Across IDEAL stages, 30 (75.0%) studies were prospective, 29 (85.3%) reported ethical oversight, and 39 (90.7%) captured treatment-related harms. None of the studies collected information on physician experience.

CONCLUSIONS

The IDEAL framework has found widespread adoption in the urology literature as witnessed by a large number of original manuscripts and secondary publications citing IDEAL; however, its application is largely limited to the early stages of surgical innovation, frequently with inappropriate and incomplete implementation. Further efforts are needed to guide investigators in the optimal use of the IDEAL framework as it relates to surgical innovation in urology.

Impact on genitourinary function and quality of life following focal irreversible electroporation of different prostate segments

PURPOSE

We aimed to evaluate the genitourinary function and quality of life (QoL) following the ablation of different prostate segments with irreversible electroporation (IRE) for localized prostate cancer (PCa).

METHODS

Sixty patients who received primary focal IRE for organ-confined PCa were recruited for this study. Patients were evaluated for genitourinary function and QoL per prostate segment treated (anterior vs. posterior, apex vs. base vs. apex-to-base, unilateral vs. bilateral). IRE system settings and patient characteristics were compared between patients with preserved vs. those with impaired erectile function and urinary continence. Data were prospectively collected at baseline, 3, 6, and 12 months using the expanded prostate cancer index composite, American Urological Association symptom score, SF-12 physical and mental component summary surveys. Difference over time within segments per questionnaire was evaluated using the Wilcoxon's signed rank test. Outcome differences between segments were assessed using covariance models. Baseline measurements included questionnaire scores, age, and prostate volume.

RESULTS

There were no statistically significant changes over time for overall urinary (P = 0.07-0.89), bowel (P = 0.06-0.79), physical (P = 0.18-0.71) and mental (P = 0.45-0.94) QoL scores within each segment. Deterioration of sexual function scores was observed at 6 months within each segment (P = 0.001-0.16). There were no statistically significant differences in QoL scores between prostate segments (P = 0.08-0.97). Older patients or those with poor baseline sexual function at time of treatment were associated with a greater risk of developing erectile dysfunction.

CONCLUSION

IRE is a feasible modality for all prostate segments without any significantly different effect on the QoL outcomes. Older patients and those with poor sexual function need to be counseled regarding the risk of erectile dysfunction.

Numerical simulation modeling of the irreversible electroporation treatment zone for focal therapy of prostate cancer, correlation with whole-mount pathology and T2-weighted MRI sequences

BACKGROUND

At present, it is not possible to predict the ablation zone volume following irreversible electroporation (IRE) for prostate cancer (PCa). This study aimed to determine the necessary electrical field threshold to ablate human prostate tissue in vivo with IRE.

METHODS

In this prospective multicenter trial, patients with localized PCa were treated with IRE 4 weeks before their scheduled radical prostatectomy. In 13 patients, numerical models of the electrical field were generated and compared with the ablation zone volume on whole-mount pathology and T2-weighted magnetic resonance imaging (MRI) sequences. Volume-generating software was used to calculate the ablation zone volumes on histology and MRI. The electric field threshold to ablate prostate tissue was determined for each patient.

RESULTS

A total of 13 patients were included for histological and simulation analysis. The median electrical field threshold was 550 V/cm (interquartile range 383-750 V/cm) for the software-generated histology volumes. The median electrical field threshold was 500 V/cm (interquartile range 386-580 V/cm) when the ablation zone volumes were used from the follow-up MRI.

CONCLUSIONS

The electrical field threshold to ablate human prostate tissue in vivo was determined using whole-mount pathology and MRI. These thresholds may be used to develop treatment planning or monitoring software for IRE prostate ablation; however, further optimization of simulation methods are required to decrease the variance that was observed between patients.

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.

Ablation energies for focal treatment of prostate cancer

Context

In recent years, focal therapy has emerged as a treatment option for a selected group of men with localized prostate cancer. Cryotherapy and high-intensity focused ultrasound (HIFU) are the most investigated types of focal treatment with other options currently under evaluation.

Objective

The objective of the study was to give a comprehensive overview of six available focal treatment options for prostate cancer with their rationale, delivery mechanism, and outcomes.

Information acquisition

The SIU ICUD chapter on available Energies to Treat Prostate Cancer was used as a guide to describe the different technologies. For outcomes, a literature search was conducted using PubMed key words including focal therapy, HIFU, cryotherapy, irreversible electroporation, vascular-targeted photodynamic therapy, laser interstitial therapy, radiofrequency ablation, microwave therapy, and their synonyms in MeSH terms.

Conclusion

Focal therapy appears to have encouraging outcomes on quality of life and urinary and erectile function. For oncological outcomes, it is challenging to fully interpret the outcomes due to heterogeneity in patient selection and short-term follow-up.

Electronic supplementary material

The online version of this article (10.1007/s00345-018-2364-x) contains supplementary material, which is available to authorized users.

[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.

The prostate cancer focal therapy

Despite prostate cancer (PCa) is the leading form of non-cutaneous cancer in men, most patients with PCa die with disease rather than of the disease. Therefore, the risk of overtreatment should be considered by clinicians who have to distinguish between patients with high risk PCa (who would benefit from radical treatment) and patients who may be managed more conservatively, such as through active surveillance or emerging focal therapy (FT). The aim of FT is to eradicate clinically significant disease while protecting key genito-urinary structures and function from injury. While effectiveness studies comparing FT with conventional care options are still lacking, the rationale supporting FT relies on evidence-based advances such as the understanding of the index lesion's central role in the natural history of the PCa and the improvement of multiparametric magnetic resonance imaging (mpMRI) in the detection and risk stratification of PCa. In this literature review, we want to highlight the rationale for FT in PCa management and the current evidence on patient eligibility. Furthermore, we summarize the best imaging modalities to localize the target lesion, describe the current FT techniques in PCa, provide an update on their oncological outcomes and highlight trends for future research.

Pair-matched patient-reported quality of life and early oncological control following focal irreversible electroporation versus robot-assisted radical prostatectomy

Purpose

The design, conduct and completion of randomized trials for curative prostate cancer (PCa) treatments are challenging. To evaluate the effect of robot-assisted radical prostatectomy (RARP) versus focal irreversible electroporation (IRE) on patient-reported quality of life (QoL) and early oncological control using propensity-scored matching.

Methods

Patients with T1c–cT2b significant PCa (high-volume ISUP 1 or any 2/3) who received unifocal IRE were pair-matched to patients who received nerve-sparing RARP. Patient-reported outcomes were prospectively assessed using the Expanded Prostate Cancer Index Composite (EPIC), AUA symptom score and Short Form of Health Survey (SF-12) physical and mental components. Oncological failure was defined as biochemical recurrence (RARP) or positive follow-up biopsies (IRE). Generalized mixed-effect models were used to compare IRE and RARP.

Results

50 IRE patients were matched to 50 RARP patients by propensity score. IRE was significantly superior to RARP in preserving pad-free continence (UC) and erections sufficient for intercourse (ESI). The absolute differences were 44, 21, 13, 14% for UC and 32, 46, 27, 22% for ESI at 1.5, 3, 6, and 12 months, respectively. The EPIC summary scores showed no statistically significant differences. Urinary symptoms were reduced for IRE and RARP patients at 12 months, although IRE patient initially had more complaints. IRE patients experienced more early oncological failure than RARP patients.

Conclusions

These data demonstrated the superior preservation of UC and ESI with IRE compared to RARP up to 12 months after treatment. Long-term oncological data are warranted to provide ultimate proof for or against focal therapy.

Electronic supplementary material

The online version of this article (10.1007/s00345-018-2281-z) contains supplementary material, which is available to authorized users.