Radiation Therapy and IRreversible Electroporation for Intermediate Risk Prostate Cancer (RTIRE)

This is a single-site trial for 42 subjects with intermediate risk prostate cancer who undergo Irreversible Electroporation (IRE) followed by Magnetic Resonance guided Radiotherapy MRgRT. The investigators hypothesize that the combined therapy will feasible and be safe to perform with low morbidity. Ultimately, RTIRE may provide optimal treatment for intermediate risk prostate cancer patients.

The primary objective is to determine feasibility of combining IRE and SBRT. Feasibility is defined at 80% of subjects assessed at 12 weeks post-IRE/6 weeks post-MRgRT within 1 year from first subject enrollment. Rationale 1. Focal therapy with IRE offers a low side effect profile of treatment but risk of recurrence 2. Lower dose MRgRT offers the potential benefit of limiting radiation dose received by normal tissues, namely the bladder and rectum, with advanced MR image guidance, real- time volume adaptability and dose delivery techniques. 3. Combined IRE and MRgRT may provide optimal treatment of prostate cancer while minimizing side effects Patients with intermediate risk prostate cancer are at higher risk of progressing while on active surveillance when compared to men with low-risk prostate cancer. The benefits of definitive treatment with RT or surgery may not outweigh the risks of surveillance in intermediate risk prostate cancer patients due to increased morbidity of treatment. Focal therapy with IRE is effective in treating prostate cancer with minimal side effects but has a high risk of recurrence, especially in patients with nontreated low risk prostate cancer. Lower dose RT may treat low risk prostate cancer and reduce the risk of recurrence after treatment. RTIRE may be a treatment option for some patients with intermediate risk prostate cancer. Study Completion A participant is considered to have completed the study if he has completed all phases of the study including the last visit or the last scheduled procedure. The end of the study is defined as completion of the last visit or procedure shown in the SoA in the trial globally. Treatment Phase Irreversible Electroporation Subjects will be placed in the dorsal lithotomy position under sterile technique. The NanoKnife procedure will be carried out under general anesthesia. A Foley catheter will be placed to aid in draining the bladder during treatment. Prior to NanoKnife treatment, subjects will receive an antibiotic of choice selected by the treating physician via intravenous infusion to reduce the chance of infection. A negative urine culture will be obtained prior to treatment. The area of the prostate that was positive for cancer based on the transperineal prostate biopsy will be targeted for ablation via the NanoKnife System. An MRI/TRUS fusion device probe will be placed in the rectum and the prostate will be visualized in both sagittal and axial views. The ultrasound grid which was used during the mapping biopsy will be oriented using anatomical landmarks and used to identify the location of the positive biopsy cores. The NanoKnife Single Electrode Probes will be percutaneously inserted into the prostate through the perineum using MRI/TRUS fusion guidance and the ultrasound grid for guidance. The location of the probes will be documented via ultrasound imaging After placement of the NanoKnife probes in the prostate and immediately prior to NanoKnife treatment, a nondepolarizing neuromuscular blocking agent will be administered to reduce skeletal muscle contraction which is associated with the use of the NanoKnife System. The pulse treatment dose will be determined using standard protocol and a pre-treatment checklist will be performed prior to ablation. Post ablation assessment will be performed by assessing changes in voltage parameters during treatment and after confirmation of adequate ablation the probes will be removed. An immediate post ablation MRI will also be assessed to determine the effectiveness of ablation. The Foley catheter will be left in place after the procedure and removed at the discretion of the treating physician. The IRE treatment will be scheduled as an outpatient procedure. Patients will be discharged from the hospital with a foley catheter and scheduled for a void trial prior to removal. The void trial will include a post void residual to confirm safety for catheter removal. Radiotherapy After consent, eligibility verification, and IRE patients will undergo CT/MRI simulation and radiotherapy planning. Patients will receive treatment to the prostate + seminal vesicles to 32.5 Gy in 5 fractions. Immobilization Immobilization of the hips and feet using a cradle should be considered. Each patient will be positioned in the supine position. Prone positioning for treatment is not permitted. Simulation Treatment planning CT/MRI will be performed with vac loc immobilization. Patients will be advised to drink 2-3 cups of water 30 minutes prior to the MRI simulation to allow for a comfortably full bladder, as tolerated. Rectal Filling - An overly distended rectum can introduce a systematic positioning error that may increase the probability of missing the clinical target volume (CTV). Patients should be simulated with the rectum as empty as possible and \<3 cm in the anterior-posterior dimension is ideal. Rectal balloons for planning and treatment are not permitted. Enema may be necessary for subjects. Bladder Filling - Patients should also have a comfortably full bladder (the patient should not be uncomfortable at simulation because it is likely that he will have more difficulty maintaining a full bladder during treatment). Contours The prostate + seminal vesicles will be contoured as the clinical target volume (CTV). The planning target volume (PTV) expansion for the CTV will be 2 mm. The rectum will be drawn from the bottom of the ischial tuberosities to the sigmoid flexure. The bladder, bladder wall (bladder - 4 mm isotropic constriction), urethra (contoured with 10 mm brush on sagittal view), femoral heads, and penile bulb will also be contoured as normal structures. Dose/Treatment Planning Parameters PTV will be treated to the prescribed dose 32.5 Gy in 5 fractions. VPrescription Dose (volume of the PTV receiving Prescription Dose) should be ≥ 95% and not exceed 115% (hotspot) Urethra should be expanded with a 3 mm PRV and should not receive more than the prescription dose