Biochemical Response of <0.1 ng/ml Predicts Therapy-free Survival of Prostate Cancer Patients following Prostate-specific Membrane Antigen-targeted Salvage Surgery.

BACKGROUND: In a subset of patients with oligorecurrent prostate cancer (PCa), salvage surgery with prostate-specific membrane antigen (PSMA) radioguided surgery (PSMA-RGS) seems to be of value. OBJECTIVE: To evaluate whether a lower level of postoperative prostate-specific antigen (PSA; <0.1 ng/ml) is predictive of therapy-free survival (TFS) following salvage PSMA-RGS. DESIGN, SETTING, AND PARTICIPANTS: This cohort study evaluated patients with biochemical recurrence after radical prostatectomy and oligorecurrent PCa on PSMA positron emission tomography treated with PSMA-RGS in three tertiary care centers (2014-2022). INTERVENTION: PSMA-RGS. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Postsalvage surgery PSA response was categorized as <0.1, 0.1-<0.2, or >0.2 ng/ml. Kaplan-Meier and multivariable Cox regression models evaluated TFS according to PSA response. RESULTS AND LIMITATIONS: Among 553 patients assessed, 522 (94%) had metastatic soft tissue lesions removed during PSMA-RGS. At 2-16 wk after PSMA-RGS, 192, 62, and 190 patients achieved PSA levels of <0.1, 0.1-<0.2, and >0.2 ng/ml, respectively. At 2 yr of follow-up, TFS rate was 81.1% versus 56.1% versus 43.1% (p < 0.001) for patients with PSA <0.1 versus 0.1-<0.2 versus >0.2 ng/ml. In multivariable analyses, PSA levels of 0.1-0.2 ng/ml (hazard ratio [HR]: 1.9, confidence interval [CI]: 1.1-3.1) and ≥0.2 ng/ml (HR: 3.2, CI: 2.2-4.6, p < 0.001) independently predicted the need for additional therapy after PSMA-RGS. The main limitation is the lack of a control group. CONCLUSIONS: For patients after salvage PSMA-RGS, a lower biochemical response (PSA <0.1 ng/ml) seems to predict longer TFS. This insight may help in counseling patients postoperatively as well as guiding the timely selection of additional therapy. PATIENT SUMMARY: We studied what happened to prostate cancer patients in three European centers who had salvage surgery using a special method called prostate-specific membrane antigen-targeted radioguidance. We found that patients who had low prostate-specific antigen levels soon after surgery were less likely to need further treatment for a longer time.

Strong Correlation Between SUVmax on PSMA PET/CT and Numeric Drop-In γ-Probe Signal for Intraoperative Identification of Prostate Cancer Lesions.

Prostate-specific membrane antigen (PSMA) PET is used to select patients with recurrent prostate cancer for metastasis-directed therapy. A surgical approach can be achieved through radioguided surgery (RGS), using a Drop-In γ-probe that traces lesions that accumulate the radioactive signal. With the aim of guiding patient selection for salvage surgery, we studied the correlation between the SUVmax of lesions on preoperative PSMA PET/CT and their intraoperative counts/s measured using the Drop-In γ-probe. Methods: A secondary analysis based on the prospective, single-arm, and single-center feasibility study was conducted (NCT03857113). Patients (n = 29) with biochemical recurrence after previous curative-intent therapy and a maximum of 3 suggestive lesions within the pelvis on preoperative PSMA PET/CT were included. Patients treated with androgen deprivation therapy within 6 mo before surgery were excluded. All patients received an intravenous injection of 99mTc-PSMA-I&S 1 d before surgery. Radioguidance was achieved using a Drop-In γ-probe. Correlation was determined using the Spearman rank correlation coefficient (ρs). Subgroup analysis was based on the median SUVmax Results: In total, 33 lesions were visible on the PSMA PET/CT images, with a median overall SUVmax of 6.2 (interquartile range [IQR], 4.2-9.7). RGS facilitated removal of 31 lesions. The median Drop-In counts/s were 134 (IQR, 81-220) in vivo and 109 (IQR, 72-219) ex vivo. The intensity of the values correlated with SUVmax (ρs = 0.728 and 0.763, respectively; P < 0.001). Subgroup analysis based on median SUVmax in the group with an SUVmax of less than 6 showed no statistically significant correlation with the numeric signal in vivo (ρs = 0.382; P = 0.221) or the signal-to-background-ratio (ρs = 0.245; P = 0.442), whereas the group with an SUVmax of 6 or more showed respective statistically significant positive correlations (ρs = 0.774 [P < 0.001] and ρs = 0.647 [P = 0.007]). Conclusion: Our findings indicate that there is a direct relation between SUVmax on PSMA PET/CT and the readout recorded by the surgical Drop-In probe, thereby indicating that SUVmax can be used to select patients for PSMA RGS. For more definitive subgroup definitions for treatment recommendations, further studies are necessary to validate the present findings.

99mTcPSMA-radioguided surgery in oligorecurrent prostate cancer: the randomised TRACE-II trial.

OBJECTIVE: To investigate whether combination treatment of prostate-specific membrane antigen (PSMA)-based radioguided surgery (RGS) with short-term androgen deprivation therapy (ADT) improves oncological outcomes in men with oligorecurrent prostate cancer (PCa) as compared to treatment with short-term ADT only. METHODS: The TRACE-II study is an investigator-initiated, prospective, randomised controlled clinical trial. Patients (aged >18 years) with hormone-sensitive recurrent PCa after radical prostatectomy or radiotherapy (brachytherapy or external beam radiotherapy), with involvement of ≤2 lymph nodes or local oligorecurrent disease within the pelvis as determined by PSMA positron emission tomography (PET)/computed tomography (CT) are randomly assigned in a 1:1 ratio between 6-month ADT (Arm A) or 6-month ADT plus RGS (Arm B). The primary objective is to determine clinical progression-free survival (CPFS) at 24 months. After PSMA-RGS, CPFS is defined as the time between the start of treatment and the appearance of a re-recurrence (any N1 or M1) as suggested by PSMA-PET/CT or symptoms related to progressive PCa, or death from any cause. The secondary objectives include metastasis-free survival at 2, 5 and 10 years, biochemical progression-free survival at 2 years, and patient-reported quality of life at 2, 5 and 10 years. A total of 60 patients, 30 per arm, will be included. The trial is powered (80%) to detect at least a 30% absolute difference in CPFS between the two study arms in the period 2 years after randomisation. We expect to enrol the required participants in 3 years. The study has an expected duration of 5 years in total. CONCLUSIONS: Combining RGS with short-term ADT might be oncologically beneficial for patients with oligorecurrent PCa. In this first randomised controlled trial, we are investigating the potential oncological benefits of this combined treatment, while also focusing on maintaining quality of life.

Delphi consensus project on prostate-specific membrane antigen (PSMA)-targeted surgery-outcomes from an international multidisciplinary panel.

PURPOSE: Prostate-specific membrane antigen (PSMA) is increasingly considered as a molecular target to achieve precision surgery for prostate cancer. A Delphi consensus was conducted to explore expert views in this emerging field and to identify knowledge and evidence gaps as well as unmet research needs that may help change practice and improve oncological outcomes for patients. METHODS: One hundred and five statements (scored by a 9-point Likert scale) were distributed through SurveyMonkey®. Following evaluation, a consecutive second round was performed to evaluate consensus (16 statements; 89% response rate). Consensus was defined using the disagreement index, assessed by the research and development project/University of California, Los Angeles appropriateness method. RESULTS: Eighty-six panel participants (72.1% clinician, 8.1% industry, 15.1% scientists, and 4.7% other) participated, most with a urological background (57.0%), followed by nuclear medicine (22.1%). Consensus was obtained on the following: (1) The diagnostic PSMA-ligand PET/CT should ideally be taken < 1 month before surgery, 1-3 months is acceptable; (2) a 16-20-h interval between injection of the tracer and surgery seems to be preferred; (3) PSMA targeting is most valuable for identification of nodal metastases; (4) gamma, fluorescence, and hybrid imaging are the preferred guidance technologies; and (5) randomized controlled clinical trials are required to define oncological value. Regarding surgical margin assessment, the view on the value of PSMA-targeted surgery was neutral or inconclusive. A high rate of "cannot answer" responses indicates further study is necessary to address knowledge gaps (e.g., Cerenkov or beta-emissions). CONCLUSIONS: This Delphi consensus provides guidance for clinicians and researchers that implement or develop PSMA-targeted surgery technologies. Ultimately, however, the consensus should be backed by randomized clinical trial data before it may be implemented within the guidelines.

The Diagnostic Value of the Sentinel Node Procedure to Detect Occult Lymph Node Metastases in PSMA PET/CT Node-Negative Prostate Cancer Patients.

Our objective was to assess the diagnostic value of the sentinel node (SN) procedure for lymph node staging in primary intermediate- and high-risk prostate cancer patients with node-negative results on prostate-specific membrane antigen PET/CT (miN0). Methods: From 2016 to 2022, 154 patients with primary, miN0 PCa were retrospectively included. All patients had a Briganti nomogram-assessed nodal risk of more than 5% and underwent a robot-assisted SN procedure for nodal staging. The prevalence of nodal metastases at histopathology and the occurrence of surgical complications according to the Clavien-Dindo classification were evaluated. Results: The SN procedure yielded 84 (14%) tumor-positive lymph nodes with a median metastasis size of 3 mm (interquartile range, 1-4 mm). In total, 55 patients (36%) were reclassified as pN1. A complication of Clavien-Dindo grade 3 or higher occured in 1 patient (0.6%). Conclusion: The SN procedure classified 36% of patients with miN0 prostate cancer with an elevated risk of nodal metastases as pN1.

Treating Primary Node-Positive Prostate Cancer: A Scoping Review of Available Treatment Options.

There is currently no consensus on the optimal treatment for patients with a primary diagnosis of clinically and pathologically node-positive (cN1M0 and pN1M0) hormone-sensitive prostate cancer (PCa). The treatment paradigm has shifted as research has shown that these patients could benefit from intensified treatment and are potentially curable. This scoping review provides an overview of available treatments for men with primary-diagnosed cN1M0 and pN1M0 PCa. A search was conducted on Medline for studies published between 2002 and 2022 that reported on treatment and outcomes among patients with cN1M0 and pN1M0 PCa. In total, twenty-seven eligible articles were included in this analysis: six randomised controlled trials, one systematic review, and twenty retrospective/observational studies. For cN1M0 PCa patients, the best-established treatment option is a combination of androgen deprivation therapy (ADT) and external beam radiotherapy (EBRT) applied to both the prostate and lymph nodes. Based on most recent studies, treatment intensification can be beneficial, but more randomised studies are needed. For pN1M0 PCa patients, adjuvant or early salvage treatments based on risk stratification determined by factors such as Gleason score, tumour stage, number of positive lymph nodes, and surgical margins appear to be the best-established treatment options. These treatments include close monitoring and adjuvant treatment with ADT and/or EBRT.

Real-Time Identification of Nodal Metastases With 99m Tc-Prostate-Specific Membrane Antigen-Based Radioguidance and Indocyanine Green Fluorescence Imaging in Primary Prostate Cancer Surgery-On the Road to Hybrid Image-Guided Surgery.

ABSTRACT: Recent developments in image-guided prostate cancer surgery focus on extending prostate-specific membrane antigen-directed radioguidance with optical tumor detection using fluorescence, as radio- and fluorescence signals complement each other with in-depth detection and real-time visualization, respectively. As a step in this direction, we report here the integration of indocyanine green fluorescence imaging into a 99m Tc-prostate-specific membrane antigen-targeted radioguided surgery workflow.

First-in-patient study of OTL78 for intraoperative fluorescence imaging of prostate-specific membrane antigen-positive prostate cancer: a single-arm, phase 2a, feasibility trial.

BACKGROUND: Targeted real-time imaging during robot-assisted radical prostatectomy provides information on the localisation and extent of prostate cancer. We assessed the safety and feasibility of the prostate-specific membrane antigen (PSMA)-targeted fluorescent tracer OTL78 in patients with prostate cancer. METHODS: In this single-arm, phase 2a, feasibility trial with an adaptive design was carried out in The Netherlands Cancer Institute, Netherlands. Male patients aged 18 years or older, with PSMA PET-avid prostate cancer with an International Society of Urological Pathology (ISUP) grade group of 2 or more, who were scheduled to undergo robot-assisted radical prostatectomy with or without extended pelvic lymph node dissection were eligible. All patients had a robot-assisted radical prostatectomy using OTL78. Based on timing and dose, patients received a single intravenous infusion of OTL78 (0·06 mg/kg 1-2 h before surgery [dose cohort 1], 0·03 mg/kg 1-2 h before surgery [dose cohort 2], or 0·03 mg/kg 24 h before surgery [dose cohort 3]). The primary outcomes, assessed in all enrolled patients, were safety and pharmacokinetics of OTL78. This study is completed and is registered in the European Trial Database, 2019-002393-31, and the International Clinical Trials Registry Platform, NL8552, and is completed. FINDINGS: Between June 29, 2020, and April 1, 2021, 19 patients were screened for eligibility, 18 of whom were enrolled. The median age was 69 years (IQR 64-70) and median prostate-specific antigen concentration was 15 ng/mL (IQR 9·3-22·0). In 16 (89%) of 18 patients, robot-assisted radical prostatectomy was accompanied by an extended pelvic lymph node dissection. Three serious adverse events occurred in one (6%) patient: an infected lymphocele, a urosepsis, and an intraperitoneal haemorrhage. These adverse events were considered unrelated to the administration of OTL78 or intraoperative fluorescence imaging. No patient died, required a dose reduction, or required discontinuation due to drug-related toxicity. The dose-normalised maximum serum concentration (Cmax/dose) in patients was 84·1 ng/mL/mg for the 0·03 mg/kg dose and 79·6 ng/mL/mg for the 0·06 mg/kg dose, the half-life was 5·1 h for the 0·03 mg/kg dose and 4·7 h for the 0·06 mg/kg dose, the volume of distribution was 22·9 L for the 0·03 mg/kg dose and 19·5 L for the 0·06 mg/kg dose, and the clearance was 3·1 L/h for the 0·03 mg/kg dose and 3·0 L/h for the 0·06 mg/kg dose. INTERPRETATION: This first-in-patient study showed that OTL78 was well tolerated and had the potential to improve prostate cancer detection. Optimal dosing was 0·03 mg/kg, 24 h preoperatively. PSMA-directed fluorescence imaging allowed real-time identification of visually occult prostate cancer and might help to achieve complete oncological resections. FUNDING: On Target Laboratories.

Sentinel Node Procedure to Select Clinically Localized Prostate Cancer Patients with Occult Nodal Metastases for Whole Pelvis Radiotherapy.

Background: Accurate identification of men who harbor nodal metastases is necessary to select patients who most likely benefit from whole pelvis radiotherapy (WPRT). Limited sensitivity of diagnostic imaging approaches for the detection of nodal micrometastases has led to the exploration of the sentinel lymph node biopsy (SLNB). Objective: To evaluate whether SLNB can be used as a tool to select pathologically node-positive patients who likely benefit from WPRT. Design setting and participants: We included 528 clinically node-negative primary prostate cancer (PCa) patients with an estimated nodal risk of >5% treated between 2007 and 2018. Intervention: A total of 267 patients were directly treated with prostate-only radiotherapy (PORT; non-SLNB group), while 261 patients underwent SLNB to remove lymph nodes directly draining from the primary tumor prior to radiotherapy (SLNB group); pN0 patients were treated with PORT, while pN1 patients were offered WPRT. Outcome measurements and statistical analysis: Biochemical recurrence-free survival (BCRFS) and radiological recurrence-free survival (RRFS) were compared using propensity score weighted (PSW) Cox proportional hazard models. Results and limitations: The median follow-up was 71 mo. Occult nodal metastases were found in 97 (37%) SLNB patients (median metastasis size: 2 mm). Adjusted 7-yr BCRFS rates were 81% (95% confidence interval [CI] 77-86%) in the SLNB group and 49% (95% CI 43-56%) in the non-SLNB group. The corresponding adjusted 7-yr RRFS rates were 83% (95% CI 78-87%) and 52% (95% CI 46-59%), respectively. In the PSW multivariable Cox regression analysis, SLNB was associated with improved BCRFS (hazard ratio [HR] 0.38, 95% CI 0.25-0.59, p < 0.001) and RRFS (HR 0.44, 95% CI 0.28-0.69, p < 0.001). Limitations include the bias inherent to the study's retrospective nature. Conclusions: SLNB-based selection of pN1 PCa patients for WPRT was associated with significantly improved BCRFS and RRFS compared with (conventional) imaging-based PORT. Patient summary: Sentinel node biopsy can be used to select patients who will benefit from the addition of pelvis radiotherapy. This strategy results in a longer duration of prostate-specific antigen control and a lower risk of radiological recurrence.

Role of Local and/or Metastasis-directed Therapy in Patients with Hormone-sensitive M1a Prostate Cancer-A Systematic Review.

CONTEXT: It remains unclear whether men with hormone-sensitive prostate cancer (PCa) metastasized to nonregional lymph nodes (M1a) benefit from prostate-directed therapy (PDT) and/or metastasis-directed therapy (MDT). OBJECTIVE: To systematically summarize the literature regarding oncological outcomes of de novo and recurrent M1a PCa patients treated with PDT and/or MDT. EVIDENCE ACQUISITION: We searched Medline (Ovid), Embase, and Scopus according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines for reports on oncological outcomes of de novo or recurrent hormone-sensitive M1a PCa patients treated with PDT (radical prostatectomy or radiotherapy) and/or MDT (nodal radiotherapy or salvage lymph node dissection) with or without androgen deprivation therapy. A descriptive data synthesis and a methodological quality assessment were performed to evaluate the impact of PDT and/or MDT on survival in M1a PCa patients. EVIDENCE SYNTHESIS: A total of 6136 articles were screened and 24 studies were included in this systematic review. In de novo M1a PCa patients, PDT was associated with improved oncological outcomes compared with no PDT. In recurrent M1a PCa, MDT could delay the need for systemic treatment in a selection of patients, but high-level evidence from prospective phase III randomized controlled trials is still awaited. CONCLUSIONS: This systematic review summarized the limited literature data on the management of M1a PCa. Subgroup analyses suggest a role for PDT plus systemic therapy in de novo M1a PCa. MDT to distant nodal metastases delayed the need for systemic therapy in recurrent disease, but robust data are lacking. The predominantly retrospective nature of the included studies and significant heterogeneity in study designs limit the strength of evidence. PATIENT SUMMARY: We reviewed the treatment of patients with prostate cancer that has spread to lymph nodes outside the pelvis without metastases in other organ systems. There is evidence that treatment of the primary prostate tumor improves outcomes in well-selected patients and that treatment targeting distant lymph node metastases can delay the start of systemic treatment.

Cohort Study of Oligorecurrent Prostate Cancer Patients: Oncological Outcomes of Patients Treated with Salvage Lymph Node Dissection via Prostate-specific Membrane Antigen-radioguided Surgery.

BACKGROUND: In a subset of patients with recurrent oligometastatic prostate cancer (PCa) salvage surgery with prostate-specific membrane antigen (PSMA)-targeted radioguidance (PSMA-RGS) might be of value. OBJECTIVE: To evaluate the oncological outcomes of salvage PSMA-RGS and determine the predictive preoperative factors of improved outcomes. DESIGN, SETTING, AND PARTICIPANTS: A cohort study of oligorecurrent PCa patients with biochemical recurrence (BCR) after radical prostatectomy and imaging with PSMA positron emission tomography (PET), treated with PSMA-RGS in two tertiary care centers (2014-2020), was conducted. INTERVENTION: PSMA-RGS. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Kaplan-Meier and multivariable Cox regression models were used to assess BCR-free (BFS) and therapy-free (TFS) survival. Postoperative complications were classified according to Clavien-Dindo. RESULTS AND LIMITATIONS: Overall, 364 patients without concomitant treatment were assessed. At PSMA-RGS, metastatic soft-tissue PCa lesions were removed in 343 (94%) patients. At 2-16 wk after PSMA-RGS, 165 patients reached a prostate-specific antigen (PSA) level of <0.2 ng/ml. Within 3 mo, 24 (6.6%) patients suffered from Clavien-Dindo complications grade III-IV. At 2 yr, BFS and TFS rates were 32% and 58%, respectively. In multivariable analyses, higher preoperative PSA (hazard ratio [HR]: 1.07, 95% confidence interval [CI]: 1.02-1.12), higher number of PSMA-avid lesions (HR: 1.23, CI: 1.08-1.40), multiple (pelvic plus retroperitoneal) localizations (HR: 1.90, CI: 1.23-2.95), and retroperitoneal localization (HR: 2.04, CI: 1.31-3.18) of lesions in preoperative imaging were independent predictors of BCR after PSMA-RGS. The main limitation is the lack of a control group. CONCLUSIONS: As salvage surgery in oligorecurrent PCa currently constitutes an experimental treatment approach, careful patient selection is mandatory based on life expectancy, low PSA values, and low number of PSMA PET-avid lesions located in the pelvis. PATIENT SUMMARY: We looked at the outcomes from prostate cancer patients with recurrent disease after radical prostatectomy. We found that surgery may be an opportunity to prolong treatment-free survival, but patient selection criteria need to be very narrow.

Predictive Value of Cribriform and Intraductal Carcinoma for the Nomogram-based Selection of Prostate Cancer Patients for Pelvic Lymph Node Dissection.

OBJECTIVE: To assess the predictive value of biopsy-identified cribriform carcinoma and/or intraductal carcinoma (CR/IDC) within the Briganti and MSKCC nomograms predicting lymph node metastasis (LNM) in patients with primary prostate cancer (PCa). METHODS: We retrospectively included 393 PCa patients who underwent radical prostatectomy with extended pelvic lymph node dissection at 3 tertiary referral centers. We externally validated 2 prediction tools: the Briganti 2012 nomogram and the Memorial Sloan Kettering Cancer Center (MSKCC) nomogram. Both nomograms were augmented with CR/IDC. The original model was compared with the CR/IDC-updated model using the likelihood ratio test. The performance of the prediction tools was assessed using calibration, discrimination, and clinical utility. RESULTS: Overall, 109 (28%) men were diagnosed with LNM. Calibration plots of the Briganti and MSKCC nomograms demonstrated an underestimation of the LNM risk across clinically relevant thresholds (≤15%). The addition of CR/IDC to the Briganti nomogram increased the fit of the data (χ2(1) = 4.30, P = .04), but did not improve the area under the curve (AUC) (0.69, 95% CI 0.63-0.75 vs 0.69, 95% CI 0.64-0.75). Incorporation of CR/IDC in the MSKCC nomogram resulted in an increased fit on the data (χ2(1) = 10.04, P <.01), but did not increase the AUC (0.66, 95% CI 0.60-0.72 vs 0.68, 95% CI 0.62-0.74). The addition of CR/IDC to the Briganti and MSKCC nomograms did not improve the clinical risk prediction. CONCLUSION: Incorporation of CR/IDC into the 2 clinically most used pre-radical prostatectomy nomograms does not improve LNM prediction in a multinational, contemporary PCa cohort.

Drug-Induced Epigenomic Plasticity Reprograms Circadian Rhythm Regulation to Drive Prostate Cancer toward Androgen Independence.

In prostate cancer, androgen receptor (AR)-targeting agents are very effective in various disease stages. However, therapy resistance inevitably occurs, and little is known about how tumor cells adapt to bypass AR suppression. Here, we performed integrative multiomics analyses on tissues isolated before and after 3 months of AR-targeting enzalutamide monotherapy from patients with high-risk prostate cancer enrolled in a neoadjuvant clinical trial. Transcriptomic analyses demonstrated that AR inhibition drove tumors toward a neuroendocrine-like disease state. Additionally, epigenomic profiling revealed massive enzalutamide-induced reprogramming of pioneer factor FOXA1 from inactive chromatin sites toward active cis-regulatory elements that dictate prosurvival signals. Notably, treatment-induced FOXA1 sites were enriched for the circadian clock component ARNTL. Posttreatment ARNTL levels were associated with patients' clinical outcomes, and ARNTL knockout strongly decreased prostate cancer cell growth. Our data highlight a remarkable cistromic plasticity of FOXA1 following AR-targeted therapy and revealed an acquired dependency on the circadian regulator ARNTL, a novel candidate therapeutic target. SIGNIFICANCE: Understanding how prostate cancers adapt to AR-targeted interventions is critical for identifying novel drug targets to improve the clinical management of treatment-resistant disease. Our study revealed an enzalutamide-induced epigenomic plasticity toward prosurvival signaling and uncovered the circadian regulator ARNTL as an acquired vulnerability after AR inhibition, presenting a novel lead for therapeutic development. See related commentary by Zhang et al., p. 2017. This article is highlighted in the In This Issue feature, p. 2007.

Robot-assisted Prostate-specific Membrane Antigen-radioguided Salvage Surgery in Recurrent Prostate Cancer Using a DROP-IN Gamma Probe: The First Prospective Feasibility Study.

BACKGROUND: It has been proven that intraoperative prostate-specific membrane antigen (PSMA)-targeted radioguidance is valuable for the detection of prostate cancer (PCa) lesions during open surgery. Rapid extension of robot-assisted, minimally invasive surgery has increased the need to make PSMA-radioguided surgery (RGS) robot-compliant. OBJECTIVE: To evaluate whether the miniaturized DROP-IN gamma probe facilitates translation of PSMA-RGS to robotic surgery in men with recurrent PCa. DESIGN, SETTING, AND PARTICIPANTS: This prospective feasibility study included 20 patients with up to three pelvic PCa recurrences (nodal or local) on staging PSMA positron emission tomography (PET) after previous curative-intent therapy. SURGICAL PROCEDURE: Robot-assisted PSMA-RGS using the DROP-IN gamma probe was carried out 19-23 h after intravenous injection of 99mtechnetium PSMA-Investigation & Surgery (99mTc-PSMA-I&S). MEASUREMENTS: The primary endpoint was the feasibility of robot-assisted PSMA-RGS. Secondary endpoints were a comparison of the radioactive status (positive or negative) of resected specimens and final histopathology results, prostate-specific antigen (PSA) response following PSMA-RGS, and complications according to the Clavien-Dindo classification. RESULTS AND LIMITATIONS: Using the DROP-IN probe, 19/21 (90%) PSMA-avid lesions could be resected robotically. On a per-lesion basis, the sensitivity and specificity of robot-assisted PSMA-RGS was 86% and 100%, respectively. A prostate-specific antigen (PSA) reduction of >50% and a complete biochemical response (PSA <0.2 ng/ml) were seen in 12/18 (67%) and 4/18 (22%) patients, respectively. During follow-up of up to 15 mo, 4/18 patients (22%) remained free of biochemical recurrence (PSA ≤0.2 ng/ml). One patient suffered from a Clavien-Dindo grade >III complication. CONCLUSIONS: The DROP-IN probe helps in realizing robot-assisted PSMA-RGS. The procedure is technically feasible for intraoperative detection of nodal or local PSMA-avid PCa recurrences. PATIENT SUMMARY: A device called the DROP-IN probe facilitates minimally invasive, robot-assisted surgery guided by radioactive tracers in patients with recurrent prostate cancer. This procedure holds promise for improving the intraoperative identification and removal of prostate cancer lesions.

Occupational Radiation Exposure of Radiopharmacy, Nuclear Medicine, and Surgical Personnel During Use of [99mTc]Tc-PSMA-I&S for Prostate Cancer Surgery.

The aim of this study was to estimate and subsequently measure the occupational radiation exposure for all personnel involved in producing, administering, or performing imaging or surgery with [99mTc]Tc-PSMA-I&S, which has been introduced for identification of tumor-positive lymph nodes during salvage prostate cancer surgery. Methods: The effective dose was estimated and subsequently measured with electronic personal dosimeters for the following procedures and personnel: labeling and quality control by the radiopharmacy technologist, syringe preparation by the nuclear medicine laboratory technologist, patient administration by the nuclear medicine physician, patient imaging by the nuclear medicine imaging technologist, and robot-assisted laparoscopic salvage lymph node dissection attended by an anesthesiology technologist, scrub nurse, surgical nurse, and surgeon. The dose rate of the patient was measured immediately after administration of [99mTc]Tc-PSMA-I&S, after imaging, and after surgery. Results: The estimated dose per procedure ranged from 1.59 × 10-10 µSv (imaging technologist) to 9.74 µSv (scrub nurse). The measured effective dose ranged from 0 to 5 µSv for all personnel during a single procedure with [99mTc]Tc-PSMA-I&S. The highest effective dose was received by the scrub nurse (3.2 ± 1.3 µSv), whereas the lowest dose was measured for the surgical nurse (0.2 ± 0.5 µSv). If a single scrub nurse were to perform as many as 100 procedures with [99mTc]Tc-PSMA-I&S in a year, the total effective dose would be 320 µSv/y. Immediately after administration, the dose rate at 50 cm from the patient was 18.5 ± 1.6 µSv/h, which dropped to 1.8 ± 0.3 µSv/h after imaging the following day, reducing even further to 0.56 ± 0.33 µSv/h after surgery. Conclusion: The effective dose for personnel involved in handling [99mTc]Tc-PSMA-I&S is comparable to that of other 99mTc-radiopharmaceuticals and therefore safe for imaging and radioguided surgery.