Impact of 68Ga-PSMA-11 PET/CT on the Management of Prostate Cancer Patients with Biochemical Recurrence

Recent advancements in personalized management of prostate cancer biochemical recurrence after radical prostatectomy

PURPOSE OF REVIEW

Biochemical recurrence (BCR) after radical prostatectomy exhibits heterogeneous prognostic implications. Recent advancements in imaging and biomarkers have high potential for personalizing care.

RECENT FINDINGS

Prostate-specific membrane antigen imaging (PSMA)-PET/CT has revolutionized the BCR management in prostate cancer by detecting microscopic lesions earlier than conventional staging, leading to improved cancer control outcomes and changes in treatment plans in approximately two-thirds of cases. Salvage radiotherapy, often combined with androgen deprivation therapy, remains the standard treatment for high-risk BCR postprostatectomy, with PSMA-PET/CT guiding treatment adjustments, such as the radiation field, and improving progression-free survival. Advancements in biomarkers, genomic classifiers, and artificial intelligence-based models have enhanced risk stratification and personalized treatment planning, resulting in both treatment intensification and de-escalation.

SUMMARY

While conventional risk grouping relying on Gleason score and PSA level and kinetics remain the foundation for BCR management, PSMA-PET/CT, novel biomarkers, and artificial intelligence may enable more personalized treatment strategies.

Prostate-specific membrane antigen positron-emission tomography for novel risk-stratification of biochemical recurrence

PURPOSE OF REVIEW

The variety of prostate cancer aggressiveness in patients with biochemical recurrence (BCR) leads to the unmet need of accurate risk stratification. This review examined the recently published risk stratification tool using prostate-specific membrane antigen positron-emission tomography (PSMA-PET) compared to the risk categories by European Association of Urology (EAU).

RECENT FINDINGS

The risk stratification by EAU was proposed for patients with BCR, including the doubling time of the prostate-specific-antigen and Gleason score as predictors for survival. Although stratification into low- vs. high-risk groups reached significant differences in the external validation, C-indices determined moderate discriminative ability and the need to improve the EAU risk categories. PSMA-PET was recently validated as prognostic biomarker and PSMA-PET standardized by Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) metrics were combined to create a visual and a quantitative nomogram to predict overall survival.

SUMMARY

The unmet need to improve risk stratification for prostate cancer patients experiencing BCR was addressed with PSMA-PET PROMISE (PPP) nomograms. Although PPP nomograms are not applied for individual patient counselling yet, they can be used additionally to EAU risk categories.

Diffuse Peritoneal Carcinomatosis of Prostate Cancer Unveiled by [89Zr]Zr-PSMA-617 PET/CT

ABSTRACT

We report an interesting case of a 64-year-old man with a history of radical prostatectomy for prostate cancer. The patient presented with steady increasing prostate-specific antigen levels, but with negative findings on previous multiple conventional prostate-specific membrane antigen (PSMA) PET/CT (with [68Ga]Ga-PSMA-11) and [18F]FDG PET/CT. A recently introduced PSMA tracer using long-lived 89Zr (half-life 3.3 days), [89Zr]Zr-PSMA-617, was administered in attempt to localize potential local recurrence or metastasis. [89Zr]Zr-PSMA-617 PET/CT clearly revealed diffuse peritoneal carcinomatosis and local recurrence of the prostate cancer, which were unidentified on previous conventional PET/CT scans. This case highly demonstrates the potential of PET imaging with the novel PSMA tracer [89Zr]Zr-PSMA-617.

Tc-99m labeled PSMA-617 as a potential SPECT radiotracer for prostate cancer diagnostics: Complexation optimization and its in vitro/vivo evaluation

Technetium-99m (Tc-99m) is the most employed radionuclide in nuclear imaging diagnostics worldwide for many diseases. The ideal physiochemical properties of Tc-99m (such as half-life and pure gamma energy) make it favorable for Single Photon Emission Computed Tomography (SPECT). In this study, we aim to expand the utilization of Tc-99m radiopharmaceutical toward prostate cancer diagnostics which is currently no FDA approved products and has been intensively examined for a potential candidate. The new formulation for Tc-99m complexation with PSMA-617, a current ligand for radionuclide therapy of prostate cancer with lutetium-177 (Lu-177), has been investigated. Co-complexation with citrate was utilized to improve the labeling efficiency by over 97 %. The stability of the new radiopharmaceutical was in vitro evaluated confirming that the Tc-99m labeled PSMA-617 remained stable for over a single half-life of Tc-99m in normal saline solution and in human serum. The in vivo study in the LNCaP xenografted mouse model confirmed a high selectivity of the new tracer toward prostate cancer.

Implementing evidence-based strategies for men with biochemically recurrent and advanced prostate cancer: Consensus recommendations from the US Prostate Cancer Conference 2024

Current US clinical practice guidelines for advanced prostate cancer management contain recommendations based on high-level evidence from randomized controlled trials; however, these guidelines do not address the nuanced clinical questions that are unanswered by prospective trials but nonetheless encountered in day-to-day practice. To address these practical questions, the 2024 US Prostate Cancer Conference (USPCC 2024) was created to generate US-focused expert clinical decision-making guidance for circumstances in which level 1 evidence is lacking. At the second annual USPCC meeting (USPCC 2024), a multidisciplinary panel of experts convened to discuss ongoing clinical challenges related to 5 topic areas: biochemical recurrence; metastatic, castration-sensitive prostate cancer; poly [ADP-ribose] polymerase inhibitors; prostate-specific membrane antigen radioligand therapy; and metastatic, castration-resistant prostate cancer. Through a modified Delphi process, 34 consensus recommendations were developed and are intended to provide clinicians who manage prostate cancer with guidance related to the implementation of novel treatments and technologies. In this report, the authors review the areas of consensus identified by the USPCC 2024 experts and evaluate ongoing unmet needs regarding translational application of the current clinical evidence.

Added Value of [18F]PSMA-1007 PET/CT and PET/MRI in Patients With Biochemically Recurrent Prostate Cancer: Impact on Detection Rates and Clinical Management

BACKGROUND

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) can change management in a large fraction of patients with biochemically recurrent prostate cancer (BCR).

PURPOSE

To investigate the added value of PET to MRI and CT for this patient group, and to explore whether the choice of the PET paired modality (PET/MRI vs. PET/CT) impacts detection rates and clinical management.

STUDY TYPE

Retrospective.

SUBJECTS

41 patients with BCR (median age [range]: 68 [55-78]).

FIELD STRENGTH/SEQUENCE

3T, including T1-weighted gradient echo (GRE), T2-weighted turbo spin echo (TSE) and dynamic contrast-enhanced GRE sequences, diffusion-weighted echo-planar imaging, and a T1-weighted TSE spine sequence. In addition to MRI, [18F]PSMA-1007 PET and low-dose CT were acquired on the same day.

ASSESSMENT

Images were reported using a five-point Likert scale by two teams each consisting of a radiologist and a nuclear medicine physician. The radiologist performed a reading using CT and MRI data and a joint reading between radiologist and nuclear medicine physician was performed using MRI, CT, and PET from either PET/MRI or PET/CT. Findings were presented to an oncologist to create intended treatment plans. Intrareader and interreader agreement analysis was performed.

STATISTICAL TESTS

McNemar test, Cohen's κ, and intraclass correlation coefficients. A P-value <0.05 was considered significant.

RESULTS

7 patients had positive findings on MRI and CT, 22 patients on joint reading with PET/CT, and 18 patients joint reading with PET/MRI. For overall positivity, interreader agreement was poor for MR and CT (κ = 0.36) and almost perfect with addition of PET (PET/CT κ = 0.85, PET/MRI κ = 0.85). The addition of PET from PET/CT and PET/MRI changed intended treatment in 20 and 18 patients, respectively. Between joint readings, intended treatment was different for eight patients.

DATA CONCLUSION

The addition of [18F]PSMA-1007 PET/MRI or PET/CT to MRI and CT may increase detection rates, could reduce interreader variability, and may change intended treatment in half of patients with BCR.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 3.

Long Axial Field-of-View (LAFOV) PET/CT in Prostate Cancer

PSMA-targeted PET/CT is currently considered the most effective non-invasive diagnostic technique for imaging PSMA-positive lesions in prostate cancer (PC), and its introduction has significantly enhanced the role of nuclear medicine in both the diagnosis and therapy (theranostics) of this oncological entity. In line with developments in radiopharmaceuticals, significant progress has been made in the development of PET/CT systems. In particular, the advent of long axial field-of-view (LAFOV) PET/CT scanners has represented a major leap forward in molecular imaging, with early results from clinical applications of these systems showing significant improvements over previous standard axial field-of-view systems in terms of sensitivity, image quality and lesion quantification, while enabling whole-body dynamic PET imaging. In this context, the introduction of the new LAFOV scanners may further enhance the use and potential of PSMA-ligand PET/CT in the diagnosis and management of PC. The initial but steadily growing literature on the application of the new technology in the field of PSMA-ligand PET/CT has already yielded encouraging results regarding the detection of PC lesions with high sensitivity while providing the possibility of ultra-fast or ultra-low dose examinations. Moreover, whole-body dynamic PET has rendered for the first time feasible to capture the pharmacokinetics PSMA-ligands in all major organs and most tumor lesions with high temporal resolution. The main results of these studies are presented in this review.

Early Oncological Outcomes in Patients who Underwent Staging Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Compared with Conventional Imaging Before Radical Prostatectomy and Extended Pelvic Lymph Node Dissection

BACKGROUND AND OBJECTIVE

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) is increasingly used for primary staging in prostate cancer. Owing to accurate detection of small metastases on PSMA-PET/CT, patient selection for robot-assisted radical prostatectomy (RARP) has likely changed. This study analyzes oncological outcomes in patients undergoing RARP and extended pelvic lymph node dissection (ePLND) after PSMA-PET/CT staging, compared with those without PSMA-PET/CT.

METHODS

Patients who underwent staging with PSMA-PET/CT before RARP and ePLND ("PSMA cohort"; 2016-2021) were compared with patients staged without PSMA-PET/CT ("historical cohort"; 2013-2016). Propensity score matching using preoperative variables was performed to limit confounding. As primary outcome measure of biochemical recurrence (BCR)-free survival (BFS) was analyzed, with BCR defined as a prostate specific antigen value of ≥0.2 ng/ml or start of additional therapy after surgery.

KEY FINDINGS AND LIMITATIONS

After matching, 880 patients were included (440 in each cohort). The median follow-up was 35 mo (interquartile range 21-60) for the entire cohort. In the PSMA cohort, 126/440 patients (29%) experienced BCR versus 205/440 (47%) in the historical cohort (log-rank test p = 0.032). A multivariable Cox regression analysis showed an independent effect of preoperative PSMA-PET/CT staging on BFS (hazard ratio 0.70, 95% confidence interval 0.55-0.89, p = 0.0030).

CONCLUSIONS AND CLINICAL IMPLICATIONS

Patients who underwent staging with PSMA-PET/CT had longer biochemical progression-free survival after RARP and ePLND than those without PSMA-PET/CT. This suggests that PSMA-PET/CT staging alters patient selection for RARP and ePLND, and is associated with improved early oncological outcomes for patients who still undergo surgery.

PATIENT SUMMARY

Prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) at the diagnosis of prostate cancer leads to better visualization of metastases and therefore better selection of prostate cancer patients for surgery. Patients who underwent a PSMA-PET/CT scan at the time of diagnosis showed improved oncological outcomes, including longer progression-free survival and less prostate-specific antigen persistence after surgery.

The role of the radiologist in the prostate cancer multidisciplinary conference

The broad range of disease aggressiveness together with imperfect screening, diagnostic, and treatment options in prostate cancer (PCa) makes medical decision-making complex. The primary goal of a multidisciplinary conference is to improve patient outcomes by combining evidence-based data and expert opinion to discuss optimal management, including for those patients with challenging presentations. The primary purpose of the genitourinary imaging specialist in the prostate cancer multidisciplinary conference is to use imaging findings to reduce uncertainty by answering clinical questions. In this review, we discuss the role and the opportunities for an imaging specialist to add value in the care of men with prostate cancer discussed at multidisciplinary conferences.

[89Zr]Zr-PSMA-617 PET/CT in a Patient with Biochemical Recurrence of Prostate Cancer and Prior Indetermined Findings on [18F]PSMA-1007 Imaging

We report a case of a 79-year-old male patient with a history of radical prostatectomy for prostate cancer. The patient presented with biochemical reoccurrence; however, previous conventional PSMA PET/CT using [18F]PSMA-1007 showed two indetermined findings with low uptake in the right iliac lymph nodes. Further MRI evaluation provided no additional information. A recently introduced PSMA tracer, [89Zr]Zr-PSMA-617 (half-life: 3.3 days), was administered in an attempt to confirm the diagnosis and aid in potential radiation planning. [89Zr]Zr-PSMA-617 PET/CT clearly revealed the previously indetermined right iliac lymph nodes as definitely metastatic and also identified additional lymph node metastases that were undetected in prior scans. This case highlights the potential superior sensitivity of [89Zr]Zr-PSMA-617 PET/CT in detecting recurrent disease, especially in unclear settings of [18F]PSMA-1007 PET/CT and demonstrates its potential for guiding targeted radiation therapy with curative intent.

Clinical Factors That Influence Repeat 68Ga-PSMA-11 PET/CT Scan Positivity in Patients with Recurrent Prostate Cancer Under Observation After a Negative 68Ga-PSMA-11 PET/CT Scan: A Single-Center Retrospective Study

This analysis aimed to identify clinical factors associated with positivity on repeat 68Ga-PSMA-11 PET/CT after a negative scan in patients with recurrent prostate cancer (PCa) under observation. Methods: This single-center, retrospective analysis included patients who underwent at least 2 68Ga-PSMA-11 PET/CT scans (PET1 and PET2) at UCLA between October 2016 and June 2021 for recurrent PCa with negative PET1 and no PCa-related treatments between the 2 scans. Using Prostate Cancer Molecular Imaging Standardized Evaluation criteria to define negative and positive scans, the final cohort was divided into PET2-negative (PET2-Neg) and PET2-positive (PET2-Pos). The same PET1 was used twice in the more than 2 PET cases with inclusion criteria fulfilled. Patient characteristics and clinical parameters were compared between the 2 cohorts using Mann-Whitney U test and Fisher exact test. Areas under the curve (AUCs) of the receiver operating characteristic and the Youden index were computed to determine the discrimination ability of statistically significant factors and specific cut points that maximized sensitivity and specificity, respectively. Results: The final analysis included 83 sets of 2 PET/CT scans from 70 patients. Thirty-nine of 83 (47%) sets were PET2-Neg, and 44 of 83 (53%) sets were PET2-Pos. Prostate-specific antigen (PSA) increased from PET1 to PET2 for all 83 (100%) sets of scans. Median PSA at PET1 was 0.4 ng/mL (interquartile range, 0.2-1.0) and at PET2 was 1.6 ng/mL (interquartile range, 0.9-3.8). We found higher serum PSA at PET2 (median, 1.8 vs. 1.1 ng/mL; P = 0.015), absolute PSA difference (median, 1.4 vs. 0.7 ng/mL; P = 0.006), percentage of PSA change (median, +270.4% vs. +150.0%: P = 0.031), and median PSA velocity (0.044 vs. 0.017 ng/mL/wk, P = 0.002) and shorter PSA doubling time (DT; median, 5.1 vs. 8.3 mo; P = 0.006) in the PET2-Pos cohort than in the PET2-Neg cohort. Receiver operating characteristic curves showed cutoffs for PSA at PET2 of 4.80 ng/mL (sensitivity, 34%; specificity, 92%; AUC, 0.66), absolute PSA difference of 0.95 ng/mL (sensitivity, 62%; specificity, 71%; AUC, 0.68), percentage of PSA change of a positive 289.50% (sensitivity, 48%; specificity, 82%; AUC, 0.64), PSA velocity of 0.033 ng/mL/wk (sensitivity, 57%; specificity, 80%; AUC, 0.70), and PSA DT of 7.91 mo (sensitivity, 71%; specificity, 62%; AUC, 0.67). Conclusion: Patients with recurrent PCa under observation after a negative 68Ga-PSMA-11 PET/CT scan with markedly elevated serum PSA levels and shorter PSA DT are more likely to have positive findings on repeat 68Ga-PSMA-11 PET/CT.

Prostate Cancer Recurrence: Examining the Role of Salvage Radiotherapy Field and Risk Factors for Regional Disease Recurrence Captured on 18F-DCFPyL PET/CT

PURPOSE

The role of elective pelvic nodal irradiation in salvage radiotherapy (sRT) remains controversial. Utilizing 18F-DCFPyL PET/CT, this study aimed to investigate differences in disease distribution after whole pelvic (WPRT) or prostate bed (PBRT) radiotherapy and to identify risk factors for pelvic lymph node (LN) relapse.

METHODS

This retrospective study included patients with PSA > 0.1 ng/mL post-radical prostatectomy (RP) or post-RP and sRT who underwent 18F-DCFPyL PET/CT. Disease distribution on 18F-DCFPyL PET/CT after sRT was compared using Chi-square tests. Risk factors were tested for association with pelvic LN relapse after RP and salvage PBRT using logistic regression.

RESULTS

979 18F-DCFPyL PET/CTs performed at our institution between 1/1/2022 - 3/24/2023 were analyzed. There were 246 patients meeting criteria, of which 84 received salvage RT after RP (post-salvage RT group) and 162 received only RP (post-RP group). Salvage PBRT patients (n = 58) had frequent pelvic nodal (53.6%) and nodal-only (42.6%) relapse. Salvage WPRT patients (n = 26) had comparatively lower rates of pelvic nodal (16.7%, p = 0.002) and nodal-only (19.2%, p = 0.04) relapse. The proportion of distant metastases did not differ between the two groups. Multiple patient characteristics, including ISUP grade and seminal vesicle invasion, were associated with pelvic LN disease in the post-RP group.

CONCLUSION

At PSA persistence or progression, salvage WPRT resulted in lower rates of nodal involvement than salvage PBRT, but did not reduce distant metastases. Certain risk factors increase the likelihood of pelvic LN relapse after RP and can help inform salvage RT field selection.

Comparison of digital and analog [68Ga]Ga-PSMA-11 PET/CT for detecting post-prostatectomy biochemical recurrence in prostate cancer patients: a prospective study

Digital positron emission tomography/computed tomography (PET/CT) has shown enhanced sensitivity and spatial resolution compared with analog PET/CT. The present study compared the diagnostic performance of digital and analog PET/CT with [68Ga]Ga-PSMA-11 in prostate cancer patients who experienced biochemical recurrence (BCR) after prostatectomy. Forty prostate cancer patients who experienced BCR, defined as serum prostate-specific antigen (PSA) concentrations exceeding 0.2 ng/mL after prostatectomy, were prospectively recruited. These patients were stratified into three groups based on their serum PSA levels. [68Ga]Ga-PSMA-11 was injected into each patient, and images were acquired using both analog and digital PET/CT scanners. Analog and digital PET/CT showed comparable lesion detection rate (71.8% vs. 74.4%), sensitivity (85.0% vs. 90.0%), and positive predictive value (PPV, 100.0% vs. 100.0%). However, digital PET/CT detected more lesions (139 vs. 111) and had higher maximum standardized uptake values (SUVmax, 14.3 vs. 10.3) and higher kappa index (0.657 vs. 0.502) than analog PET/CT, regardless of serum PSA levels. On both analog and digital PET/CT, lesion detection rates and interrater agreement increased with increasing serum PSA levels. Compared with analog PET/CT, digital PET/CT detected more lesions with a higher SUVmax and better interrater agreement in prostate cancer patients who experienced BCR after prostatectomy.

A Comparison of Arterial Input Function Interpolation Methods for Patlak Plot Analysis of 68Ga-PSMA-11 PET Prostate Cancer Studies

Positron emission tomography (PET) imaging enables quantitative assessment of tissue physiology. Dynamic pharmacokinetic analysis of PET images requires accurate estimation of the radiotracer plasma input function to derive meaningful parameter estimates, and small discrepancies in parameter estimation can mimic subtle physiologic tissue variation. This study evaluates the impact of input function interpolation method on the accuracy of Patlak kinetic parameter estimation through simulations modeling the pharmacokinetic properties of [68Ga]-PSMA-11. This study evaluated both trained and untrained methods. Although the mean kinetic parameter accuracy was similar across all interpolation models, the trained node weighting interpolation model estimated accurate kinetic parameters with reduced overall variability relative to standard linear interpolation. Trained node weighting interpolation reduced kinetic parameter estimation variance by a magnitude approximating the underlying physiologic differences between normal and diseased prostatic tissue. Overall, this analysis suggests that trained node weighting improves the reliability of Patlak kinetic parameter estimation for [68Ga]-PSMA-11 PET.

Development and Internal Validation of a Novel Nomogram Predicting the Outcome of Salvage Radiation Therapy for Biochemical Recurrence after Radical Prostatectomy in Patients without Metastases on Restaging Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography

Background and objective

Owing to the greater use of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) in patients with biochemical recurrence (BCR) of prostate cancer (PCa) after robot-assisted radical prostatectomy (RARP), patient selection for local salvage radiation therapy (sRT) has changed. Our objective was to determine the short-term efficacy of sRT in patients with BCR after RARP, and to develop a novel nomogram predicting BCR-free survival after sRT in a nationwide contemporary cohort of patients who underwent PSMA PET/CT before sRT for BCR of PCa, without evidence of metastatic disease.

Methods

All 302 eligible patients undergoing PCa sRT in four reference centers between September 2015 and August 2020 were included. We conducted multivariable logistic regression analysis using a backward elimination procedure to develop a nomogram for predicting biochemical progression of PCa, defined as prostate-specific antigen (PSA) ≥0.2 ng/ml above the post-sRT nadir within 1 yr after sRT.

Key findings and limitations

Biochemical progression of disease within 1 yr after sRT was observed for 56/302 (19%) of the study patients. The final predictive model included PSA at sRT initiation, pathological grade group, surgical margin status, PSA doubling time, presence of local recurrence on PSMA PET/CT, and the presence of biochemical persistence (first PSA result ≥0.1 ng/ml) after RARP. The area under the receiver operating characteristic curve for this model was 0.72 (95% confidence interval 0.64-0.79). Using our nomogram, patients with a predicted risk of >20% had a 30.8% chance of developing biochemical progression within 1 yr after sRT.

Conclusions

Our novel nomogram may facilitate better patient counseling regarding early oncological outcome after sRT. Patients with high risk of biochemical progression may be candidates for more extensive treatment.

Patient summary

We developed a new tool for predicting cancer control outcomes of radiotherapy for patients with recurrence of prostate cancer after surgical removal of their prostate. This tool may help in better counseling of these patients with recurrent cancer regarding their early expected outcome after radiotherapy.

Radiotheranostics in advanced prostate cancer: Current and future directions

The discovery of small molecules that target the extracellular domain of prostate-specific membrane antigen (PSMA) has led to advancements in diagnostic imaging and the development of precision radiopharmaceutical therapies. In this review, we present the available existing data and highlight the key ongoing clinical evaluations of PSMA-based imaging in the management of primary, biochemically recurrent, and metastatic prostate cancer. We also discuss clinical studies that explore the use of PSMA-based radiopharmaceutical therapy (RPT) in metastatic prostate cancer and forthcoming trials that investigate PSMA RPT in earlier disease states. Multidisciplinary collaboration in clinical trial design and therapeutic administration is critical to the continued progress of this evolving radiotheranostics field.

Prostate-Specific Membrane Antigen: Gateway to Management of Advanced Prostate Cancer

Prostate-specific membrane antigen (PSMA) as a transmembrane protein is overexpressed by prostate cancer (PC) cells and is accessible for binding antibodies or low-molecular-weight radioligands due to its extracellular portion. Successful targeting of PSMA began with the development of humanized J591 antibody. Due to their faster clearance compared to antibodies, small-molecule radioligands for targeted imaging and therapy of PC have been favored in recent development efforts. PSMA positron emission tomography (PET) imaging has higher diagnostic performance than conventional imaging for initial staging of high-risk PC and biochemical recurrence detection/localization. However, it remains to be demonstrated how to integrate PSMA PET imaging for therapy response assessment and as an outcome endpoint measure in clinical trials. With the recent approval of 177Lu-PSMA-617 by the US Food and Drug Administration for metastatic castration-resistant PC progressing after chemotherapy, the high value of PSMA-targeted therapy was confirmed. Compared to standard of care, PSMA-based radioligand therapy led to a better outcome and a higher quality of life. This review, focusing on the advanced PC setting, provides an overview of different approved and nonapproved PSMA-targeted imaging and therapeutic modalities and discusses the future of PSMA-targeted theranostics, also with an outlook on non-radiopharmaceutical-based PSMA-targeted therapies.

PSMA PET for Detection of Recurrence

Prostate cancer (PC) is a significant health concern worldwide, with high incidence and mortality rates. Early and accurate detection and localization of recurrent disease at biochemical recurrence (BCR) is critical for guiding subsequent therapeutic decisions and improving patient outcomes. At BCR, conventional imaging consisting of CT, MRI, and bone scintigraphy are recommended by US and European guidelines, however, these modalities all bear certain limitations in detecting metastatic disease, particularly in low-volume relapse at low prostate-specific antigen (PSA) levels. Molecular imaging with PET/CT or PET/MRI using prostate-specific membrane antigen (PSMA) targeting radiopharmaceuticals has revolutionized imaging of PC. Particularly at BCR PC, PSMA PET has shown better diagnostic performance compared to conventional imaging in detecting local relapse and metastases, even at very low PSA levels. The most recent version of the National Comprehensive Cancer Network (NCCN) guideline has included PSMA-targeted PET/CT or PET/MRI for the localization of BCR PC. There are several different PSMA-targeting radiopharmaceuticals labeled with different radioisotopes, each with slightly different characteristics, but overall similar high sensitivity and specificity for PC. PSMA-targeted PET has the potential to significantly impact patient care by guiding personalized treatment decisions and thus improving outcomes in BCR PC patients.

Prostate-specific membrane antigen radioguided surgery with negative histopathology: an in-depth analysis

PURPOSE

To identify reasons for negative histopathology of specimens from prostate-specific membrane antigen (PSMA) radioguided surgery (PSMA-RGS) in recurrent prostate cancer (PCa) after prostatectomy.

METHODS

Of 302 patients who underwent PSMA-RGS, 17 (5.6%) demonstrated a negative histopathology. Preoperative data, PSMA PET, PSMA SPECT, and follow-up information were analyzed retrospectively to differentiate true/false positive (TP/FP) from true/false negative (TN/FN) lesions.

RESULTS

The median prostate-specific antigen at PET was 0.4 ng/ml (interquartile range [IQR] 0.3-1.2). Twenty-five index lesions (median short axis 7 mm, IQR 5-8; median long-axis 12 mm, IQR 8-17) had a median SUVmax of 4 (IQR 2.6-6; median PSMA expression score 1, IQR 1-1). Six lesions were TP, twelve were FP, one was TN, and six remained unclear. All TP lesions were in the prostatic fossa or adjacent to the internal iliac arteries. Three suspected local recurrences were FP. All FP lymph nodes were located at the distal external iliac arteries or outside the pelvis. A low PSMA-expressing TN node was identified next to a common iliac artery. Unclear lesions were located next to the external iliac arteries or outside the pelvis.

CONCLUSION

In most cases with a negative histopathology from PSMA-RGS, lesions were FP on PSMA PET. Unspecific uptake should be considered in low PSMA-expressing lymph nodes at the distal external iliac arteries or outside the pelvis, especially if no PSMA-positive lymph nodes closer to the prostatic fossa are evident. Rarely, true positive metastases were missed by surgery or histopathology.

Diagnostic Performance of 99mTc-iPSMA SPECT/CT in the Initial Staging of Patients with Unfavorable Intermediate-, High-, and Very High-Risk Prostate Cancer: A Comparative Analysis with 18F-PSMA-1007 PET/CT

Prostate cancer is a leading cause of cancer death in men worldwide. Imaging plays a key role in disease detection and initial staging. Emerging data has shown the superiority of PSMA imaging with PET/CT over conventional imaging for primary diagnoses. Single photon emission computed tomography is more available worldwide, and the imaging agent is low in cost. The aim of this study is to compare the diagnostic accuracy of 99mTc-EDDA/HYNIC-iPSMA SPECT/CT to 18F-PSMA-1007 PET/CT in the primary diagnosis of prostate cancer and the impact on clinical staging.

METHODS

In this prospective controlled study, 18 patients with histologically confirmed prostate cancer with unfavorable intermediate-, high-, and very high-risk characteristics were recruited to undergo 18F-PSMA-PET/CT and 99mTc-iPSMA SPECT/CT. The median age of the patients was 71 years old, and the median PSA level was 23.3 ng/mL. Lesions were divided into the prostate, seminal vesicles, lymph nodes, bone, and visceral metastases. Volumetric analysis was also performed between the two imaging modalities and correlated with PSA levels.

RESULTS

A total of 257 lesions were detected on 18F-PSMA-PET/CT: prostate (n = 18), seminal vesicles (n = 12), locoregional lymph nodes (n = 62), non-locoregional (n = 67), bone (n = 90), and visceral (n = 8). Of these, 99mTc-iPSMA-SPECT/CT detected 229 lesions, while both reviewers detected 100% of the lesions in the prostate (18/18), seminal vesicles (12/12), and visceral (8/8); LN LR (56/62; 90%), NLR (57/67; 85%), and bone (78/90; 86%). There were no statistically significant differences between volumetric parameters (t = -0.02122; p = 0.491596).

CONCLUSIONS

99mTc-iPSMA SPECT/CT is useful in the primary diagnosis of prostate cancer. Despite it showing a slightly lower lesion detection rate compared to 18F-PSMA PET/CT, it exhibited no impact on clinical staging and, consequently, the initial treatment intention.

Lessons from a 3-Year Review of PSMA PET-CT in a Tertiary Setting: Can We Fine Tune Referral Criteria by Identifying Factors Predicting Positivity and Negativity?

AIM OF THE STUDY

To draw inferences from a retrospective evaluation of PSMA PET CT scans performed for the evaluation of biochemical recurrence.

MATERIAL AND METHODS

A retrospective analysis of 295 PSMA PET CT scans spanning 3 years between 2020 and 2022 was undertaken.

RESULTS

Of 295 PET CT scans, 179 were positive, 66 were negative and 50 had indeterminate findings. In the positive group, 67 had radical prostatectomy and PSMA avid lesions were seen most commonly in pelvic lymph nodes. The remaining 112 positive scans were in the non-radical prostatectomy group; 25 had recurrence only in the prostate, 17 had recurrence involving the prostate bed; 28 had no recurrence in the prostate gland, while 42 had recurrence in the prostate as well as in extra-prostatic sites. Overall, in the non-prostatectomy group, 75% of the population was harboring a PSMA avid lesion in the prostate gland while in the remaining 25% of the population, recurrence did not involve the prostate gland. The majority of indeterminate findings were seen in small pelvic or retroperitoneal lymph nodes or skeletal regions (ribs/others) and in nine patients indeterminate focus was seen in the prostate bed only. Follow-up PSMA PET CT was helpful in prior indeterminate findings and unexplained PSA rise.

CONCLUSION

A higher recurrence in the prostate bed while evaluating biochemical recurrence prompts the following: question: should prostatectomy be offered more proactively? Follow-up PSMA PET CT is helpful for indeterminate findings; a PSA rise of 0.7 ng/mL in 6 months can result in positive PSMA PET CT while negative scans can be seen up to a 2 ng/mL PSA rise in 6 months.

68Ga-PSMA PET-CT and PSMA score affecting therapeutic decision-making in high-risk prostatic carcinoma

Purpose

This research study was conducted to evaluate the impact of (68Ga)-tagged prostatic-specific membrane antigen (68Ga-PSMA) positron emission tomography and computed tomography (PET-CT), compare its role with conventional radiology in early staging of high-risk prostate cancer, and calculate the PSMA score evaluating its usefulness in 68Ga-PSMA PET-CT reporting in our patient population.

Material and methods

68Ga-PSMA PET-CT of 65 high-risk cases of prostate cancer was performed for staging purpo-ses. Any change in disease stage was noted after 68Ga-PSMA PET-CT findings and PSMA score leading to a change in the management plan.

Results

Change in disease stage post-PSMA imaging was seen in 39% cases, high PSMA score (03) was noted in > 80% of upstaged cases, while low score (0) and (1) was seen in 65% and 35% down-staged individuals, respectively. Change in therapeutic decision-making was observed in 32% (21) of patients.

Conclusions

68Ga-PSMA PET-CT scans have a significant influence on the planned clinical management of high-risk prostate cancer patients; hence, they can be utilized as a replacement for radiological imaging tools, particularly in the detection of pelvic nodal and distant metastatic disease. PSMA score can be considered as an effective tool in standardized reporting of 68Ga-PSMA imaging.

New perspectives on metabolic imaging in the management of prostate cancer in 2022: A focus on radiolabeled PSMA‑PET/CT (Review)

Nuclear medicine is an essential part of prostate cancer management concerning initial staging, patient follow-up and even therapy. Prostate-specific membrane antigen (PSMA) is a glutamate carboxypeptidase II transmembrane glycoprotein expressed by 80% of prostatic cells. The interest in this protein is due to its specificity for prostatic tissue. The use of 68GaPSMA PET/CT in the context of disease staging is thus well-established and recommended, especially for high-risk disease with metastases and lymph node involvement. However, the risk of false positives raises questions regarding its place in the management of patients with prostate cancer. The present study aimed to determine the use of PET-PSMA in the care of patients with prostate cancer but also to assess its limits of use.

The efficacy of 99mTc-HYNIC-PSMA SPECT/CT in detecting primary lesions and metastasis in newly diagnosed prostate cancer

Purpose

Compared with PET/CT or PET/MRI, SPECT/CT is cheaper and more readily accessible. This study was designed to investigate the efficacy of ^99mTc-HYNIC-PSMA SPECT/CT in detecting primary tumors and metastases in patients with newly diagnosed prostate cancer (PCa).

Methods

A retrospective analysis of 31 patients with pathologically proven PCa was performed at Shanghai General Hospital from November 2020 to November 2021. Planar whole-body imaging was performed on all patients with a SPECT/CT scan of PSMA-positive regions 3-4 h after intravenous injection of 740 MBq ^99mTc-HYNIC-PSMA. Positive PSMA uptake lesions were evaluated, and SUVmean and SUVmax were measured in each lesion. Associations between SPECT/CT parameters and clinicopathologic factors (tPSA and Gleason Score) were analyzed. The diagnostic capability of SPECT/CT parameters, tPSA, and GS in distant metastatic detection was evaluated by logistic regression.

Results

The SUVmean and SUVmax of the high-risk stratification subgroups (tPSA>20 ng/ml, GS ≥8, and tPSA >20 ng/ml and GS≥8) were higher than those of the low-moderate risk stratification subgroups, with sensitivities of 92% and 92%, respectively. Neither SPECT/CT parameters (SUVmean, SUVmax) nor clinicopathologic factors (tPSA, GS) had high sensitivity (80%, 90%, 80%, and 90%, respectively, P <0.05) in distant metastatic prediction. For both the guideline tPSA level (20 ng/ml) and the cut-off level (84.3 ng/ml), the difference in the distant metastasis detection rate between the low predicted tPSA group and the high predicted tPSA group was statistically significant (0% vs. 47.62%, P = 0.005; 9.09% vs. 88.89%, P = 0.000, respectively). Twenty patients with pathological 99mTc-PSMA avid only in the prostate beds underwent radical prostatectomy. Seven of them underwent lymph node dissection, a total of 35 lymph nodes were removed, and no lymph nodes were detected with metastasis, which was consistent with ^99mTc-HYNIC-PSMA SPECT/CT.

Conclusion

^99mTc-HYNIC-PSMA SPECT/CT is effective in the risk stratification and distant metastasis detection of primary PCa patients. It is of great value in guiding treatment strategies.

PSMA-PET Guided Treatment in Prostate Cancer Patients with Oligorecurrent Progression after Previous Salvage Treatment

Background: Prostate Specific Membrane Antigen-Positron Emission Tomography (PSMA-PET) is used to select recurrent prostate cancer (PCa) patients for metastases-directed therapy (MDT). We aimed to evaluate the oncologic outcomes of second-line PSMA-guided MDT in oligo-recurrent PCa patients. Methods: we performed a retrospective analysis of 113 recurrent PCa after previous radical prostatectomy and salvage therapies with oligorecurrent disease at PSMA-PET (≤3 lesions in N1/M1a-b) in three high-volume European centres. Patients underwent second-line salvage treatments: MDT targeted to PSMA (including surgery and/or radiotherapy), and the conventional approach (observation or Androgen Deprivation Therapy [ADT]). Patients were stratified according to treatments (MDT vs. conventional approach). Patients who underwent MDT were stratified according to stage in PSMA-PET (N1 vs. M1a-b). The primary outcome of the study was Progression-free survival (PFS). Secondary outcomes were Metastases-free survival (MFS) and Castration Resistant PCa free survival (CRPC-FS). Kaplan-Meier analyses assessed PFS, MFS and CRPC-FS. Multivariable Cox regression models identified predictors of progression and metastatic disease. Results: Overall, 91 (80%) and 22 (20%) patients were treated with MDT and the conventional approach, respectively. The median follow-up after PSMA-PET was 31 months. Patients who underwent MDT had a similar PFS compared to the conventional approach (p = 0.3). Individuals referred to MDT had significantly higher MFS and CRPC-FS compared to those who were treated with the conventional approach (73.5% and 94.7% vs. 30.5% and 79.5%; all p ≤ 0.001). In patients undergoing MDT, no significant differences were found for PFS and MFS according to N1 vs. M1a-b disease, while CRPC-FS estimates were significantly higher in patients with N1 vs. M1a-b (100% vs. 86.1%; p = 0.02). At multivariable analyses, age (HR = 0.96) and ADT during second line salvage treatment (HR = 0.5) were independent predictors of PFS; MDT (HR 0.27) was the only independent predictor of MFS (all p ≤ 0.04) Conclusion: Patients who underwent second-line PSMA-guided MDT experienced higher MFS and CRPC-FS compared to men who received conventional management.

Comparison of Hormone-Sensitive Oligorecurrent Prostate Cancer Patients Based on Routine Use of Choline and/or PSMA PET/CT to Guide Metastasis-Directed Therapy

BACKGROUND

In hormone-sensitive oligorecurrent prostate cancer (PC), the literature showed [68Ga]Ga-PSMA (PSMA) and [18F]F-choline (FCH) PET/CT can successfully guide metastasis-directed therapies (MDT). This observational retrospective study aimed to explore, in routine use, the impact of FCH or PSMA PET/CT in guiding MDT for hormone-sensitive oligometastatic PC at different recurrences.

METHODS

In 2017-2020, patients initially treated with radical prostatectomy but, in biochemical recurrence (with PSA ≤ 2 ng/mL), diagnosed as oligometastatic based on FCH or PSMA PET/CT, were identified. MDT was stereotactic body radiotherapy (SBRT), elective nodal or prostate bed radiotherapy ± boost and ± androgen deprivation therapy (ADT). The primary endpoint was biochemical relapse-free survival (BR-FS), defined as a PSA increase ≥ 0.2 ng/mL above the nadir and increasing over two successive samples and the secondaries were ADT-free survival (ADT-FS).

RESULTS

123 patients (70 PSMA and 53 FCH) were included. The median follow-up was 42.2 months. The median BR-FS was 24.7 months in the PSMA group versus 13.0 months in the FCH group (p = 0.008). Similarly, ADT-FS (p = 0.001) was longer in patients in the PSMA group. In multivariate analysis, a short PSA doubling time before imaging (p = 0.005) and MDT with SBRT (p = 0.001) were poor prognostic factors for BR-FS.

CONCLUSIONS

Routine use of FCH or PSMA PET/CT in hormone-sensitive PC showed an advantage for using PSMA PET/CT to guide MDT in terms of BR-FS and ADT-FS in patients with low PSA value. Prospective studies are needed to confirm these hypotheses.

Combined forced diuresis and late acquisition on [68Ga]Ga-PSMA-11 PET/CT for biochemical recurrent prostate cancer: a clinical practice-oriented study

OBJECTIVES

Increased detection of prostate cancer (PCa) recurrences using [⁶⁸Ga]Ga-PSMA-11 PET/CT has been reported by adding forced diuresis or late-phase imaging to the standard protocol. However, the combination of these procedures in the clinical setting is still not standardized.

METHODS

One hundred prospectively recruited biochemical recurrent PCa patients were restaged with dual-phase [⁶⁸Ga]Ga-PSMA-11 PET/CT from September 2020 to October 2021. All patients received a standard scan (60 min), followed by diuretics (140 min) and a late-phase abdominopelvic scan (180 min). PET readers with low (n = 2), intermediate (n = 2), or high (n = 2) experience rated (i) standard and (ii) standard + forced diuresis late-phase images in a stepwise fashion according to E-PSMA guidelines, scoring their level of confidence. Study endpoints were (i) accuracy against a composite reference standard, (ii) reader's confidence level, and (iii) interobserver agreement.

RESULTS

Forced diuresis late-phase imaging increased the reader's confidence category for local and nodal restaging (both p < 0.0001), and the interobserver agreement in identifying nodal recurrences (from moderate to substantial, p < 0.01). However, it significantly increased diagnostic accuracy exclusively for local uptakes rated by low-experienced readers (from 76.5 to 84%, p = 0.05) and for nodal uptakes rated as uncertain at standard imaging (from 68.1 to 78.5%, p < 0.05). In this framework, SUVmax kinetics resulted in an independent predictor of PCa recurrence compared to standard metrics, potentially guiding the dual-phase PET/CT interpretation.

CONCLUSIONS

The present results do not support the systematic combination of forced diuresis and late-phase imaging in the clinical setting, but allow the identification of patients-, lesions-, and reader-based scenarios that might benefit from it.

KEY POINTS

• Increased detection of prostate cancer recurrences has been reported by adding diuretics administration or an additional late abdominopelvic scan to the standard [⁶⁸Ga]Ga-PSMA-11 PET/CT procedure. • We verified the added value of combined forced diuresis and delayed imaging, showing that this protocol only slightly increases the diagnostic accuracy of [⁶⁸Ga]Ga-PSMA-11 PET/CT, thus not justifying its systematic use in clinics. • However, it can be helpful in specific clinical scenarios, e.g., when PET/CT is reported by low-experienced readers. Moreover, it increased the reader's confidence and the agreement among observers.

Feasibility of 99mTc-MIP-1404 for SPECT/CT Imaging and Subsequent PSMA-Radioguided Surgery in Early Biochemically Recurrent Prostate Cancer: A Case Series of 9 Patients

This case series evaluated the feasibility of prostate-specific membrane antigen (PSMA)-radioguided surgery (RGS) with ^99mTc-MIP-1404 in recurrent prostate cancer. Methods: Nine patients with PSMA-positive lesions on PET/CT received ^99mTc-MIP-1404 (median, 747 MBq; interquartile range [IQR], 710-764 MBq) 17.2 h (IQR, 16.9-17.5 h) before SPECT/CT and 22.3 h (IQR, 20.8-24.0 h) before RGS. Results: Seventeen PSMA-positive lesions were detected on PET/CT (median short-axis diameter, 4 mm; IQR, 3-6 mm; median SUV_max, 8.9; IQR, 5.2-12.6). Nine of 17 (52.9%) were visible on SPECT/CT (median SUV_max, 13.8; IQR, 8.0-17.9). Except for 2 foci, all PET/CT-positive findings demonstrated intraoperative count rates above the background level (median count, 31; IQR, 17-89) and were lymph node metastases. Moreover, PSMA-RGS identified 2 additional metastases compared with PET/CT. Prostate-specific antigen values decreased after RGS in 6 of 9 patients (67%). Conclusion: PSMA-RGS with ^99mTc-MIP-1404 identified lymph node metastases in all patients, including 2 additional lesions compared with PET/CT.

The Impact of PSMA-PET on Oncologic Control in Prostate Cancer Patients Who Experienced PSA Persistence or Recurrence

Background: Prostate Specific Membrane Antigen-Positron Emission Tomography (PSMA-PET) is currently recommended to restage prostate cancer (PCa) and to guide the delivery of salvage treatments. We aim to evaluate the oncologic outcomes of patients with recurrent PCa who received PSMA-PET. Methods: 324 hormone-sensitive PCa with PSA relapse after radical prostatectomy who underwent PSMA-PET in three high-volume European Centres. Patients have been stratified as pre-salvage who never received salvage treatments (n = 134), and post-salvage, including patients who received previous salvage therapies (n = 190). Patients with oligorecurrent (≤3 lesions), PSMA-positive disease underwent PSMA-directed treatments: salvage radiotherapy (sRT) or Metastases-directed therapy (MDT). Patients with polirecurrent (>3 lesions) PSMA-positive disease were treated with systemic therapy. Patients with negative PSMA-PET were treated with sRT or systemic therapies or observation. The primary outcome of the study was Progression-free survival (PFS). Secondary outcomes were: Metastases-free survival (MFS) and Castration Resistant Pca free survival (CRPC-FS). Results: median follow up was 23 months. In the pre-salvage setting, the PFS, MFS and CRPC-FS estimates at 3 years were 66.2% vs. 38.9%, 95.2% vs. 73.7% and 94.9% vs. 93.1% in patients with negative vs. positive PSMA-PET, respectively (all p ≥ 0.2). In the post-salvage setting, the PFS, MFS and CRPC-FS estimates at 3 years were 59.5% vs. 29.1%, 92.7% vs. 65.1% and 98.8% vs. 88.8% in patients with negative vs. positive PSMA-PET, respectively (all p ≤ 0.01). At multivariable analyses, a positive PSMA-PET was an independent predictor of progression (HR = 2.15) and metastatic disease (HR 2.37; all p ≤ 0.03). Conclusion: PSMA-PET in recurrent PCa detects the site of recurrence guiding salvage treatments and has a prognostic role in patients who received previous salvage treatments.

Evaluation of [68 Ga]Ga-PSMA-I&T PET/CT with additional late scans of the pelvis in prostate-specific antigen recurrence using the PROMISE criteria

Background

PSMA PET/CT is the recommended imaging test in cases with prostate-specific antigen (PSA) recurrence after primary therapy of prostate cancer (PCa). However, imaging protocols remain a topic of active research. The aim of the presented study was to examine the impact of additional late scans of the pelvis in [⁶⁸ Ga]Ga-PSMA-I&T PET/CT of patients with rising PSA after prostatectomy.

Methods

A total of 297 patients (median PSA 0.35 ng/ml, interquartile range (IQR) 0.2–0.8) who underwent early whole-body [⁶⁸ Ga]Ga-PSMA-I&T PET/CT (median dose 141 MBq, IQR 120–163; median 86 min, IQR 56–107) and additional late scans of the pelvis (median 180 min, IQR 170–191) were investigated retrospectively. Early and late images were staged separately according to the PROMISE criteria and compared with a final consensus of both. Standardized uptake values were analyzed for early and late scans.

Results

One hundred and thirty-four (45.1%) [⁶⁸ Ga]Ga-PSMA-I&T PET/CT showed evidence of recurrent PCa (114/38.4% early, 131/44.1% late). Of 195 lesions, 144 (73.8%) were identified correctly on early scans. 191 (97.9%) lesions were detected on late imaging. The lesion SUVmax (median 3.4, IQR 0.4–6.5 vs. median 3.9, IQR 2.6–8.2) as well as the SUVmax to background ratio (median 9.4, IQR 1.7–19.1 vs. median 15.5, IQR 9.6–34.1) increased significantly between the imaging time points (p < 0.01, respectively). Compared to the final consensus, the miTNM-staging of early scans changed in 58 (19.5%) cases. Of these, 31 patients (10.4%) with negative early scans (T0 N0 M0) were upstaged. Twenty-seven (9.1%) patients with PCa characteristic lesions on early imaging (> T0 N0 M0) were up- and/or downstaged. In 4 (1.3%) cases, PCa-related lesions were only detectable on early PET/CT leading to upstagings of late imaging.

Conclusions

Additional late scans of the pelvis in [⁶⁸ Ga]Ga-PSMA-I&T PET/CT detected more lesions and an increasing contrast compared to early imaging. This influenced the final miTNM-staging substantially.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00938-3.

The Value of Phenotypic Precision Medicine in Prostate Cancer

Prostate cancer is the most common cancer among men and the second leading cause of cancer-related death. For patients who develop metastatic disease, tissue-based and circulating-tumor-based molecular and genomic biomarkers have emerged as a means of improving outcomes through the application of precision medicine. However, the benefit is limited to a minority of patients. An additional approach to further characterize the biology of advanced prostate cancer is through the use of phenotypic precision medicine, or the identification and targeting of phenotypic features of an individual patient's cancer. In this review article, we will discuss the background, potential clinical benefits, and limitations of genomic and phenotypic precision medicine in prostate cancer. We will also highlight how the emergence of image-based phenotypic medicine may lead to greater characterization of advanced prostate cancer disease burden and more individualized treatment approaches in patients.

Impact of 18F-PSMA-11 PET/CT on Management of Biochemical Recurrence and High-Risk Prostate Cancer Staging : 18F-PSMA-11 PET/CT and Impact on Prostate Cancer Management

PURPOSE

In this study, we evaluated the impact of 18F-PSMA-11 PET/CT on the patient management plan in patients with primary or recurrent disease. Furthermore, a correlation between PET findings and other modalities was performed.

PROCEDURES

In this prospective observational study, 60 prostate cancer patients (9 primary staging, 51 biochemical recurrence) were imaged with 18F-PSMA-11 PET/CT. Pre- and post-scan questionnaires were completed by the treating physician to observe changes in therapy intent. Follow-up data (histological confirmation, MRI imaging, and PSA values after radiotherapy without implementation of systemic therapy) was correlated with the 18F-PSMA-11 findings.

RESULTS

The patient-based detection rate was 82% and a management change was seen in 52% of the cases. The heterogeneous characteristics of the included patients resulted in a widely varying treatment change, mostly originating from an increase of disease extent on 18F-PSMA-11 PET/CT.

CONCLUSION

18F-PSMA-11 PET/CT showed to be a highly promising method for the detection of prostate cancer lesions.

The clinical consequences of routine 68Ga-PSMA-11 PET/CT in patients with newly diagnosed prostate cancer, ISUP grade 5 and no metastases based on standard imaging - preliminary results

AIM

To evaluate the clinical consequences of prostate specific membrane antigen (PSMA) PET/CT for primary staging in patients with ISUP grade 5 (Gleason score ≥9) prostate cancer (PCa), and no definitive distant metastases based on standard imaging.

METHODS

At our tertial referral center, PSMA PET/CT became standard of care from August 2018 for primary staging of prostate cancer given the following criteria: (1) no prior treatment for prostate cancer, (2) ISUP grade 5, (3) no definitive metastases on standard imaging (contrast enhanced CT and bone scintigraphy), and (4) deemed suitable for treatment with curative intent based on comorbidity and life expectancy. We present the preliminary results of first six months recruitment with 12 months of follow-up.

RESULTS

Forty-eight patients (mean age 69 years, median PSA 13.0 ng/mL, 20 patients with locally advanced PCa) were included. CT was positive in pelvic lymph nodes in two patients, bone scintigraphy was equivocal in three patients. PSMA PET/CT showed pathological uptake outside the prostatic bed in 22 patients (46%) of which 13 patients (27%) showed lesions confined to regional lymph nodes, and nine patients (19%) showed nonregional lymph node metastases and/or bone metastases. PSMA PET/CT changed the treatment strategy from curatively intended treatment to palliative treatment in 18 patients (38%).

CONCLUSION

PMSA PET/CT revealed pathological uptake in a large proportion of high-risk patients at primary staging among patients with no definite metastases on standard imaging leading to change of patient management in 38% of the patients.

Predictors of Bone Metastases at 68Ga-PSMA-11 PET/CT in Hormone-Sensitive Prostate Cancer (HSPC) Patients with Early Biochemical Recurrence or Persistence

Prostate-specific-membrane-antigen/positron-emission-tomography (PSMA-PET) can accurately detect disease localizations in prostate cancer (PCa) patients with early biochemical recurrence/persistence (BCR/BCP), allowing for more personalized image-guided treatments in oligometastatic patients with major impact in the case of bone metastases (BM). Therefore, this study aimed to identify predictors of BM at PSMA-PET in early-BCR/BCP hormone-sensitive PCa (HSPC) patients, previously treated with radical intent (radiotherapy or radical prostatectomy ± salvage-radiotherapy (SRT)). A retrospective analysis was performed on 443 ⁶⁸Ga-PSMA-11-PET/CT scans. The cohort median PSA at PET-scan was 0.60 (IQR: 0.38–1.04) ng/mL. PSMA-PET detection rate was 42.0% (186/443), and distant lesions (M1a/b/c) were found in 17.6% (78/443) of cases. BM (M1b) were present in 9.9% (44/443) of cases, with 70.5% (31/44) showing oligometastatic spread (≤3 PSMA-positive lesions). In the multivariate binary logistic regression model (accuracy: 71.2%, Nagelkerke-R²: 13%), T stage ≥ 3a (OR: 2.52; 95% CI: 1.13–5.60; p = 0.024), clinical setting (previous SRT vs. first-time BCR OR: 2.90; 95% CI: 1.32–6.35; p = 0.008), and PSAdt (OR: 0.93; 95% CI: 0.88–0.99; p = 0.026) were proven to be significant predictors of bone metastases, with a 7% risk increment for each single-unit decrement of PSAdt. These predictors could be used to further refine the indication for PSMA-PET in early BCR/BCP HSPC patients, leading to higher detection rates of bone disease and more personalized treatments.

Update of PSMA Theranostics in Prostate Cancer: Current Applications and Future Trends

There is now an increasing trend for targeting cancers to go beyond early diagnosis and actually improve Progression-Free Survival and Overall Survival. Identifying patients who might benefit from a particular targeted treatment is the main focus for Precision Medicine. Radiolabeled ligands can be used as predictive biomarkers which can confirm target expression by cancers using positron emission tomography (PET). The same ligand can subsequently be labeled with a therapeutic radionuclide for targeted radionuclide therapy. This combined approach is termed “Theranostics”. The prostate-specific membrane antigen (PSMA) has emerged as an attractive diagnostic and therapeutic target for small molecule ligands in prostate cancer. It can be labeled with either positron emitters for PET-based imaging or beta and alpha emitters for targeted radionuclide therapy. This review article summarizes the important concepts for Precision Medicine contributing to improved diagnosis and targeted therapy of patients with prostate cancer and we identify some key learning points and areas for further research.

The impact of PSMA PET on the treatment and outcomes of men with biochemical recurrence of prostate cancer: a systematic review and meta-analysis

BACKGROUND

Prostate-specific membrane antigen (PSMA) PET is highly sensitive in identifying disease recurrence in men with biochemical recurrence of prostate cancer (BCR) after primary therapy and is rapidly being adopted in clinical practice. The purpose of this systematic review and meta-analysis was to assess the documented impact of PSMA-PET on patient management and outcomes, including prostate-specific antigen (PSA) response, and intermediate and long-term outcome measures.

MATERIALS AND METHODS

MBASE, PubMed, Web of Science, Cochrane and OVID databases were searched for studies reporting on the impact of PSMA-PET on the management and outcomes of patients with BCR after definitive primary therapy. Outcome measures assessed included biochemical response to therapy after PET and BCR-free survival (BRFS). The proportions of patients in whom management changed, and the proportion of patients in whom each outcome measure was obtained were tabulated and pooled into meta-analysis using DerSimonian-Laird method.

RESULTS

A total of 34 studies with 3680 men reported change in management after PSMA-PET and 27 studies with 2639 men reported on at least one outcome measure and had follow-up data. PSMA-PET was positive in 2508/3680 (68.2%). The pooled proportion of change in management after PSMA-PET was 56.4% (95% CI, 48.0-63.9%). A decrease in serum PSA was documented in 72.4% of men (95% CI, 63.4-81.5%), and complete biochemical response in 23.3% (95% CI, 14.6-32.0%) at a median follow-up of 8.1 and 11 months, respectively. The pooled BRFS rate was 60.2% (95% CI, 49.1-71.4%) at a median follow-up of 20 months.

CONCLUSION

In conclusion, PSMA PET is positive in more than 2/3 of men with BCR and impacts patient management in more than half of the men. BRFS after PET-directed management is 60% at a median of 20 months after salvage therapy, and complete biochemical response may be achieved in up to a quarter of men.

Event-free survival after 68 Ga-PSMA-11 PET/CT in recurrent hormone-sensitive prostate cancer (HSPC) patients eligible for salvage therapy

Background/aim

Prostate-specific-membrane-antigen/positron emission tomography (PSMA-PET) detects with high accuracy disease-recurrence, leading to changes in the management of biochemically-recurrent (BCR) prostate cancer (PCa). However, data regarding the oncological outcomes of patients who performed PSMA-PET are needed. The aim of this study was to evaluate the incidence of clinically relevant events during follow-up in patients who performed PSMA-PET for BCR after radical treatment.

Materials and methods

This analysis included consecutive, hormone-sensitive, hormone-free, recurrent PCa patients (HSPC) enrolled through a prospective study. All patients were eligible for salvage therapy, having at least 24 months of follow-up after PSMA-PET. The primary endpoint was the Event-Free Survival (EFS), defined as the time between the PSMA-PET and the date of event/last follow-up. The Kaplan–Meier method was used to estimate the EFS curves. EFS was also investigated by Cox proportional hazards regression. Events were defined as death, radiological progression, or PSA recurrence after therapy.

Results

One-hundred and seventy-six (n = 176) patients were analyzed (median PSA 0.62 [IQR: 0.43–1.00] ng/mL; median follow-up of 35.4 [IQR: 26.5–40.3] months). The EFS was 78.8% at 1 year, 65.2% (2 years), and 52.2% (3 years). Patients experiencing events during study follow-up had a significantly higher median PSA (0.81 [IQR: 0.53–1.28] vs 0.51 [IQR: 0.36–0.80] ng/mL) and a lower PSA doubling time (PSAdt) (5.4 [IQR: 3.7–11.6] vs 12.7 [IQR: 6.6–24.3] months) (p < 0.001) compared to event-free patients. The Kaplan–Meier curves showed that PSA > 0.5 ng/mL, PSAdt ≤ 6 months, and a positive PSMA-PET result were associated with a higher event rate (p < 0.01). No significant differences of event rates were observed in patients who received changes in therapy management after PSMA-PET vs. patients who did not receive therapy changes. Finally, PSA > 0.5 ng/mL and PSAdt ≤ 6 months were statistically significant event-predictors in multivariate model (p < 0.001).

Conclusion

Low PSA and long PSAdt were significant predictors of longer EFS. A lower incidence of events was observed in patients having negative PSMA-PET, since longer EFS was significantly more probable in case of a negative scan.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05741-9.

Targeting PSMA Revolutionizes the Role of Nuclear Medicine in Diagnosis and Treatment of Prostate Cancer

Targeting the prostate-specific membrane antigen (PSMA) protein has become of great clinical value in prostate cancer (PCa) care. PSMA positron emission tomography/computed tomography (PET/CT) is increasingly used in initial staging and restaging at biochemical recurrence in patients with PCa, where it has shown superior detection rates compared to previous imaging modalities. Apart from targeting PSMA for diagnostic purposes, there is a growing interest in developing ligands to target the PSMA-protein for radioligand therapy (RLT). PSMA-based RLT is a novel treatment that couples a PSMA-antibody to (alpha or beta-emitting) radionuclide, such as Lutetium-177 (177Lu), to deliver high radiation doses to tumor cells locally. Treatment with 177Lu-PSMA RLT has demonstrated a superior overall survival rate within randomized clinical trials as compared to routine clinical care in patients with metastatic castration-resistant prostate cancer (mCRPC). The current review provides an overview of the literature regarding recent developments in nuclear medicine related to PSMA-targeted PET imaging and Theranostics.

[Prostate-specific membrane antigen positron emission tomography (PSMA PET) for urologists-when and which tracer?]

BACKGROUND

Prostate-specific membrane antigen positron emission tomography (PSMA PET) is increasingly replacing conventional imaging for staging of prostate cancer. A major challenge is its appropriate use and correct interpretation.

OBJECTIVES

How and when is PSMA PET used in patient care to optimally direct therapy?

MATERIALS AND METHODS

Systematic presentation and discussion of the current state of knowledge, guidelines and expert knowledge on PSMA PET with a summary of ongoing studies.

CONCLUSION

PSMA PET is the new standard for systemic staging of prostate cancer, enabling precision patient care with novel local, oligometastatic, and systemic treatment approaches.

Positron emission tomography in the COVID-19 pandemic era

Coronavirus disease 2019 (COVID-19) has become a major public health problem worldwide since its outbreak in 2019. Currently, the spread of COVID-19 is far from over, and various complications have roused increasing awareness of the public, calling for novel techniques to aid at diagnosis and treatment. Based on the principle of molecular imaging, positron emission tomography (PET) is expected to offer pathophysiological alternations of COVID-19 in the molecular/cellular perspectives and facilitate the clinical management of patients. A number of PET-related cases and research have been reported on COVID-19 over the past one year. This article reviews the current studies of PET in the diagnosis and treatment of COVID-19, and discusses potential applications of PET in the development of management strategy for COVID-19 patients in the pandemic era.

Establishing a Provincial Registry for Recurrent Prostate Cancer: Providing Access to PSMA PET/CT in Ontario, Canada

Prostate Specific Membrane Antigen (PSMA) positron emission tomography/computed tomography (PET/CT) is becoming established as a standard of care for the (re)staging of high-risk primary and prostate cancer recurrence after primary therapy. Despite the favorable performance of this imaging modality with high accuracy in disease detection, the availability of PSMA PET/CT varies across jurisdictions worldwide due to variability in the selection of PSMA PET/CT agent, regulatory approvals and funding. In Canada, PSMA based radiopharmaceuticals are still considered investigational new drug (IND), creating limitations in the deployment of these promising imaging agents. While regulatory approval rests with Health Canada, as a single payer health system, funding for Health Canada approved drugs and devices is decided by Provincial Health Ministries. Ontario Health (Cancer Care Ontario) (OH-CCO) is the agency of the Ministry of Health (MOH) in Ontario responsible for making recommendations to the MOH around the organization and funding of cancer services within Ontario (population of 15 million), and the PET Steering Committee of OH-CCO is responsible for providing recommendations on the introduction of new PET radiopharmaceuticals and indications. For Health Canada approved PET radiopharmaceuticals like 18F-FDG, OH-CCO (on behalf of the MOH) provides coverage based on levels of evidence and specific PET Registries are established to aid in real-world evidence collection to inform OH-CCO regarding emerging PET applications. In the case of PSMA PET/CT, adapting this model to an IND PSMA PET/CT agent, 18F-DCFPyL, necessitated the creation of a hybrid Registry-Study model to leverage the existing OH-CCO Registry structure while respecting the need for a Health Canada Clinical Trials Application (CTA) for the deployment of this agent in the province. Within the first 2 years of the registry, over 1700 men have been imaged resulting in a change in management (compared to pre-PET management plans) in over half of the men imaged. In this article, we describe the organization and deployment of the PSMA PET/CT (PREP) Registry throughout the province to provide access for men with suspected prostate cancer recurrence along with key stakeholder perspectives and preliminary results.

PSMA Theranostics: Current Landscape and Future Outlook

INTRODUCTION

Prostate-specific membrane antigen (PSMA) is a promising novel molecular target for imaging diagnostics and therapeutics (theranostics). There has been a growing body of evidence supporting PSMA theranostics approaches in optimizing the management of prostate cancer and potentially altering its natural history.

METHODS

We utilized PubMed and Google Scholar for published studies, and clinicaltrials.gov for planned, ongoing, and completed clinical trials in PSMA theranostics as of June 2021. We presented evolving evidence for various PSMA-targeted radiopharmaceutical agents in the treatment paradigm for prostate cancer, as well as combination treatment strategies with other targeted therapy and immunotherapy. We highlighted the emerging evidence of PSMA and fluorodeoxyglucose (FDG) PET/CT as a predictive biomarker for PSMA radioligand therapy. We identified seven ongoing clinical trials in oligometastatic-directed therapy using PSMA PET imaging. We also presented a schematic overview of 17 key PSMA theranostic clinical trials throughout the various stages of prostate cancer.

CONCLUSIONS

In this review, we presented the contemporary and future landscape of theranostic applications in prostate cancer with a focus on PSMA ligands. As PSMA theranostics will soon become the standard of care for the management of prostate cancer, we underscore the importance of integrating nuclear medicine physicians into the multidisciplinary team.

A comprehensive assessment of 68Ga-PSMA-11 PET in biochemically recurrent prostate cancer: Results from a prospective multi-center study in 2005 patients

We prospectively investigated the performance of the prostate-specific membrane antigen (PSMA) ligand ⁶⁸Ga-PSMA-11 for detecting prostate adenocarcinoma in patients with elevated prostate-specific-antigen (PSA) after initial therapy. Methods: ⁶⁸Ga-PSMA-11 hybrid positron emission tomography (PET) was performed in 2005 patients at the time of biochemical recurrent prostate cancer (BCR) following either radical prostatectomy (RP) (50.8 %), definitive radiation therapy (RT) (19.7 %), or RP with post-operative RT (PORT) (29.6 %). Presence of prostate cancer was assessed qualitatively (detection rate = positivity rate) and quantitatively on a per-patient and per-region basis creating a disease burden estimate from presence or absence of local (prostate/prostate bed), nodal (N1: pelvis) and distant metastatic (M1: distant soft tissue and bone) disease. The primary study endpoint was the positive predictive value (PPV) of ⁶⁸Ga-PSMA-11 PET/CT confirmed by histopathology. Results: Following prostatectomy, the scan detection rate increased significantly with rising PSA levels (44.8 % at PSA < 0.25 to 96.2 % at PSA > 10 ng/mL; P < 0.001). The detection rate significantly increased with rising PSA levels in each individual region, overall disease burden, prior androgen deprivation, clinical T-stage, and Gleason grading from prostatectomy specimen (P < 0.001). Following RT, the detection rate for in-gland prostate recurrence was 64.0 % compared to 20.6 % prostate bed recurrences after RP and 13.3 % following PORT. PSMA-positive pelvic nodal disease was detected in 42.7 % following RP, in 40.8 % after PORT and 38.8 % after RT. In patients with histopathologic validation the PPV per-patient was 0.82 (146/179). The SUV_max of histologically proven true positive lesions was significantly higher than false positive lesions (median 11.0 (IQR 6.3 - 22.2) vs 5.1 (IQR 2.2 - 7.4) P < 0.001). Conclusion: We confirmed a high PPV of ⁶⁸Ga-PSMA-11 PET in BCR and the PSA level as the main predictor of scan positivity.

Assessing the accuracy of 68 Ga-PSMA PET/CT compared with MRI in the initial diagnosis of prostate malignancy: A cohort analysis of 114 consecutive patients

INTRODUCTION

Prostate cancer diagnosis is shifting towards a minimally invasive approach, maintaining accuracy and efficacy while reducing morbidity. We aimed to assess if PSMA-Ga68 PET/CT can accurately grade and localise prostatic malignancy using objective methods, compared with pathology and MRI.

METHODS

Retrospective analysis on 114 consecutive patients undergoing staging PSMA PET/CT scans over 12 months was carried out. The SUVmax and site of highest PSMA activity within the prostate gland were recorded. Pathology/biopsy review assessed maximum Gleason score (and location). MRI analysis assessed the highest PIRADS score and location. The grade, location and size of malignant tissue on biopsy, and PSA, were correlated with the SUVmax and the PIRADS score.

RESULTS

SUVmax was significantly elevated in cases with PSA ≥10 (P = 0.003) and Gleason score ≥8 (P = 0.0002). SUVmax demonstrated equivalent sensitivity to MRI-PIRADS in predicting Gleason ≥8 disease, with higher specificity when tested under a high-specificity regime (SUVmax ≥10, PIRADS = 5, P = 0.002). Furthermore, the region of highest SUVmax was superior to MRI-PIRADS for localising the highest grade tumour region, correctly identifying 71% of highest grade regions compared to 54% with MRI (P = 0.015).

CONCLUSION

PSMA PET/CT is as effective as MRI in identifying high-grade prostate malignancy. Our findings also support previous studies in showing a significant relationship between SUVmax and Gleason grade. These benefits, along with the known advantage in identifying distant metastases and the reduced cost, further support the argument that PSMA PET/CT should be offered as an initial investigation in the workup of prostate cancer.