Clinical impact of PSMA-based 18F-DCFBC PET/CT imaging in patients with biochemically recurrent prostate cancer after primary local therapy

Head-to-head comparison of prostate-specific membrane antigen positron emission tomography/computed tomography and multiparametric magnetic resonance imaging in the detection of biochemical recurrence of prostate cancer: a systematic review and meta-analysis

AIM

Our main goal of this meta-analytical analysis was to evaluate the diagnostic effectiveness of prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) against multiparametric magnetic resonance imaging (mpMRI) in the context of identifying biochemical recurrence in patients with prostate cancer (PCa).

MATERIALS AND METHODS

A thorough search covering articles published until March 2023 was carried out across major databases such as PubMed, Embase, and Web of Science. Studies examining the direct comparison of PSMA PET/CT and mpMRI in patients with PCa suffering biochemical recurrence were included in the inclusion criteria. Using the renowned Quality Assessment of Diagnostic Performance Studies-2 technique, each study's methodological rigor was assessed.

RESULTS

We analyzed data from six eligible studies involving 290 patients in total. The combined data showed that for PSMA PET/CT and mpMRI, respectively, the pooled overall detection rates for recurrent PCa after definitive treatment were 0.69 (95% confidence interval [CI]: 0.45-0.89) and 0.70 (95% CI: 0.44-0.91). The detection rates for local recurrence were specifically 0.52 (95% CI: 0.39-0.65) and 0.62 (95% CI: 0.31-0.89), while they were 0.50 (95% CI: 0.26-0.74) and 0.32 (95% CI: 0.18-0.48) for lymph node metastasis. Notably, there was no discernible difference between the two imaging modalities in terms of the overall detection rate (P = 0.95). The detection rates for local recurrence and lymph node metastasis did not differ statistically significantly (P = 0.55, 0.23).

CONCLUSION

The performance of PSMA PET/CT and mpMRI in identifying biochemical recurrence in PCa appears to be comparable. However, the meta-analysis' findings came from research with modest sample sizes. In this context, more extensive research should be conducted in the future.

Phase I/IIa trial of 18F-prostate specific membrane antigen (PSMA) 1007 PET/CT in healthy volunteers and prostate cancer patients

OBJECTIVE

18F-PSMA 1007 is a promising PET tracer for prostate cancer. We aimed to examine the safety, biodistribution, radiation dosimetry, and clinical effectiveness in Japanese healthy volunteers and patients with prostate cancer.

METHODS

Part A evaluated the pharmacokinetics and exposure doses in three healthy volunteers. Part B evaluated the diagnostic accuracy in patients with untreated preoperative prostate cancer (Cohort 1, n = 7) and patients with biochemical recurrence (Cohort 2, n = 3). All subjects received a single dose of 3.7 MBq/kg 18F-PSMA 1007. Results: 18F-PSMA 1007 was found to be safe and well tolerated in all subjects. No serous AEs or drug-related AEs were identified during the present study. The average blood radioactivity concentration reached a maximum of 47.87 ± 1.05 (percentage of injected dose [%ID]/ml) at 5 min and then decreased to 1.60 ± 0.78 in 6 h. The systemic radioactivity reached a maximum of 211.05 ± 6.77 (%ID$\times$103) at 5 min and decreased to 7.18 ± 3.91 in 6 h. The sensitivity and positive predictive value were 100% and 100% based on both pathologic and imaging confirmation as gold standard. In Cohort 1, 15 primary foci (11.9%) were >5 mm in the largest diameter and identified in 39 of 126 segments (30.1%). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for 60 min uptake time acquisition were 80.0, 96.5, 91.4, 91.2 and 91.3%, respectively.

CONCLUSIONS

Our study revealed that 18F-PSMA 1007 was safe, well tolerated and showed high accuracy in the diagnosis of prostate cancer.

Molecular imaging reveals the heterogeneous progression of tumor cells and tumor stroma: a practice of FDG PET and FAPI PET in diagnosing PSMA-negative bone metastases of progressive prostate cancer

Tumors are often with complex and heterogeneous biological processes, such as glycometabolism and fibrosis, which are the main biochemical pathways that determine therapeutic effects. Specifically, this study aims to assess the diagnosing performance of 18F-FDG and 68Ga-FAPI-04 PET for different stages of progressive bone metastases with PSMA-negative pathology. Bone metastatic mouse model of prostate cancer was constructed via intra-bone injection of PSMA-negative prostate cancer PC3 cells. Cellular uptakes of 18F-FDG and 68Ga-FAPI-04 were separately performed on PC3, NIH-3T3 (FAP-positive) and a mixture. 68Ga-PSMA-11, 18F-FDG and 68Ga-FAPI-04 PET/CT imaging were performed at 2, 4 weeks after tumor cell transplantation. Furthermore, PSMA and FAP expression in bone metastases were assessed by immunohistochemistry, and then compared with the imageological findings. On the cellular level, the independent tracer uptake on the basis of glycometabolism and fibrosis was observed. For animal imaging, 68Ga-PSMA-11 imaging showed weak or absent tracer uptake in PSMA-negative bone metastatic lesions. In contrast, 68Ga-FAPI-04 PET of bone metastases had a higher uptake and tumor-to-muscle (T/M) ratio than 18F-FDG PET that was relative steady during the observation, but T/M ratio of fibrosis gradually decreased with increasing tumor growth, which ranged from 5.11 ± 1.26 at 2 weeks to 3.54 ± 0.23 at 4 weeks, revealing the delayed formation of tumor stroma in rapid proliferation. In addition, PET imaging results were corroborated by immunohistochemical assessment. In conclusion, molecular imaging approach revealed the heterogeneous progression of tumor cells and tumor stroma of bone metastasis of prostate cancer, and further confirming the necessity of multi-molecular imaging in cancer imaging.

The Impact of Positron Emission Tomography Imaging and Tumor Molecular Profiling on Risk Stratification, Treatment Choice, and Oncological Outcomes of Patients with Primary or Relapsed Prostate Cancer: An International Collaborative Review of the Existing Literature

CONTEXT

The clinical introduction of next-generation imaging methods and molecular biomarkers ("radiogenomics") has revolutionized the field of prostate cancer (PCa). While the clinical validity of these tests has thoroughly been vetted, their clinical utility remains a matter of investigation.

OBJECTIVE

To systematically review the evidence to date on the impact of positron emission tomography (PET) imaging and tissue-based prognostic biomarkers, including Decipher, Prolaris, and Oncotype Dx, on the risk stratification, treatment choice, and oncological outcomes of men with newly diagnosed PCa or those with biochemical failure (BCF).

EVIDENCE ACQUISITION

We performed a quantitative systematic review of the literature using the MEDLINE, EMBASE, and Web of Science databases (2010-2022) following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement guidelines. The validated Quality Assessment of Diagnostic Accuracy Studies 2 scoring system was used to assess the risk of bias.

EVIDENCE SYNTHESIS

A total of 148 studies (130 on PET and 18 on biomarkers) were included. In the primary PCa setting, prostate-specific membrane antigen (PSMA) PET imaging was not useful in improving T staging, moderately useful in improving N staging, but consistently useful in improving M staging in patients with National Comprehensive Cancer Network (NCCN) unfavorable intermediate- to very-high-risk PCa. Its use led to a management change in 20-30% of patients. However, the effect of these treatment changes on survival outcomes was not clear. Similarly, biomarkers in the pretherapy primary PCa setting increased and decreased the risk, respectively, in 7-30% and 32-36% of NCCN low-risk and 31-65% and 4-15% of NCCN favorable intermediate-risk patients being considered for active surveillance. A change in management was noted in up to 65% of patients, with the change being in line with the molecular risk-based reclassification, but again, the impact of these changes on survival outcomes remained unclear. Notably, in the postsurgical primary PCa setting, biomarker-guided adjuvant radiation therapy (RT) was associated with improved oncological control: Δ↓ 2-yr BCF by 22% (level 2b). In the BCF setting, the data were more mature. PSMA PET was consistently useful in improving disease localization-Δ↑ detection for T, N, and M staging was 13-32%, 19-58%, and 9-29%, respectively. Between 29% and 73% of patients had a change in management. Most importantly, these management changes were associated with improved survival outcomes in three trials: Δ↑ 4-yr disease-free survival by 24.3%, Δ↑ 6-mo metastasis-free survival (MFS) by 46.7%, and Δ↑ androgen deprivation therapy-free survival by 8 mo in patients who received PET-concordant RT (level 1b-2b). Biomarker testing in these patients also appeared to be helpful in risk stratifying and guiding the use of early salvage RT (sRT) and concomitant hormonal therapy. Patients with high-genomic-risk scores benefitted from treatment intensification: Δ↑ 8-yr MFS by 20% with the use of early sRT and Δ↑ 12-yr MFS by 11.2% with the use of hormonal therapy alongside early sRT, while low-genomic-risk score patients did equally well with initial conservative management (level 3).

CONCLUSIONS

Both PSMA PET imaging and tumor molecular profiling provide actionable information in the management of men with primary PCa and those with BCF. Emerging data suggest that radiogenomics-guided treatments translate into direct survival benefits for patients, however, additional prospective data are awaited.

PATIENT SUMMARY

In this review, we evaluated the utility of prostate-specific membrane antigen positron emission tomography and tumor molecular profiling in guiding the care of men with prostate cancer (PCa). We found that these tests augmented risk stratification, altered management, and improved cancer control in men with a new diagnosis of PCa or for those experiencing a relapse.

Current status of PSMA-targeted imaging and therapy

Currently, the incidence of prostate cancer is increasing, and it has become a great threat to men's health. The detection, staging, and follow-up of prostate cancer patients are inseparable from morphology or magnetic resonance imaging (MRI). However, these do not fully meet the needs of diagnosis and patient management. In particular, owing to the late diagnosis, metastatic castration-resistant prostate cancer (mCRPC) patients usually have poor survival and few options for further effective treatment. Prostate-specific membrane antigen (PSMA), because of its overexpression on prostate cancer cells, has gained interest due to its application in the imaging and theranostics field. Several PSMA radioligands have been developed for imaging and treating prostate cancer. Many clinical trials have assessed the efficacy and safety profiles of these radionuclide agents and show promise in patients who have exhausted other standard treatment options. To date, several small compounds for targeting PSMA have been developed, and 68Ga-PSMA-11 and 18F-DCFPyL have been approved by the United States (US) Food and Drug Administration (FDA) for imaging of prostate cancer. 111In- or 99mTc-labeled PSMA-ligand can guide surgeons searching for radioactive metastatic lymph nodes, and 177Lu- or 225Ac-labeled PSMA-ligand can be used for internal radiotherapy. Moreover, some molecules for therapeutic application are undergoing different stages of clinical trials. In this review, we present current perspectives on the use of PSMA-targeted imaging and theranostics in prostate cancer. As PSMA-targeted imaging and therapeutics are becoming the standard of care for prostate cancer patients, we emphasize the importance of integrating nuclear medicine physicians into multidisciplinary oncology teams.

Management of Patients with Recurrent and Metachronous Oligometastatic Prostate Cancer in the Era of PSMA PET

Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scans have higher sensitivity and specificity for detecting lymph nodes or metastatic disease relative to conventional imaging in prostate cancer staging. Since its FDA approval and incorporation into treatment guidelines, the use of PSMA PET has increased in patients undergoing initial staging, those with recurrence after initial definitive treatment, and patients with metastatic disease. Although the early detection of metastatic lesions is changing disease management, it is unclear whether this impact on management translates into clinical benefit. This review will summarize evidence pertaining to the change in patient management due to PSMA PET use and will discuss the implications of PSMA PET on treatment decisions in prostate cancer, particularly in the settings of biochemical recurrence and metachronous oligometastatic disease.

The Role of PSMA PET/CT in the Primary Diagnosis and Follow-Up of Prostate Cancer-A Practical Clinical Review

Simple Summary

The combination of positron emission tomography (PET)-diagnostics with ligands binding to the prostate-specific membrane antigen (PSMA) has been a diagnostic milestone in the situation of biochemical recurrence of prostate cancer and is gaining importance in primary diagnostics, providing a highly specific and sensitive diagnostic method in various clinical situations. However, the clinical application of this method requires a comprehensive knowledge of its advantages and disadvantages, potential pitfalls and influencing factors. This review aims to provide a practical clinical review of the currently available background data on PSMA PET/CT, as well as the clinical implications. Although a large amount of data already exist, a thorough analysis is complicated by study heterogeneity, showing the need for future systematic and prospective research.

Abstract

The importance of PSMA PET/CT in both primary diagnostics and prostate cancer recurrence has grown steadily since its introduction more than a decade ago. Over the past years, a vast amount of data have been published on the diagnostic accuracy and the impact of PSMA PET/CT on patient management. Nevertheless, a large heterogeneity between studies has made reaching a consensus difficult; this review aims to provide a comprehensive clinical review of the available scientific literature, covering the currently known data on physiological and pathological PSMA expression, influencing factors, the differences and pitfalls of various tracers, as well as the clinical implications in initial TNM-staging and in the situation of biochemical recurrence. This review has the objective of providing a practical clinical overview of the advantages and disadvantages of the examination in various clinical situations and the body of knowledge available, as well as open questions still requiring further research.

The future of PSMA PET and WB MRI as next-generation imaging tools in prostate cancer

Radiolabelled prostate-specific membrane antigen (PSMA)-based PET-CT has been shown in numerous studies to be superior to conventional imaging in the detection of nodal or distant metastatic lesions. ⁶⁸Ga-PSMA PET-CT is now recommended by many guidelines for the detection of biochemically relapsed disease after radical local therapy. PSMA radioligands can also function as radiotheranostics, and Lu-PSMA has been shown to be a potential new line of treatment for metastatic castration-resistant prostate cancer. Whole-body (WB) MRI has been shown to have a high diagnostic performance in the detection and monitoring of metastatic bone disease. Prospective, randomized, multicentre studies comparing ⁶⁸Ga-PSMA PET-CT and WB MRI for pelvic nodal and metastatic disease detection are yet to be performed. Challenges for interpretation of PSMA include tracer trapping in non-target tissues and also urinary excretion of tracers, which confounds image interpretation at the vesicoureteral junction. Additionally, studies have shown how long-term androgen deprivation therapy (ADT) affects PSMA expression and could, therefore, reduce tracer uptake and visibility of PSMA⁺ lesions. Furthermore, ADT of short duration might increase PSMA expression, leading to the PSMA flare phenomenon, which makes the accurate monitoring of treatment response to ADT with PSMA PET challenging. Scan duration, detection of incidentalomas and presence of metallic implants are some of the major challenges with WB MRI. Emerging data support the wider adoption of PSMA PET and WB MRI for diagnosis, staging, disease burden evaluation and response monitoring, although their relative roles in the standard-of-care management of patients are yet to be fully defined.

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.

Role of 68Ga and 18F PSMA PET/CT and PET/MRI in biochemical recurrence of prostate cancer: a systematic review of prospective studies

OBJECTIVE

To systematically review the prospective literature on the role of 68Ga and 18F PSMA PET/CT and PET/MRI as a tool for functional imaging in prostate cancer biochemical recurrence (BCR), particularly with respect to detection efficacy and impact on management.

METHODS

We performed a systematic literature search using PubMed in July 2021, focusing on original prospective studies looking at PSMA PET/CT and PET/MRI in BCR.

RESULTS

We included 20 prospective studies reporting on 68Ga and 18F PSMA PET/CT and PET/MRI. Pooled PSMA PET positivity was 66.6% out of 2110 patients. The only factor consistently reported as associated with PSMA PET positivity was PSA level at the time of the study. Analysis of PSMA PET positivity rates in differing PSA ranges confirmed increasing positivity with increasing PSA levels. No significant adverse reactions were reported in the 20 studies, but only 6 studies mentioned safety or adverse reactions. A major change of management occurred in 42.7% of all patients scanned with PSMA PET/CT and more specifically 63.2% of those patients positive on PSMA PET/CT. There are no long-term studies that prove a survival benefit from these changes in management.

CONCLUSION

There is prospective evidence for efficacy of PSMA PET/CT and PET/MRI in localizing disease recurrence in BCR, which increases with increasing PSA level at the time of scanning. There are no reported significant adverse effects related to the PSMA PET ligands. There is evidence of major change in management but no evidence for whether this achieves any improvement in outcome.

Synthesis, preclinical evaluation, and first-in-human study of Al18F-PSMA-Q for prostate cancer imaging

PURPOSE

To investigate the potential of a novel Al¹⁸F-labeled PSMA-targeted radiotracer for PCa diagnosis through both preclinical and pilot clinical studies.

METHODS

Al¹⁸F-PSMA-Q was prepared automatically. The binding affinity to PSMA was evaluated in vitro using the 22Rv1 (PSMA +) and PC-3 (PSMA -) cell lines. Pharmacokinetics evaluation, biodistribution study, Micro-PET imaging of Al¹⁸F-PSMA-Q in normal mice and tumor-bearing mice, and a comparison with ¹⁸F-DCFPyL were performed. PET/CT imaging was performed on 8 healthy volunteers and 20 newly diagnosed PCa patients at 1 h post-injection (p.i.). The biodistribution in human and preliminary diagnostic efficacy of Al¹⁸F-PSMA-Q were evaluated, and the radiation dosimetry was estimated using OLINDA/EXM 2.0 software.

RESULT

Qualified Al¹⁸F-PSMA-Q was efficiently prepared with a non-decay-corrected radiochemical yield (RCY) of 22.0-28.3%, a specific activity (SA) of > 50 GBq/μmol. The hydrophilicity was comparably high with a log P value of - 3.69 ± 0.39. Al¹⁸F-PSMA-Q was found to bind to PSMA specifically with a Ki value of 17.05 ± 1.14 nM. The distribution and elimination half-lives of Al¹⁸F-PSMA-Q were 3.93 min and 14.22 min, respectively, which were shorter than those of ¹⁸F-DCFPyL. Micro-PET imaging of Al¹⁸F-PSMA-Q can clearly differentiate 22Rv1 tumors from PC-3 tumors and background with a high SUVmax of 2.17 ± 0.42 and a tumor-to-muscle ratio of 84.37 ± 31.62, which were higher than those of ¹⁸F-DCFPyL (1.79 ± 0.39 and 13.25 ± 1.65). The uptake of Al¹⁸F-PSMA-Q in 22Rv1 cells and tumors can be substantially blocked by 2-PMPA. High level accumulation of Al¹⁸F-PSMA-Q was observed in organs physiologically expressing PSMA. Twenty-six tumor lesions were detected in 20 PCa patients, and the mean SUVmax values of primary tumors, lymph node metastasis, bone metastases, and tumor-muscle ratios were 19.71 ± 16.52, 5.11, 31.30 ± 29.85, and 44.77 ± 22.29, respectively. The mean SUVmax of tumors in patients with PSA > 10 ng/mL was significantly higher than that in patients with PSA ≤ 10 ng/mL (25.97 ± 18.64 vs. 10.33 ± 3.74). Meanwhile, the mean SUVmax of tumors in patients with a Gleason score ≥ 8 was significantly higher than that in patients with a Gleason score < 8 (31.85 ± 22.09 vs. 13.18 ± 11.58). The kidneys received the highest estimated dose of 0.098 ± 0.006 mGy/MBq, and the effective dose was calculated as 0.0128 ± 0.007 mGy/MBq.

CONCLUSION

The novel qualified PSMA-targeted radiotracer Al¹⁸F-PSMA-Q was conveniently prepared with favorable yield and SA. The results of preclinical and pilot clinical studies exhibited a high specific uptake in PCa lesions and an excellent tumor-to-background ratio with a reasonable radiation exposure, which indicated the great potential of Al¹⁸F-PSMA-Q for PCa imaging.

TRIAL REGISTRATION

Chinese Clinical trial registry ChiCTR2100053507, Registered 23 November 2021, retrospectively registered.

18F-DCFPyL PET/CT in Newly Diagnosed Prostate Cancer: Diagnostic Value of Intraprostatic PSMA Uptake in Risk Classification of Prostate Cancer

PURPOSE

¹⁸F-DCFPyL prostate-specific membrane antigen (PSMA) PET/CT is commonly applied to locate lesions of prostate cancer (PCa), but its diagnostic function of quantitative parameters is ignored. Our study evaluates the parameters of intraprostatic PSMA uptake in patients newly diagnosed with PCa and explores their predictive value in risk classification, which is similar to D'Amico criteria.

MATERIALS AND METHODS

We quantified the maximal standardized uptake value (SUVmax), mean SUV (SUVmean), total lesion (TL)-PSMA, prostate/muscle (P/M) ratio of the primary tumor, and PSMA-derived tumor volume (PSMA-TV) from 62 patients with histologically proven PCa. Patients newly diagnosed with PCa were allocated into risk groups (at low, intermediate, and high risk, respectively) in accordance with D'Amico criteria. Afterwards, the five parameters mentioned above among three different risk groups were compared, and their predictive values in the risk classification of PCa were explored.

RESULTS

Significantly decreased levels of SUVmax, SUVmean, TL-PSMA, and P/M ratio were observed in the risk groups of low or intermediate or both, compared with the high-risk group. However, only the P/M ratio significantly elevated in patients with intermediate risk [mean ± SD (median): 46.58 ± 9.74 (45.27), P = 0.042] or high risk [98.95 ± 38.83 (97.52), P < 0.001], compared with low-risk patients [12.33 ± 5.93 (9.81)]. When P/M ratio was used to distinguish between low-risk and intermediate-risk patients, its c-statistics was 0.660. On the other hand, when distinguishing between intermediate-risk and high-risk groups, the c-statistics of P/M ratio was 0.667. Finally, when P/M ratio was used to distinguish between low-risk and high-risk patients, the c-statistics was 0.969. P/M ratio had a positive correlation with prostate-specific antigen in all enrolled PCa patients.

CONCLUSION

The quantitative parameters of ¹⁸F-DCFPyL PET/CT, including SUVmax, SUVmean, and P/M ratio, might assist in distinguishing low-risk or intermediate-risk groups from the high-risk group. Of these parameters, P/M ratio appears to be the better promising parameter for risk classification of prostate cancer than SUVmax.

PSMA-Targeting Imaging and Theranostic Agents-Current Status and Future Perspective

In the past two decades, extensive efforts have been made to develop agents targeting prostate-specific membrane antigen (PSMA) for prostate cancer imaging and therapy. To date, represented by two recent approvals of [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]F-DCFPyL by the United States Food and Drug Administration (US-FDA) for positron emission tomography (PET) imaging to identify suspected metastases or recurrence in patients with prostate cancer, PSMA-targeting imaging and theranostic agents derived from small molecule PSMA inhibitors have advanced to clinical practice and trials of prostate cancer. The focus of current development of new PSMA-targeting agents has thus shifted to the improvement of in vivo pharmacokinetics and higher specific binding affinity with the aims to further increase the detection sensitivity and specificity and minimize the toxicity to non-target tissues, particularly the kidneys. The main strategies involve systematic chemical modifications of the linkage between the targeting moiety and imaging/therapy payloads. In addition to a summary of the development history of PSMA-targeting agents, this review provides an overview of current advances and future promise of PSMA-targeted imaging and theranostics with focuses on the structural determinants of the chemical modification towards the next generation of PSMA-targeting agents.

Comparing the diagnostic performance of radiotracers in prostate cancer biochemical recurrence: a systematic review and meta-analysis

OBJECTIVES

To systematically assess the early detection rate of biochemical prostate cancer recurrence using choline, fluciclovine, and PSMA.

METHODS

Under the guidance of the Preferred Reporting Items for Systematic reviews and Meta-Analysis Diagnostic Test Accuracy guidelines, literature that assessed the detection rates (DRs) of choline, fluciclovine, and PSMA in prostate cancer biochemical recurrence was searched in PubMed and EMBASE databases for our systematic review from 2012 to July 15, 2021. In addition, the PSA-stratified performance of detection positivity was obtained to assess the DRs for various methods, including fluciclovine, PSMA, or choline PET/CT, with respect to biochemical recurrence based on different PSA levels.

RESULTS

In total, 64 studies involving 11,173 patients met the inclusion criteria. Of the studies, 12, 7, and 48 focused on choline, fluciclovine, and PSMA, respectively. The pooled DRs were 24%, 37%, and 44%, respectively, for a PSA level less than 0.5 ng/mL (p < 0.001); 36%, 44%, and 60% for a PSA level of 0.5-0.99 ng/mL (p < 0.001); and 50%, 61%, and 80% for a PSA level of 1.0-1.99 ng/mL (p < 0.001). The DR with ¹⁸F-labeled PSMA was higher than that with ⁶⁸Ga-labeled PSMA, and the DR was 58%, 72%, and 88% for PSA levels < 0.5 ng/mL, 0.5-0.9 ng/mL, and 1.0-1.99 ng/mL, respectively.

CONCLUSION

The DRs of PSMA-radiotracers were greater than those of choline-radiotracers and fluciclovine-radiotracers at the patient level. ¹⁸F-labeled PSMA achieved a higher DR than ⁶⁸Ga-labeled PSMA.

KEY POINTS

• The DRs of PSMA-radiotracers were greater than those of choline-radiotracers and fluciclovine-radiotracers at the patient level. • ¹⁸F-labeled PSMA achieved a higher DR than ⁶⁸Ga-labeled PSMA.

Monitoring PSMA Responses to ADT in Prostate Cancer Patient-Derived Xenograft Mouse Models Using [18F]DCFPyL PET Imaging

PURPOSE

PSMA overexpression has been associated with aggressive prostate cancer (PCa). However, PSMA PET imaging has revealed highly variable changes in PSMA expression in response to ADT treatment ranging from increases to moderate decreases. To better understand these PSMA responses and potential relationship to progressive PCa, the PET imaging agent, [¹⁸F]DCFPyL, was used to assess changes in PSMA expression in response to ADT using genomically characterized LuCaP patient-derived xenograft mouse models (LuCaP-PDXs) which were found to be sensitive to ADT (LuCaP73 and LuCaP136;CS) or resistant (LuCaP167;CR).

METHODS

[¹⁸F]DCFPyL (2-(3-{1-carboxy-5-[(6-[¹⁸F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid) was used to assess PSMA in vitro (saturation assays) in LuCaP tumor membrane homogenates and in vivo (imaging/biodistribution) in LuCaP-PDXs. Control and ADT-treated LuCaPs were imaged before ADT (0 days) and 2-, 7-, 14-, and 21-days post-ADT from which tumor:muscle ratios (T:Ms) were determined and concurrently tumor volumes were measured (caliper). After the 21-day imaging, biodistributions and histologic/genomic (PSMA, AR) analysis were done.

RESULTS

[¹⁸F]DCFPyL exhibited high affinity for PSMA and distinguished different levels of PSMA in LuCaP tumors. Post-ADT CS LuCaP73 and LuCaP136 tumor volumes significantly decreased at day 7 or 14 respectively vs controls, whereas the CR LuCaP167 tumor volumes were minimally changed. [¹⁸F]DCFPyL imaging T:Ms were increased 3-5-fold in treated LuCaP73 tumors vs controls, while treated LuCaP136 T:Ms remained unchanged which was confirmed by day 21 biodistribution results. For treated LuCaP167, T:Ms were decreased (~ 45 %) vs controls but due to low T:M values (<2) may not be indicative of PSMA level changes. LuCaP73 tumor PSMA histologic/genomic results were comparable to imaging/biodistribution results, whereas the results for other tumor types varied.

CONCLUSION

Tumor responses to ADT varied from sensitive to resistant among these LuCaP PDXs, while only the high PSMA expressing LuCaP model exhibited an increase in PSMA levels in response to ADT. These models may be useful in understanding the clinical relevance of PSMA PET responses to ADT and potentially the relationship to disease progression as it may relate to the genomic signature.

A decade of multi-modality PET and MR imaging in abdominal oncology

OBJECTIVES

To investigate trends observed in a decade of published research on multimodality PET(/CT)+MR imaging in abdominal oncology, and to explore how these trends are reflected by the use of multimodality imaging performed at our institution.

METHODS

First, we performed a literature search (2009-2018) including all papers published on the multimodality combination of PET(/CT) and MRI in abdominal oncology. Retrieved papers were categorized according to a structured labelling system, including study design and outcome, cancer and lesion type under investigation and PET-tracer type. Results were analysed using descriptive statistics and evolutions over time were plotted graphically. Second, we performed a descriptive analysis of the numbers of MRI, PET/CT and multimodality PET/CT+MRI combinations (performed within a ≤14 days interval) performed during a similar time span at our institution.

RESULTS

Published research papers involving multimodality PET(/CT)+MRI combinations showed an impressive increase in numbers, both for retrospective combinations of PET/CT and MRI, as well as hybrid PET/MRI. Main areas of research included new PET-tracers, visual PET(/CT)+MRI assessment for staging, and (semi-)quantitative analysis of PET-parameters compared to or combined with MRI-parameters as predictive biomarkers. In line with literature, we also observed a vast increase in numbers of multimodality PET/CT+MRI imaging in our institutional data.

CONCLUSIONS

The tremendous increase in published literature on multimodality imaging, reflected by our institutional data, shows the continuously growing interest in comprehensive multivariable imaging evaluations to guide oncological practice.

ADVANCES IN KNOWLEDGE

The role of multimodality imaging in oncology is rapidly evolving. This paper summarizes the main applications and recent developments in multimodality imaging, with a specific focus on the combination of PET+MRI in abdominal oncology.

Postoperative radiotherapy after upfront radical prostatectomy: debated issues at a turning point-a survey exploring management trends on behalf of AIRO (Italian Association of Radiotherapy and Clinical Oncology)

OBJECTIVES

Postoperative prostate cancer patients are a heterogeneous population, and many prognostic factors (e.g., local staging, PSA kinetics, margin status, histopathological features) may influence their clinical management. In this complex scenario, univocal recommendations are often lacking. For these reasons, the present survey was developed by the Italian Association of Radiotherapy and Clinical Oncology (AIRO) to collect the opinion of Italian radiation oncologists and delineate a representation of current clinical practice in our country.

METHODS

A questionnaire was administered online to AIRO (Italian Association of Radiotherapy and Clinical Oncology) members registered in 2020 with a clinical interest in uro-oncological disease.

RESULTS

Sixty-one per cent of AIRO members answered the proposed survey. Explored topics included career and expertise, indications to adjuvant RT, additional imaging in biochemical recurrence setting, use of salvage radiotherapy (SRT), management of clinically evident locoregional recurrence and future considerations.

CONCLUSIONS

Overall, good level of agreement was found between participants for most of the topics. Most debated issues regarded, as expected, implementation of new imaging methods in this setting. Notably, trend in favour of early SRT vs. immediate adjuvant RT was underlined, and preference for global evaluation rather than isolated risk factors for RT indications was noticed.

Seek and Find: Current Prospective Evidence for Prostate-specific Membrane Antigen Imaging to Detect Recurrent Prostate Cancer

CONTEXT

Men with biochemically relapsed prostate cancer face a clinical conundrum. Depending on the detected distribution of disease, treatment goals may range from cure with focal therapy to palliative with systemic therapy to expectant observation. Retrospective studies of prostate-specific membrane antigen (PSMA)-based imaging demonstrate higher disease detection rates than conventional imaging.

OBJECTIVE

This review focuses on available prospective evidence for diagnostic use of PSMA-based imaging to accurately restage recurrent prostate cancer and explores the potential clinical impact, near future uses, and challenges for PSMA-based imaging in this setting.

EVIDENCE ACQUISITION

PubMed and EMBASE databases were searched for prospective studies with primary, secondary, or exploratory endpoints evaluating PSMA-based imaging for patients with recurrent prostate cancer published in English in the past 10 yrs.

EVIDENCE SYNTHESIS

We reviewed 48 prospective studies evaluating the role of PSMA positron emission tomography (PET) in recurrent prostate cancer. These studies establish the diagnostic accuracy and safety of PSMA PET using the 68Ga-PSMA-11 and 18F-DCFPyL radiotracers even at lower prostate-specific antigen (PSA) levels (0.5 ≤ PSA < 1.0 ng/m: disease detection rate 51-78%). The use of PSMA PET has been shown to result in changes in management in up to two-thirds of patients.

CONCLUSIONS

There is now higher-level regulatory-quality prospective evidence for PSMA-based imaging for the detection of recurrent prostate cancer. There is prospective evidence of superiority over cross-sectional imaging and bone scintigraphy, as well as for the alterations in disease management as a result of PSMA-based imaging.

PATIENT SUMMARY

When the prostate-specific antigen (PSA) level is rising after primary therapy, prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is excellent at detecting and localizing prostate cancer, even at low PSA levels. Those who benefit best from treatment modifications based on PSMA PET findings are yet to be defined.

Clinical Utility of 18F-PSMA-1007 Positron Emission Tomography/Magnetic Resonance Imaging in Prostate Cancer: A Single-Center Experience

Purpose

This study aimed to evaluate the clinical utility of ¹⁸F-PSMA-1007 positron emission tomography (PSMA PET)/magnetic resonance imaging (MRI) imaging in patients with suspected or defined prostate cancer.

Methods

In the pilot study, we retrospectively investigated 62 patients who underwent PSMA-PET/MRI for suspected or defined PCa between June 2019 and June 2020. Patients were grouped into three subgroups: (1) suspected PCa without histological evidence, (2) primary PCa, (3) biochemical recurrent prostate cancer (BRPCa). Two nuclear physicians independently interpreted the results of PSMA-PET/MRI. Management strategies before PSMA-PET/MRI were retrospectively reported, and the management strategy was re-evaluated for each patient considering the PSMA-PET/MRI result. The changes in strategies were recorded. Besides, the correlation between prostate specific antigen (PSA) level and management changes was also accessed by Fisher exact test, and two-side p < 0.05 was assumed as statistical significance.

Results

There were 28 patients in the suspected PCa group (group 1), 12 in the primary PCa group (group 2), and 22 in the BRPCa group (group 3). Overall, the intended decisions were changed in 26 (41.9%) of 62 patients after PSMA-PET/MRI, including 11/28 (39.3%) in suspected PCa group, 1/12 (8.4%) in primary PCa group, and 14/24 (63.6%) in BCR group. In group 1, the main impact on subsequent management included decreased active surveillance (from 20 to 9) and increased prostate biopsy (from 8 to 19). PSA levels were not significantly associated with management changes in suspected PCa patients (p = 0.865). In group 2, the main impact on subsequent management included decreased radical surgery (from 8 to 7), and multimodal therapy appearance (n = 1). Only in the category of PSA levels of ≥20 ng/ml, the management of primary PCa was changed. In group 3, the main impact on subsequent management included decreased salvage radiotherapy (from 5 to 2), increased systemic therapy (from 6 to 7), and increased multimodal therapy (from 11 to 13). The highest proportion of management changes occurred in BCR patients with 0.5≤PSA<1 ng/ml.

Conclusion

From our preliminary experience, PSMA-PET/MRI may be a valued tool for defining PCa lesions and changing management. The biggest impact of management intent was in patients with BRPCa, especially in patients with 0.5≤PSA<1 ng/ml. However, further studies are needed to confirm our pilot findings.

Pattern of failure in prostate cancer previously treated with radical prostatectomy and post-operative radiotherapy: a secondary analysis of two prospective studies using novel molecular imaging techniques

Background

Prostate Membrane Specific Antigen (PSMA) positron emission tomography (PET) and multiparametric MRI (mpMRI) have shown high accuracy in identifying recurrent lesions after definitive treatment in prostate cancer (PCa). In this study, we aimed to outline patterns of failure in a group of post-prostatectomy patients who received adjuvant or salvage radiation therapy (PORT) and subsequently experienced biochemical recurrence, using ¹⁸F-PSMA PET/CT and mpMRI.

Methods

PCa patients with biochemical failure post-prostatectomy, and no evident site of recurrence on conventional imaging, were enrolled on two prospective trials of first and second generation ¹⁸F-PSMA PET agents (¹⁸F-DCFBC and ¹⁸F-DCFPyL) in combination with MRI between October 2014 and December 2018. The primary aim of our study is to characterize these lesions with respect to their location relative to previous PORT field and received dose.

Results

A total of 34 participants underwent ¹⁸F-PSMA PET imaging for biochemical recurrence after radical prostatectomy and PORT, with 32/34 found to have ¹⁸F-PSMA avid lesions. On ¹⁸F-PSMA, 17/32 patients (53.1%) had metastatic disease, 8/32 (25.0%) patients had locoregional recurrences, and 7/32 (21.9%) had local failure in the prostate fossa. On further exploration, we noted 6/7 (86%) of prostate fossa recurrences were in-field and were encompassed by 100% isodose lines, receiving 64.8–72 Gy. One patient had marginal failure encompassed by the 49 Gy isodose.

Conclusions

¹⁸F-PSMA PET imaging demonstrates promise in identifying occult PCa recurrence after PORT. Although distant recurrence was the predominant pattern of failure, in-field recurrence was noted in approximately 1/5th of patients. This should be considered in tailoring radiotherapy practice after prostatectomy.

Trial registrationwww.clinicaltrials.gov, NCT02190279 and NCT03181867. Registered July 12, 2014, https://clinicaltrials.gov/ct2/show/NCT02190279 and June 8 2017, https://clinicaltrials.gov/ct2/show/NCT03181867.

Prostate-specific membrane antigen expression in melanoma metastases

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a prostatic epithelial protein that is used as a radiotracer (68Ga-PSMA-11) for prostate cancer staging. PSMA-PET/CT (positron emission tomography/computed tomography) performed for prostate cancer has been observed to detect melanoma metastases. The aim of this study was to investigate the performance of PSMA immunohistochemistry on resected melanoma metastases to explore its use as a diagnostic imaging biomarker for melanoma.

METHODS

A total of 41 specimens with stage III/IV melanoma were stained with PSMA immunohistochemistry. All specimens required both disease and control regions. Two pathologists scored the specimens and a receiver operating characteristic (ROC) curve was plotted. Western blot and multiplex immunofluorescence were also performed.

RESULTS

The area under the ROC curve was 0.82, suggesting that PSMA has excellent discriminatory power in melanoma metastases. Sensitivity is 82.9% and specificity 73.2%. Immunohistochemistry and Western blot reveal that PSMA staining in melanoma consistently and most intensely occurs in tumor neovasculature. Multiplex immunofluorescence shows that melanocytes may also weakly express PSMA.

CONCLUSION

The performance of PSMA immunohistochemistry in melanoma metastases contrasts with that reported in prostate cancer studies. This study indicates that PSMA shows promise for use as a novel biomarker in melanoma and justifies further research in the clinical setting with potential as a PET/CT radiotracer and intraoperative fluorescence marker for melanoma.

The Role of PET-CT Imaging in Prostate Cancer

Prostate cancer is the commonest malignancy to affect men in the United Kingdom. Extraprostatic disease detection at staging and in the setting of biochemical recurrence is essential in determining treatment strategy. Conventional imaging including computed tomography and bone scintigraphy are limited in their ability to detect sites of loco-regional nodal and metastatic bone disease, particularly at clinically relevant low prostate-specific antigen levels. The use of positron emission tomography-computed tomography has helped overcome these deficiencies and is leading a paradigm shift in the management of prostate cancer using a wide range of radiopharmaceuticals. Their mechanisms of action, utility in both staging and biochemical recurrence, and comparative strengths and weaknesses will be covered in this article.

Molecular imaging of prostate cancer: Review of imaging agents, modalities, and current status

INTRODUCTION

The clinical course of Prostate cancer (PCa) are markedly diverse, ranging from indolent to highly aggressive disseminated disease. Molecular imaging techniques are playing an increasing role in early PCa detection, staging and disease recurrence. There are some molecular imaging modalities, radiotracers agents and its performance are important in current clinical practice PCa.

OBJECTIVE

This review summarizes the latest information regarding molecular imaging of PCa and is designed to assist urologists with ordering and interpreting these modalities and different radiotracers for different patients.

EVIDENCE ACQUISITION

A PubMed-based literature search was conducted up to September 2019. We selected the most recent and relevant original articles, metanalysis and reviews that have provided relevant information to guide molecular imaging modalities and radiotracers use.

EVIDENCE SYNTHESIS

In this review, we discuss 3 main molecular imaging modalities and 7 radiotracer technologies available.

CONCLUSIONS

The use molecular imaging modalities and radiotracers has a unique role in biochemical recurrence and diagnosis of ganglionar and bone progression of PCa. In the present time, no one of these molecular imaging modalities can be recommended over the classical work-up of abdominopelvic CT scan and bone scan, and large-scale and multi-institutional studies are required to validate the efficacy and cost utility of these new technologies.

Prostate-specific membrane antigen (PSMA)-ligand positron emission tomography and radioligand therapy (RLT) of prostate cancer

From a clinical perspective, prostate-specific membrane antigen (PSMA) is a valuable target for both diagnosis and radioligand therapy (RLT) of prostate cancer. The term ‘specific’ has been used to characterize a histologic hallmark of overexpression in the membrane of most prostate cancer. Many PSMA ligands have been developed since the previous decade and have been used in several clinical trials and clinical studies. However, procedure, specification, protocol, interpretation criteria, radiation dose, and cost-effectiveness of PSMA ligands have not been fully explained. Regardless of worldwide use of promising PSMA-ligand PET and RLT, it has not been approved in Japan. Expedited introduction of PSMA-ligand PET and RLT to Japan and implementation of clinical study are eager for many patients with prostate cancer.

Comparison of cross-sectional imaging techniques for the detection of prostate cancer lymph node metastasis: a critical review

Conventional staging for prostate cancer (PCa) is performed for men diagnosed with unfavorable-intermediate or higher risk disease. Computed tomography (CT) of the abdomen and pelvis and whole body bone scan remains the standard of care for the detection of visceral, nodal, and bone metastasis. The implementation of the 2012 United States Preventive Services Task Force recommendation against routine prostate specific antigen (PSA) screening resulted in a rise of metastatic PCa at the time of diagnosis, emphasizing the importance of effective imaging modalities for evaluating metastatic disease. CT plays a major role in clinical staging at the time of PCa diagnosis, but multi-parametric magnetic resonance imaging (MRI) is now integrated into many prostate biopsy protocols for the detection of primary PCa, and may be a surrogate for CT for nodal staging. Current guidelines incorporate both CT and MRI as appropriate cross-sectional imaging modalities for the identification of nodal metastasis in indicated patients. There is an ongoing debate about the utility of traditional cross-sectional imaging modalities as well as advanced imaging modalities in detection of both organ-confined PCa detection and nodal involvement.

A microdose clinical trial to evaluate [18F]Florastamin as a positron emission tomography imaging agent in patients with prostate cancer

PURPOSE

To evaluate the biodistribution of [¹⁸F]Florastamin, a novel ¹⁸F-labelled positron emission tomography (PET) tracer for prostate-specific membrane antigen (PSMA) for the diagnosis of prostate cancer.

METHODS

PET was performed for five healthy controls and 10 patients with prostate cancer at 0, 10, 30, 70, and 120 mins after injecting 370 MBq of [¹⁸F]Florastamin. The maximum standardised uptake value (SUV_max) was evaluated in the primary tumour. The mean SUV_max (SUV_mean) was evaluated in normal organs. Furthermore, the residence time was evaluated by assessing radioactivity in each organ. The internal radiation dosimetry was calculated using the OLINDA/EXM software.

RESULTS

The SUV_max in primary tumours increased with time. A favourable tumour to background ratio was also observed over time. Multiple lymph nodes and bone metastases were also evaluated and showed a similar pattern to SUV_max in the primary tumour. In one patient, a tiny lymph node metastasis was identified using [¹⁸F]Florastamin PET, which was not observed using other modalities, and was histologically confirmed. The highest absorbed dose was observed in the kidney (0.062 ± 0.015 mGy/MBq), followed by the bladder (0.032 ± 0.013 mGy/MBq), liver (0.022 ± 0.006 mGy/MBq), and salivary gland (0.018 ± 0.006 mGy/MBq). The effective dose with a 370 MBq injection of [¹⁸F]Florastamin was 1.81 mSv. No adverse events related to [¹⁸F]Florastamin were reported.

CONCLUSION

We identified a novel PSMA-targeted PET ligand, [¹⁸F]Florastamin, for imaging prostate cancer. [¹⁸F]Florastamin showed a high SUV_max and relatively high tumour to background ratio in both primary tumour and metastatic lesions, which suggests its high sensitivity to detect tumours without any adverse events.

TRIAL REGISTRATION

KCT0003924 registered at https://cris.nih.go.kr/ .

Immunohistochemical PSMA expression patterns of primary prostate cancer tissue are associated with the detection rate of biochemical recurrence with 68Ga-PSMA-11-PET

Prostate-specific membrane antigen (PSMA) targeted PET has a high detection rate for biochemical recurrence (BCR) of prostate cancer (PCa). Nevertheless, even at high prostate-specific antigen (PSA) levels (> 3 ng/ml), a relevant number of PSMA-PET scans are negative, mainly due to PSMA-negative PCa. Our objective was to investigate whether PSMA-expression patterns of the primary tumour on immunohistochemistry (IHC) are associated with PSMA-PET detection rate of recurrent PCa. Methods: Retrospective institutional review board approved single-centre analysis of patients who had undergone ⁶⁸Ga-PSMA-11-PET for BCR after radical prostatectomy (RPE) between 04/2016 and 07/2019, with tumour specimens available for PSMA-IHC. Clinical information (age, PSA-level, ongoing androgen deprivation therapy (ADT), Gleason score) and PSMA-IHC of the primary tumour were collected and their relationship to results from PSMA-PET (positive/negative) was investigated using a multiple logistic regression analysis. Results: 120 PSMA-PET scans in 74 patients were available for this analysis. Overall detection rate was 62% (74/120 scans), with a mean PSA value at scan time of 0.99 ng/ml (IQR 0.32-4.27). Of the clinical factors, only PSA-level and ADT were associated with PSMA-PET positivity. The percentage of PSMA-negative tumour area on IHC (PSMA_%neg) had a significant association to PSMA-PET negativity (OR = 2.88, p < 0.001), while membranous PSMA-expression showed no association (p = 0.73). The positive predictive value of PSMA_%neg ≥ 50% for a negative PSMA-PET was 85% (13/11) and for a PSMA_%neg of 80% or more, 100% (9/9). Conclusions: PSMA-negative tumour area on IHC exhibited the strongest association with negative PSMA-PET scans, beside PSA-level and ADT. Even at very high PSA levels, PSMA-PET scans were negative in most of the patients with PSMA_%neg ≥ 50%.

PSMA-targeted Radiotracers versus 18F Fluciclovine for the Detection of Prostate Cancer Biochemical Recurrence after Definitive Therapy: A Systematic Review and Meta-Analysis

Background National guidelines endorse fluorine 18 (¹⁸F) fluciclovine PET/CT for the detection of prostate cancer (PCa) in men with biochemically recurrent PCa. The comparative performance between fluciclovine and gallium 68 or ¹⁸F prostate-specific membrane antigen (PSMA) PET/CT, a newer examination, is unclear. Purpose To compare the detection of biochemical recurrence using fluciclovine versus PSMA-targeted radiotracers in patients with a prostate-specific antigen (PSA) level less than 2 ng/mL. Materials and Methods With use of the Preferred Reporting Items for a Systematic Review and Meta-Analysis of Diagnostic Test Accuracy, or PRISMA-DTA, guidelines, a systematic review of PubMed and EMBASE databases between 2012 and 2019 was performed. Studies of fluciclovine PET/CT or PSMA PET/CT in biochemical recurrence were identified. PSA levels, clinical data, and reference standards were obtained when available. A random-effects model was applied to pooled estimates and 95% confidence intervals (CIs) around the prevalence of a positive examination, stratified according to PSA tier. Results Quantitative analysis included 482 patients (median age, 67 years; interquartile range, 67-67 years) in six fluciclovine studies and 3217 patients (median age, 68 years; interquartile range, 67-70 years) in 38 PSMA studies. Pooled detection rates for PSMA and fluciclovine were 45% (95% CI: 38%, 52%) and 37% (95% CI: 25%, 49%), respectively, for a PSA level less than 0.5 ng/mL (P = .46); 59% (95% CI: 52%, 66%) and 48% (95% CI: 34%, 61%) for a PSA level of 0.5-0.9 ng/mL (P = .19); and 80% (95% CI: 75%, 85%) and 62% (95% CI: 54%, 70%) for a PSA level of 1.0-1.9 ng/mL (P = .01). A reference standard was positive in 703 of 735 patients (96%) in the PSMA cohort and 247of 256 (97%) in the fluciclovine cohort. Conclusion Patient-level detection rates for biochemically recurrent prostate cancer were greater for prostate-specific membrane antigen-targeted radiotracers than fluciclovine for prostate specific antigen levels of 1.0-1.9 ng/mL. © RSNA, 2020 Online supplemental material is available for this article.

68Ga-PSMA PET/CT versus CT and bone scan for investigation of PSA failure post radical prostatectomy

Objective

To evaluate the use of Gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (⁶⁸Ga-PSMA PET/CT), compared with conventional CT abdomen/pelvis (CTAP) and whole body single photon emission CT bone scan (BS), for detection of local or distant metastasis following biochemical failure/recurrence in post-prostatectomy patients.

Methods

We conducted a review of our prospectively maintained, institutional database to identify 384 patients with post-prostatectomy biochemical failure/recurrence who underwent PSMA PET/CT, CTAP and BS from February 2015 to August 2017 in Nepean Hospital, tertiary referral centre. The results of the three imaging modalities were analysed for their ability to detect local recurrence and distant metastases. PSMA PET/CT and CTAP imaging were separately performed on the same day and the BS was performed within several days (mostly in 24 h). Difference in detection rates was determined between the modalities and the Chi square test was used to determine significance.

Results

A total of 384 patients were identified with a median prostate-specific antigen (PSA) of 0.465 ng/mL (interquartile range =0.19–2.00 ng/mL). Overall, PSMA PET/CT was positive for 245 (63.8%) patients whereas CTAP and BS were positive in 174 patients (45.3%). A total of 98 patients (25.5%) had local or distant metastasis detected on PSMA only, while 20 patients (5.2%) had recurrences detected on CTAP but not on PSMA PET/CT.

Conclusion

The use of PSMA PET/CT has a higher detection rate of predicted local or distant metastasis compared to CTAP and BS in the staging of patients with biochemical recurrences after radical prostatectomy.

Imaging for Metastasis in Prostate Cancer: A Review of the Literature

Background: Initial staging and assessment of treatment activity in metastatic prostate cancer (PCa) patients is controversial. Indications for the various available imaging modalities are not well-established due to rapid advancements in imaging and treatment.

Methods: We conducted a critical literature review of the main imaging abnormalities that suggest a diagnosis of metastasis in localized and locally advanced PCa or in cases of biological relapse. We also assessed the role of the various imaging modalities available in routine clinical practice for the detection of metastases and response to treatment in metastatic PCa patients.

Results: In published clinical trials, the most commonly used imaging modalities for the detection and evaluation of therapeutic response are bone scan, abdominopelvic computed tomography (CT), and pelvic and bone magnetic resonance imaging (MRI). For the detection and follow-up of metastases during treatment, modern imaging techniques i.e., choline-positron emission tomography (PET), fluciclovine-PET, or Prostate-specific membrane antigen (PSMA)-PET provide better sensitivity and specificity. This is particularly the case of fluciclovine-PET and PSMA-PET in cases of biochemical recurrence with low values of prostate specific antigen.

Conclusions: In routine clinical practice, conventional imaging still have a role, and communication between imagers and clinicians should be encouraged. Present and future clinical trials should use modern imaging methods to clarify their usage.

18F-Labeled, PSMA-Targeted Radiotracers: Leveraging the Advantages of Radiofluorination for Prostate Cancer Molecular Imaging

Prostate-specific membrane antigen (PSMA)-targeted PET imaging for prostate cancer with 68Ga-labeled compounds has rapidly become adopted as part of routine clinical care in many parts of the world. However, recent years have witnessed the start of a shift from 68Ga- to 18F-labeled PSMA-targeted compounds. The latter imaging agents have several key advantages, which may lay the groundwork for an even more widespread adoption into the clinic. First, facilitated delivery from distant suppliers expands the availability of PET radiopharmaceuticals in smaller hospitals operating a PET center but lacking the patient volume to justify an onsite 68Ge/68Ga generator. Thus, such an approach meets the increasing demand for PSMA-targeted PET imaging in areas with lower population density and may even lead to cost-savings compared to in-house production. Moreover, 18F-labeled radiotracers have a higher positron yield and lower positron energy, which in turn decreases image noise, improves contrast resolution, and maximizes the likelihood of detecting subtle lesions. In addition, the longer half-life of 110 min allows for improved delayed imaging protocols and flexibility in study design, which may further increase diagnostic accuracy. Moreover, such compounds can be distributed to sites which are not allowed to produce radiotracers on-site due to regulatory issues or to centers without access to a cyclotron. In light of these advantageous characteristics, 18F-labeled PSMA-targeted PET radiotracers may play an important role in both optimizing this transformative imaging modality and making it widely available. We have aimed to provide a concise overview of emerging 18F-labeled PSMA-targeted radiotracers undergoing active clinical development. Given the wide array of available radiotracers, comparative studies are needed to firmly establish the role of the available 18F-labeled compounds in the field of molecular PCa imaging, preferably in different clinical scenarios.

Sequencing of Androgen-Deprivation Therapy With External-Beam Radiotherapy in Localized Prostate Cancer: A Phase III Randomized Controlled Trial

PURPOSE

Dose-escalated radiotherapy (RT) with androgen-deprivation therapy (ADT) is a standard definitive treatment of localized prostate cancer (LPCa). The optimal sequencing of these therapies is unclear. Our phase III trial compared neoadjuvant versus concurrent initiation of ADT in combination with dose-escalated prostate RT (PRT).

PATIENTS AND METHODS

Patients with newly diagnosed LPCa with Gleason score ≤ 7, clinical stage T1b to T3a, and prostate-specific antigen < 30 ng/mL were randomly allocated to neoadjuvant and concurrent ADT for 6 months starting 4 months before RT (neoadjuvant group) or concurrent and adjuvant ADT for 6 months starting simultaneously with RT (concurrent group). The primary end point was biochemical relapse-free survival (bRFS). Stratified log-rank test was used to compare bRFS and overall survival (OS). Incidence of grade ≥ 3 late RT-related toxicities was compared by log-rank test.

RESULTS

Overall, 432 patients were randomly assigned to the neoadjuvant (n = 215) or concurrent group (n = 217). At 10 years, bRFS rates for the two groups were 80.5% and 87.4%, respectively. Ten-year OS rates were 76.4% and 73.7%, respectively. There was no significant difference in bRFS (P = .10) or OS (P = .70) between the two groups. Relative to the neoadjuvant group, the hazard ratio for the concurrent group was 0.66 (95% CI, 0.41 to 1.07) for bRFS and 0.94 (95% CI, 0.68 to 1.30) for OS. No significant difference was observed in the 3-year incidence of late RT-related grade ≥ 3 GI (2.5% v 3.9%) or genitourinary toxicity (2.9% v 2.9%).

CONCLUSION

In our study, there was no statistically significant difference in bRFS between the two treatment groups. Similarly, no difference was seen in OS or late RT-related toxicities. On the basis of these results, both neoadjuvant and concurrent initiations of short-term ADT with dose-escalated PRT are reasonable standards of care for LPCa.

Impact of 68Ga-PSMA-11 PET staging on clinical decision-making in patients with intermediate or high-risk prostate cancer

BACKGROUND

Accurate staging is of major importance to determine the optimal treatment modality for patients with prostate cancer. Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) is a promising technique that outperformed conventional imaging in the detection of nodal and distant metastases in previous studies. However, it is still unclear whether the superior sensitivity and specificity also translate into improved patient management. The aim of this study was to assess the performance of ⁶⁸Ga-PSMA-11 PET for staging of intermediate and high-risk prostate cancer and its potential impact on disease management.

METHODS

In this retrospective analysis, 116 patients who underwent ⁶⁸Ga-PSMA-11 PET/CT or MRI scans for staging of their intermediate or high-risk prostate cancer between April 2016 and May 2018 were included. The potential impact of ⁶⁸Ga-PSMA-11 PET staging on patient management was assessed within a simulated multidisciplinary tumour board where hypothetical treatment decisions based on clinical information and conventional imaging alone was determined. This treatment decision was compared with the treatment recommendation based on clinical information and ⁶⁸Ga-PSMA-11 PET imaging.

RESULTS

The primary tumour was positive on ⁶⁸Ga-PSMA-11 PET in 113 patients (97%). Nodal metastases were detected in 28 patients (24%) and bone metastases in 14 patients (12%). Compared with clinical staging and conventional imaging, ⁶⁸Ga-PSMA-11 PET resulted in new information in 42 of 116 patients (36%). In 32 of 116 patients (27%), this information would most likely have changed the management into a different therapy modality (15 patients, 13%) or adjusted treatment details (e.g. modification of radiotherapy field or lymph node dissection template; 17 patients, 14%).

CONCLUSION

Information from ⁶⁸Ga-PSMA-11 PET staging has the potential to change the management in more than a fourth of the patients who underwent PET staging for their intermediate to high-risk prostate cancer. Whether these more personalized ⁶⁸Ga-PSMA-11 PET-based treatment decisions will improve patient outcome needs further investigation.

18F-DCFPyL PET/CT Imaging in Patients with Biochemically Recurrent Prostate Cancer After Primary Local Therapy

Our objective was to investigate the lesion detection rate of ¹⁸F-DCFPyL PET/CT, a prostate-specific membrane antigen (PSMA)-targeted PET agent, in patients with biochemically relapsed prostate cancer after primary local therapy. Methods: This was a prospective institutional review board-approved study of 90 patients with documented biochemical recurrence (median prostate-specific antigen [PSA], 2.5 ng/mL; range, 0.21-35.5 ng/mL) and negative results on conventional imaging after primary local therapies, including radical prostatectomy (n = 38), radiation (n = 27), or a combination of the two (n = 25). Patients on androgen deprivation therapy were excluded. Patients underwent whole-body ¹⁸F-DCFPyL PET/CT (299.9 ± 15.5 MBq) at 2 h after injection. The PSMA PET lesion detection rate was correlated with PSA, PSA kinetics, and original primary tumor grade. Results: Seventy patients (77.8%) showed positive PSMA PET results, with a total of 287 lesions identified: 37 prostate bed foci, 208 lesions in lymph nodes, and 42 in distant sites in bones or organs, Eleven patients had negative results, and 9 patients showed indeterminate lesions, which were considered negative in this study. The detection rates were 47.6% (n = 10/21), 50% (n = 5/10), 88.9% (n = 8/9), and 94% (n = 47/50) for PSA levels of >0.2 to <0.5, 0.5 to <1.0, 1 to <2.0, and ≥2.0 ng/mL, respectively. In postsurgical patients, PSA, PSA doubling time, and PSA velocity correlated with PET results, but the same was not true for postradiation patients. These parameters also correlated with the extent of disease on PET (intrapelvic vs. extrapelvic). There was no significant difference in the rate of positive scans between patients with higher-grade and lower-grade primary tumors (Gleason score of ≥4 + 3 vs. <3 + 4). Tumor recurrence was histology-confirmed in 40% (28/70) of patients. On a per-patient basis, positive predictive value was 93.3% (95% confidence interval, 77.6%-99.2%) by histopathologic validation and 96.2% (95% confidence interval, 86.3%-99.7%) by the combination of histology and imaging/clinical follow-up. Conclusion: ¹⁸F-DCFPyL PET/CT imaging offers high detection rates in biochemically recurrent prostate cancer patients and is positive in about 50% of patients with a PSA level of less than 0.5 ng/mL, which could substantially impact clinical management. In postsurgical patients, ¹⁸F-DCFPyL PET/CT correlates with PSA, PSA doubling time, and PSA velocity, suggesting it may have prognostic value. ¹⁸F-DCFPyL PET/CT is highly promising for localizing sites of recurrent prostate cancer.

Salvage lymphadenectomy in recurrent prostate cancer: is there evidence of real benefit?

PURPOSE

Nodal recurrent prostate cancer (PCa) after primary radical treatment represents a heterogeneous entity with many treatment options. In some cases, surgical removal of metastatic nodes seems to improve cancer control and delay systemic treatments. The objectives of this study were to analyze the available literature on salvage lymphadenectomy for the treatment of nodal recurrent PCa and to elucidate the real oncological benefit deriving from this procedure.

METHODS

A PubMed search was performed using the following terms: prostate cancer, metastatic, oligometastatic, salvage lymphadenectomy, salvage lymph node dissection, salvage lymph node excision, and cytoreductive surgery. We included in the study all papers on salvage lymphadenectomy in nodal recurrent PCa, with no temporal limits. In addition, several papers addressing cytoreductive surgery and the biology of oligometastatic disease, published in different medical and basic research journals, were included.

RESULTS

Salvage lymphadenectomy is still characterized by a lack of standardization in patient selection and surgical template. Its primary objectives are to prolong progression-free survival and to delay the need for systemic therapy. The improvements in preoperative imaging techniques in conjunction with the wide use of minimally invasive surgery have generated growing interest in this procedure.

CONCLUSION

Salvage lymphadenectomy is a promising treatment approach; however, its real oncological benefit is still far from proven. Prospective randomized trials need to be designed to improve understanding of this issue.

Semiquantitative Parameters in PSMA-Targeted PET Imaging with [18F]DCFPyL: Intrapatient and Interpatient Variability of Normal Organ Uptake

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging has impacted the management of patients with prostate cancer (PCa) in many parts of the world. PSMA-targeted endoradiotherapies are also being increasingly utilized and for these applications, the radiopharmaceutical distribution in normal organs is particularly important because it may limit the dose that can be delivered to tumors. In this study, we measured both interpatient and intrapatient variability of [¹⁸F]DCFPyL uptake in the most relevant normal organs.

PROCEDURES

Baseline and 6-month follow-up PSMA-targeted [¹⁸F]DCFPyL PET/computed tomography (CT) scans from 39 patients with PCa were reviewed. Volumes of interest were manually drawn using the best visual approximation of the organ edge for both lacrimal glands, all four major salivary glands, the liver, the spleen, and both kidneys for all patients. The average SUV_mean, the COVs, and intraclass correlation coefficients (ICCs) across scans were calculated. Bland-Altman analyses were performed for all organs to derive repeatability coefficients (RCs).

RESULTS

The liver demonstrated the lowest interpatient variability (13.0 and 16.6 % at baseline and follow-up, respectively), while the spleen demonstrated the largest interpatient variability (44.6 and 51.0 % at baseline and follow-up, respectively). The lowest intrapatient variability was found in the spleen (ICC 0.86) while the highest intrapatient variability was in the kidneys (ICCs 0.40-0.50). Bland-Altman analyses showed 95 % repeatability coefficients for mean uptake > 40 % for multiple organs and were highest for the lacrimal glands, kidneys, and spleen.

CONCLUSIONS

Normal organs demonstrate significant variability in uptake of the PSMA-targeted radiotracer [¹⁸F]DCFPyL. Depending on the organ, different contributions of interpatient and intrapatient factors affect the intrinsic variability. The RCs also vary significantly among the different organs were highest for the lacrimal glands, kidneys, and spleen. These findings may have important implications for the design of clinical protocols and personalized dosimetry for PSMA-targeted endoradiotherapies.

Detection Rate of 18F-Labeled PSMA PET/CT in Biochemical Recurrent Prostate Cancer: A Systematic Review and a Meta-Analysis

Background: The use of radiolabeled prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) for biochemical recurrent prostate cancer (BRPCa) is increasing worldwide. Recently, ¹⁸F-labeled PSMA agents have become available. We performed a systematic review and meta-analysis regarding the detection rate (DR) of ¹⁸F-labeled PSMA PET/CT in BRPCa to provide evidence-based data in this setting. Methods: A comprehensive literature search of PubMed/MEDLINE, EMBASE, and Cochrane Library databases through 23 April 2019 was performed. Pooled DR was calculated on a per-patient basis, with pooled proportion and 95% confidence interval (95% CI). Furthermore, pooled DR of ¹⁸F-PSMA PET/CT using different cut-off values of prostate-specific antigen (PSA) was obtained. Results: Six articles (645 patients) were included in the meta-analysis. The pooled DR of ¹⁸F-labeled PSMA PET/CT in BRPCa was 81% (95% CI: 71–88%). The pooled DR was 86% for PSA ≥ 0.5 ng/mL (95% CI: 78–93%) and 49% for PSA < 0.5 ng/mL (95% CI: 23–74%). Statistical heterogeneity was found. Conclusions: ¹⁸F-labeled PSMA PET/CT demonstrated a good DR in BRPCa. DR of ¹⁸F-labeled PSMA PET/CT is related to PSA values with significant lower DR in patients with PSA < 0.5 ng/mL. Prospective multicentric trials are needed to confirm these findings.

PSMA-Targeted Radiopharmaceuticals for Imaging and Therapy

As described in more detail in other contributions in this issue of Seminars in Nuclear Medicine, prostate-specific membrane antigen (PSMA) has become one of the most promising molecular targets in nuclear medicine. Due to its overexpression on prostate cancer cells in proportion to the stage and grade of tumour progression, especially in androgen-independent, advanced and metastatic disease, various tracers for the detection and treatment of prostate cancer by means of radioligand imaging, radioligand therapy or radioguided surgery have been developed and transferred to clinical applications. Even though monoclonal antibodies were investigated and introduced as first PSMA-targeted probes, the inherent advantage of fast tumour uptake and rapid excretion of small molecules has shifted the research focus during the last decade to low molecular weight inhibitors with high affinity to PSMA, such as [¹⁸F]FDCFPyL, [¹⁸F]PSMA-1007, [⁶⁸Ga]PSMA-HBED, [¹⁷⁷Lu]PSMA-617, [¹⁷⁷Lu]PSMA-I&T, [^99mTc]MIP-1404 or [^99mTc]PSMA I&S, to mention only a few. Due to the plethora of such PSMA probes described during the last years, this review aims to give an overview over the specific characteristics of those radiopharmaceuticals that have already found widespread clinical application. In addition, recently introduced concepts such as PSMA-tracers with increased plasma protein binding, are discussed.

Advances in prostate-specific membrane antigen PET of prostate cancer

PURPOSE OF REVIEW

In recent years, a large number of reports have been published on prostate-specific membrane antigen (PSMA)/PET in prostate cancer (PCa). This review highlights advances in PSMA PET in PCa during the past year.

RECENT FINDINGS

PSMA PET/computed tomography (CT) is useful in detection of biochemical recurrence, especially at low prostate-specific antigen (PSA) values. The detection rate of PSMA PET is influenced by PSA level. For primary PCa, PSMA PET/CT shows promise for tumour localization in the prostate, especially in combination with multiparametric MRI (mpMRI). For primary staging, PSMA PET/CT can be used in intermediate and high-risk PCa. Intraoperative PSMA radioligand guidance seems promising for detection of malignant lymph nodes. While the use of PSMA PET/MRI in primary localized disease is limited to high and intermediate-risk patients and localized staging, in the recurrence setting, PET/MRI can be particularly helpful when the lesions are subtle. PSMA PET/CT is superior to choline PET/CT and other conventional imaging modalities.

SUMMARY

Molecular imaging with PSMA PET continues to pave the way for personalized medicine in PCa.However, large prospective clinical studies are still needed to fully evaluate the role of PSMA PET/CT and PET/MRI in the clinical workflow of PCa.

Recent Advances in Prostate-Specific Membrane Antigen-Based Radiopharmaceuticals

BACKGROUND

Prostate cancer (PCa) is the most common sex-related malignancy with high mortality in men worldwide. Prostate-specific membrane antigen (PSMA) is overexpressed on the surface of most prostate tumor cells and considered a valuable target for both diagnosis and therapy of prostate cancer. A series of radiolabeled agents have been developed based on the featured PSMA ligands in the previous decade and have demonstrated promising outcomes in clinical research of primary and recurrent PCa. Furthermore, the inspiring response and safety of lutetium-177-PSMA-617 (177Lu-PSMA-617) radiotherapy represent the potential for expanded therapeutic options for metastatic castration-resistant PCa. Retrospective cohort studies have revealed that radiolabeled PSMA agents are the mainstays of the current success, especially in detecting prostate cancer with metastasis and biochemical recurrence.

OBJECTIVE

This review is intended to present a comprehensive overview of the current literature on PSMA ligand-based agents for both radionuclide imaging and therapeutic approaches, with a focus on those that have been clinically adopted.

CONCLUSION

PSMA-based diagnosis and therapy hold great promise for improving the clinical management of prostate cancer.

Evaluation of lymph node status in patients with urothelial carcinoma-still in search of the perfect imaging modality: a systematic review

While accurate lymph node status evaluation in urothelial carcinoma patients is essential for the correct disease staging and, hence, establishing the most beneficial treatment strategy, the diagnostic performance of routine imaging in regards to this issue is not satisfactory. For the purpose of this article, we systematically reviewed the contemporary literature on the sensitivity and specificity of particular imaging modalities which have been studied for detecting lymph node metastases in patients diagnosed with urothelial carcinoma. The evidence reviewed shows that computed tomography (CT), although recognized as the imaging modality of choice, is associated with marked limitations, resulting in its low sensitivity for lymph node involvement detection in urothelial carcinoma patients, with no study reporting a value higher than 46% using standard cut-off values. Markedly higher sensitivity rates may be achieved with magnetic resonance imaging (MRI), especially when using ultrasmall superparamagnetic iron oxide as the contrast agent, however, no uniform protocol has been systematically studied up to date. The vast majority of recent evidence concerns positron emission tomography (PET), which is being reported to improve the diagnostic performance of CT alone, as has been demonstrated in multiple articles, which investigated the accuracy of PET/CT at primary or post-treatment staging of urothelial carcinoma patients. However, there has been substantial heterogeneity in terms of methodology and results between those studies, making it premature to draw any definitive conclusions. The results of this review lead to a conclusion, that while CT, despite being not fully satisfactory, still remains the gold-standard method of imaging for staging purposes in urothelial carcinoma, other imaging modalities are under investigation, with promising results.

68Ga-PSMA-PET: added value and future applications in comparison to the current use of choline-PET and mpMRI in the workup of prostate cancer

Positron emission tomography (PET) has been commonly and successfully used, in combination with computed tomography (CT) and more recently magnetic resonance (MRI), in the workup of intermediate or high-risk prostate cancer (PCa). Nowadays, new specific receptor targeted PET tracers in prostate cancer imaging have been introduced; one of the most used is ⁶⁸Ga-PSMA, that evaluates the expression of prostate-specific membrane antigen (PSMA). This tracer has been rapidly taken into account for its better sensitivity and specificity compared to lipid metabolism tracers, such as ¹¹C/¹⁸F labelled fluorocholine. Besides, in the era of theranostics, this tracer is having a useful application not only for imaging but also for therapeutic purposes. The aim of this review article is, in the first part, to give an overview of the main indications and future development of ⁶⁸Ga-PSMA imaging, using PET/CT or PET/MRI, according to the clinical course of the disease and in view of the current use of multiparametric MRI (mpMRI) and choline PET in the management of PCa. In the second part, a brief overview of the promising ¹⁸F-labelled PSMA tracers and the current use of PSMA radionuclide therapy will be provided.

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

In this prospective survey of referring physicians, we investigated whether and how ⁶⁸Ga-labeled prostate-specific membrane antigen 11 (⁶⁸Ga-PSMA-11) PET/CT affects the implemented management of prostate cancer patients with biochemical recurrence (BCR). Methods: We conducted a prospective survey of physicians (NCT02940262) who referred 161 patients with prostate cancer BCR (median prostate-specific antigen value, 1.7 ng/mL; range, 0.05-202 ng/mL). Referring physicians completed one questionnaire before the scan to indicate the treatment plan without ⁶⁸Ga-PSMA-11 PET/CT information (Q1; n = 101), one immediately after the scan to denote intended management changes (Q2; n = 101), and one 3-6 mo later to document the final implemented management (Q3; n = 56). The implemented management was also obtained via electronic chart review or patient contact (n = 45). Results: A complete documented management strategy (Q1 + Q2 + implemented management) was available for 101 of 161 patients (63%). Seventy-six of these (75%) had a positive ⁶⁸Ga-PSMA-11 PET/CT result. The implemented management differed from the prescan intended management (Q1) in 54 of 101 patients (53%). The postscan intended management (Q2) differed from the prescan intended management (Q1) in 62 of 101 patients (61%); however, these intended changes were not implemented in 29 of 62 patients (47%). Pelvic nodal and extrapelvic metastatic disease on ⁶⁸Ga-PSMA-11 PET/CT (PSMA T0N1M0 and PSMA T0N1M1 patterns) was significantly associated with implemented management changes (P = 0.001 and 0.05). Conclusion: Information from ⁶⁸Ga-PSMA-11 PET/CT brings about management changes in more than 50% of prostate cancer patients with BCR (54/101; 53%). However, intended management changes early after ⁶⁸Ga-PSMA-11 PET/CT frequently differ from implemented management changes.