Comparison of 18F-based PSMA radiotracers with [68Ga]Ga-PSMA-11 in PET/CT imaging of prostate cancer-a systematic review and meta-analysis

Evaluating the Heterogeneity of Advanced Prostate Cancer by 18F-DCFPyL and 18F-FDG PET/CT in a Prospective Cohort

PURPOSE

18F-DCFPyL (targeted PSMA) and 18F-FDG dual-tracer PET/CT combination with next-generation sequencing was applied in a prospective cohort of men with prostate cancer to identify the clinical and genetic characteristics with heterogeneous PET/CT imaging features.

METHODS

104 men with documented prostate cancer underwent 18F-DCFPyL and 18F-FDG PET/CT, of which 83 underwent next-generation sequencing for detecting variation of AR, TP53, RB1, PTEN, etc. Lesions were classified into DCFPyL+FDG± lesions and DCFPyL-FDG+ lesions and analyzed for heterogeneous distribution. We divided the patients with positive lesions into DCFPyL+FDG± group and DCFPyL-FDG+ group, then compared the differences in clinical features and genetic mutations between the two groups with CRPC.

RESULTS

Overall, 92 men had positive lesions detected. By comparing lesion distribution with the DCFPyL+FDG ± , DCFPyL-FDG+ disease had higher proportions of visceral metastases (4.1% vs. 1.0%, p = 0.002). DCFPyL-FDG+ was more frequently found in CRPC cohorts, and in the CRPC cohort, patients with DCFPyL-FDG+ lesions often had worse PSA response. Exploratory analysis showed that TP53 and/or RB1 mutations might be a risk factor for DCFPyL-FDG+ disease (OR = 10.625, 95% CI 3.492-32.332, p < 0.001).

CONCLUSION

Patients with DCFPyL-FDG+ lesions were more likely to have visceral metastases detected, be found in castration-resistant cohorts, have TP53 and/or RB1 mutations detected, and have poor therapeutic response compared to patients with DCFPyL+FDG± lesions. Therefore, dual-tracer (18F-DCFPyL and 18F-FDG) PET/CT is recommended for patients with low PSMA expression incompatible with the true burden of the disease and those with TP53 and/or RB1 mutations to better evaluate the disease burden, tumor heterogeneity, and prognosis.

Impact of intraprostatic PSMA maximum standardised uptake value following prostatectomy: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis to assess the relationship between intraprostatic maximum standardised uptake value (SUVmax) of the dominant prostatic lesion as measured on preoperative prostate-specific membrane antigen (PSMA) positron emission tomography (PET) with radical prostatectomy International Society of Urological Pathology (ISUP) Grade Group, pathological tumour (pT) staging, and biochemical recurrence (BCR).

METHODS

Prostate-specific membrane antigen PET may offer non-invasive assessment of histopathological and oncological outcomes before definitive treatment. SUVmax of the dominant lesion has been explored as a prognostic biomarker. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, we performed reviews of digital libraries and databases and retrieved studies reporting SUVmax quantified on PSMA PET computed tomography or magnetic resonance imaging and subsequent radical prostatectomy ISUP Grade Group, pT stage, and BCR. Quality assessment was performed using Quality Assessment of Diagnostic Accuracy Studies-2 and Prediction model Risk of Bias Assessment tools. Random effects meta-analysis and meta-regression by ISUP Grade Group and pT2 vs pT3/4 stage was performed. This study was registered on the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023408170).

EVIDENCE SYNTHESIS

After removing duplicates, 23 studies were included for review. Pooled SUVmax (95% confidence interval [CI]) increased monotonically with advancing ISUP Grade Group, with ISUP 1: 5.8 (95% CI 3.9-7.7), through to ISUP 5: 17.3 (95% CI 13.1-21.5). For pT2 disease, pooled SUVmax: 9.7 (95% CI 7.8-11.5) increasing to 13.8 (95% CI 10.9-16.7) for pT3/4 disease. Substantial inconsistency was noted (I2 >50%) for all subgroups. This was not attenuated by restricting analysis only to studies using [68Ga]Ga-PSMA-11. Narrative synthesis of six papers reporting BCR showed increasing SUVmax was associated with reduced time to BCR.

CONCLUSION

Preoperative intraprostatic PSMA SUVmax increases monotonically with higher ISUP Grade Group and pathological tumour stage. Higher SUVmax is associated with reduced BCR-free survival. However, the use of single SUVmax thresholds for clinical decision making is not recommended as variability between studies is high.

Impact of PSMA-PET/CT on Radiotherapy Decisions: Is There a Clinical Benefit?

Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT) has emerged as a game-changing imaging modality in prostate cancer, offering superior sensitivity and specificity compared to conventional imaging techniques. Its increasing adoption has significantly influenced radiotherapy decision-making, yet its true clinical impact remains under investigation. This narrative review explores the role of PSMA-PET/CT in guiding radiotherapy decisions across different clinical scenarios, from primary treatment planning to biochemical recurrence and oligometastatic disease. We assess its impact on target delineation, treatment modifications, and overall patient management while addressing existing knowledge gaps.

Diagnostic Capability and Improved Clinical Management of 18F-DCFPyL-PSMA PET/CT in Occult Biochemical Recurrence of Prostate Cancer After Prostatectomy

Biochemical recurrence (BCR) occurs in 20-50% of patients with localized prostate cancer (PC) after radical prostatectomy (RP). Conventional imaging often fails to detect early local or systemic recurrences at low PSA levels. Positron emission tomography/computed tomography (PET/CT) with 18F-DCFPyL PSMA offers improved sensitivity and specificity for detecting recurrent disease. This study evaluates the diagnostic capability of 18F-DCFPyL PET/CT in early BCR of PC following RP and its impact on therapeutic decision-making and clinical management.

METHODS

In a prospective study, 85 patients with BCR (PSA 0.2-2.0 ng/mL) and negative conventional imaging underwent 18F-DCFPyL PET/CT. Detection rates (DRs) were analyzed against clinical variables, including PSA levels and PSA doubling time (DT-PSA). Lesions were classified into local recurrence, lymph node involvement, bone, and visceral disease. Therapeutic decisions were adjusted based on PET/CT findings.

RESULTS

18F-DCFPyL PET/CT identified lesions in 53% of patients, with DRs of 31.3%, 60%, and 77.8% for PSA levels <0.5, 0.5-1, and >1 ng/mL, respectively. DRs were significantly associated with shorter DT-PSAs (<6 months: 61.5%). The lesions detected included 22.2% local recurrences, 51.1% lymph node disease, 20% bone, and 6.7% visceral involvement. ROC analysis determined optimal PSA and DT-PSA cutoffs of 0.55 ng/mL and 9.2 months, respectively. Therapeutic strategies were modified in 84.4% of PET-positive cases.

CONCLUSIONS

18F-DCFPyL PET/CT demonstrates high sensitivity for detecting recurrent PC at low PSA levels, significantly impacting therapeutic decisions and optimizing clinical management. These findings support its integration into guidelines for managing early BCR of PC.

End-to-end [18F]PSMA-1007 PET/CT radiomics-based pipeline for predicting ISUP grade group in prostate cancer

OBJECTIVES

To develop an end-to-end radiomics-based pipeline for the prediction of International Society of Urological Pathology grade group (ISUP GG) in prostate cancer (PCa).

METHODS

This retrospective study includes 356 patients (241 in training set and 115 in independent test set) with histopathologically confirmed PCa who underwent [18F]PSMA-1007 PET/CT scan. Patients were classified into two groups according to their ISUP GG (1-3 vs. 4-5). Radiomics features were extracted from the whole, automatically segmented prostate on PET/CT images, 30 models were constructed by combining 6 feature selection algorithms and 5 machine learning classifiers. The clinical model incorporated age, total prostate-specific antigen (tPSA), maximum standardized uptake value (SUVmax), and prostate volume. The predictive performance of the models was evaluated using the area under the receiver operating characteristic curve (AUC), balanced accuracy (bAcc), and decision curve analysis (DCA).

RESULTS

The best-performing radiomics model significantly outperformed clinical model (AUC 0.879 ± 0.041 vs. 0.799 ± 0.051, bAcc 0.745 ± 0.074 vs. 0.629 ± 0.045). On an external independent test set, best-performing radiomics model perform better than clinical model, with an AUC of 0.861 vs. 0.750, p = 0.002 (Delong), and bAcc of 0.764 vs. 0.582, p = 0.043 (McNemar). The learning curve, calibration curve and DCA demonstrated goodness-of-fit and improved benefits in clinical practice.

CONCLUSION

The end-to-end radiomics-based pipeline is an effective non-invasive tool to predict ISUP GG in PCa.

The Role of 18F PSMA-1007 PET/CT in the Staging and Detection of Recurrence of Prostate Cancer, A Scoping Review

BACKGROUND

To determine and review the currently available literature behind the staging capabilities of 18F-PSMA-1007 PET/CT in the setting of initial staging and detection of recurrent disease for patients with prostate cancer. Prostate cancer (PCa), one of the most diagnosed malignancies affecting adult men worldwide, requires accurate staging and early detection of recurrent disease to guide treatment decisions and improve oncological outcomes. 18F-PSMA-1007 PET/CT is a novel radiotracer with favorable imaging characteristics suggesting an important role within the Prostate Cancer management landscape.

METHODS

The Arksey and O'Malley Framework was used to guide this review. PubMed/MEDLINE, EMBASE, EBSCO, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases were used, and relevant titles were screened for eligibility.

RESULTS

404 database results were returned; 343 titles were excluded due to irrelevance and duplicates. A total of 61 papers were included for title and abstract review with a subsequent 26 excluded due to not meeting the inclusion criteria. A total of 35 papers proceeded to full-text review and 35 papers were included in this review. Evidence was grouped under three major themes: (1) The role of 18F-PSMA-1007 PET/CT in Initial staging; (2) The role of 18F-PSMA-1007 PET/CT in the detection of recurrent Prostate Cancer and (3) The Role of 18F-PSMA-1007 PET/CT in Salvage Therapy. The findings suggest 18F-PSMA-1007 PET/CT has superior diagnostic accuracy and sensitivity for the initial staging of prostate cancer compared with conventional imaging and other commonly used radiotracers. Strengths included the detection of pelvic and locoregional disease. Limitations included poor specificity for the detection of bone lesions, inconsistent urinary excretion patterns, and high inter-reader variability.

CONCLUSIONS

18F-PSMA-1007 PET/CT demonstrates superior diagnostic accuracy and sensitivity in both initial staging and detection of prostate cancer recurrence; however, it is limited by poor specificity for bone lesions and inconsistent urinary excretion patterns. Prospective multicenter trials are required to clearly delineate its role in the initial staging of prostate cancer and detection of recurrent disease.

Prospective Head-to-Head Comparison of 18F-PSMA PET/CT and 18F-NaF PET/CT for Assessing Bone Metastases in 160 Patients with Newly Diagnosed High-Risk Prostate Cancer

Prostate-specific membrane antigen (PSMA) PET/CT is increasingly used for primary staging in prostate cancer (PC), mainly because of its improved accuracy in detecting lymph node metastases compared with conventional imaging. However, the diagnostic benefit of PSMA PET/CT for detecting bone metastases is less well established. This study compares the diagnostic accuracy of 18F-PSMA PET/CT and 18F-NaF PET/CT for detecting bone metastases in patients newly diagnosed with PC. Methods: This prospective study included patients with histologically confirmed high-risk PC. All participants were referred from the department of urology to 18F-NaF PET/CT and underwent 18F-PSMA PET/CT within 3 weeks. Images were reviewed by 2 nuclear medicine physicians unaware of the results of the other imaging modality. Presence or absence of bone metastases and number of metastatic lesions were recorded. A reference standard was established at the patient level based on agreement between the 2 imaging modalities. In cases of concordance, both modalities were deemed correct. In cases of discordance, additional follow-up scans were performed. Diagnostic performance metrics, including sensitivity, specificity, and accuracy, were calculated. Results: In total, 160 participants were included. Sensitivity, specificity, and accuracy for detecting bone metastases at the patient level were 0.98, 0.99, and 0.99, respectively, for 18F-PSMA PET/CT, and 0.91, 1.00, and 0.97, respectively, for 18F-NaF PET/CT. No significant differences were found. The concordance rate of bone metastases between 18F-NaF and 18F-PSMA PET/CT at the patient level was observed in 154 patients (96.3%). 18F-PSMA PET/CT tended to identify more bone metastases per patient than 18F-NaF PET/CT. Conclusion: Both 18F-NaF and 18F-PSMA PET/CT exhibit high diagnostic accuracy for detecting bone metastases in newly diagnosed high-risk PC patients. 18F-PSMA PET/CT may detect additional metastatic lesions compared with 18F-NaF PET/CT. Subsequent 18F-NaF PET/CT may be redundant if no bone metastases are found on 18F-PSMA PET/CT.

Do you know your PSMA-tracer? Variability in the biodistribution of different PSMA ligands and its potential impact on defining PSMA-positivity prior to PSMA-targeted therapy

BACKGROUND

In clinical practice, several radiopharmaceuticals are used for PSMA-PET imaging, each with distinct biodistribution patterns. This may impact treatment decisions and outcomes, as eligibility for PSMA-directed radioligand therapy is usually assessed by comparing tumoral uptake to normal liver uptake as a reference. In this study, we aimed to compare tracer uptake intraindividually in various reference regions including liver, parotid gland and spleen as well as the respective tumor-to-background ratios (TBR) of different 18F-labeled PSMA ligands to today's standard radiopharmaceutical 68Ga-PSMA-11 in a series of patients with biochemical recurrence of prostate cancer who underwent a dual PSMA-PET examination as part of an individualized diagnostic approach.

RESULTS

Differences in background activity among different PSMA-PET tracers lead to variations in tumor-to-background ratios (TBR). In [18F]F-DCFPyL-PET, TBR with the liver as the reference organ (TBRliver) was comparable to [68Ga]Ga-PSMA-11-PET, while [18F]F-PSMA-1007-PET and [18F]F-JK-PSMA-7-PET showed significantly lower values. Using the parotid gland as the reference (TBRparotidgland), [18F]F-DCFPyL-PET exhibited significantly higher values, whereas [18F]F-PSMA-1007-PET and [18F]F-JK-PSMA-7-PET were comparable. For the spleen (TBRspleen), [18F]F-JK-PSMA-7-PET was comparable, but [18F]F-DCFPyL-PET and [18F]F-PSMA-1007-PET showed significantly higher and lower values, respectively. An additional Bland-Altman analyses revealed low bias for [18F]F-DCFPyL-PET in TBRparotidgland, whereas significant differences in TBRliver and TBRspleen for the other tracers resulted in higher bias.

CONCLUSION

Different PSMA-PET tracers exhibit distinct biodistribution patterns, leading to variations in tumor-to-background ratios (TBR) in reference organs such as the liver, parotid gland, and spleen. Patient selection for PSMA-directed radioligand therapy is currently based on a semiquantitative approach using the liver as a reference region in [68Ga]Ga-PSMA-11-PET. Thus, the use of alternative [18F]-labeled tracers may result in under- or overestimation of a patient's suitability for therapy. This highlights the importance of a comprehensive understanding of the differences in tracer-specific uptake behavior for accurate decisions regarding PSMA-expression levels. However, as the patient cohort in this study is at earlier disease stages, the generalizability of these findings to later-stage patients remains unclear and requires further investigation.

Evaluating the Added Value of Concurrent Contrast-enhanced Diagnostic CT for PSMA-PET/CT Interpretation

RATIONALE AND OBJECTIVES

To determine whether concurrent contrast-enhanced diagnostic CT (DxCT) confers added diagnostic certainty compared to PSMA-PET/CT alone.

MATERIALS AND METHODS

This retrospective multi-reader study analyzed imaging comprising combined F-18-piflufolastat PSMA-PET/CT with diagnostic chest/abdominopelvic CT from prostate cancer patients within the first 6 months of FDA-approval of the PET agent. Six nuclear radiology readers were randomly presented with PSMA-PET/CT studies with or without DxCT and asked to report their diagnostic certainty for PSMA-avid lesions found on PET. Subsequently, readers re-reviewed the same study after an interlude (with the CT if not previously presented and vice-versa) to determine if DxCT altered their diagnostic assessment. Inter-rater concordance was assessed on a subset of images read by all readers. Diagnostic certainties for PSMA-PET/CT with and without DxCT were compared, and the variables for which DxCT may add value were examined.

RESULTS

Good inter-rater concordance across readers was noted for both PET/CT (Finn's coefficient of reliability for overall scan certainty: 0.85,p < 0.01) and combined DxCT-PET/CT (0.59,p < 0.01). Overall certainty and concordance between PET/CT and combined DxCT-PET/CT datasets were similar (overall scan certainty: 92% ± 16 vs. 92% ± 17,p = 0.43), with no significant advantage for adding DxCT across different anatomic locations or clinical parameters. A slight predilection for combined DxCT-PET/CT was noted when interpreting images acquired for the initial staging of prostate cancer (89% ± 16 vs. 93% ± 17,p = 0.08).

CONCLUSION

Good inter-reader concordance can be achieved across different training levels with PSMA-PET/CT. Furthermore, using DxCT concurrent with PSMA-PET/CT does not significantly improve diagnostic certainty for most indications but may be useful for initial staging.

Current Clinical Applications of PSMA-PET for Prostate Cancer Diagnosis, Staging, and Treatment

Over the past decade, prostate-specific membrane antigen positron emission tomography (PSMA-PET) has revolutionized prostate cancer (PCa) imaging, offering greater sensitivity and specificity compared to conventional imaging modalities such as CT, MRI, and bone scintigraphy. PSMA-PET is particularly valuable in staging newly diagnosed patients with intermediate- and high-risk disease, detecting biochemical recurrence, and evaluating metastatic cases. By utilizing radiotracers that accumulate specifically in PSMA-expressing cells, even small metastases can be detected, offering a detailed assessment of cancer extent and enabling more targeted diagnostic evaluations. Among the most utilized radiotracers, [68Ga]- and [18F]-labeled PSMA tracers enable precise imaging even with low disease burden. This diagnostic precision also supports advanced therapeutic approaches, including metastasis-directed therapy for oligometastatic cases and systemic treatment options, such as radioligand therapy, which presents new treatment perspectives for metastatic, castration-resistant PCa. This review examines the evolution of PSMA-PET in the diagnostics and therapy of PCa while comparing the current recommendations from leading clinical guidelines. The integration of PSMA-PET into clinical practice has redefined the management of PCa, improving diagnostic accuracy and enabling personalized treatment strategies, while lacking prospective long-term outcome data. As PSMA-PET continues to expand in clinical application, this review highlights its significant advancements while critically addressing limitations to ensure balanced and evidence-based implementation in prostate cancer care.

PSMA-RADS to improve evaluation and management of prostate cancer

Prostate-Specific Membrane Antigen (PSMA) positron emission tomography (PET) / computed tomography (CT) has become essential in managing prostate cancer, offering superior diagnostic accuracy. The introduction of the U.S. Food and Drug Administration (FDA)-approved theranostic agent (177Lutetium-PSMA-617) has further enhanced the significance of PSMA PET/CT imaging. Despite its benefits, PSMA-PET/CT is not without challenges, as PSMA expression is not exclusive to prostate cancer cells. Therefore, standardized interpretation criteria are necessary for consistent and reliable communication among physicians. The PSMA- reporting and data system (RADS) provides a structured approach for assessing PSMA-PET/CT scans. Updated in 2023, PSMA-RADS 2.0 addresses previous limitations and introduces a new category, PSMA-RADS 5T, for treated metastases. This system categorizes lesions based on their likelihood of prostate cancer involvement, improving longitudinal monitoring and guiding management strategies. By familiarizing radiologists with PSMA-RADS through case-based reviews, this primer aims to enhance diagnostic accuracy and treatment planning for patients with prostate cancer.

The association of quantitative PSMA PET parameters with pathologic ISUP grade: an international multicenter analysis

PURPOSE

To assess if PSMA PET quantitative parameters are associated with pathologic ISUP grade group (GG) and upgrading/downgrading.

METHODS

PCa patients undergoing radical prostatectomy with or without pelvic lymph node dissection staged with preoperative PSMA PET at seven referral centres worldwide were evaluated. PSMA PET parameters which included SUVmax, PSMAvolume, and total PSMA accumulation (PSMAtotal) were collected. Multivariable logistic regression evaluated the association between PSMA PET quantified parameters and surgical ISUP GG. Decision-tree analysis was performed to identify discriminative thresholds for all three parameters related to the five ISUP GGs The ROC-derived AUC was used to determine whether the inclusion of PSMA quantified parameters improved the ability of multivariable models to predict ISUP GG ≥ 4.

RESULTS

A total of 605 patients were included. Overall, 2%, 37%, 37%, 10% and 13% patients had pathologic ISUP GG1, 2, 3, 4, and 5, respectively. At multivariable analyses, all three parameters SUVmax, PSMAvolume and PSMAtotal were associated with GG ≥ 4 at surgical pathology after accounting for PSA and clinical T stage based on DRE, hospital and radioligand (all p < 0.05). Addition of all three parameters significantly improved the discrimination of clinical models in predicting GG ≥ 4 from 68% (95%CI 63 - 74) to 74% (95%CI 69 - 79) for SUVmax, 72% (95%CI 67 - 76) for PSMAvolume, 74% (70 - 79) for PSMAtotal and 75% (95%CI 71 - 80) when all parameters were included (all p < 0.05). Decision-tree analysis resulted in thresholds that discriminate between GG (SUVmax 0-6.5, 6.5-15, 15-28, > 28, PSMAvol 0-2, 2-9, 9-20 and > 20 and PSMAtotal 0-12, 12-98 and > 98). PSMAvolume was significantly associated with GG upgrading (OR 1.03 95%CI 1.01 - 1.05). In patients with biopsy GG1-3, PSMAvolume ≥ 2 was significantly associated with higher odds for upgrading to ISUP GG ≥ 4, compared to PSMAvolume < 2 (OR 6.36, 95%CI 1.47 - 27.6).

CONCLUSION

Quantitative PSMA PET parameters are associated with surgical ISUP GG and upgrading. We propose clinically relevant thresholds of these parameters which can improve in PCa risk stratification in daily clinical practice.

Update on PSMA-based Prostate Cancer Imaging

The increased use of prostate-specific membrane antigen (PSMA) based PET imaging for prostate cancer (Pca) detection has revolutionized the clinical management of Pca, with higher diagnostic sensitivity for extraprostatic disease and increasing clinical utility across different stages of the disease. The integration of PSMA PET imaging into clinical guidelines and consensus documents reflects its growing importance in the personalized management of Pca. This review of recent literature highlights the rapid evolution of PSMA PET into the mainstream of staging and restaging and the decreasing reliance on conventional imaging modalities. This comprehensive review serves as a resource for clinicians and researchers involved in the domains of Pca diagnosis and management.

Biology-guided radiotherapy in metastatic prostate cancer: time to push the envelope?

The therapeutic landscape of metastatic prostate cancer has undergone a profound revolution in recent years. In addition to the introduction of novel molecules in the clinics, the field has witnessed a tremendous development of functional imaging modalities adding new biological insights which can ultimately inform tailored treatment strategies, including local therapies. The evolution and rise of Stereotactic Body Radiotherapy (SBRT) have been particularly notable in patients with oligometastatic disease, where it has been demonstrated to be a safe and effective treatment strategy yielding favorable results in terms of disease control and improved oncological outcomes. The possibility of debulking all sites of disease, matched with the ambition of potentially extending this treatment paradigm to polymetastatic patients in the not-too-distant future, makes Biology-guided Radiotherapy (BgRT) an attractive paradigm which can be used in conjunction with systemic therapy in the management of patients with metastatic prostate cancer.

Imaging and therapy in prostate cancer using prostate specific membrane antigen radioligands

Prostate specific membrane antigen (PSMA) directed PET imaging has rapidly transformed prostate cancer workup over the past decade and paved the way for a theranostic approach using 177Lu-labelled PSMA radioligand therapy (RLT). This review gives an overview of the underlying principles behind PSMA as a target; the current use of PSMA PET in prostate cancer imaging and benefits compared to conventional imaging; and therapeutic applications including optimisation of patient selection. It also explores the evidence base of PSMA PET for other indications not in routine clinical use and the future of PSMA-directed RLT.

Advances in PSMA Alpha Theragnostics

Alpha theranostics offer an attractive alternative form of therapy, which has best been investigated and documented with 225Ac-PSMA in patients with prostate cancer. Advantages offered by targeted alpha therapy include overcoming radiation resistance, oxygen independence, effecting double-stranded DNA breakages within the tumors with anticipated improved clinical outcomes and an acceptable side effect profile. The previous Seminars article on this topic, published in 2020, had to rely mostly on published case reports and small observational studies. In the last few years, however, several meta-analyses have emerged that evaluate the safety and efficacy of 225Ac-PSMA in prostate cancer patients, followed most recently by a multi-center retrospective study initiated by WARMTH. The findings of these publications, together with the exploration of TAT offered in clinical conditions other than as a last resort, is the focus of this updated overview. Unresolved clinical issues that remain, include the appropriate selection of patients that would benefit most from treatment with 225Ac-PSMA, treatment timing within the disease landscape, optimal dosing schedule, dosimetry, when and how to best use combination therapies and minimization and treatment of side effects, particularly that of xerostomia.

[68Ga]PSMA-11 for positron emission tomography (PET) imaging of prostate-specific membrane antigen (PSMA)-positive lesions in men with prostate cancer

INTRODUCTION

Theranostics targeting prostate-specific membrane antigen (PSMA) represent a new targeted approach for prostate cancer care that combines diagnostic and therapeutic radiopharmaceuticals to diagnose and treat the disease. Positron emission tomography (PET) is the imaging method of choice and several diagnostic radiopharmaceuticals for quantifying PSMA have received FDA approval and are in clinical use. [68Ga]Ga-PSMA-11 is one such imaging agent and the focus of this article. One beta-emitting radioligand therapy ([177Lu]Lu-PSMA-617) has also received FDA approval for prostate cancer treatment, and several other alpha- and beta-emitting radioligand therapies are in clinical trials.

AREAS COVERED

Theranostics targeting PSMA in men with prostate cancer are discussed with a focus on use of [68Ga]Ga-PSMA-11 for imaging PSMA-positive lesions in men with prostate cancer. The review covers [68Ga]Ga-PSMA-11 manufacture, current regulatory status, comparison of [68Ga]Ga-PSMA-11 to other imaging techniques, clinical updates, and emerging applications of artificial intelligence for [68Ga]Ga-PSMA-11 PET.

EXPERT OPINION

[68Ga]Ga-PSMA-11 is used in conjunction with a PET/CT scan to image PSMA positive lesions in men with prostate cancer. It is manufactured by chelating precursor with68Ga, either from a generator or cyclotron, and has regulatory approval around the world. It is widely used clinically in conjunction with radioligand therapies like [177Lu]Lu-PSMA-617.

Prostate cancer brain metastases: Monitoring response to treatment with PSMA PET/CT

Prostate cancer brain metastases are rare but increasingly recognized with prostate-specific membrane antigen (PSMA) PET/CT. Distinguishing tumor response from postradiation changes are challenging on MRI. PSMA PET/CT may clarify equivocal brain lesions after radiotherapy. A 71-year-old man with metastatic prostate cancer developed 2 new brain lesions on PSMA PET/CT. Lesions were high PSMA-avid and MRI follow up showed enhancing masses with edema, consistent with metastases. He underwent whole-brain radiation. Follow-up PSMA PET/CT after radiotherapy demonstrated significantly decreased lesion size and activity, with activity lower than blood pool, indicating a treatment response. MRI also showed near-resolution of the lesions. This case highlights the potential utility of PSMA PET/CT for detecting prostate cancer brain metastases and monitoring treatment response. PSMA PET/CT provides valuable complementary information to MRI for managing irradiated prostate cancer brain metastases.

Clinical Positron Emission Tomography/Computed Tomography: Quarter-Century Transformation of Prostate Cancer Molecular Imaging

Although positron emission tomography/computed tomography (PET/CT) underwent rapid growth during the last quarter-century, becoming a new standard-of-care for imaging most cancer types, CT and bone scan remained the gold standard for patients with prostate cancer. This occurred as 2-fluorine-18-fluoro-2-deoxy-d-glucose was perceived to have a limited role owing to low sensitivity in many patients. A resurgence of interest occurred with the use of fluorine-18-sodium-fluoride PET/CT as a replacement for bone scintigraphy, and then choline, fluciclovine, and dihydrotestosterone (DHT) PET/CT as prostate "specific" radiotracers. The last decade, however, has seen a true revolution with the meteoric rise of prostate-specific membrane antigen PET/CT.

The Current Landscape of Prostate-Specific Membrane Antigen (PSMA) Imaging Biomarkers for Aggressive Prostate Cancer

The review examines the vital role of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) in the diagnosis, staging, and treatment of prostate cancer (PCa). It focuses on the superior diagnostic abilities of PSMA PET/CT for identifying both nodal and distant PCa, and its potential as a prognostic indicator for biochemical recurrence and overall survival. Additionally, we focused on the variability of PSMA's expression and its impact on personalised treatment, particularly the use of [177Lu] Lu-PSMA-617 radioligand therapy. This review emphasises the essential role of PSMA PET/CT in enhancing treatment approaches, improving patient outcomes, and reducing unnecessary interventions, positioning it as a key element in personalised PCa management.

Molecular Mechanisms of Prostate Cancer Development in the Precision Medicine Era: A Comprehensive Review

The progression of prostate cancer (PCa) relies on the activation of the androgen receptor (AR) by androgens. Despite efforts to block this pathway through androgen deprivation therapy, resistance can occur through several mechanisms, including the abnormal activation of AR, resulting in castration-resistant PCa following the introduction of treatment. Mutations, amplifications, and splicing variants in AR-related genes have garnered attention in this regard. Furthermore, recent large-scale next-generation sequencing analysis has revealed the critical roles of AR and AR-related genes, as well as the DNA repair, PI3K, and cell cycle pathways, in the onset and progression of PCa. Moreover, research on epigenomics and microRNA has increasingly become popular; however, it has not translated into the development of effective therapeutic strategies. Additionally, treatments targeting homologous recombination repair mutations and the PI3K/Akt pathway have been developed and are increasingly accessible, and multiple clinical trials have investigated the efficacy of immune checkpoint inhibitors. In this comprehensive review, we outline the status of PCa research in genomics and briefly explore potential future developments in the field of epigenetic modifications and microRNAs.

A Systematic Review on Artificial Intelligence Evaluating Metastatic Prostatic Cancer and Lymph Nodes on PSMA PET Scans

Early detection of metastatic prostate cancer (mPCa) is crucial. Whilst the prostate-specific membrane antigen (PSMA) PET scan has high diagnostic accuracy, it suffers from inter-reader variability, and the time-consuming reporting process. This systematic review was registered on PROSPERO (ID CRD42023456044) and aims to evaluate AI's ability to enhance reporting, diagnostics, and predictive capabilities for mPCa on PSMA PET scans. Inclusion criteria covered studies using AI to evaluate mPCa on PSMA PET, excluding non-PSMA tracers. A search was conducted on Medline, Embase, and Scopus from inception to July 2023. After screening 249 studies, 11 remained eligible for inclusion. Due to the heterogeneity of studies, meta-analysis was precluded. The prediction model risk of bias assessment tool (PROBAST) indicated a low overall risk of bias in ten studies, though only one incorporated clinical parameters (such as age, and Gleason score). AI demonstrated a high accuracy (98%) in identifying lymph node involvement and metastatic disease, albeit with sensitivity variation (62-97%). Advantages included distinguishing bone lesions, estimating tumour burden, predicting treatment response, and automating tasks accurately. In conclusion, AI showcases promising capabilities in enhancing the diagnostic potential of PSMA PET scans for mPCa, addressing current limitations in efficiency and variability.

A Systematic Review on Prostate-Specific Membrane Antigen Positron Emission Tomography (PSMA PET) Evaluating Localized Low- to Intermediate-Risk Prostate Cancer: A Tool to Improve Risk Stratification for Active Surveillance?

Active surveillance remains a treatment option for low- to intermediate-risk prostate cancer (PCa) patients. Prostate-specific membrane antigen positron emission tomography and computed tomography (PSMA PET/CT) has emerged as a useful modality to assess intraprostatic lesions. This systematic review aims to evaluate PSMA PET/CT in localized low- to intermediate-risk PCa to determine its role in active surveillance. Following PRISMA guidelines, a search was performed on Medline, Embase, and Scopus. Only studies evaluating PSMA PET/CT in localized low- to intermediate-risk PCa were included. Studies were excluded if patients received previous treatment, or if they included high-risk PCa. The search yielded 335 articles, of which only four publications were suitable for inclusion. One prospective study demonstrated that PSMA PET/CT-targeted biopsy has superior diagnostic accuracy when compared to mpMRI. One prospective and one retrospective study demonstrated MRI occult lesions in 12.3-29% of patients, of which up to 10% may harbor underlying unfavorable pathology. The last retrospective study demonstrated the ability of PSMA PET/CT to predict the volume of Gleason pattern 4 disease. Early evidence demonstrated the utility of PSMA PET/CT as a tool in making AS safer by detecting MRI occult lesions and patients at risk of upgrading of disease.

The quantitative impact of prostate-specific membrane antigen (PSMA) PET/CT staging in newly diagnosed metastatic prostate cancer and treatment-decision implications

Objectives

To quantify the stage-shift with prostate-specific membrane antigen (PSMA) PET/CT imaging in metastatic prostate cancer and explore treatment implications.

Methods

Single-centre, retrospective analysis of patients with newly diagnosed [18F]PSMA-1007 or [68Ga]Ga-PSMA-11 PET/CT-detected metastatic prostate cancer who had baseline bone scintigraphy between January 2015 and May 2021. Patients were subclassified into oligometastatic and polymetastatic disease utilizing the STAMPEDE2 trial (ISRCTN66357938/NCT06320067) definition. Patient, tumour, and treatment characteristics were collected. PSMA PET/CT concordance with conventional imaging (bone scintigraphy and low-dose CT of PET) was identified by number and site of metastases, and subgroup assigned. Spearman's rank correlation and linear regression modelling determined the association between the imaging modalities.

Results

We analysed 62 patients with a median age was 72 years (range 48-86). On PSMA PET/CT, 31/62 (50%) patients had oligometastatic disease, and 31/62 (50%) had polymetastatic disease. Prostate radiotherapy was delivered in 20/31 (65%) patients with oligometastatic disease and 17/31 (55%) with polymetastatic disease. 23/62 (37%) patients were reclassified as M0 on conventional imaging. PSMA PET/CT had a 2.9-fold increase in detecting bone metastases. Bone metastases concordance was found in 10/50 (20%) by number and 30/33 (91%) by site. PSMA PET/CT had a 2.2-fold increase in detecting nodal metastases. Nodal metastases concordance was found in 5/46 (11%) by number and 25/26 (96%) by site. There was significant positive correlation between PSMA PET/CT and conventional imaging for detecting bone [R 2 = 0.25 (P < 0.001)] and nodal metastases [R 2 = 0.19 (P < 0.001)]. 16/31 (52%) had oligometastatic disease concordance.

Conclusion

The magnitude of PSMA PET/CT-driven stage-shift is highly variable and unpredictable with implications on treatment decisions, future trial design, and potentially clinical outcomes.

Advances in knowledge

The magnitude of "frame-shift" with PSMA PET/CT imaging is highly variable and unpredictable which may unreliably change treatment decisions dependent on image-defined disease extent. Prospective randomized trials are required to determine the relationship between PSMA PET/CT-guided treatment choices and outcomes.