Clinical Trial Protocol for PRIMARY2: A Multicentre, Phase 3, Randomised Controlled Trial Investigating the Additive Diagnostic Value of [68Ga]Ga-PSMA-11 Positron Emission Tomography/Computed Tomography in Men with Negative or Equivocal Multiparametric Magnetic Resonance Imaging for the Diagnosis of Clinically Significant Prostate Cancer

A Comprehensive Systematic Review and Meta-analysis of the Role of Prostate-specific Membrane Antigen Positron Emission Tomography for Prostate Cancer Diagnosis and Primary Staging before Definitive Treatment

BACKGROUND AND OBJECTIVE

Positron emission tomography (PET) with prostate-specific membrane antigen (PSMA) in the diagnosis and primary staging of patients with prostate cancer (PCa) has an established role, but recent summative evidence on its actual diagnostic and staging value is still missing. We aimed to collect and analyze published studies reporting the accuracy of PSMA PET for the diagnosis of clinically significant prostate cancer (csPCa) and detection of distant metastases at primary staging before definitive treatment.

METHODS

We performed a systematic review of the literature, by searching the PubMed/MEDLINE, Cochrane library's CENTRAL, EMBASE, and Scopus databases, from inception to April 2024. Two coprimary outcomes were assessed: first, to evaluate the sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of PSMA PET in detecting intraprostatic csPCa on a per-patient level, and second, to assess the positivity rates of metastatic disease in the primary staging, prior to definitive therapy. As a secondary outcome, the diagnostic accuracy of PET PSMA for the detection of lymph nodal invasion (LNI) was tested in a per-patient-level analysis of studies where pelvic lymph node dissection (PLND) was available as the reference standard. Positivity and detection rates were pooled using random-effect models. Preplanned subgroup analyses tested the diagnostic accuracy of PET PSMA across different study cohorts. Variation in PPV and NPV over csPCa and LNI prevalence was evaluated.

KEY FINDINGS AND LIMITATIONS

In total, 12 and 99 studies, with a total of 1533 and 18 649 participants, respectively, were included in the quantitative synthesis for intraprostatic diagnosis and staging. For intraprostatic disease, the sensitivity, specificity, PPV, and NPV of PSMA PET for csPCa were 82% (95% confidence interval [CI] 73-90%), 67% (95% CI 46-85%), 77% (95% CI 63-88%), and 73% (95% CI 56-87%), respectively. At a bivariate analysis, the diagnostic accuracy of PSMA PET estimated through a summary receiver operating characteristic curve-derived area under the curve was 84%, increasing up to 88% when combined with magnetic resonance imaging (MRI). On staging level, PSMA PET results were positive outside the prostate in 23% of the patients, with substantial variation in positivity rates between high-risk (31%) and intermediate-risk (12%) subcohorts. When using PLND as the reference standard (51 studies, 7713 patients), the sensitivity, specificity, PPV, and NPV of PSMA PET were, respectively, 54%, 94%, 77%, and 86%. With higher csPCa and LNI prevalence, a similar increase in PPV and a decrease in NPV were observed.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The current updated systematic review and meta-analysis provides updated evidence on the diagnostic and staging accuracy of PSMA PET in PCa. We reported good accuracy of PSMA PET to discriminate csPCa, particularly when added to MRI, but NPV alone is insufficient to omit a biopsy. Regarding staging, PSMA PET cannot be used alone to determine the need for lymph node dissection (LND) and should be combined with additional clinical information within predictive tools. As such, further research should develop and validate models that incorporate PSMA PET to reliably inform biopsy or LND.

PSMA-Targeted Biopsy With Fusion Guidance for Detecting Clinically Significant Prostate Cancer in Men With Negative MRI-Feasibility and Diagnostic Performance of a Pilot Single-Center Prospective Study

INTRODUCTION

Contemporary prostate biopsy utilizes multiparametric magnetic resonance (MRI) guidance; however, it may fail to identify a non-negligible proportion of men with clinically significant (csPCa). The main objective of this study was to assess the feasibility and diagnostic performance of Prostate Specific Membrane Antigen-Target biopsy (PSMA-TB) to diagnose csPCa in men with negative MRI and high clinical risk of PCa.

PATIENTS AND METHODS

Open-label, single-center, nonrandomized, prospective study.

INCLUSION CRITERIA

PSA density (PSAd) ≥0.2 ng/ml2 in men with PIRADS 1-2; PSA >10 ng/ml or abnormal digital rectal examination or strong familiar history for PCa or known genetic mutation. Each patients underwent PSMA-PET and transperineal fusion PSMA-TB ± systematic biopsy (SB).

RESULTS

Overall, 35 patients were enrolled; 23 (65.7%) men had positive PSMA-PET (PRIMARY score ≥3). Overall, 14 (40%) men had csPCA and 21 (60%) patients had any PCa at PSMA-TB+SB. Only 1 patient (8.3%) with negative PSMA-PET had csPCa (ISUP 3) at SB (92% Negative Predictive Value [NPV]). Fusion PSMA-TB alone detected csPCa in 12 out of 23 (52.2%) patients with positive PSMA-PET; fusion PSMA-TB with concomitant SB increased the detection of csPCa to 56.5% (added value of 4.3%). The sensitivity, specificity, Positive Predictive Value (PPV), NPV and AUC of PSMA-TB+SB were 93%, 57%, 59%, 92% and 0.75 for detection of csPCa and 91%, 79%, 86%, 95% and 0.84 for detection of any PCa, respectively. The main limitation of this study is its small sample size.

CONCLUSIONS

Fusion PSMA-TB is technically feasible and may improve the detection of csPCa in patients with negative MRI.

A Vision for Gastrin-Releasing Peptide Receptor Targeting for Imaging and Therapy: Perspective from Academia and Industry

The gastrin-releasing peptide receptor (GRPR) is overexpressed in various cancers, including prostate cancer, breast cancer, small cell and non-small cell lung cancer, uterine and ovarian cancer, colon cancer, and gastrointestinal stromal tumors. This makes GRPR a multicancer target for theranostics, that is, molecular imaging and therapy. Here, we explore the current state of GRPR-targeted theranostics from bench to bedside, highlighting the preclinical development of various GRPR-targeting compounds and clinical applications. We review the role of GRPR-targeted molecular imaging for all stages of prostate cancer, breast cancer, and other tumors and provide a quo vadis GRPR. We aimed to offer a comprehensive overview of GRPR-targeted theranostics to inform researchers, clinicians, pharma, and regulators of the potential benefits and emerging opportunities in the pursuit of personalized precision cancer care.

Exploring the value of multiparametric quantitative magnetic resonance imaging in avoiding unnecessary biopsy in patients with PI-RADS 3-4

PURPOSE

To validate the performance of three multiparametric quantitative sequences, including amide proton transfer-weighted (APTw) MRI, diffusion kurtosis imaging (DKI) and apparent diffusion coefficient (ADC), in the enhancement of biopsy decision-making in patients with Prostate Imaging-Reporting and Data System (PI-RADS) core of 3-4.

MATERIALS AND METHODS

A total of 96 participants who scored as PI-RADS 3-4 according to PI-RADS v2.1 and pathologically confirmed were enrolled. The mean of APT, ADC, mean diffusivity (MD) and mean kurtosis (MK) values were acquired by two radiologists and a senior radiologist. The univariate and multivariate logistic regression analyses were performed for parameters selection. Receiver operating characteristic (ROC) analysis was employed to assess the performance of models. The Delong test was applied to compare the area under the ROC curves (AUCs) between models. The proportion of unnecessary biopsies avoided (specificity) and csPCa missed (1-sensitivity) were calculated for each model.

RESULTS

In this PI-RADS 3-4 cohort, the AUCs for the diagnosis of csPCa were 0.730 (95%CI: 0.626, 0.834), 0.682(95%CI: 0.562, 0.802), 0.610(95%CI: 0.482, 0.739) and 0.706(95%CI: 0.593, 0.819) for APT, MD, MK and ADC values, respectively. The combined model yielded the significantly higher AUC of 0.851 (95%CI: 0.767, 0.934) (P < 0.05), and achieved a best trade-off between missing csPCa and avoiding unnecessary biopsy than other models (Youden = 0.615).

CONCLUSION

A novel diagnostic model incorporating APTw-MRI, DKI and ADC has been shown to provide incremental diagnostic value in stratifying biopsy necessity for patients with PI-RADS 3-4 lesions.

Real-time diagnosis of sampled lesions in targeted biopsy of prostate Cancer using a novel tracer [64Cu] Cu-DOTA-PSMA-3Q: a pilot preclinical study

PURPOSE

Prostate-specific membrane antigen positron emission tomography (PSMA-PET) guided targeted biopsy has shown potential for detecting more prostate cancer (PCa) cases. However, relying exclusively on imaging may risk missing lesions, an issue that could be addressed by incorporating radiation-guided technology. Accordingly, we aimed to develop a novel PSMA radiotracer with a long half-life, [64Cu]Cu-DOTA-PSMA-3Q, and evaluate its targeting accuracy. Additionally, this research explored the practicability of real-time lesion verification during surgical interventions.

METHODS

In this study, we synthesized the radiotracer [64Cu]Cu-DOTA-PSMA-3Q and verified its PSMA specificity and safety. We prospectively enrolled 18 patients with suspected PCa for PET/CT imaging to assess the efficacy of PCa detection; 10 patients underwent targeted biopsy combined with standard template biopsy at an interval of 24 h after injection. The radioactivity of the biopsy tissue was quantified in counts per minute (CPM) using a gamma spectrometer intraoperatively.

RESULTS

The efficacy and specificity of [64Cu]Cu-DOTA-PSMA-3Q were confirmed through preclinical cell and animal studies. In clinical settings, PET/CT imaging performed 2 h after injection visualized all of the PSMA-positive lesions both within and outside the prostate. The assessment of human organ radiation exposure indicated that the kidneys received the highest absorbed dose, followed by the bladder wall, salivary glands, and liver. In 10 patients, a total of 132 biopsy cores were extracted, with 53 cores histologically confirmed as PCa. The median CPM for PCa tissues was significantly greater at 134,148 CPM compared to 18,39 CPM for normal prostate tissues (P < 0.001). Receiver operating characteristic (ROC) curve analysis yielded an AUC of 0.8837, suggesting high diagnostic accuracy. The optimal diagnostic cut-off was established at 66 CPM, achieving a sensitivity of 77.36%.

CONCLUSIONS

Radiation-guided technology using [64Cu]Cu-DOTA-PSMA-3Q improves the reliability of PSMA-PET image-guided biopsy, enables instant confirmation of sample lesions during surgical procedures, and holds potential for achieving optimized puncture outcomes.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2300072655, Registered 20 June 2023.

Using a novel PSMA-PET and PSA-based model to enhance the diagnostic accuracy for clinically significant prostate cancer and avoid unnecessary biopsy in men with PI-RADS ≤ 3 MRI

INTRODUCTION

The diagnostic evaluation of men with suspected prostate cancer (PCa) yet inconclusive MRI (PI-RADS ≤ 3) presents a common clinical challenge. [68Ga]Ga-labelled prostate-specific membrane antigen ([68Ga]Ga-PSMA) positron emission tomography/computed tomography (PET/CT) has shown promise in identifying clinically significant PCa (csPCa). We aim to establish a diagnostic model incorporating PSMA-PET to enhance the diagnostic process of csPCa in PI-RADS ≤ 3 men.

MATERIALS AND METHODS

This study retrospective included 151 men with clinical suspicion of PCa and PI-RADS ≤ 3 MRI. All men underwent [68Ga]Ga-PSMA PET/CT scans and ultrasound/MRI/PET fusion-guided biopsies. csPCa was defined as Grade Group ≥ 2. PRIMARY-scores from PSMA-PET scans were evaluated. A diagnostic model incorporating PSMA-PET and prostate-specific antigen (PSA)-derived parameters was developed. The discriminative performance and clinical utility were compared with conventional methods. Internal validation was conducted using a fivefold cross-validation with 1000 iterations.

RESULTS

In this PI-RADS ≤ 3 cohort, areas-under-the-curve (AUCs) for detecting csPCa were 0.796 (95%CI, 0.738-0.853), 0.851 (95%CI, 0.783-0.918) and 0.806 (95%CI, 0.742-0.870) for PRIMARY-score, SUVmax and routine clinical PSMA-PET assessment, respectively. The diagnostic model comprising PRIMARY-score, SUVmax and serum free PSA/total PSA (fPSA/tPSA) achieved a significantly higher AUC of 0.906 (95%CI, 0.851-0.961) compared to strategies based on PRIMARY-score or SUVmax (P < 0.05) and markedly superior to conventional strategies typically based on PSA density (P < 0.001). The average fivefold cross-validated AUC with 1000 iterations was 0.878 (95%CI, 0.820-0.954). Theoretically, using a threshold of 21.6%, the model could have prevented 78% of unnecessary biopsies while missing only 7.8% of csPCa cases in this cohort.

CONCLUSIONS

A novel diagnostic model incorporating PSMA-PET derived metrics-PRIMARY-score and SUVmax-along with serum fPSA/tPSA, has been developed and validated. The integrated model may assist clinical decision-making with enhanced diagnostic accuracy over the individual conventional metrics. It has great potential to reduce unnecessary biopsies for men with PI-RADS ≤ 3 MRI results and warrants further prospective and external evaluations.

Evolving Paradigms in Prostate Cancer: The Integral Role of Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography in Primary Staging and Therapeutic Decision-Making

Prostate-specific membrane antigen (PSMA) positron emission tomography or computed tomography (PET/CT) has emerged as a superior imaging option to conventional imaging for prostate cancer. The majority of early evidence and prospective trials evaluated PSMA PET/CT in the biochemical recurrence or metastatic setting. However, there has been an increasing number of prospective trials in the primary setting. The purpose of this narrative review was to describe the role of PSMA PET/CT in localized primary prostate cancer. This narrative review focuses on the prospective evidence available in this setting. We detail the current practice and future potential for PSMA PET/CT to be used in multiple stages of localized primary prostate cancer. The most common practice currently for PSMA PET/CT is in the primary nodal and metastatic staging of high-risk prostate cancer. We describe other roles of PSMA PET/CT, including in intermediate-risk prostate cancer as well as local staging and the impact on radiation therapy and surgical management. We also discuss the potential future roles of PSMA PET/CT in prediagnosis such as risk stratification for biopsy, prognosis, and specific surgical roles. Potential pitfalls of PSMA PET/CT are also addressed. PSMA PET/CT has already had a significant influence on prostate cancer, and there will continue to be a greater role for this imaging modality in localized primary prostate cancer.

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.

PSMA-based therapeutics for prostate cancer

INTRODUCTION

The prostate cancer (PCa) consists the most frequently diagnosed malignancy of urogenital system in males. Traditionally, treatment of localized PCa was based on surgery or radiotherapy while hormonotherapy was used in more advanced stages. However, the implementation of radiolabels has revolutionized the landscape of prostate cancer. Specifically, prostate-specific membrane antigen (PSMA) has been investigated in different aspects of PCa therapeutic era.

AREAS COVERED

A literature review is presented about the implications of PSMA radiolabels on prostate cancer treatment. PSMA tracers were initially used as an imaging technique. Afterwards, PSMA labeled with isotopes presenting cytotoxic abilities, such as lutetium-117 and actinium-225, while reports exist about the use of radioligand immunotherapy. Meanwhile, ongoing trials examine the development of novel radionuclides as well as the evolution of the PSMA-targeted ligands.

EXPERT OPINION

Currently, PSMA radioligand treatment of prostate cancer is approved in the metastatic stage of the disease. Meanwhile, a variety of trials exist about its possible role in less advanced stages. However, plenty of parameters should be addressed before these implementations, such as PSMA dosage, dosimetry issues, and its safety profile. A future well-designed study with proper patient selection is mandatory to further explore PSMA radioligand theranostics perspectives.