18F-fluciclovine PET-CT and 68Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: a prospective, single-centre, single-arm, comparative imaging trial

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.

Role of PSMA PET/CT in imaging and management of prostate cancer

PURPOSE OF REVIEW

In the era of precision medicine, the introduction of FDA-approved prostate-specific membrane antigen (PSMA) targeting tracers has revolutionized prostate cancer imaging. These tracers enable functional positron emission tomography (PET) imaging, allowing for precise identification of the location and extent of prostate cancer spread. This review serves as a practical guide for multidisciplinary teams caring for prostate cancer patients, outlining the current approved uses of PET imaging with PSMA tracers and exploring its future applications.

RECENT FINDINGS

PSMA PET/CT has become a reliable modality for initial staging in patients with intermediate-to-high risk prostate cancer, restaging in cases of biochemical recurrence and further clarifying disease status among patients with conventional imaging based nonmetastatic castrate resistant prostate cancer and metastatic prostate cancer. Additionally, it has promising roles in selecting patients for radioligand therapy, monitoring treatment response, and guiding therapeutic decision-making.

SUMMARY

PSMA PET/CT is currently a crucial imaging tool used at key stages of prostate cancer management, with ongoing research exploring its potential for additional clinical applications.

PSMA PET/CT in biochemical recurrence of prostate cancer with PSA levels ≤ 0.2 ng/mL: a German multicenter analysis of conventional PSMA tracers, including [68Ga]Ga-PSMA-11, [68Ga]Ga-PSMA I&T, and [18F]PSMA-1007

BACKGROUND

Prostate-specific membrane antigen (PSMA)-directed positron emission tomography/computed tomography (PET/CT) has emerged as a highly accurate imaging modality for detecting tumor lesions in patients with biochemical recurrence (BCR) of prostate cancer (PC). While detection rates of lesions suspicious for PC relapse are known to increase with rising prostate-specific antigen (PSA) levels, data on the efficacy of PSMA PET/CT at very low PSA values (≤ 0.2 ng/mL) remain limited.

METHODS

In this multicenter study, we analyzed 321 patients with BCR and a PSA value ≤ 0.2 ng/mL across five German academic centers, using three different PSMA-targeted radiotracers: [68Ga]Ga-PSMA-11, [68Ga]Ga-PSMA I&T, and [18F]PSMA-1007 and analyzed the detection rates and potential predictive parameters.

RESULTS

The overall pooled detection rate was 29.6%. No statistically significant differences in detection rates were observed between the three radiotracers ([68Ga]Ga-PSMA-11 29.4% vs. [68Ga]Ga-PSMA I&T, 22.5% vs. [18F]PSMA-1007 32.4%, p ≥ 0.314). Detection rates were significantly higher in patients with a PSA level > 0.15 ng/mL (p = 0.029, φ = 0.122), in those with an initial Gleason score > 7 (p = 0.018, φ = 0.141) and in those receiving androgen deprivation therapy (p = 0.031, φ = 0.120).

CONCLUSION

All three radiotracers demonstrated comparable diagnostic performance, with no significant superiority observed between the 68Ga- and 18F-labeled tracers in the patient sample investigated (overall pooled detection rate: 29.6%). This positivity rate can serve as an expectation horizon for both the attending physician and the patient in the case of low PSA values. Further studies with larger cohorts, preferably conducted in a prospective setting, are needed to confirm and expand upon our findings.

Preclinical and clinical evaluation of [64Cu]Cu-PSMA-Q PET/CT for prostate cancer detection and its comparison with [18F]FDG imaging

This study aimed to develop and evaluate [64Cu]Cu-PSMA-Q as a novel positron emission tomography (PET) imaging agent for prostate cancer detection, assessing its diagnostic accuracy and clinical applicability in comparison to [18F]FDG PET imaging. [64Cu]Cu-PSMA-Q was synthesized, purified, and subjected to comprehensive quality control. Its binding affinity, cellular uptake, and internalization were assessed in vitro using prostate-specific membrane antigen (PSMA)-positive LNCaP C4-2B cells. In vivo toxicity studies were conducted in 12 mouse models (6 per group). Small-animal PET/CT (positron emission tomography/computed tomography) imaging and biodistribution studies were performed on tumor-bearing mice. Clinical evaluation involved PET/CT imaging with [64Cu]Cu-PSMA-Q in 29 prostate cancer patients, with comparative analysis against [18F]FDG PET/CT imaging. Radiation dosimetry was calculated using OLINDA/EXM software, and diagnostic performance metrics, including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), and tumor-to-background ratio, were analyzed using SPSS v24.0, with P < 0.05 considered statistically significant. Comparative analyses utilized t-tests or Mann-Whitney U tests as appropriate. [64Cu]Cu-PSMA-Q achieved over 99% radiochemical purity and a specific activity of 20.5 ± 1 GBq/μmol. In vitro studies demonstrated a dissociation constant (Kd) of 4.083 nM, along with high cellular uptake and internalization in LNCaP C4-2B cells. No significant toxicity was observed in mouse models. Small -animal PET/CT imaging revealed peak tumor uptake at 4 h post-injection in LNCaP C4-2B tumor xenografts. In clinical evaluations, [64Cu]Cu-PSMA-Q PET/CT detected more lesions than [18F]FDG, with significantly higher SUVmax, SUVmean, and tumor-to-background ratios. The mean effective radiation dose was calculated as 4.48 ± 0.99 mSv. [64Cu]Cu-PSMA-Q PET/CT demonstrated superior lesion detection and higher tumor-to-background ratios compared to [18F]FDG PET/CT for prostate cancer visualization. Its advantageous properties, including a favorable half-life, excellent safety profile, and enhanced diagnostic accuracy, support its potential for broad clinical adoption. This study establishes a foundation for further validation of [64Cu]Cu-PSMA-Q in prostate cancer management.

Bone metastases of prostate cancer: Molecular mechanisms, targeted diagnosis and targeted therapy (Review)

Prostate cancer (PCa) is second only to lung cancer in terms of death among men worldwide. Advanced PCa frequently results in bone metastases, which occur in ~90% of patients and frequently result in severe skeleton‑related events. Currently, the treatment for this disease is limited to alleviating its clinical symptoms and cannot provide a complete cure. Therefore, the development of novel treatment strategies is particularly important. In recent years, numerous novel strategies for the diagnosis and treatment of PCa have emerged, resulting in good clinical efficacy. For example, strategies targeting prostate specific membrane antigen, poly ADP‑ribose polymerase and programmed cell death protein 1 have been applied to PCa‑induced bone metastasis, and have shown initial efficacy and great potential. Therefore, understanding the molecular mechanisms underlying the formation of bone metastases in patients with PCa is of importance for the effective management of this disease. The purpose of the present review is to comprehensively outline the roles of protein‑coding genes and non‑coding RNAs in the development of bone metastases of PCa to elucidate their significance in the management of PCa. The aim is to offer clinicians and researchers a comprehensive understanding of this topic.

Novel Methods to Assess Tumor Burden and Minimal Residual Disease in Genitourinary Cancers

BACKGROUND AND OBJECTIVE

Advances in molecular diagnostics have ushered in a new era for patients with prostate, renal, and urothelial cancers, with novel radiographic and molecular modalities for the assessment of disease burden and minimal residual disease (MRD). Conventional imaging has a limited threshold for disease detection and is often unable to discern clinically occult disease with varying risks of false-negative or false-positive findings depending on the disease state and type of imaging.

METHODS

We provide an overview of emerging radiographic and molecular tools in development within the genitourinary (GU) disease space. A literature review of contemporary basic, translational, and clinical research studies was performed, covering the timeframe of 1980-2024 through the MEDLINE (via PubMed) and Scopus databases. We highlight select examples of emerging technologies and biomarker-informed clinical trials, which aim to quantify disease at lower thresholds and have the potential for integrating MRD in clinical practice for GU patients.

KEY FINDINGS AND LIMITATIONS

The development of novel radiotracers, such as prostate-specific membrane antigen or carbonic anhydrase IX, is being evaluated in both clinical practice and trial setting, aiming to change the management of these tumors. Molecular tools including circulating tumor cells and byproducts such as plasma and urine cell-free circulating tumor DNA provide the opportunity for MRD detection. MRD capture on single-cell or cellular byproducts can serve as a conduit for genomic and transcriptomic analyses, providing insight into the molecular underpinnings and clonal evolution of disease.

CONCLUSIONS AND CLINICAL IMPLICATIONS

While the full potential for MRD applications has yet to be realized, we are witnessing the emergence of novel techniques aimed at MRD detection and the rapid development of elegantly designed studies implementing iterative detection of MRD as means to provide biological rationale and tailor therapeutic options in GU tumors.

Integrating Prostate Specific Membrane Antigen-PET into Clinical Practice for Prostate Cancer

Prostate surface membrane antigen (PSMA)-PET imaging has significantly shaped the clinical management of prostate cancer, from localized to metastatic disease. It outperforms conventional imaging in both primary staging and detecting recurrence. PSMA-PET incorporation into the clinical workflow can alter treatment decisions, though the impact of observed stage migration on patient outcomes has yet to be well-characterized. There is growing interest in using PSMA-PET to predict treatment response across all stages of prostate cancer, and to select patients for PSMA radioligand therapy. Use of PSMA-PET will continue to expand for clinical applications as its role becomes better defined through prospective studies.

Current Approaches to Radiation Oncology Target Volume Delineation Using PET/Computed Tomography

PET is a versatile imaging modality widely used in oncology for diagnosing, staging, predicting outcomes, and surveillance for a variety of cancers. In radiation oncology, combining PET and computed tomography imaging can markedly enhance treatment planning through improved target volume delineation. This review examines data and clinical approaches across 3 major cancer types to evaluate the role of PET in target volume delineation, with data and current approaches for thoracic, genitourinary, and head and neck malignancies detailed. Additionally, it emphasizes various practical applications of PET in radiation therapy planning, several of which have been recently demonstrated in clinical trials.

Kinetics of PSMA PET signal after radiotherapy in prostate cancer lesions: A single-center retrospective study

PURPOSE

To evaluate the kinetics of prostate-specific membrane antigen (PSMA) PET uptake in irradiated lesions using serial PSMA PET/CT scans.

METHODS

Patients with prostate cancer who underwent 68Ga-PSMA-11 PET/CT before (PET1) and after radiotherapy (PET2) were retrospectively included. Percentage changes in SUVmax (ΔSUVmax) of the irradiated lesion were measured. The presence of residual uptake was visually assessed on PET2. When available, follow-up imaging was used for lesion validation. Morphologic or uptake disappearance on follow-up scans was defined as loco-regional complete response (L-CR). Clinical and PET characteristics were compared between lesions with and without residual uptake. An optimal timing for response assessment was calculated by receiver-operating-curve analysis.

RESULTS

Eighty-nine patients with 217 irradiated lesions (106 lymph nodes, 85 bone, 21 prostate/prostate bed) receiving ablative radiotherapy were included. Lesion uptake was lower at later time points and was lowest at 9-12 months after radiotherapy. Sixty-eight lesions showed residual uptake on PET2. Residual uptake was more common in lesions imaged at an earlier time point after radiotherapy (median: 7.9 vs. 13.0 months, p = 0.001), lesions in the prostate/prostate bed (p < 0.001), and lesions with higher baseline SUVmax (p = 0.001). Thirty-one residual uptake-positive lesions had available follow-up imaging, of which 24 lesions were confirmed to be L-CR. Risk factors for not achieving L-CR were lesions with prolonged uptake (p = 0.002) and those in the prostate/prostate bed (p = 0.003). The optimal time point for predicting L-CR was 8.6 months.

CONCLUSIONS

Timing and tumor site affect the PSMA PET signal after radiotherapy, and should be considered when assessing response on post-radiotherapy PSMA PET.

How Standard of Truth Methodology Impacts Diagnostic PSMA-Targeting Radiopharmaceutical Evaluation: Learnings from the Phase 3 SPOTLIGHT Study

Objectives: To explore the impact of different standard of truth (SoT) methodologies on efficacy endpoints traditionally used in clinical trials of diagnostic radiopharmaceuticals, using data from the SPOTLIGHT study (NCT04186845) in patients with recurrent prostate cancer. Methods: Data from patients with baseline prostate-specific antigen (PSA) ≤ 5 ng/mL, who underwent 18F-flotufolastat imaging and had data for SoT determination, were reviewed. Majority-read patient level endpoints (verified detection rate [VDR] and patient-level positive predictive value [PPV]), and region-level PPV (in the prostate/prostate bed, pelvic lymph nodes, and extrapelvic sites) according to on-study reads by three blinded readers, were stratified by the SoT methodology (histopathology; post-PET confirmatory imaging; baseline/historic conventional imaging) used by the independent Truth Panel to verify 18F-flotufolastat-avid lesions. Differences between SoT groups for each endpoint were compared using a chi-square test (statistically significant if p < 0.0167). Results: Our analysis included 297 patients (median baseline PSA = 0.8 ng/mL): 56% (n = 166) had post-PET confirmatory imaging, 26% (n = 78) had baseline/historic conventional imaging, and 18% (n = 53) had histopathological confirmation of ≥1 PET-positive lesion. For all endpoints assessed, the highest majority-read values were achieved with histopathology SoT. For histopathology versus baseline/historic conventional imaging, VDR (77%) was 3.6-fold higher (p < 0.0001), patient-level PPV (79%) was 2.2-fold higher (p < 0.0001), and region-level PPV (50%) was 3.7-fold higher in the prostate/prostate bed (p = 0.009); smaller increases were seen in majority-read PPV in the pelvic lymph nodes (77%; 1.5-fold) and other sites (75%; 1.3-fold), but these were not of statistical significance. Conclusions: These data illustrate how SoT methods can substantially impact efficacy endpoints traditionally used in clinical trials of diagnostic radiopharmaceuticals. Notably lower endpoint values are achieved with imaging SoT than with histopathology.

CTR-FAPI PET Enables Precision Management of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) can only be cured through the excision of all metastatic lesions, but current clinical practice fails to localize the disease in 29% to 60% of patients. Previously, we developed a fibroblast activation protein inhibitor (FAPI)-based covalent targeted radioligand (CTR) for improved detection sensitivity and accuracy. In this first-in-class clinical trial, we head-to-head compared [68Ga]Ga-CTR-FAPI PET-CT and [18F]fluorodeoxyglucose ([18F]FDG) PET-CT in 50 patients with MTC. The primary endpoint was the patient-based detection rate, with [68Ga]Ga-CTR-FAPI exhibiting higher detection than [18F]FDG (98% vs. 66%, P = 0.0002). This improved detection was attributed to increased tumor uptake (maximum standardized uptake value = 11.71 ± 9.16 vs. 2.55 ± 1.73, P < 0.0001). Diagnostic accuracy, validated on lesions with gold-standard pathology, was greater for [68Ga]Ga-CTR-FAPI compared with [18F]FDG (96.7% vs. 43.3%, P < 0.0001). Notably, the management of 32% of patients was altered following [68Ga]Ga-CTR-FAPI PET-CT, and the surgical plan was changed for 66.7% of patients. Overall, [68Ga]Ga-CTR-FAPI PET-CT provided superior detection and diagnostic accuracy compared with [18F]FDG PET-CT, enabling precision management of patients with MTC. Significance: In this first-in-class clinical trial of CTR, [68Ga]Ga-CTR-FAPI demonstrated an improved patient-based detection rate (98%), tumor uptake (maximum standardized uptake value = 11.71 ± 9.16), and pathology-validated diagnostic accuracy (96.7%) compared with the currently approved method in MTC treatment. It directly altered management in 32% of patients, enabling precision diagnosis and management of MTC. See related commentary by Witney, p. 264.

PSMA-PET/CT Findings in Patients With High-Risk Biochemically Recurrent Prostate Cancer With No Metastatic Disease by Conventional Imaging

Importance

The phase 3 randomized EMBARK trial evaluated enzalutamide with or without leuprolide in high-risk nonmetastatic hormone-sensitive prostate cancer. Eligibility relied on conventional imaging, which underdetects metastatic disease compared with prostate-specific membrane antigen-positron emission tomography (PSMA-PET).

Objective

To describe the staging information obtained by PSMA-PET/computed tomography (PSMA-PET/CT) in a patient cohort eligible for the EMBARK trial.

Design, Setting, and Participants

This post hoc, retrospective cross-sectional study included 182 patients from 4 prospective studies conducted from September 15, 2016, to September 27, 2021. All patients had recurrent prostate cancer after radical prostatectomy (RP), definitive radiotherapy (dRT), or salvage radiotherapy (SRT). Analysis was performed from January 2023 to July 2024.

Exposures

Patients included had increasing prostate-specific antigen (PSA) levels greater than 1.0 ng/mL (after RP and SRT) or 2.0 ng/mL above the nadir value (after dRT), PSA doubling time of 9 months or less, and a serum testosterone level of 150 ng/dL or greater. Exclusion criteria were distant metastatic disease on radiographic imaging and prior hormonal or systemic therapy.

Main Outcomes and Measures

Staging information obtained by PSMA-PET/CT in patients with nonmetastatic disease according to conventional imaging.

Results

From 2002 patients screened, 182 (median age at PET/CT scan, 69 years [IQR, 64-73 years]) were included. Median prescan PSA levels were 2.4 ng/mL (IQR, 1.4-4.8 ng/mL) after RP (n = 91), 6.9 ng/mL (IQR, 3.5-18.5 ng/mL) after dRT (n = 39), 2.6 ng/mL (IQR, 1.6-5.2 ng/mL) after RP and SRT (n = 52), and 2.8 ng/mL (IQR, 1.7-6.6 ng/mL) overall (n = 182). Results of PSMA-PET were positive in 80% of patients (73 of 91) after RP, 92% of patients (36 of 39) after dRT, 85% of patients (44 of 52) after RP and SRT, and 84% of patients (153 of 182) overall. PSMA-PET detected any distant metastatic disease (miTxNxM1) in 34% of patients (31 of 91) after RP, 56% of patients (22 of 39) after dRT, 60% of patients (31 of 52) after RP and SRT, and 46% of patients (84 of 182) overall. Polymetastatic disease (≥5 lesions) was found in 19% of patients (17 of 91) after RP, 36% of patients (14 of 39) after dRT, 23% of patients (12 of 52) after RP and SRT, and 24% of patients (43 of 182) overall.

Conclusions and Relevance

In a cohort of patients with high-risk hormone-sensitive prostate cancer without evidence of metastatic disease by conventional imaging, PSMA-PET results were positive in 84% of patients, detected M1 disease stage in 46% of patients, and found polymetastatic disease (≥5 lesions) in 24% of patients, suggesting that patients' high-risk nonmetastatic hormone-sensitive prostate cancers are understaged by conventional imaging. The results challenge the interpretation of previous studies, such as the EMBARK trial, and support the evolving role of PSMA-PET for patient selection in clinical and trial interventions in prostate cancer. Further studies are needed to assess its independent prognostic value and use for treatment guidance.

Timing and Patterns of Potentially Salvageable Recurrences Following Stereotactic Body Radiation Therapy for Clinically Localized Prostate Cancer Assessed by Preferential Amino Acid Uptake

PURPOSE

18F-fluciclovine is a radiolabeled amino acid analog that is preferentially taken up by prostate cancer cells. 18F-fluciclovine PET/CT scans are approved for the detection of biochemically recurrent prostate cancer. Stereotactic body radiation therapy (SBRT) is increasingly offered for the treatment of localized prostate cancer. Limited data exist on the patterns of failure following prostate SBRT. The impact of scan timing before or after meeting the Phoenix criteria is unknown. Here, we characterize 18F-fluciclovine-defined recurrences for patients with rising prostate-specific antigens (PSAs) following SBRT.

METHODS

Between 2017 and 2022, 50 consecutive patients underwent an 18F-fluciclovine scan for suspected recurrence. All patients were treated on an institutional protocol with either SBRT (35-36.25 Gy) or SBRT boost (19.5 Gy) with intensity-modulated radiotherapy (IMRT). A total of 38% of the patients were high-risk, and 46% received androgen deprivation therapy (ADT) as part of their initial treatment. Patterns of failure were classified as PSA-only, local (prostate), lymph node (LN), bone, visceral, or combined. Patients were considered salvageable if all evidence of disease could be safely treated with local therapy (radiation, surgery, or interventional radiology (IR) ablation).

RESULTS

The median time from treatment was 39 months, and the median pre-scan PSA was 2.8 ng/mL. The overall scan positivity rate in our cohort was 34/51 (67%). The most common sites for initial disease recurrence were the prostate (22%), pelvic and para-aortic lymph node basins (40%), and bone (6%). A total of 21/51 scans (41%) were performed prior to reaching the Phoenix definition (nadir + 2) at a median PSA of 1.14 ng/mL. Of these patients, 12 (57%) had evidence of disease recurrence, all of which were potentially salvageable local or LN recurrences. The remaining 30/51 (59%) scans were performed after meeting the Phoenix definition (median PSA = 5.65 ng/mL). Of these, 22/30 (73%) had disease recurrence and 82% were potentially salvageable.

CONCLUSIONS

The diagnosis and management of recurrence following prostate SBRT continues to evolve. Approximately 50% of patients in our cohort who had yet to meet the Phoenix definition had scan evidence of disease recurrence, all of which were potentially salvageable with additional local therapy. Additional research is needed to identify factors predictive of disease recurrence on 18F-fluciclovine scans prior to reaching the Phoenix definition when they may be most curable.

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.

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

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

Atypical Metastases from Prostate Cancer: Alpha-Methylacyl-Coenzyme A Racemase (AMACR) as a Potential Molecular Target in Prostate-Specific Membrane Antigen-Negative Prostate Adenocarcinoma

Prostate cancer (PCa) is a high-prevalence disease usually characterized by metastatic spread to the pelvic lymph nodes and bones and the development of visceral metastases only in the late stages of disease. Positron Emission Tomography (PET) plays a key role in the detection of PCa metastases. Several PET radiotracers are used in PCa patients according to the stage and pathological features of the disease, in particular 68Ga/18F-prostate-specific membrane antigen (PSMA) ligands. Moreover, 2-deoxy-2-[18F]fluoro-D-glucose 18F-FDG PET usually shows metastases in the late stages of disease, when dedifferentiated neoplastic clones lose PSMA expression. In some cases, PCa patients may present atypical sites of metastases, with uncommon appearance at PET imaging with different radiotracers. We present the case of a patient with biochemical recurrence of PCa (ISUP Grade Group IV; PSA 4.7 ng/mL) showing atypical sites of metastases (the testis and multiple lung nodules) with absent PSMA expression and high [18F]FDG avidity. The patient showed diffuse positivity to alpha-methylacyl-coenzyme A racemase (AMACR). Moreover, a literature review was performed by collecting cases of PCa patients with atypical metastatic spread detected via PET imaging, with the aim of highlighting the relationship between atypical sites of metastases, imaging presentation, and pathology findings.

FAP and PSMA Expression by Immunohistochemistry and PET Imaging in Castration-Resistant Prostate Cancer: A Translational Pilot Study

Prostate-specific membrane antigen (PSMA) is a theranostic target for metastatic prostate cancer (PCa). However, castration-resistant PCa (CRPC) may lose PSMA expression after systemic therapy. Fibroblast activation protein (FAP), expressed by carcinoma-associated fibroblasts in various cancer types, including PCa, has the potential to be an alternative target. In this study, we evaluated FAP expression in CRPC to assess its potential, using PSMA as a comparison. Methods: FAP expression was assessed using immunohistochemistry in 116 CRPC tumors: 78 adenocarcinomas, 11 small cell carcinomas, and 27 anaplastic carcinomas. Correlation analysis between manual scoring and automated scoring was performed on 54 whole-slide sections of metastatic CRPC. Paired FAP and PSMA stains were assessed in tissue microarray cores of CRPC (n = 62), consisting of locally advanced CRPC (n = 9) and metastatic CRPC (n = 53). FAP and PSMA positivity was defined by an immunohistochemistry score of at least 10. To explore the correlation of PSMA and FAP inhibitor (FAPi) PET imaging and immunohistochemistry, a preliminary analysis of 4 patients included in a [68Ga]-FAPi-46 imaging trial (NCT04457232) was conducted. Results: Manual and automated scoring of FAP yielded results with strong correlations. Overall, FAP expression in CRPC was notably lower than PSMA expression (median immunoscores, 14 vs. 72; P < 0.001). Different histologic subtypes of CRPC demonstrated distinct levels of PSMA expression, whereas their FAP expression levels were comparable. Among the 19 PSMA-negative tumors, 11 (58%) exhibited FAP positivity. FAP expression levels in lymph node metastases were significantly lower than those in nonnodal metastases (P = 0.021). Liver metastases showed significant enrichment of tumors with strong FAP expression compared with nonliver lesions (P = 0.016). In the 4 clinical trial patients, the biopsied metastatic lesions showed lower uptake on FAPi PET than on PSMA PET (median SUVmax, 9.6 vs. 14.5), consistent with FAP expression that was lower than PSMA expression in the corresponding tumor biopsy samples (median immunoscores, 30 vs. 160). Conclusion: Because of the low FAP expression levels in CRPC, the utility of FAPi PET imaging may be limited. Although FAPi PET imaging may be further tested in PSMA-negative CRPC, such as small cell carcinoma, other molecular imaging modalities should be evaluated as alternative choices.

[18F]PSMA-1007 PET for biochemical recurrence of prostate cancer, a comparison with [18F]Fluciclovine

AIM

The objective of this study was to compare the detection rates of [18F]PSMA-1007 and [18F]Fluciclovine in early biochemical recurrence (BCR) of prostate cancer, i.e. with low prostate-specific antigen (PSA) levels (0.2-5.0 µg/L).

METHODS

This was a prospective, single-center (Radboudumc; Nijmegen, The Netherlands), comparative phase II diagnostic imaging study (NCT04239742). The main inclusion criteria were histologically proven adenocarcinoma of the prostate, BCR after radical treatment with two consecutive (rising) PSA values (0.2-5.0 µg/L). Patients underwent both [18F]PSMA-1007 PET/CT and [18F]Fluciclovine PET/CT within two weeks. Both scans were blindly scored by three independent nuclear medicine physicians. Hereafter, a result per scan and region was generated by consensus. The primary outcome was to compare the detection rate on a patient and region level. Secondary objectives were to determine detection rate stratified for PSA value, inter-reader agreement, and SUV measurements. For lesion confirmation a composite reference score was established using follow-up data.

RESULTS

Data of fifty patients were included, median age of 71 (IQR: 67-74) years and median PSA value of 0.38 (IQR: 0.30-1.55) µg/L. Detection rates were 68% (34/50) for [18F]PSMA-1007 and 42% (21/50) for [18F]Fluciclovine on a patient level (p < 0.001). Detection rates stratified for PSA value of [18F]PSMA-1007 in comparison with [18F]Fluciclovine were for PSA 0.2-0.5 µg/L; 60.7% versus 25.0% (p = 0.002); and for PSA ≥ 0.5 µg/L; 77.3% versus 63.6% (p = 0.250). There was a trend for higher inter-reader agreement with [18F]PSMA-1007. SUVmax (p < 0.001) was significantly higher for [18F]PSMA-1007 in comparison to [18F]Fluciclovine.

CONCLUSION

In patients with early BCR of prostate cancer after radical surgery or radiotherapy, [18F]PSMA-1007 demonstrated a significantly higher detection rate than [18F]Fluciclovine. This is particularly relevant since earlier and more accurate detection of a BCR can guide salvage therapy into a tailored strategy which may improve outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04239742. Registered 02 January 2020, https://clinicaltrials.gov/study/NCT04239742 .

Better Oncological Outcomes After Prostate-specific Membrane Antigen Positron Emission Tomography-guided Salvage Radiotherapy Following Prostatectomy

BACKGROUND AND OBJECTIVE

Up to 50% of patients with prostate cancer experience prostate-specific antigen (PSA) relapse following primary radical prostatectomy (RP). Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is increasingly being used for staging after RP owing to its high detection rate. Our aim was to compare outcomes for patients who received salvage radiotherapy (sRT) with versus without PSMA PET guidance.

METHODS

In this observational case-control study, the control group consisted of 344 patients from the SAKK09/10 trial (sRT without PSMA PET guidance from 2011 to 2014). The treatment group consisted of 1548 patients from a retrospective multicenter cohort (PSMA PET-guided sRT from July 2013 to 2020). Data were collected up to November 2023. Patients with pN1 status at RP, initial cM1 status, cM1 status on PET, or PSA >0.5 ng/ml were excluded. Patients with detectable PSA after RP who were treated with sRT were eligible. We assessed 3-yr biochemical recurrence-free survival (BRFS) and metastasis-free survival (MFS).

KEY FINDINGS AND LIMITATIONS

The study population of 717 patients comprised a control group (n = 255) with median follow-up of 75 mo and a PSMA PET group (n = 462) with median follow-up of 31 mo. In the PSMA PET cohort, 103 patients (22.3%) had PSMA-positive pelvic lymph nodes (PLNs), 85 (18.4%) received androgen deprivation therapy (ADT), and 104 (22.5%) underwent PLN irradiation. The BRFS rate at 3 yr was 71% (95% confidence interval [CI] 64-78%) for the control group and 77% (95% CI 72-82%) for the PSMA PET group. The PSMA PET group had favorable BRFS at 18-24 mo after sRT (hazard ratio 0.32, 95% CI 0.0.14-0.75; p = 0.01) and a lower rate of lymph node relapse after sRT (standardized mean difference 0.603). The MFS rate at 3 yr was 89.2% (95% CI 84.6-94.1%) for the control group and 91.2% (95% CI 88.1-94.4%) for the PSMA PET group.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Our results suggest a moderate improvement in short-term BRFS if PSMA PET is used to guide sRT. One possible reason is individualized PLN coverage facilitated by PET. MFS was not improved by PSMA PET guidance for sRT.

PATIENTS' SUMMARY

For patients who experience recurrence of prostate cancer after surgical removal of their prostate, salvage radiotherapy (sRT) is a further treatment option. We found that a type of scan called PSMA PET (prostate-specific membrane antigen positron emission tomography) to identify recurrence and guide sRT can improve recurrence-free survival because of better targeting of pelvic lymph nodes that may contain cancer cells.

Enhancing the diagnostic capacity of [18F]PSMA-1007 PET/MRI in primary prostate cancer staging with artificial intelligence and semi-quantitative DCE: an exploratory study

BACKGROUND

To investigate the ability of artificial intelligence (AI)-based and semi-quantitative dynamic contrast enhanced (DCE) multiparametric MRI (mpMRI), performed within [18F]-PSMA-1007 PET/MRI, in differentiating benign from malignant prostate tissues in patients with primary prostate cancer (PC).

RESULTS

A total of seven patients underwent whole-body [18F]-PSMA-1007 PET/MRI examinations including a pelvic mpMRI protocol with T2w, diffusion weighted imaging (DWI) and DCE image series. Conventional analysis included visual reading of PET/MRI images and Prostate Imaging Reporting & Data System (PI-RADS) scoring of the prostate. On the prostate level, we performed manual segmentations for time-intensity curve parameter formation and semi-quantitative analysis based on DCE segmentation data of PC-suspicious lesions. Moreover, we applied a recently introduced deep learning (DL) pipeline previously trained on 1010 independent MRI examinations with systematic biopsy-enhanced histopathological targeted biopsy lesion ground truth in order to perform AI-based lesion detection, prostate segmentation and derivation of a deep learning PI-RADS score. DICE coefficients between manual and automatic DL-acquired segmentations were compared. On patient-based analysis, PET/MRI revealed PC-suspicious lesions in the prostate gland in 6/7 patients (Gleason Score-GS ≥ 7b) that were histologically confirmed. Four of these patients also showed lymph node metastases, while two of them had bone metastases. One patient with GS 6 showed no PC-suspicious lesions. Based on DCE segmentations, a distinction between PC-suspicious and normal appearing tissue was feasible with the parameters fitted maximum contrast ratio (FMCR) and wash-in-slope. DICE coefficients (manual vs. deep learning) were comparable with literature values at a mean of 0.44. Further, the DL pipeline could identify the intraprostatic PC-suspicious lesions in all six patients with clinically significant PC.

CONCLUSION

Firstly, semi-quantitative DCE analysis based on manual segmentations of time-intensity curves was able to distinguish benign from malignant tissues. Moreover, DL analysis of the MRI data could detect clinically significant PC in all cases, demonstrating the feasibility of AI-supported approaches in increasing diagnostic certainty of PSMA-radioligand PET/MRI.

Molecular Imaging Biomarkers for Early Cancer Detection: A Systematic Review of Emerging Technologies and Clinical Applications

BACKGROUND

Early cancer detection is crucial for improving patient outcomes. Molecular imaging biomarkers offer the potential for non-invasive, early-stage cancer diagnosis.

OBJECTIVES

To evaluate the effectiveness and accuracy of molecular imaging biomarkers for early cancer detection across various imaging modalities and cancer types.

METHODS

A comprehensive search of PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and Scopus was performed, covering the period from January 2010 to December 2023. Eligibility criteria included original research articles published in English on molecular imaging biomarkers for early cancer detection in humans. The risk of bias for included studies was evaluated using the QUADAS-2 tool. The findings were synthesized through narrative synthesis, with quantitative analysis conducted where applicable.

RESULTS

In total, 50 studies were included. Positron emission tomography (PET)-based biomarkers showed the highest sensitivity (mean: 89.5%, range: 82-96%) and specificity (mean: 91.2%, range: 85-100%). Novel tracers such as [68Ga]-PSMA for prostate cancer and [18F]-FES for breast cancer demonstrated promising outcomes. Optical imaging techniques showed high specificity in intraoperative settings.

CONCLUSIONS

Molecular imaging biomarkers show significant potential for improving early cancer detection. Integration into clinical practice could lead to earlier interventions and improved outcomes. Further research is needed to address standardization and cost-effectiveness.

French AFU Cancer Committee Guidelines - Update 2024-2026: Prostate cancer - Management of metastatic disease and castration resistance

PURPOSE OF THIS DOCUMENT

The Oncology Committee of the French Urology Association is proposing updated recommendations for the management of recurrent and/or metastatic prostate cancer (PCa).

METHODS

A systematic review of the literature from 2022 to 2024 was conducted by the CCAFU on the therapeutic management of recurrent PCa following local or metastatic treatment, assessing the references based on their level of evidence.

RESULTS

Molecular imaging is the standard approach for assessing recurrence after local treatment and should not delay early salvage treatment. Androgen deprivation therapy (ADT) is the primary treatment option for metastatic PCa. Intensification of ADT, now cononsidered standard care for metastatic PCa, involves incorporating at least one new-generation hormone therapy (ARPI). For patients with high-volume metastatic disease at diagnosis, adding docetaxel to ADT+ARPI may be considered for eligible patients. In castration-resistant PCa (CRPC) patients, poly(ADP) ribose polymerase (PARP) inhibitors and PSMA radioligand therapy are new treatment options. The combination and sequencing of treatmentsare influenced by several factors, including patient and disease characteristics, prior therapies, genomic status, and molecular imaging findings.

CONCLUSION

This update of French recommendations should help to improve the management recurrent or metastatic PCa patients.

PSMA PET improves characterization of dural-based intracranial lesions in patients with metastatic prostate cancer

PURPOSE

Theranostic approaches combining prostate-specific membrane antigen (PSMA)-PET/CT or PET/MRI with PSMA-targeted radionuclide therapy have improved clinical outcomes in patients with prostate cancer (PCa) especially metastatic castrate resistant prostate cancer. Dural metastases in PCa are rare but can pose a diagnostic challenge, as meningiomas, a more common dural based lesions have been shown to express PSMA. The aim of this study is to compare PSMA PET parameters between brain lesions classified as dural metastases and meningiomas in prostate cancer patients.

METHODS

A retrospective analysis of PSMA PET/CT scans in patients with PCa and intracranial lesions was conducted. Brain lesions were categorized as dural metastases or meningiomas based on MRI characteristics, longitudinal follow-up, and histopathological characteristics. Standardized uptake values (SUVmax) of each brain lesion were measured, along with SUV ratio referencing parotid gland (SUVR). SUVs between lesions classified as metastases and meningiomas, respectively, were compared using Mann-Whitney-test. Diagnostic accuracy was evaluated using ROC analysis.

RESULTS

26 male patients (median age: 76.5 years, range: 59-96 years) met inclusion criteria. A total of 44 lesions (7 meningiomas and 37 metastases) were analyzed. Median SUVmax and SUVR were significantly lower in meningiomas compared to metastases (SUVmax: 2.7 vs. 11.5, p = 0.001; SUVR: 0.26 vs. 1.05, p < 0.001). ROC analysis demonstrated AUC 0.903; the optimal cut-off value for SUVR was 0.81 with 81.1 % sensitivity and 100 % specificity.

CONCLUSION

PSMA PET has the potential to differentiate meningiomas from dural-based metastases in patients with PCa, which can optimize clinical management and thus improve patient outcomes.

Five-Year Prostate-Specific Membrane Antigen Positron Emission Tomography-Based Outcomes of Spot-Scanning Proton Radiation Therapy for Localized Prostate Cancer: A Single Institution Experience

Purpose

We report 5-year oncologic outcomes of a prospective series of patients with prostate cancer treated with spot-scanning proton therapy (SSPT).

Methods and Materials

A prospective registry identified patients with prostate cancer treated with SSPT between January 2016 and December 2018. Five-year overall survival, local control, biochemical failure, regional and distant failures, and adverse events (AEs) were assessed. Biochemical failure was defined as rise in prostate-specific antigen ≥ 2.0 ng/mL above nadir prostate-specific antigen. Baseline-adjusted toxicities were assigned using the Common Terminology Criteria for Adverse Events version 5.0.

Results

With a median follow-up of 4.4 years, 284 patients with prostate cancer were treated with SSPT. Median total radiation dose was 79.2 Gy over 44 fractions, 70 Gy over 28 fractions, and 38 Gy over 5 fractions for conventional fractionation (CF), hypofractionation (HF), and stereotactic body radiation therapy (SBRT), respectively. Biochemical failure rate for all patients was 6.7%. Five-year local control rates for CF, HF, and SBRT were 100%, 100%, and 97.3%, respectively (P = .07). Regional recurrences occurred in 12 (4.2%) patients: 8 treated with CF, 2 with HF, and 2 with SBRT (P = .62). Distant failures occurred in 12 patients (4.2%): 5 treated with CF, 7 with HF, and none with SBRT (P = .05). Five-year overall survival for patients treated with CF, HF, and SBRT SSPT were 88.1%, 86.1%, and 97.2%, respectively (P = .1). Acute and chronic grade 2+ gastrointestinal AEs occurred in 8 (2.8%) and 51 (18.0%) patients, respectively. Acute and chronic grade 3+ gastrointestinal AEs occurred in 3 (1.1%) and 4 (1.4%) patients, respectively. Acute and chronic grade 2+ genitourinary-related AEs were observed in 71 (25%) and 63 (22.2%) patients, respectively. Acute and chronic grade 3+ genitourinary toxicity were observed in 3 (1.1%) and 6 (2.1%) patients, respectively.

Conclusions

SSPT provides high local control rates and excellent oncologic outcomes across different fractionation schedules with low long-term AE rates.

Biochemical Relapse-Free Survival in Postprostatectomy Patients Receiving 18F-Fluciclovine-Guided Prostate Bed-Only Radiation: Post Hoc Analysis of a Prospective Randomized Trial

PURPOSE

Whole-pelvis (WP) radiation therapy (radiation) improved biochemical relapse-free survival (bRFS) compared with prostate bed (PB)-only radiation in the Radiation Therapy Oncology Group 0534, but was performed in an era prior to positron emission tomography (PET) staging. Separately, 18F-fluciclovine PET/CT-guided postprostatectomy radiation improved 3-year bRFS versus radiation guided by conventional imaging alone. We hypothesized that patients who were changed from WP to PB-only radiation after PET would have bRFS that was: (a) no higher than patients initially planned for PB-only radiation; and (b) lower than patients planned for WP radiation without PET guidance.

METHODS AND MATERIALS

We conducted a post hoc analysis of a prospective, randomized trial comparing conventional (arm 1) versus PET-guided (arm 2) postprostatectomy radiation. In arm 2, pre-PET treatment field decisions were recorded and post-PET fields were defined per protocol; pathologic node negative (pN0) without pelvic or extrapelvic PET uptake received PB-only radiation. Three-year bRFS was compared in patients planned for WP with change to PB-only radiation (arm 2 [WP:PB]) vs arm 2 patients planned for PB-only with final radiation to PB-only (arm 2 [PB:PB]) and arm 1 pN0 patients treated with WP radiation (arm 1 [WP]) using the Z test and log-rank test. Demographics were compared using the chi-square test, Fisher exact test, or analysis of variance, as appropriate.

RESULTS

We identified 10 arm 2 (WP:PB), 31 arm 2 (PB:PB) and 11 arm 1 (WP) patients. Androgen deprivation was used in 50.0% of arm 2 (WP:PB) and 3.2% of arm 2 (PB:PB) patients, P < .01. Median preradiation prostate-specific antigen was higher in arm 2 (WP:PB) vs arm 2 (PB:PB) patients (0.4 vs 0.2 ng/mL, P = .03); however, there were no significant differences in T stage, Gleason score, or margin positivity. Three-year bRFS was 80% in arm 2 (WP:PB) vs 87.4% in arm 2 (PB:PB), P = .47, respectively. Arm 1(WP) patients had significantly worse 3-year (23%) bRFS vs arm 2 (WP:PB), P < .01.

CONCLUSIONS

Patients initially planned for WP radiation with field decision change to PB-only radiation after PET showed (1) no significant difference in 3-year bRFS compared with patients initially planned for PB-only radiation; and (2) improved bRFS compared with patients receiving WP radiation without PET guidance. PET-guided volume de-escalation in selected patients may be 1 approach to mitigating toxicity without compromising outcomes.

Negative 18 F-Piflufolastat PET/CT, But Positive 18 F-Fluciclovine PET/CT, in a Patient With Biochemically Recurrent Prostate Cancer

ABSTRACT

An 83-year-old man with prostate cancer post external beam radiotherapy presented with biochemical recurrence (PSA, 29.7 ng/mL). PSMA-targeted 18 F-Piflufolastat PET/CT was performed, but no avid lesions were identified. Given the high PSA and high suspicion for recurrence, an 18 F-Fluciclovine PET/CT was performed. Fifteen 18 F-fluciclovine-avid pelvic, abdominal, retrocrural, and left supraclavicular nodal metastases were then identified. Although the majority of prostate cancer metastases are avid on PSMA-targeted PET, some metastases are not. This case demonstrates the ability of metabolic tracers such as 18 F-Fluciclovine PET to localize and quantitate disease extent in a patient whose metastases are not avid on PSMA-targeted PET.

Real-world evidence of 18F-fluciclovine Positron emission tomography/computed tomography performance for recurrent prostate cancer in the Veterans Affairs Health System

BACKGROUND

There are no population-level studies assessing 18F-fluciclovine (fluciclovine) utilization of Positron emission tomography/computed tomography (PET/CT) for biochemically recurrent prostate cancer (PC). We assessed fluciclovine PET/CT in the Veterans Affairs Health Care System.

METHODS

Of 1153 men with claims suggesting receipt of fluciclovine PET/CT, we randomly reviewed charts of 300 who indeed underwent fluciclovine PET/CT. The primary outcome was fluciclovine PET/CT result (positive or negative). Comparison among groups stratified by androgen deprivation therapy (ADT) (yes vs. no) and prostate-specific antigen (PSA) (≤1 vs. >1 ng/mL) at imaging were performed. Logistic regression tested associations between PSA, ADT receipt, and race with fluciclovine PET/CT positive imaging.

RESULTS

Fluciclovine PET/CT positivity rate was 33% for patients with PSA 0-0.5 ng/mL, 21% for >0.5-1.0, 54% for >1.0-2.0, and 66% for >2.0 (p < 0.01). A 59% positivity rate ocurred in patients treated with concurrent ADT versus 37% in those not on ADT (p < 0.01). White were more likely to have a positive scan versus Black patients (55% vs. 38%; p = 0.02). Patients whose primary treatment was radical prostatectomy had a lower positivity rate (33%) versus those treated with radiotherapy (55%) (p < 0.001). On multivariable logistic regression, PSA > 1 ng/mL (all men odds ratio [OR]: 4.06, 95% confidence interval [CI]: 2.07-7.96; men on ADT only OR: 4.42, 95% CI: 1.73-11.26) and use of ADT (OR: 3.94, 95% CI: 1.32-11.75), and White (all men OR: 2.22, 95% CI: 1.20-4.17) predicted positive fluciclovine PET/CT.

CONCLUSION

This real-world study assessing 18F-fluciclovine PET/CT performance in an equal access health care system confirms higher detection rates than traditional imaging methods, but positivity is highly influenced by PSA at time of imaging. Additionally, patients currently receiving ADT have at least four times higher likelihood of a positive scan, showing that scan positivity isn't negatively affected by ADT status in this study. Finally, White men were more likely to have a positive scan, the reasons for which should be explored in future studies.

Machine learning predicts conventional imaging metastasis-free survival (MFS) for oligometastatic castration-sensitive prostate cancer (omCSPC) using prostate-specific membrane antigen (PSMA) PET radiomics

PURPOSE

This study investigated imaging biomarkers derived from PSMA-PET acquired pre- and post-metastasis-directed therapy (MDT) to predict 2-year metastasis-free survival (MFS), which provides valuable early response assessment to improve patient outcomes.

MATERIALS/METHODS

An international cohort of 117 oligometastatic castration-sensitive prostate cancer (omCSPC) patients, comprising 34 from John Hopkins Hospital (JHH) and 83 from Baskent University (BU), were treated with stereotactic ablative radiation therapy (SABR) MDT with both pre- and post-MDT PSMA-PET/CT scans acquired. PET radiomic features were analyzed from a CT-PET fusion defined gross tumor volume ((GTV) or zone 1), and a 5 mm expansion ring area outside the GTV (zone 2). A total of 1748 PET radiomic features were extracted from these zones. The six most significant features selected using the Chi2 method, along with five clinical parameters (age, Gleason score, number of total lesions, untreated lesions, and pre-MDT prostate-specific antigen (PSA)) were extracted as inputs to the models. Various machine learning models, including Random Forest, Decision Tree, Support Vector Machine, and Naïve Bayesian, were employed for 2-year MFS prediction and tested using leave-one-out and cross-institution validation.

RESULTS

Six radiomic features, including Total Energy, Entropy, and Standard Deviation from pre-PSMA-PET zone 1, Total Energy and Contrast from post-PSMA-PET zone 1, and Entropy from pre-PSMA-PET zone 2, along with five clinical parameters were selected for predicting 2-year MFS. In a leave-one-out test with all the patients, random forest achieved an accuracy of 80 % and an AUC of 0.82 in predicting 2-year MFS. In cross-institution validation, the model correctly predicted 2-year MFS events with an accuracy of 75 % and an AUC of 0.77 for patients from JHH, and an accuracy of 78 % and an AUC of 0.80 for BU patients, respectively.

CONCLUSION

Our study demonstrated the promise of using pre- and post-MDT PSMA-PET-based imaging biomarkers for MFS prediction for omCSPC patients.

Long-Term Outcomes of Prostate-Specific Membrane Antigen-PET Imaging of Recurrent Prostate Cancer

Importance

Although prostate-specific membrane antigen positron emission tomography (PSMA-PET) has shown improved sensitivity and specificity compared with conventional imaging for the detection of biochemical recurrent (BCR) prostate cancer, the long-term outcomes of a widespread shift in imaging are unknown.

Objective

To estimate long-term outcomes of integrating PSMA-PET into the staging pathway for recurrent prostate cancer.

Design, Setting, and Participants

This decision analytic modeling study simulated outcomes for patients with BCR following initial definitive local therapy. Inputs used were from the literature and a retrospective cohort study conducted at 2 institutions. The base case analysis assumed modest benefits of earlier detection and treatment, and scenario analyses considered prostate-specific antigen (PSA) level at imaging and different outcomes of earlier vs delayed treatment. The analysis was performed between April 1, 2023, and May 1, 2024.

Exposures

(1) Immediate PSMA-PET imaging, (2) conventional imaging (computed tomography and bone scan [CTBS]) followed by PSMA-PET if CTBS findings were negative or equivocal, and (3) CTBS alone.

Main Outcomes and Measures

The main outcomes were detection of metastases, deaths from prostate cancer, and life-years and quality-adjusted life-years (QALYs) gained.

Results

The model estimated that per 1000 simulated patients with BCR (assumed median age, 66 years), PSMA-PET is expected to diagnose 611 (95% uncertainty interval [UI], 565-656) patients with metastasis compared with 630 (95% UI, 586-675) patients diagnosed using CTBS followed by PSMA-PET and 297 (95% UI, 202-410) patients diagnosed using CTBS alone. Moreover, the estimated number of prostate cancer deaths was 512 (95% UI, 472-552 deaths) with PSMA-PET, 520 (95% UI, 480-559 deaths) with CTBS followed by PSMA-PET, and 587 (95% UI, 538-632 deaths) with CTBS alone. Imaging with PSMA-PET yielded the highest number of QALYs, which were 824 (95% UI, 698-885) higher than CTBS. These results differed by PSA level at the time of testing, with the highest incremental life-years and QALYs and lowest number of deaths from prostate cancer among patients with PSA levels of at least 5.0 ng/mL. Finally, the estimates were sensitive to the expected benefit of initiating therapy for recurrent prostate cancer earlier in the disease course.

Conclusions and Relevance

The results of this decision-analytic model suggest that upfront PSMA-PET imaging for the evaluation of BCR is expected to be associated with reduced cancer mortality and gains in life-years and QALYs compared with the conventional imaging strategy, assuming modest benefits of earlier detection and treatment.

PSMA PET/CT quick procedure guide

The application of PET/CT with radiopharmaceuticals targeting PSMA is significantly transforming the diagnostic and therapeutic strategies of patients with prostate cancer. In Spain, the availability and access to positron-emitting radiopharmaceuticals targeting Prostate-Specific Membrane Antigen (PSMA) have significantly changed in recent months. These changes are affecting their use in diagnostic procedures. As a result, its use within diagnostic protocols for patients with prostate cancer is undergoing significant modifications. In this collective and cooperative document, the authors have selected the most robust evidence accumulated to date to generate a clinical guide to achieve appropriate use of this technology. A format that presents the most frequent clinical situations and the patient profiles in which PSMA PET/CT plays a significant role or will do so in the immediate future has been chosen. It should be taken into account that regulatory restrictions mediate the current indications for its use in Spain, as well as its current cost and the production capacity of radiopharmaceuticals. The guideline presents a review of the established methodology for optimized imaging with each of the radiopharmaceutical variants targeting PSMA and recommendations for structured and accurate reporting of metabolic findings in combination with CT.

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.

Overview of Radiation Therapy in the Management of Localized and Metastatic Prostate Cancer

PURPOSE OF REVIEW

The goal is to describe the evolution of radiation therapy (RT) utilization in the management of localized and metastatic prostate cancer.

RECENT FINDINGS

Long term data for a variety of hypofractionated definitive RT dose-fractionation schemes has matured, allowing patients and providers many standard-of-care options to choose from. Post-prostatectomy, adjuvant RT has largely been replaced by an early salvage approach. Multiparametric MRI and PSMA PET have enabled increasingly targeted RT delivery to the prostate and oligometastatic tumors. Areas of active investigation include determining the value of proton beam therapy and perirectal spacers, and optimally incorporate genomic tumor profiling and next generation hormonal therapies with RT in the curative setting. The use of radiation therapy to treat prostate cancer is rapidly evolving. In the coming years, there will be continued improvements in a variety of areas to enhance the value of RT in multidisciplinary prostate cancer management.

Martin B, Jacobsen NE, Evans H, Gao Y, Hung R, Abele J, Dromparis P, Lima JF, Bismar T, Michelakis E, Sutendra G, Wuest F, Tu W, Adam BA, Fung C, Tamm A, Kinnaird A. Fluorine-18 Prostate-Specific Membrane Antigen-1007 PET/CT vs Multiparametric MRI for Locoregional Staging of Prostate Cancer

Importance

Prostate-specific membrane antigen (PSMA) demonstrates overexpression in prostate cancer and correlates with tumor aggressiveness. PSMA positron emission tomography (PET) is superior to conventional imaging for the metastatic staging of prostate cancer per current research but studies of second-generation PSMA PET radioligands for locoregional staging are limited.

Objective

To determine the accuracy of fluorine-18 PSMA-1007 PET/computed tomography (18F-PSMA-1007 PET/CT) compared to multiparametric magnetic resonance imaging (MRI) in the primary locoregional staging of intermediate-risk and high-risk prostate cancers.

Design, Setting, and Participants

The Next Generation Trial was a phase 2 prospective validating paired cohort study assessing the accuracy of 18F-PSMA-1007 PET/CT and MRI for locoregional staging of prostate cancer, with results of histopathologic examination as the reference standard comparator. Radiologists, nuclear medicine physicians, and pathologists were blinded to preoperative clinical, pathology, and imaging data. Patients underwent all imaging studies and radical prostatectomies at 2 tertiary care hospitals in Alberta, Canada. Eligible participants included men with intermediate-risk or high-risk prostate cancer who consented to radical prostatectomy. Participants who underwent radical prostatectomy were included in the final analysis. Patients were recruited between March 2022 and June 2023, and data analysis occurred between July 2023 and December 2023.

Exposures

All participants underwent both 18F-PSMA-1007 PET/CT and MRI within 2 weeks of one another and before radical prostatectomy.

Main Outcomes and Measures

The primary outcome was the correct identification of the prostate cancer tumor stage by each imaging test. The secondary outcomes were correct identification of the dominant nodule, laterality, extracapsular extension, and seminal vesical invasion.

Results

Of 150 eligible men with prostate cancer, 134 patients ultimately underwent radical prostatectomy (mean [SD] age at prostatectomy, 62.0 [5.7] years). PSMA PET was superior to MRI for the accurate identification of the final pathological tumor stage (61 [45%] vs 38 [28%]; P = .003). PSMA PET was also superior to MRI for the correct identification of the dominant nodule (126 [94%] vs 112 [83%]; P = .01), laterality (86 [64%] vs 60 [44%]; P = .001), and extracapsular extension (100 [75%] vs 84 [63%]; P = .01), but not for seminal vesicle invasion (122 [91%] vs 115 [85%]; P = .07).

Conclusions and Relevance

In this phase 2 prospective validating paired cohort study, 18F-PSMA-1007 PET/CT was superior to MRI for the locoregional staging of prostate cancer. These findings support PSMA PET in the preoperative workflow of intermediate-risk and high-risk tumors.

Pelvic lymph node mapping in prostate cancer: examining the impact of PSMA PET/CT on radiotherapy decision-making in patients with node-positive disease

INTRODUCTION

Prostate Specific Membrane Antigen (PSMA) imaging with Positron Emission Tomography (PET) plays a crucial role in prostate cancer management. However, there is a lack of comprehensive data on how PSMA PET/CT (Computed Tomography) influences radiotherapeutic decisions, particularly in node-positive prostate cancer cases. This study aims to address this gap by evaluating two primary objectives: (1) Mapping the regional and non-regional lymph nodes (LNs) up to the aortic bifurcation and their distribution using conventional methods with CT compared to PSMA PET/CT, and (2) assessing the impact of PSMA PET/CT findings on radiotherapeutic decisions.

METHODS

A retrospective analysis of 95 node-positive prostate cancer patients who underwent both CT and PSMA PET/CT imaging prior to primary radiotherapy and androgen deprivation therapy (ADT) was conducted. The analysis focused on identifying LNs in various regions including the common iliac, external iliac, internal iliac, obturator, presacral, mesorectal, inguinal, and other stations. Treatment plans were reviewed for modifications based on PSMA PET/CT findings, and statistical analysis was performed to identify predictors for exclusive nodal positivity on PSMA PET/CT scans.

RESULTS

PSMA PET/CT identified additional positive nodes in 48% of cases, resulting in a staging shift from N0 to N1 in 29% of patients. The most frequent metastatic LNs were located in the external iliac (76 LNs; 34%), internal iliac (43 LNs; 19%), and common iliac (35 LNs; 15%) stations. In patients with nodes only detected on PSMA PET the most common nodes were in the external iliac (27, 40%), internal iliac (13, 19%), obturator (11, 15%) stations. Within the subgroup of 28 patients exclusively demonstrating PSMA PET-detected nodes, changes in radiotherapy treatment fields were implemented in 5 cases (18%), and a dose boost was applied for 23 patients (83%). However, no discernible predictors for exclusive nodal positivity on PSMA PET/CT scans emerged from the analysis.

DISCUSSION

The study underscores the pivotal role of PSMA PET/CT compared to CT alone in accurately staging node-positive prostate cancer and guiding personalized radiotherapy strategies. The routine integration of PSMA PET/CT into diagnostic protocols is advocated to optimize treatment precision and improve patient outcomes.

Prostate-specific Membrane Antigen: Interpretation Criteria, Standardized Reporting, and the Use of Machine Learning

Prostate-specific membrane antigen targeting positron emission tomography (PSMA-PET) is routinely used for the staging and restaging of patients with various stages of prostate cancer. For clear communication with referring physicians and to improve inter-reader agreement, the use of standardized reporting templates is mandatory. Increasingly, tumor volume is used by reporting and response assessment frameworks to prognosticate patient outcome or measure response to therapy. However, the quantification of tumor volume is often too time-consuming in routine clinical practice. Machine learning-based tools can facilitate the quantification of tumor volume for improved outcome prognostication.

Prostate-Specific Membrane Antigen PET Response Associates with Metastasis-Free Survival After Stereotactic Ablative Radiation in Oligometastatic Prostate Cancer

PURPOSE

Emerging data suggest that metastasis-directed therapy (MDT) improves outcomes in patients with oligometastatic castration-sensitive prostate cancer (omCSPC). Prostate-specific membrane antigen positron emission tomography (PSMA-PET) can detect occult metastatic disease, and PSMA response has been proposed as a biomarker for treatment response. Herein, we identify and validate a PSMA-PET biomarker for metastasis-free survival (MFS) following MDT in omCSPC.

METHODS AND MATERIALS

We performed an international multi-institutional retrospective study of patients with omCSPC, defined as ≤3 lesions, treated with metastasis-directed stereotactic ablative radiation who underwent PSMA-PET/computed tomography (CT) before and after (median, 6.2 months; range, 2.4-10.9 months) treatment. Pre- and post-MDT PSMA-PET/CT maximum standardized uptake value (SUVmax) was measured for all lesions, and PSMA response was defined as the percent change in SUVmax of the least responsive lesion. PSMA response was both evaluated as a continuous variable and dichotomized into PSMA responders, with a complete/partial response (at least a 30% reduction in SUVmax), and PSMA nonresponders, with stable/progressive disease (less than a 30% reduction in SUVmax). PSMA response was correlated with conventional imaging-defined metastasis-free survival (MFS) via Kaplan-Meier and Cox regression analysis.

RESULTS

A total of 131 patients with 261 treated metastases were included in the analysis, with a median follow-up of 29 months (IQR, 18.5-41.3 months). After stereotactic ablative radiation, 70.2% of patients were classified as PSMA responders. Multivariable analysis demonstrated that PSMA response as a continuous variable was associated with a significantly worse MFS (hazard ratio = 1.003; 95% CI, 1.001-1.006; P = .016). Patients classified as PSMA responders were found to have a significantly improved median MFS of 39.9 versus 12 months (P = .001) compared with PSMA nonresponders. Our study is limited as it is a retrospective review of a heterogenous population.

CONCLUSIONS

After stereotactic ablative radiation, PSMA-PET response appears to be a radiographic biomarker that correlates with MFS in omCSPC. This approach holds promise for guiding clinical management of omCSPC and should be validated in a prospective setting.

Impact of Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography on Prostate Cancer Salvage Radiotherapy Management: Results from a Prospective Multicenter Randomized Phase 3 Trial (PSMA-SRT NCT03582774)

BACKGROUND AND OBJECTIVE

Both imaging and several prognostic factors inform the planning of salvage radiotherapy (SRT). Prostate-specific membrane antigen positron emission tomography (PSMA-PET) can localize disease unseen by other imaging modalities. The main objective of the study was to evaluate the impact of PSMA-PET on biochemical recurrence-free survival rate after SRT.

METHODS

This prospective randomized, controlled, phase 3 clinical trial randomized 193 patients with biochemical recurrence of prostate cancer after radical prostatectomy to proceed with SRT (control arm, n = 90) or undergo a PSMA-PET/computed tomography (CT) scan prior to SRT planning (investigational arm, n = 103) from June 2018 to August 2020. Any other approved imaging modalities were allowed in both arms (including fluciclovine-PET). This is a secondary endpoint analysis: impact of PSMA-PET on SRT planning. Case-report forms were sent to referring radiation oncologists to collect the management plans before randomization and after completion of SRT. The relative frequency (%) of management changes within each arm were compared using chi-square and Fisher's exact tests.

KEY FINDINGS AND LIMITATIONS

The delivered SRT plan was available in 178/193 patients (92.2%;76/90 control [84.4%] and 102/103 PSMA-PET [99%]). Median prostate-specific antigen levels at enrollment was 0.30 ng/ml (interquartile range [IQR] 0.19-0.91) in the control arm and 0.23 ng/ml (IQR 0.15-0.54) in the PSMA-PET arm. Fluciclovine-PET was used in 33/76 (43%) in the control arm. PSMA-PET localized recurrence(s) in 38/102 (37%): nine of 102 (9%) outside of the pelvis (M1), 16/102 (16%) in the pelvic LNs (N1, with or without local recurrence), and 13/102 (13%) in the prostate fossa only. There was a 23% difference (95% confidence interval [CI] 9-35%, p = 0.002) of frequency of major changes between the control arm (22% [17/76]) and the PSMA-PET intervention arm (45%[46/102]). Of the major changes in the intervention group, 33/46 (72%) were deemed related to PSMA-PET. There was a 17.6% difference (95% CI 5.4-28.5%, p = 0.005) of treatment escalation frequency between the control arm (nine of 76 [12%]) and the intervention arm (30/102 [29%]). Treatment de-escalation occurred in the control and intervention arms in eight of 76 (10.5%) and 12/102 (11.8%) patients, and mixed changes in zero of 76 (0%) and four of 102 (3.9%) patients, respectively.

CONCLUSIONS AND CLINICAL IMPLICATIONS

In this prospective randomized phase 3 study, PSMA-PET findings provided information that initiated major management changes to SRT planning in 33/102 (33%) patients. The final readout of the primary endpoint planned in 2025 may provide evidence on whether these changes result in improved outcomes.

PATIENT SUMMARY

Prostate-specific membrane antigen positron emission tomography leads to management changes in one-third of patients receiving salvage radiotherapy for post-radical prostatectomy biochemical recurrence of prostate cancer.

[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.

Randomized Trial of Prostate-Specific Membrane Antigen PET/CT Before Definitive Radiotherapy for Unfavorable Intermediate- and High-Risk Prostate Cancer (PSMA-dRT Trial)

This multicenter randomized phase III trial (NCT04457245) evaluated the effect of performing prostate-specific membrane antigen (PSMA) PET/CT before definitive radiotherapy. Methods: Men with unfavorable intermediate- or high-risk prostate cancer were randomized 1.08:1 between receiving and not receiving a PSMA PET/CT scan before definitive radiotherapy. All other imaging modalities were allowed in the control arm. The primary endpoint was 5-y progression-free survival. Results: Fifty-four men were randomized between November 2020 and December 2021 (PSMA PET/CT, n = 25; control, n = 29). The trial closed early after approval and insurance coverage of PSMA PET/CT. In the PSMA PET/CT arm, 14 patients had localized disease (miT2b-cN0M0), 6 had locally advanced disease (miT3a-bN0M0), 3 had regional metastasis (miN1M0), and 1 had distant metastasis (miM1b). Four patients were upstaged. Conclusion: PSMA PET/CT upstaged 17% of patients, which allowed for more accurate radiotherapy planning. Unfortunately, this trial closed early before completion of target enrollment (54/316, 17%) and was underpowered to assess the effect of PSMA PET/CT on progression-free survival.

Combined whole-body dynamic and static PET/CT with low-dose [18F]PSMA-1007 in prostate cancer patients

AIM

In addition to significant improvements in sensitivity and image quality, the recent introduction of long axial field-of-view (LAFOV) PET/CT scanners has enabled dynamic whole-body imaging for the first time. We aim herein to determine an appropriate acquisition time range for static low-dose [18F]PSMA-1007 PET imaging and to investigate the whole-body pharmacokinetics of [18F]PSMA-1007 by dynamic PET with the LAFOV Biograph Vision Quadra PET/CT in a group of prostate cancer patients.

METHODOLOGY

In total, 38 prostate cancer patients were enrolled in the analysis for staging or re-staging purposes. Thirty-four patients underwent dynamic whole-body PET/CT (60 min) followed by static whole-body PET/CT and four patients underwent static whole-body PET/CT only. The activity applied was 2 MBq/kg [18F]PSMA-1007. The static PET images of 10-min duration (PET-10) were reconstructed and further split into 8-min (PET-8), 6-min (PET-6), 5-min (PET-5), 4-min (PET-4), and 2-min (PET-2) duration groups. Comparisons were made between the different reconstructed scan times in terms of lesion detection rate and image quality based on SUV calculations of tumor lesions and the spleen, which served as background. Analysis of the dynamic PET/CT data was based on a two-tissue compartment model using an image-derived input function obtained from the descending aorta.

RESULTS

Analysis of lesion detection rate showed no significant differences when reducing PET acquisitions from 10 up to 5 min. In particular, a total of 169 lesions were counted with PET-10, and the corresponding lesion detection rates (95% CI for the 90% quantile of the differences in tumor lesions) for shorter acquisitions were 100% (169/169) for PET-8 (95% CI: 0-0), 98.8% (167/169) for PET-6 (95% CI: 0-1), 95.9% (162/169) for PET-5 (95% CI: 0-3), 91.7% (155/169) for PET-4 (95% CI: 1-2), and 85.2% (144/169) for PET-2 (95% CI: 1-6). With the exception of PET-2, the differences observed between PET-10 and the other shorter acquisition protocols would have no impact on any patient in terms of clinical management. Objective evaluation of PET/CT image quality showed no significant decrease in tumor-to-background ratio (TBR) with shorter acquisition times, despite a gradual decrease in signal-to-noise ratio (SNR) in the spleen. Whole-body quantitative [18F]PSMA-1007 pharmacokinetic analysis acquired with full dynamic PET scanning was feasible in all patients. Two-tissue compartment modeling revealed significantly higher values for the parameter k3 in tumor lesions and parotid gland compared to liver and spleen, reflecting a higher specific tracer binding to the PSMA molecule and internalization rate in these tissues, a finding also supported by the respective time-activity curves. Furthermore, correlation analysis demonstrated a significantly strong positive correlation (r = 0.72) between SUV and k3 in tumor lesions.

CONCLUSIONS

In prostate cancer, low-dose (2 MBq/kg) [18F]PSMA-1007 LAFOV PET/CT can reduce static scan time by 50% without significantly compromising lesion detection rate and objective image quality. In addition, dynamic PET can elucidate molecular pathways related to the physiology of [18F]PSMA-1007 in both tumor lesions and normal organs at the whole-body level. These findings unfold many of the potentials of the new LAFOV PET/CT technology in the field of PSMA-based diagnosis and theranostics of prostate cancer.

Predictive Value of Multiparametric Magnetic Resonance Imaging in Risk Group Stratification of Prostate Adenocarcinoma

Purpose

The aim of this study was to further assess the clinical utility of multiparametric magnetic resonance imaging (MP-MRI) in prostate cancer (PC) staging following 2023 clinical guideline changes, both as an independent predictor of high-stage (>T3a) or high-risk PC and when combined with patient characteristics.

Methods and Materials

The present study was a retrospective review of 171 patients from 2008 to 2018 who underwent MP-MRI before radical prostatectomy at a single institution. The accuracy of clinical staging was compared between conventional staging and MP-MRI-based clinical staging. Sensitivity, specificity, positive predictive value, and negative predictive value were compared, and receiver operating characteristic curves were generated. Linear regression analyses were used to calculate concordance (C-statistic).

Results

Of the 171 patients, final pathology revealed 95 (55.6%) with T2 disease, 62 (36.3%) with T3a disease, and 14 (8.2%) with T3b disease. Compared with conventional staging, MP-MRI-based staging demonstrated significantly increased accuracy in identifying T3a disease, intermediate risk, and high/very-high-risk PC. When combined with clinical characteristics, MP-MRI-based staging improved the area under the curve from 0.753 to 0.808 (P = .0175), compared with conventional staging.

Conclusions

MP-MRI improved the identification of T3a PC, intermediate-risk PC, and high- or very-high-risk PC. Further, when combined with clinical characteristics, MP-MRI-based staging significantly improved risk stratification, compared with conventional staging. These findings represent further evidence to support the integration of MP-MRI into prostate adenocarcinoma clinical staging guidelines.

Implementation of PSMA PET/CT and alignment of ordering to SNMMI appropriate use criteria in a large network system

INTRODUCTION

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) provides appropriate use criteria (AUC) for prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) which include guidance on imaging in newly diagnosed prostate cancer and in patients with biochemically recurrent (BCR) disease. This study aims to examine trends in PSMA implementation and the prevalence and outcomes of scans ordered in scenarios deemed rarely appropriate or not meeting SNMMI AUC.

METHODS

We retrospectively identified patients who were diagnosed with presumptive National Comprehensive Cancer Network unfavorable intermediate, high, or very high risk prostate cancer, patients who underwent staging for BCR, and all patients staged with PSMA between July 2021 and March 2023. Positivity was validated by adherence to a predetermined reference standard.

RESULTS

The frequency of PSMA use increased in initial staging from 24% to 80% and work-up of BCR from 91% to 99% over our study period. In addition, 5% (17/340) of PSMA scans ordered for initial staging did not meet AUC and 3% (15/557) of posttreatment scans were deemed rarely appropriate. Initial staging orders not meeting SNMMI AUC resulted in no positivity (0/17), while rarely appropriate posttreatment scans were falsely positive in 75% (3/4) of cases. Urologists (53%, 17/32) comprised the largest ordering specialty in rarely appropriate use.

CONCLUSION

The frequency of PSMA use rose across the study period. A significant minority of patients received PSMA PET/CT in rarely appropriate scenarios yielding no positivity in initial staging and significant false positivity post-therapy. Further education of providers and electronic medical record-based interventions could help limit the rarely appropriate use of PET imaging.

Prostate cancer: nuclear medicine imaging in the biochemical recurrence and in oligometastatic disease

INTRODUCTION

The aim of this article was to offer a comprehensive non-systematic review of the literature about the use of Nuclear Medicine imaging exams for the evaluation of prostate cancer (PCa) in the recurrent setting, with a particular regard to positron emission tomography/computed tomography (PET/CT) imaging.

EVIDENCE ACQUISITION

A comprehensive nonsystematic literature review was performed in March 2024. Literature search was updated until March 2024. The most relevant studies have been summarized, giving priority to registered clinical trials and multicenter collaborations.

EVIDENCE SYNTHESIS

Restaging BCR with advanced Nuclear Medicine Imaging, such as prostate-specific membrane antigen-PET/CT could lead to stage migration and pave the way for additional management strategies, such as stereotactic ablative radiotherapy in patients with low-burden or oligometastatic disease, potentially delaying the need of systemic therapies. While OS benefits of targeting PET/CT positive disease are still lacking, data on progression- and metastasis-free-survival are emerging. Improvements in quality-of-life assessments are already evident.

CONCLUSIONS

PCa is one of the most common malignancy in men. In the last 10 years PCa imaging has become significantly more accurate and is now essential for the definition of the extent of the disease in different phases of its natural history. This opened the road to novel management strategies, especially in the recurrent setting, in which the oligometastatic state is now being explored in several trials regarding the prognostic significance of metastasis directed therapies aimed at personalizing the treatment for every single patient.

Application of next-generation imaging in biochemically recurrent prostate cancer

BACKGROUND

Biochemical recurrence (BCR) following primary interventional treatment occurs in approximately one-third of patients with prostate cancer (PCa). Next-generation imaging (NGI) can identify local and metastatic recurrence with greater sensitivity than conventional imaging, potentially allowing for more effective interventions. This narrative review examines the current clinical evidence on the utility of NGI for patients with BCR.

METHODS

A search of PubMed was conducted to identify relevant publications on NGI applied to BCR. Given other relevant recent reviews on the topic, this review focused on papers published between January 2018 to May 2023.

RESULTS

NGI technologies, including positron emission tomography (PET) radiotracers and multiparametric magnetic resonance imaging, have demonstrated increased sensitivity and selectivity for diagnosing BCR at prostate-specific antigen (PSA) concentrations <2.0 ng/ml. Detection rates range between 46% and 50%, with decreasing PSA levels for choline (1-3 ng/ml), fluciclovine (0.5-1 ng/ml), and prostate-specific membrane antigen (0.2-0.49 ng/ml) PET radiotracers. Expert working groups and European and US medical societies recommend NGI for patients with BCR.

CONCLUSIONS

Available data support the improved detection performance and selectivity of NGI modalities versus conventional imaging techniques; however, limited clinical evidence exists demonstrating the application of NGI to treatment decision-making and its impact on patient outcomes. The emergence of NGI and displacement of conventional imaging may require a reexamination of the current definitions of BCR, altering our understanding of early recurrence. Redefining the BCR disease state by formalizing the role of NGI in patient management decisions will facilitate greater alignment across research efforts and better reflect the published literature.

PET Imaging of Metabolism, Perfusion, and Hypoxia: FDG and Beyond

ABSTRACT

Imaging glucose metabolism with [18F]fluorodeoxyglucose positron emission tomography has transformed the diagnostic and treatment algorithms of numerous malignancies in clinical practice. The cancer phenotype, though, extends beyond dysregulation of this single pathway. Reprogramming of other pathways of metabolism, as well as altered perfusion and hypoxia, also typifies malignancy. These features provide other opportunities for imaging that have been developed and advanced into humans. In this review, we discuss imaging metabolism, perfusion, and hypoxia in cancer, focusing on the underlying biology to provide context. We conclude by highlighting the ability to image multiple facets of biology to better characterize cancer and guide targeted treatment.

Impact of Circulating Tumor Cell-Expressed Prostate-Specific Membrane Antigen and Prostate-Specific Antigen Transcripts in Different Stages of Prostate Cancer

PURPOSE

Prostate-specific membrane antigen (PSMA)-based images, which visually quantify PSMA expression, are used to determine prostate cancer micrometastases. This study evaluated whether a circulating tumor cell (CTC)-based transcript platform, including PSMA mRNA, could help identify potential prognostic markers in prostate cancer.

EXPERIMENTAL DESIGN

We prospectively enrolled 21 healthy individuals and 247 patients with prostate cancer [localized prostate cancer (LPCa), n = 94; metastatic hormone-sensitive prostate cancer (mHSPC), n = 44; and metastatic castration-resistant prostate cancer (mCRPC), n = 109]. The mRNA expression of six transcripts [PSMA, prostate-specific antigen (PSA), AR, AR-V7, EpCAM, and KRT 19] from CTCs was measured, and their relationship with biochemical recurrence (BCR) in LPCa and mCRPC progression-free survival (PFS) rate in mHSPC was assessed. PSA-PFS and radiological-PFS were also calculated to identify potential biomarkers for predicting androgen receptor signaling inhibitor (ARSI) and taxane-based chemotherapy resistance in mCRPC.

RESULTS

CTC detection rates were 75.5%, 95.3%, and 98.0% for LPCa, mHSPC, and mCRPC, respectively. In LPCa, PSMA [hazard ratio (HR), 3.35; P = 0.028) and PSA mRNA (HR, 1.42; P = 0.047] expressions were associated with BCR. Patients with mHSPC with high PSMA (HR, 4.26; P = 0.020) and PSA mRNA (HR, 3.52; P = 0.042) expressions showed significantly worse mCRPC-PFS rates than those with low expression. Increased PSA and PSMA mRNA expressions were significantly associated with shorter PSA-PFS and radiological PFS in mCPRC, indicating an association with drug resistance.

CONCLUSIONS

PSMA and PSA mRNA expressions are associated with BCR in LPCa. In advanced prostate cancer, PSMA and PSA mRNA can also predict rapid progression from mHSPC to mCRPC and ARSI or taxane-based chemotherapy resistance.

Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) of prostate cancer: current and emerging applications

Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) is transforming the management of patients with prostate cancer. In appropriately selected patients, PSMA-PET offers superior sensitivity and specificity compared to conventional imaging (e.g., computed tomography and bone scintigraphy) as well as choline and fluciclovine PET, with the added benefit of consolidating bone and soft tissue evaluation into a single study. Despite being a newly available imaging tool, PSMA-PET has established indications, interpretation guidelines, and reporting criteria, which will be reviewed. The prostate cancer care team, from imaging specialists to those delivering treatment, should have knowledge of physiologic PSMA radiotracer uptake, patterns of disease spread, and the strengths and limitations of PSMA-PET. In this review, current and emerging applications of PSMA-PET, including appropriateness use criteria as well as image interpretation and pitfalls, will be provided with an emphasis on clinical implications.

68Ga-RM2 PET-MRI versus MRI alone for evaluation of patients with biochemical recurrence of prostate cancer: a single-centre, single-arm, phase 2/3 imaging trial

BACKGROUND

National Comprehensive Cancer Network guidelines include prostate-specific membrane antigen (PSMA)-targeted PET for detection of biochemical recurrence of prostate cancer. However, targeting a single tumour characteristic might not be sufficient to reflect the full extent of disease. Gastrin releasing peptide receptors (GRPR) have been shown to be overexpressed in prostate cancer. In this study, we aimed to evaluate the diagnostic performance of the GRPR-targeting radiopharmaceutical 68Ga-RM2 in patients with biochemical recurrence of prostate cancer.

METHODS

This single-centre, single-arm, phase 2/3 trial was done at Stanford University (USA). Adult patients (aged ≥18 years) with biochemical recurrence of prostate cancer, a Karnofsky performance status of 50 or higher, increasing prostate-specific antigen concentration 0·2 ng/mL or more after prostatectomy or 2 ng/mL or more above nadir after radiotherapy, and non-contributory conventional imaging (negative CT or MRI, and bone scan) were eligible. All participants underwent 68Ga-RM2 PET-MRI. The primary outcome was the proportion of patients with PET-positive findings on 68Ga-RM2 PET-MRI compared with MRI alone after initial therapy, at a per-patient and per-lesion level. The primary outcome would be considered met if at least 30% of patients had one or more lesions detected by 68Ga-RM2 PET-MRI and the detection by 68Ga-RM2 PET-MRI was significantly greater than for MRI. Each PET scan was interpreted by three independent masked readers using a standardised evaluation criteria. This study is registered with ClinicalTrials.gov, NCT02624518, and is complete.

FINDINGS

Between Dec 12, 2015, and July 27, 2021, 209 men were screened for eligibility, of whom 100 were included in analyses. Median follow-up was 49·3 months (IQR 36·7-59·2). The primary endpoint was met; 68Ga-RM2 PET-MRI was positive in 69 (69%) patients and MRI alone was positive in 40 (40%) patients (p<0·0001). In the per-lesion analysis 68Ga-RM2 PET-MRI showed significantly higher detection rates than MRI alone (143 vs 96 lesions; p<0·0001). No grade 1 or worse events were reported.

INTERPRETATION

68Ga-RM2 PET-MRI showed better diagnostic performance than MRI alone in patients with biochemical recurrence of prostate cancer. Further prospective comparative studies with PSMA-targeted PET are needed to gain a better understanding of GRPR and PSMA expression patterns in these patients.

FUNDING

The US Department of Defense.