Total-Body 68Ga-PSMA-11 PET/CT for Bone Metastasis Detection in Prostate Cancer Patients: Potential Impact on Bone Scan Guidelines

De Novo Metastatic Prostate Cancer Presenting With Atypical Lower-Limb Skeletal Metastases Detected on 68 Ga-PSMA PET/CT

ABSTRACT

Metastatic prostate cancer to the appendicular skeleton is rare. We present an 86-year-old man with undiagnosed prostate cancer presenting with unilateral foot pain. CT and MRI demonstrated a sclerotic midfoot suggestive of an infiltrative process. In view of an elevated PSA, metastatic disease was suspected, and bone scan confirmed osteoblastically active pelvic and lower-limb skeletal lesions. Subsequent prostate biopsy confirmed prostate adenocarcinoma. Staging 68 Ga-PSMA PET/CT demonstrated PSMA-avid intraprostatic malignancy with pelvic and right lower-limb skeletal metastases. This is an unusual case of de novo 68 Ga-PSMA-avid metastatic prostate cancer with atypical lower-limb skeletal metastases presenting with foot pain.

Evaluating appropriateness of 18F-fluciclovine PET/CT relative to standard of care imaging guidelines and the impact of ADT on positivity: a prospective study in 62 Veterans Administration patients at a single institution

BACKGROUND

According to the National Comprehensive Cancer Network Guidelines, 18F-fluciclovine PET/CT is considered appropriate after negative standard of care (SOC) imaging.

OBJECTIVE

To prospectively compare 18F-fluciclovine to SOC imaging, investigate whether it should be done when SOC imaging is (+), and evaluate its detection rate in patients receiving androgen deprivation therapy.

METHODS

We recruited 57 prostate cancer patients with biochemical recurrence with 18F-fluciclovine PET/CT and SOC imaging within 30 days. Prostate-specific antigen (PSA) level, Gleason score (GS), history of radical prostatectomy (RP), radiation therapy (RT) or hormone therapy (HT) were reviewed.

RESULTS

The 57 patients had a median PSA of 2.6 and average GS of 7.4; 27 (47.4%) had RP, 28 (49.1%) had RT, 1 (1.75%) had HT and 1 (1.75%) observation only. 18F-fluciclovine identified disease recurrence in 45/57 patients (78.9%), including oligometastasis in 18/45 (40%). SOC imaging identified recurrent disease in 12/57 patients (21.1%) while 18F-fluciclvoine identified additional sites of disease in 11/12 (91.7%). The (+) 18F-fluciclovine studies had a median PSA 2.6 ng/ml compared to 6.0 ng/ml in the (+) SOC studies.

CONCLUSION

18F-fluciclovine was superior to SOC imaging for lesion detection, identification of oligometastasis and identification of additional sites of disease.

Bone Metastases

ABSTRACT

Bone metastases occur frequently in common malignancies such as breast and prostate cancer. They are responsible for considerable morbidity and skeletal-related events. Fortunately, there are now several systemic, focal, and targeted therapies that can improve quality and length of life, including radionuclide therapies. It is therefore important that bone metastases can be detected as early as possible and that treatment can be accurately and sensitively monitored. Several bone-specific and tumor-specific single-photon emission computed tomography and positron emission tomography molecular imaging agents are available, for detection and monitoring response to systemic therapeutics, as well as theranostic agents to confirm target expression and predict response to radionuclide therapies.

Predictive value of volumetric parameters based on 18F-PSMA-1007 PET/CT for prostate cancer metastasis

Purpose of the report

To explore the value of 18F-labeled prostate-specific membrane antigen (PSMA-1007) positron emission tomography (PET)/computed tomography (CT), the maximum standardized uptake value (SUVmax) of the primary tumor, prostate PSMA-tumor volume (PSMA-TVp), and prostate total lesion PSMA (TL-PSMAp) for predicting prostate cancer (PCa) metastasis and follow-up evaluation in primary PCa lesions.

Materials and methods

18F-PSMA-1007 PET/CT data of 110 consecutive newly diagnosed PCa patients were retrospectively analyzed. Patients were divided into non-metastatic, oligometastatic, and extensive metastatic groups. The predictive power was assessed using the receiver operating characteristic curve. Multi-group one-way analysis of variance and post-hoc tests were used to compare the groups. Patients were monitored post-therapy to evaluate treatment effectiveness.

Results

Among the 110 patients, 66.4% (73) had metastasis (29 oligometastatic, 44 extensive metastasis). AUCs for Gleason score (GS), total prostate-specific antigen(TPSA), SUVmax, TL-PSMAp, and PSMA-TVp were 0.851, 0.916, 0.834, 0.938, and 0.923, respectively. GS, TPSA, SUVmax, TL-PSMAp, and PSMA-TVp were significantly different among the groups. In the post-hoc tests, differences in GS, TPSA, SUVmax, TL-PSMAp, and PSMA-TVp between the non-metastatic and oligometastatic groups and non-metastatic and extensive metastatic groups were significant (P<0.010). Differences in TL-PSMAp and PSMA-TVp between oligometastatic and extensive metastatic groups were significant (P=0.039 and 0.015, respectively), while those among GS, TPSA, and SUVmax were not. TL-PSMAp and PSMA-TVp distinguished between oligometastatic and extensive metastases, but GS, TPSA, and SUVmax did not. In individuals with oligometastasis, the implementation of active treatment for both primary and metastatic lesions may result in a more favorable prognosis.

Conclusions

18F-PSMA-1007 PET/CT volumetric parameters PSMA-TVp and TL-PSMAp can predict PCa oligometastasis.

Machine Learning and Radiomics of Bone Scintigraphy: Their Role in Predicting Recurrence of Localized or Locally Advanced Prostate Cancer

BACKGROUND

Machine-learning (ML) and radiomics features have been utilized for survival outcome analysis in various cancers. This study aims to investigate the application of ML based on patients' clinical features and radiomics features derived from bone scintigraphy (BS) and to evaluate recurrence-free survival in local or locally advanced prostate cancer (PCa) patients after the initial treatment.

METHODS

A total of 354 patients who met the eligibility criteria were analyzed and used to train the model. Clinical information and radiomics features of BS were obtained. Survival-related clinical features and radiomics features were included in the ML model training. Using the pyradiomics software, 128 radiomics features from each BS image's region of interest, validated by experts, were extracted. Four textural matrices were also calculated: GLCM, NGLDM, GLRLM, and GLSZM. Five training models (Logistic Regression, Naive Bayes, Random Forest, Support Vector Classification, and XGBoost) were applied using K-fold cross-validation. Recurrence was defined as either a rise in PSA levels, radiographic progression, or death. To assess the classifier's effectiveness, the ROC curve area and confusion matrix were employed.

RESULTS

Of the 354 patients, 101 patients were categorized into the recurrence group with more advanced disease status compared to the non-recurrence group. Key clinical features including tumor stage, radical prostatectomy, initial PSA, Gleason Score primary pattern, and radiotherapy were used for model training. Random Forest (RF) was the best-performing model, with a sensitivity of 0.81, specificity of 0.87, and accuracy of 0.85. The ROC curve analysis showed that predictions from RF outperformed predictions from other ML models with a final AUC of 0.94 and a p-value of <0.001. The other models had accuracy ranges from 0.52 to 0.78 and AUC ranges from 0.67 to 0.84.

CONCLUSIONS

The study showed that ML based on clinical features and radiomics features of BS improves the prediction of PCa recurrence after initial treatment. These findings highlight the added value of ML techniques for risk classification in PCa based on clinical features and radiomics features of BS.

Comparison of Diagnostic Value between 99mTechnetium-Methylene Diphosphate Bone Scan and 99mTechnetium-Prostate-specific Membrane Antigen Scan in Patients with Prostate Cancer with Osseous Metastases

Background

Prostate cancer (PCa) ranks as the second most prevalent cancer among men globally. The utilization of efficient and cost-effective diagnostic and therapeutic approaches holds paramount importance in the diagnosis and treatment of these patients, significantly impacting treatment outcomes. This study focuses on the investigation and comparison of two commonly employed scans within the treatment process for these patients.

Methods

In this prospective study, which spanned over 2 years, 40 patients diagnosed with PCa underwent examination using two scans: 99m Technetium-Prostate-specific Membrane Antigen (99mTC-PSMA) Scan and between Technetium-Methylene Diphosphate (99mTC-MDP) Bone Scan. The findings of these scans were then compared with each other, as well as with the results obtained from magnetic resonance imaging and the prostate-specific antigen level. The analysis of the results was conducted utilizing SPSS 22 software, and descriptive statistical methods were employed to present the findings.

Results

In this prospective study, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the 99mTC-MDP Bone Scan were found to be 88.2%, 83.3%, 96.7%, 55.5%, and 87.5%, respectively. Similarly, for the 99mTC-PSMA Scan, the corresponding values were 94.1%, 83.3%, 96.4%, 83.3%, and 92.5%, respectively.

Conclusions

Based on the findings of this study, it can be concluded that the diagnostic accuracy of the 99mTC-PSMA Scan is marginally higher compared to the 99mTC-MDP Bone Scan. Therefore, for patients who are limited to only one scan, the 99mTC-PSMA Scan appears to be the preferable choice.

Unambiguous radiologic extranodal extension determined by MRI could be a biomarker in predicting metastatic prostate cancer

OBJECTIVE

To explore the relationship between unambiguous radiologic extranodal extension (rENE) and M1 staging in patients with metastatic PCa.

METHODS

A respective analysis of 1073 patients of PCa N1 staging from January 2004 to May 2022 was retrospectively enrolled. They were divided into rENE + and rENE -  groups and retrospectively analyzed the M staging with nuclear medicine data. The correlation index between unambiguous rENE and M1b staging was calculated. Logistic regression was used to evaluate the predictive performance of unambiguous rENE in M1b staging. ROC curves were used to investigate the relationship between unambiguous rENE and M staging in patients who underwent ⁶⁸ Ga-PSMA PET/CT.

RESULTS

A total of 1073 patients were included. Seven hundred and eighty patients were classified into the rENE + group (mean age, 69.6 years ± 8.7 [standard deviation]), and 293 were classified into rENE -  group (mean age, 66.7 years ± 9.4 [standard deviation]). Relationship between unambiguous rENE and M1b existed (r = 0.58, 95%CI: 0.52-0.64, P < 0.05). Unambiguous rENE could be an independent predictor for M1b (OR = 13.64, 95%CI: 9.23-20.14, P < 0.05). The AUC of unambiguous rENE in predicting M1b and M staging was 0.835 and 0.915, respectively, in patients who underwent ⁶⁸ Ga-PSMA PET/CT.

CONCLUSIONS

Unambiguous rENE could be a strong biomarker to predict M1b and M staging in patients with PCa. When rENE came up, patients should perform nuclear medicine immediately, and a systematic treatment should be considered.

Peptide Modification Diminishes HLA Class II-restricted CD4+ T Cell Recognition of Prostate Cancer Cells

Prostate cancer poses an ongoing problem in the western world accounting for significant morbidity and mortality in the male population. Current therapy options are effective in treating most prostate cancer patients, but a significant number of patients progress beyond a manageable disease. For these patients, immunotherapy has emerged as a real option in the treatment of the late-stage metastatic disease. Unfortunately, even the most successful immunotherapy strategies have only led to a four-month increase in survival. One issue responsible for the shortcomings in cancer immunotherapy is the inability to stimulate helper CD4⁺ T cells via the HLA class II pathway to generate a potent antitumor response. Obstacles to proper HLA class II stimulation in prostate cancer vaccine design include the lack of detectable class II proteins in prostate tumors and the absence of defined class II specific prostate tumor antigens. Here, for the first time, we show that the insertion of a lysosomal thiol reductase (GILT) into prostate cancer cells directly enhances HLA class II antigen processing and results in increased CD4⁺ T cell activation by prostate cancer cells. We also show that GILT insertion does not alter the expression of prostate-specific membrane antigen (PSMA), an important target in prostate cancer vaccine strategies. Our study suggests that GILT expression enhances the presentation of the immunodominant PSMA₄₅₉ epitope via the HLA class II pathway. Biochemical analysis showed that the PSMA₄₅₉ peptide was cysteinylated under a normal physiologic concentration of cystine, and this cysteinylated form of PSMA₄₅₉ inhibited T cell activation. Taken together, these results suggest that GILT has the potential to increase HLA class II Ag presentation and CD4⁺ T cell recognition of prostate cancer cells, and GILT-expressing prostate cancer cells could be used in designing cell therapy and/or vaccines against prostate cancer.

Prostate-Specific Membrane Antigen-Based PET Brings New Insights into the Management of Prostate Cancer

Prostate cancer (PCa) is the third most common cancer diagnosed in the world. Since its first identification in 1987 and its first molecular cloning in 1993, prostate-specific membrane antigen (PSMA) has been developed as a theragnostic imaging biomarker and therapeutic agent for PCa. For metastatic castration-resistant PCa, PSMA-based PET imaging can be applied to the monitoring of disease and response assessment with PSMA-based therapeutics. This novel imaging modality is bringing new insights into diagnosis, stratification, and clinical decision-making and treatment.

A nomogram for accurately predicting the pathological upgrading of prostate cancer, based on 68 Ga-PSMA PET/CT

PURPOSE

To develop and validate a nomogram for preoperative predicting the pathological upgrading of prostate cancer (PCa).

METHODS

The prediction model was developed in a primary cohort that consisted of 208 PCa patients. All patients included in the study possessed both biopsy pathology specimens and radical prostatectomy pathology specimens, and completed the (⁶⁸ Ga-prostate-specific membrane antigen [PSMA]) positron emission tomography/computed tomography (PET/CT) detection. The R function "createDataPartition" was used in a 7:3 ratio to randomly divide the patients into training and validation cohorts. In the training cohort, the independent predictors of pathological upgrading of PCa were determined by univariate analysis, univariate regression analysis and multivariate regression analysis. Based on these independent predictors, a nomogram was developed, and its performance was evaluated by receiver operating characteristic (ROC) curve, area under the curve (AUC) and calibration curve of training cohort and validation cohort.

RESULTS

The nomogram incorporated five independent predictors including prostate volume (PV), SUV_max of the ⁶⁸ Ga-PSMA PET/CT examination on prostate lesions (SUV_max ), body mass index (BMI); percentage of cancer positive biopsy cores (PPC) and biopsy International Society of Urological Pathology (ISUP) grade. The nomogram showed good diagnostic accuracy for the pathological upgrading of both the training cohort and the validation cohort (AUC = 0.818 and 0.806, respectively). The calibration curves for the two cohorts both showed optimal agreement between nomogram prediction and actual observation.

CONCLUSIONS

We developed and validated a nomogram to accurately predict the risk of pathological upgrading after radical PCa surgery, which can provide accurate basis for therapeutic schedule and prognostic data of PCa patients.

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

Simple Summary

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

Abstract

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

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

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

Head-to-Head Comparison of 68Ga-PSMA-11 PET/CT and 99mTc-MDP Bone Scintigraphy for the Detection of Bone Metastases in Patients With Prostate Cancer: A Meta-Analysis

Background: Bone scintigraphy (BS) using 99mTc-MDP remains the recommended imaging modality for the detection of bone metastases in patients with prostate cancer (PCa). However, PET/CT using prostate-specific membrane antigen (PSMA) ligands is increasingly recognized for evaluating disease extent in patients with PCa, including as a possible standalone test in high-risk patients. Objective: To compare the diagnostic performance of 68Ga-PSMA-PET/CT and 99mTc-MDP BS for the detection of bone metastases in patients with PCa. Evidence Acquisition: PubMed, Embase, and Cochrane Library databases were searched through October 2021 for studies reporting a head-to-head comparison of 68Ga-PSMA-PET/CT and 99mTc-MDP BS for the detection of bone metastases in patients with PCa. Only studies with a well-defined reference standard (including various combinations of imaging and/or clinical follow-up) were included. Pooled diagnostic performance was calculated using bivariate random-effects model, and AUC was derived for each test from hierarchical summary ROC analysis. The two tests' complementary roles in identifying bone metastases in patients in whom the other test was negative were summarized. Evidence Synthesis: Six studies with 546 patients were included. The pooled sensitivity and specificity were 98% (95% CI: 94%-99%) and 97% (95% CI: 91%-99%) for 68Ga-PSMA-11 PET/CT versus 83% (95% CI: 69%-91%) and 68% (95% CI: 41%-87%) for 99mTc-MDP BS. The AUC was 0.99 (95% CI: 0.96-1.00) for 68Ga-PSMA-11 PET/CT and 0.85 (95% CI: 0.81-0.87) for 99mTc-MDP BS. In 408 patients from five included studies, 68Ga-PSMA-11 PET/CT correctly identified bone metastases in 43 (22.3%) of 193 patients with negative 99mTc-MDP BS results, whereas 99mTc-MDP BS correctly identified bone metastases in 4 (1.9%) of 210 patients with negative 68Ga-PSMA-11 PET/CT results. Conclusion: On a per-patient basis, 68Ga-PSMA-11 PET/CT has superior diagnostic performance than 99mTc-MDP BS for the detection of prostate cancer bone metastases. Furthermore, 99mTc-MDP BS offers limited additional information in patients with negative 68Ga-PSMA-11 PET/CT results. Clinical impact: According to current evidence, 99mTc-MDP BS is highly unlikely to be additive to 68Ga-PSMA-11 PET/CT in identifying bone metastases in patients with prostate cancer.

Hematologic toxicity profile and efficacy of [225Ac]Ac-PSMA-617 α-radioligand therapy of patients with extensive skeletal metastases of castration-resistant prostate cancer

PURPOSE

Actinium-225-labeled prostate-specific membrane antigen ([²²⁵Ac]Ac-PSMA-617) is safe and effective in the treatment of metastatic castration-resistant prostate cancer (mCRPC). No study has specifically assessed its safety in patients with extensive skeletal metastases of mCRPC. We aimed to investigate the hematologic toxicity and efficacy of [²²⁵Ac]Ac-PSMA-617 therapy in patients with extensive skeletal metastases of mCRPC.

METHODS

We retrospectively reviewed the medical record of patients treated with [²²⁵Ac]Ac-PSMA-617 for mCRPC. We included patients with a superscan pattern of skeletal metastases and those with 20 or more multifocal sites of skeletal metastases on baseline [⁶⁸ Ga]Ga-PSMA-11 PET/CT. We reviewed the levels of hemoglobin, white blood cell (WBC), and platelet prior to each cycle of treatment and determined the presence of impaired bone marrow function at baseline and the grade of toxicity in the hematologic parameters induced by treatment. We evaluated the predictors of hematologic toxicity using binary logistic regression analysis. We also determined the presence of renal dysfunction before or during treatment. We assessed response to treatment using prostate-specific antigen response and the progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 106 patients were included. Skeletal metastasis was in the superscan pattern in 34 patients (32.1%) and multifocal in 72 patients (67.9%). The median treatment cycle was 4 (range = 1-9). Ninety-eight patients (92.5%) had abnormal baseline hematologic parameters. One patient had grade 4 thrombocytopenia. Grade 3 anemia, leukopenia, and thrombocytopenia were seen in 1 (0.9%), 3 (2.8%), and 2 (1.9%) patients, respectively. Age, the number of treatment cycles, and the presence of renal dysfunction were significant predictors of hematologic toxicity. Eighty-five patients (80.2%) achieved PSA response. The median PFS and OS of the study population were 14:00 (95%CI: 8.15-19.86) months and 15.0 (95%CI: 12.8-17.2) months, respectively.

CONCLUSIONS

[²²⁵Ac]Ac-PSMA-617 induces a good anti-tumor effect in about 80% of patients with extensive skeletal metastases of mCRPC with a rare incidence of severe hematologic toxicity. Age, number of treatment cycles, and the presence of renal dysfunction were significant risk factors for hematologic toxicity of [²²⁵Ac]Ac-PSMA-617 therapy.

Prostate-specific membrane antigen modulates the progression of prostate cancer by regulating the synthesis of arginine and proline and the expression of androgen receptors and Fos proto-oncogenes

The expression of prostate-specific membrane antigen (PSMA) is strikingly upregulated during oncogenesis and prostate cancer (PCa) progression, but the functions of this antigen in PCa remain unclear. Here, we constructed PSMA-knockdown LNCaP and 22rv1 cell lines and performed metabonomic and transcriptomic analyses to determine the effects of PSMA on PCa metabolism and transcription. The metabolism of arginine and proline was detected using specific kits. The mRNA and protein expression levels of the identified differentially expressed genes were quantified by RT-qPCR and Western blotting. The proliferation of each cell line was evaluated through CCK-8, EdU and colony formation assays. The migration and invasion abilities of each cell line were detected using wound healing and transwell assays, respectively. PSMA knockdown led to metabolic disorder and abnormal transcription in PCa and resulted in inhibition of the proliferation and metastasis of PCa cells in vitro and in vivo. The depletion of PSMA also promoted the biosynthesis of arginine and proline, inhibited the expression of AR and PSA, and induced the expression of c-Fos and FosB. PSMA plays an important role in the metabolism, proliferation and metastasis of human PCa and may be a promising therapeutic target.

Primary staging in patients with intermediate- and high-risk prostate cancer: Multiparametric MRI and 68Ga-PSMA-PET/MRI - What is the value of quantitative data from multiparametric MRI alone or in conjunction with clinical information?

PURPOSE

Comparing mpMRI and ⁶⁸Ga-PSMA-PET/MRI in primary staging of PCa and investigating the value of quantitative mpMRI-measurements for prediction of extracapsular extension and N-metastases.

METHODS

Patients with PCa undergoing ⁶⁸Ga-PSMA-PET/MRI and mpMRI during January 2016 to February 2019 were retrospectively included. Two readers each on ⁶⁸Ga-PSMA-PET/MRI or mpMRI rated extraprostatic extension (≥T3) and regional lymph-node-metastasis (N1) on a Likert-scale. A fifth reader measured tumor volume, maximum diameter, and capsular contact length on mpMRI. Probability of lymph-node-metastasis was additionally calculated using the 2018 Briganti model. Interobserver-agreement was assessed by squared Cohen's kappa, and diagnostic accuracy was determined using radical prostatectomy (n = 35/49) as reference standard.

RESULTS

49 patients (median age 66 years [IQR: 61-72 years]) were evaluated. Interobserver-agreement for mpMRI and ⁶⁸Ga-PSMA-PET/MRI was: ≥T3: κ = 0.58/0.47; N1: κ = 0.55/0.92. Diagnostic accuracy for mpMRI vs ⁶⁸Ga-PSMA-PET/MRI readers for ≥ T3 was AUC: 0.72, 0.62 vs 0.71, 0.72 (p > 0.38) and for N1 was AUC: 0.39, 0.55 vs 0.72, 0.78 (p < 0.01). Quantitative parameters delivered diagnostic accuracies of: AUC: 0.70-0.72 for ≥ T3. The 2018 Briganti model achieved an AUC of 0.89 for N1.

CONCLUSIONS

Interreader-agreement regarding ≥ T3 was similar for mpMRI and ⁶⁸Ga-PSMA-PET/MRI while for N1 it was higher for ⁶⁸Ga-PSMA-PET/MRI. Diagnostic accuracy was comparable for ≥ T3 while for N1 it was higher in ⁶⁸Ga-PSMA-PET/MRI and the 2018 Briganti model. Combining clinical data and quantitative data from mpMRI in the 2018 Briganti model yielded the highest AUC for prediction of lymph node metastasis and may aid in selecting patients who will benefit from ⁶⁸Ga-PSMA-PET/MRI for primary staging.

Salvage therapy for prostate cancer after radical prostatectomy

More than 40% of men with intermediate-risk or high-risk prostate cancer will experience a biochemical recurrence after radical prostatectomy. Clinical guidelines for the management of these patients largely focus on the use of salvage radiotherapy with or without systemic therapy. However, not all patients with biochemical recurrence will go on to develop metastases or die from their disease. The optimal pre-salvage therapy investigational workup for patients who experience biochemical recurrence should, therefore, include novel techniques such as PET imaging and genomic analysis of radical prostatectomy specimen tissue, as well as consideration of more traditional clinical variables such as PSA value, PSA kinetics, Gleason score and pathological stage of disease. In patients without metastatic disease, the only known curative intervention is salvage radiotherapy but, given the therapeutic burden of this treatment, importance must be placed on accurate timing of treatment, radiation dose, fractionation and field size. Systemic therapy also has a role in the salvage setting, both concurrently with radiotherapy and as salvage monotherapy.

Anticancer Activity of Sweroside Nanoparticles in Prostate Cancer Bone Metastasis in PC-3 Cells Involved in Wnt/β-Catenin Signaling Pathway

Bone metastasis is a significant cause of morbidity and mortality in patients with prostate cancer (PCa). This study is aimed at illustrating the mechanism of sweroside-mediated regulation in bone metastasis in PCa cells. Owing to the limitations of antitumor drugs in terms of their physical and chemical properties, making them into nanomaterials can effectively improve drug stability and bioavailability. Apoptosis was assessed with flow cytometry using the annexin V/propidium iodide binding assay; proteins, including p53, P21, Bcl-2, and Bax; and induction of intracellular reactive oxygen species (ROS). Using colony formation assay, sphere formation assay, and the expression changes in CD133 and CD44, stem cell characteristics were assessed. Epithelial-mesenchymal transition (EMT) activity was accessed by levels of the expression changes of EMT-related markers, vimentin and E-cadherin. Wnt/β-catenin signaling pathway was examined to detect the levels of the expression changes of snail and β-catenin. PC-3 cells were treated with lithium chloride (LiCl), which is an agonist of Wnt/β-catenin signaling, and the levels of CD133, CD44, vimentin, E-cadherin, snail, and β-catenin were detected. T-cell factor/lymphocyte enhancer factor (TCF/LEF) activity in cells overexpressing β-catenin was used to detect the effects on β-catenin transcription, and the expression of c-myc, Cyclin D1, Survivin, and MMP-7 were used to detect Wnt downstream target genes. Our results suggest that sweroside induces apoptosis and intracellular ROS; upregulates apoptotic proteins; and suppresses proliferation, invasion, and migration, preventing stem cell characteristics, including sphere formation, colony formation, and CD133 and CD44 expressions. Furthermore, sweroside nanoparticles exerts inhibitory effects on β-catenin transcription by suppressing TTCF/LEF activity in cells overexpressing β-catenin and downregulation of the expression of Wnt downstream target genes, including c-myc, Cyclin D1, Survivin, and MMP-7. The potential therapeutic effect of sweroside nanoparticles on bone metastatis of PCa was suggested, by these findings.

Clinical impact of whole-body 68Ga-PSMA I&T PET/CT: lesion frequency and added benefit in lower extremities

AIM

Few small-scaled studies performed systematic analysis of the benefits of extending prostate specific membrane antigen positron-emission tomography/ computed tomography (⁶⁸Ga-PSMA I&T PET/CT) to the lower extremities in prostate cancer (PCa) patients. We hypothesized that ⁶⁸Ga-PSMA I&T PET/CT positive lesions are rare in lower extremities of prostate cancer (PCa) patients, the clinical implication is negligible and may therefore be omitted.

METHODS

We retrospectively analyzed 1,068 PCa patients who received ⁶⁸Ga-PSMA I&T PET/CT in a single institution (2016-2018). Of those, 285 (26.7%) were newly diagnosed, 529 (49.5%) had biochemical recurrence (BCR) and 254 (23.8%) were castration-resistant prostate cancer (CRPC) patients.

RESULTS

Of 1,068 ⁶⁸Ga-PSMA I&T PET/CTs, positive lesions in the lower extremities were identified in 6.9% patients (n=74). Positive lesions in the lower extremities were most common in CRPC patients (19.7%; n=50), followed by newly diagnosed (3.2%; n=9) and BCR (2.8%; n=15) PCa patients. Only 3 patients presented with exclusive lesions in the lower extremities, respectively 0.8% (n=2) in CRPC and 0.4% (n=1) in newly diagnosed PCa. Both CRPC (94.1%, n=47) and BCR (80.0%, n=12) patients with PSMA-positive lesions predominantly received systemic therapy.

CONCLUSION

Identification of lower extremities lesions with PSMA PET/CT is uncommon and exclusive lesions are rare. PSMA PET/CT findings of the lower extremities did not change therapy management. Thus, scanning of the lower extremities can be omitted in standard protocols.

Ring Sclerosis in Prostate Cancer: Circle of Malignancy or Benignity?

ABSTRACT

Prostate cancer osteoblastic metastases may have different morphologies, and some of these may overlap with certain benign bone lesions. In this series of 5 prostate cancer patients, we describe bone lesions with central lucency and surrounding peripheral sclerosis and their varying appearances on different imaging modalities. Although prostate cancer metastases are commonly associated with sclerotic lesions, they can also present as osteolytic or lucent lesions, and these lesions should be carefully evaluated. The findings emphasize the importance of correlation with prior imaging, comparing findings on different imaging techniques and follow-up to differentiate benign disease from metastatic disease in these situations.

68Ga-PSMA-11 PET/CT Follow-Up of Patients with Prostate Cancer with Bone Metastases Who Had Reduced Bone Density after Androgen Deprivation Therapy

Bone metastases from prostate cancer (PCa) often show an increase in density on computed tomography (CT) after successful androgen deprivation therapy (ADT). Density may be reduced, however, as the disease progresses or, contrarily, when disease is no longer active. The current study investigated the role of 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in differentiating between these two conditions. Methods: The study cohort included 15 PCa patients with sclerotic/blastic bone metastasis in whom reduction in bone density of metastasis was noted on follow-up 68Ga-PSMA-11 PET/CT after ADT. Each patient had two PET/CT scans. Prior to the first scan, six patients were castration naïve and nine patients were already treated. All patients had ADT between the two PET/CT scans. PET parameters (SUVmax and tumor-to-background ratio), and CT parameters (HUmax) were determined and compared for each lesion on both scans. Patient’s response was based on prostate-specific antigen (PSA) levels and appearance of new lesions. The Kolmogorov–Smirnov test was used to evaluate normal distribution of the continuous variables. Results: Post-ADT reduction in bone density was identified in 37 lesions. The mean HUmax was 883.9 ± 175.1 on the first scan and 395.6 ± 157.1 on the second scan (p < 0.001). Twenty-one of the 37 lesions showed no increased tracer uptake on the second PET/CT scan raising the likelihood of a response. The other 16 lesions were associated with increased uptake suggestive of an active resistant disease. Bone density was not different in lesions that no longer showed an increased uptake as compared with those that did. Seven of the study patients responded to therapy, and none of the 16 lesions found in these patients showed increased 68Ga-PSMA-11 uptake. In eight patients with progressive disease, all 12 lesions in five of them showed increased 68Ga-PSMA-11 uptake, there was mixed response in two patients (having two lesions with increased uptake and one without) and although all three lesions no longer showed an increased uptake, new lesions were detected in the eighth patient. Conclusion: A decrease in density of bone lesions may reflect clinical progression, or contrarily, a response to therapy in patients with PCa and skeletal involvement treated with ADT. Uptake of 68Ga-PSMA-11 may separate between these two vastly opposing conditions.

Recent Advances in Nanomedicine for the Diagnosis and Treatment of Prostate Cancer Bone Metastasis

Patients with advanced prostate cancer can develop painful and debilitating bone metastases. Currently available interventions for prostate cancer bone metastases, including chemotherapy, bisphosphonates, and radiopharmaceuticals, are only palliative. They can relieve pain, reduce complications (e.g., bone fractures), and improve quality of life, but they do not significantly improve survival times. Therefore, additional strategies to enhance the diagnosis and treatment of prostate cancer bone metastases are needed. Nanotechnology is a versatile platform that has been used to increase the specificity and therapeutic efficacy of various treatments for prostate cancer bone metastases. In this review, we summarize preclinical research that utilizes nanotechnology to develop novel diagnostic imaging tools, translational models, and therapies to combat prostate cancer bone metastases.

[68Ga]Ga-PSMA-11 in prostate cancer: a comprehensive review

Imaging of the prostate-specific membrane antigen (PSMA) has become an important tool for managing patients with recurrent prostate cancer, and one of the most frequently employed radiopharmaceuticals is [68Ga]Ga-PSMA-11. Herein, we summarize the preclinical development and the clinical applications of [68Ga]Ga-PSMA-11 and present side-by-side comparisons with other radiopharmaceuticals or imaging modalities, in order to assist imagers and clinicians in recommending, performing, and interpreting the results of [68Ga]Ga-PSMA-11 PET scans in patients with prostate cancer.

Prospective evaluation of 68Ga-PSMA-11 PET/CT in Chinese men with biochemical recurrence after radical prostatectomy for prostate cancer: relationships between location of recurrence, time after prostatectomy, and serum PSA level

The purpose of this study was to prospectively evaluate the distribution of PSMA-targeted, PET-avid lesions in prostate cancer (PCa) patients with biochemical recurrence in a Chinese cohort. The relationships between PSA levels, disease-free time after prostatectomy, and ⁶⁸Ga-PSMA-11 PET/computed tomography (CT) findings were investigated. Inclusion criteria included histopathologically proven prostate adenocarcinoma, two consecutive PSA levels > 0.20 ng/mL, and negative CT of the abdomen and pelvis or magnetic resonance imaging of the pelvis and whole-body bone scan. Exclusion criteria were non-prostate malignancy within 3 years and persistent PSA after radical prostatectomy. Patients with findings of recurrent disease on re-staging conventional imaging were excluded, as were patients previously treated with systemic therapy and/or salvage therapy. 51 patients were enrolled in this study. 34/51 (66.7%) patients had at least one site of ⁶⁸Ga-PSMA-11 uptake consistent with PCa. 23.5% of patients had recurrence in the prostate bed, 27.4% had pelvic lymph nodes, 15.7% had extrapelvic lymph node metastases, and 17.6% had bone metastases. For patients with lymph node involvement/metastasis, bone metastasis, and patients with both, their median serum PSA levels were 1.83 ng/mL, 2.54 ng/mL, and 4.03 ng/mL, respectively. They were diagnosed with recurrence with a median of 2.06 years, 2.54 years, and 1.15 years after radical prostatectomy, respectively. In this study of Chinese men with biochemical recurrence, added value for the detection of lesions compatible with sites of PCa was found with ⁶⁸Ga-PSMA-11 PET/CT over conventional imaging. The observed patterns of disease spread may have implications for understanding the biology of early prostate cancer metastasis.

Prostate specific membrane antigen positron emission tomography/computed tomography and staging high risk prostate cancer: a non-systematic review of high clinical impact literature

INTRODUCTION

Prostate specific membrane antigen (PSMA) positron emission tomography (PET) with computed tomography (CT) is a promising molecular imaging technique for prostate cancer (PCa). Although not yet included in international guidelines, PSMA PET/CT is commonly used in clinical practice to stage patients with newly diagnosed PCa. This review focuses on the most up-to-date literature on staging high-risk prostate cancer with PSMA PET/CT.

EVIDENCE ACQUISITION

An online based literature research encompassing original studies, reviews and meta-analysis was performed in the month of November of 2019. The most relevant and impactful research was then extracted based on the expertise of the authors, with the specific focus of highlighting the clinical impact and appropriateness of PSMA PET/CT in staging PCa.

EVIDENCE SYNTHESIS

The use of PSMA PET/CT is appropriate in all high-risk patients with newly diagnosed PCa as it will often have a significant clinical impact. Although preliminary findings are promising, there is still a scarcity of data regarding the performance of PSMA PET/CT vs. other modalities in defining disease within the prostate gland. There is good evidence suggesting that PSMA PET/CT may be superior to every other imaging modality in assessing loco-regional and distant metastatic disease.

CONCLUSIONS

PSMA PET/CT has the potential to become a gold standard in staging high risk prostate cancer, providing clinicians with accurate information on the extent of disease within the prostate and the presence of loco-regional and distant metastatic disease within a single scan.

Factors Predicting Metastatic Disease in 68Ga-PSMA-11 PET-Positive Osseous Lesions in Prostate Cancer

Bone is the most common site of distant metastatic spread in prostate adenocarcinoma. Prostate-specific membrane antigen (PSMA) uptake has been described in both benign and malignant bone lesions, which can lead to false-positive findings on ⁶⁸Ga-PSMA-11 PET. The purpose of this study was to evaluate the diagnostic accuracy of ⁶⁸Ga-PSMA-11 PET for osseous prostate cancer metastases and improve bone uptake interpretation using semiquantitative metrics. Methods: Fifty-six prostate cancer patients (18 before prostatectomy and 38 with biochemical recurrence) who underwent ⁶⁸Ga-PSMA-11 PET/MRI or PET/CT examinations with osseous PSMA-ligand uptake were included in the study. Medical records were reviewed retrospectively by board-certified nuclear radiologists to determine true or false positivity based on a composite endpoint. For each avid osseous lesion, we measured biologic volume; size; PSMA Reporting and Data System (RADS) rating; SUV_max; and ratio of lesion SUV_max to liver, blood pool, and background bone SUV_max Differences between benign and malignant lesions were evaluated for statistical significance, and cutoffs for these parameters were determined to maximize diagnostic accuracy. Results: Among 56 participants, 13 (22.8%) had false-positive osseous ⁶⁸Ga-PSMA-11 findings and 43 (76.8%) had true-positive osseous ⁶⁸Ga-PSMA-11 findings. Twenty-two patients (39%) had 1 osseous lesion, 18 (32%) had 2-4 lesions, and 16 (29%) had 5 or more lesions. Cutoffs resulting in statistically significant (P < 0.005) differences between benign and malignant lesions were a PSMA RADS rating of at least 4, an SUV_max of at least 4.1, and SUV_max ratios of at least 2.11 for lesion to blood pool, at least 0.55 for lesion to liver, and at least 4.4 for lesion to bone. These measurements corresponded to a lesion-based ⁶⁸Ga-PSMA-11 PET lesion detection rate of 80%, 93%, 89%, 21%, and 89%, respectively, for malignancy, and a specificity of 73%, 73%, 73%, 93%, and 60%, respectively. Conclusion: PSMA RADS rating, SUV_max, and SUV_max ratio for lesion to blood pool can help differentiate benign from malignant lesions on ⁶⁸Ga-PSMA-11 PET. An SUV_max ratio of more than 2.2 for lesion to blood pool is a reasonable parameter to support image interpretation and presented a superior lesion detection rate and specificity when compared with visual interpretation by PSMA RADS. These parameters hold clinical value by improving diagnostic accuracy for metastatic prostate cancer on ⁶⁸Ga-PSMA-11 PET/MRI and PET/CT.