Metastatic Sites' Location and Impact on Patient Management After the Introduction of Prostate-specific Membrane Antigen Positron Emission Tomography in Newly Diagnosed and Biochemically Recurrent Prostate Cancer: A Critical Review

Comparative analysis of circulating tumor cells in prostatic plexus and peripheral blood of patients undergoing prostatectomy

BACKGROUND

The potential influence of radical prostatectomy on tumor cell release into the blood circulation is an under-investigated area.

METHODS

One hundred three treatment-naïve patients with early-stage prostate cancer were recruited. Blood from the prostatic venous plexus was analyzed for the local release of tumor cells during radical prostatectomy. Simultaneously, systemic spread was assessed by the presence of circulating tumor cells (CTCs) in peripheral venous blood using both the EpCAM-dependent CellSearch and the size-dependent Parsortix systems in parallel. Tumor cells in the plexus blood and CTCs were detected by epithelial keratin expression and lack of CD45 leukocyte antigen.

RESULTS

Median counts of Keratin + /CD45- cells detected in peripheral blood with the CellSearch and Parsortix systems differed significantly (p = 0.0067) with higher sensitivity of the Parsortix System (16 vs 32% positive findings). Even if the results of both assays were combined, the median number of Keratin + /CD45- cells in the prostatic plexus blood was significantly higher than in the peripheral blood (97 vs. 2 per 7.5 ml, respectively, p < 0.0001). Keratin + /CD45- cells could be identified in 85% of prostate cancer patients in the prostatic plexus blood and in 42% of patients in peripheral blood during surgery without any significant correlation. Keratin + /CD45- cell clusters were identified in the prostatic plexus in 51.2% of patients but neither these clusters nor single Keratin + /CD45- cells were associated with biochemical relapse during follow-up. The presence (p = 0.0094) and number (p = 0.0153) of CTCs in the peripheral blood was significantly associated with PSA levels at initial diagnosis. Single-cell genome-wide sequencing by NGS showed copy number alterations (CNAs) in 15 out of 26 index CTCs originating from both the prostatic plexus and peripheral blood compartments.

CONCLUSION

Combining different CTC enrichment principles increases the CTC detection rate in the peripheral blood of early-stage prostate cancer patients. Our study provides first evidence for a considerable local release of normal and malignant epithelial cells during prostatectomy, which, however, was neither associated with increased CTC detection in the peripheral blood nor with early biochemical recurrence. Longer follow up studies are required to assess whether local tumor cell spread might contribute to clinical outcome in prostate cancer.

Clinical value of a negative [18F]F-PSMA PET/CT study in patients diagnosed with prostate cancer treated with prostatectomy with PSA rising below 1 ng/mL after radical prostatectomy, on the outcome of salvage radiotherapy

OBJECTIVE

To assess the clinical value of [18F]F-PSMA negative PET/CT, in patients diagnosed with prostate cancer treated with prostatectomy with elevated PSA less than 1 ng/mL, on the outcome of salvage radiotherapy.

METHOD

We prospectively included 98 patients diagnosed with prostate cancer treated with prostatectomy with biochemical recurrence [mean PSA 0.51 ng/mL (range 0.17-1.0 ng/mL)] who were referred for an [18F]F-PSMA -PET/CT study. The [18F]F-PSMA -PET/CT scan was negative in 53/98 patients (54.09%). Differences were analysed between those patients who were or were not candidates for pelvic salvage radiotherapy (PSRT) decided upon multidisciplinary committee and patient consent, with a minimum follow-up time for 1 year. Response to treatment was defined as a 50% reduction in PSA levels. Recurrence was ascertained upon clinical, analytical and imaging follow-up outcomes.

RESULTS

54.7% (29/53) of the patients with a negative [18F]F-PSMA -PET/CT underwent PSRT. Of these, 93.1% (27/29) patients demonstrated response to treatment (PSMA false negatives). The remaining two patients showed fluctuating PSA levels without detecting disease on the [18F]F-PSMA -PET/CT follow-up study. 45.3% (24/53) of patients with negative [18F]F-PSMA -PET/CT did not undergo PSRT. Of these, progressive PSA elevation was observed in 62.5% (15/24) (PSMA false negatives), localising recurrence on the [18F]F-PSMA -PET/CT follow-up study in 4 patients. The remaining 9 patients (37.5%) showed fluctuating PSA levels without detecting disease on the [18F]F-PSMA -PET/CT follow-up study. Our series confirmed 42 (42.85%) [18F]F-PSMA -PET/CT false negatives cases.

CONCLUSION

Patients diagnosed with prostate cancer with post-prostatectomy biochemical recurrence and a negative [18F]F-PSMA -PET/CT study are likely to benefit from pelvic salvage radiotherapy, with response seen in 93.1% of our cases.

Controversies in the use of next-generation imaging for evaluation and treatment decision-making in patients with prostate cancer after biochemical recurrence: views from a Spanish expert panel

INTRODUCTION

Diagnosing and managing biochemical recurrence (BCR) of prostate cancer (PCa) following primary radical treatment remain a challenge. Implementing next-generation imaging (NGI) techniques has improved metastases detection. However, access to these techniques is heterogeneous, and controversies surround their use and subsequent treatment decisions. In November 2023, a multidisciplinary expert meeting was organized to discuss these aspects. This information was further reviewed in November 2024.

AREAS COVERED

NGI-specific tracers' selection, evidence supporting patient selection for NGI after BRC, current treatment strategies in patients with BRC, and the role of NGIs in current and future therapeutic approaches.

EXPERT OPINION

Despite improved detection performance compared to conventional imaging techniques, the application of NGIs to treatment decision-making and the impact on patient outcomes are yet to be proven. Given the lack of guidance, opinions and recommendations from multidisciplinary expert panels are valuable for diagnosing and adequately treating patients with BRC after radical treatment.

Administration and cancer-control outcomes of bone-modifying agents in real-world patients with metastatic castration-resistant prostate cancer

Hormonal agents administered for metastatic castration-resistant prostate cancer (mCRPC) may lead to osteoporosis, skeletal events, reduced quality of life, and even reduced overall survival (OS). Bone-modifying agents may prevent those events but their effect on cancer-control outcomes remains uncertain. Relying on our institutional tertiary-care database, we explored the effect of bone-modifying agents (bisphosphonates such as zoledronic acid and denosumab) on OS and progression-free survival in patients with mCRPC with at least 1 bone metastasis using Kaplan-Meyer estimates and Cox regression models. Of 420 patients with mCRPC, 60% received bone-modifying agents who were younger (68 vs 69 years), with more systemic treatment lines for mCRPC (3 vs 2), and a higher proportion of initial de novo metastatic disease (72% vs 62%, all p ≤ .04) than patients without bone-modifying agents. In progression-free survival analyses, no significant differences were observed between both groups. In OS analyses, significant median OS differences were observed in favor of patients with bone-modifying agents (58 vs 45 months; hazard ratio [HR]: 0.66), even after multivariable adjustment (HR: 0.37; both p ≤ .01). In bone-modifying agent-stratified analyses, 57% received denosumab vs 43% bisphosphonates, with a significantly higher rate of Eastern Cooperative Oncology Group status of ≥2 in the bisphosphonates group. In progression-free and OS analyses, no significant differences were observed between bisphosphonates and denosumab patients, with numerically better results in progression-free survival analysis for denosumab after adjusting for covariates. The cumulative rate of osteonecrosis of the jaw at any treatment time was 12% in both groups and significantly decreased over time. Real-world data suggest a relatively low administration rate of bone-modifying agents in patients with osseous mCRPC. However, real-world data also suggest an OS benefit when bone-modifying agents are used, even after controlling for possible confounding patient and tumor characteristics.

Impact of time to metastatic disease onset and extent of disease volume across metastatic hormone-sensitive and castration-resistant prostate cancer

OBJECTIVE

In recently published phase III trials, overall survival (OS) differences were demonstrated in patients with secondary vs. De Novo and low vs. high volume metastatic hormone-sensitive prostate cancer (mHSPC). We hypothesized that these factors may also be attributable in real-world setting of new intensified combination therapies and in metastatic castration resistant prostate cancer (mCRPC) patients.

MATERIALS AND METHODS

We relied on an institutional tertiary-care database to identify mHSPC and subsequent mCRPC patients. The main outcome consisted of time to mCRPC and OS. Patients were stratified according to De Novo vs. secondary and low vs. high volume mHSPC and mCRPC, respectively.

RESULTS

Of 504 mHSPC patients, 371 (73.6%) were De Novo vs. 133 (26.4%) secondary mHSPC. Patients with De Novo and high volume mHSPC harbored shorter time to mCRPC and OS than secondary and low volume mHSPC patients (both P < 0.01). After stratification regarding disease volume, median time to mCRPC differed significantly between De Novo high volume (DNHV) vs. De Novo low volume (DNLV) vs. secondary high volume (SecHV) vs. secondary low volume mHSPC patients (SecLV, P < 0.001). Similarly in OS analyses, median OS was 44 vs. 53 vs. 88 vs. 120 months for respectively DNHV vs. SecHV vs. SecLV vs. DNLV mHSPC (P < 0.001). After progression to mCRPC, the effect of onset of metastatic disease and metastatic volume was still observed (all P < 0.01).

CONCLUSION

Patients with DNHV mHSPC harbor worse prognosis in a real world setting and in the light of combination therapies. This effect is also discernible in the context of mCRPC.

Advanced prostate cancer diagnosed by bone metastasis biopsy immediately after initial negative prostate biopsy: a case report and literature review

Prostate cancer (PCa) is a prevalent male malignancy that originates in the epithelial cells of the prostate. In terms of incidence and mortality of malignant tumors in men, PCa ranks second and fifth globally and first and third among men in Europe and the United States, respectively. These figures have gradually increased in recent years. The primary modalities used to diagnose PCa include prostate-specific antigen (PSA), multiparametric magnetic resonance imaging (mpMRI), and prostate puncture biopsy. Among these techniques, prostate puncture biopsy is considered the gold standard for the diagnosis of PCa; however, this method carries the potential for missed diagnoses. The preoperative evaluation of the patient in this study suggested advanced PCa. However, the initial prostate puncture biopsy was inconsistent with the preoperative diagnosis, and instead of waiting for a repeat puncture of the prostate primary, we performed a biopsy of the rib metastasis, which was later diagnosed as advanced PCa.

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.

How to Report PSMA PET

Prostate cancer (PCa) is the most common cancer diagnosed in men in most developed countries and a leading cause of cancer-related morbidity and mortality. Prostate-specific membrane antigen positron emission tomography (PSMA-PET) has become a valuable tool in the staging and assessment of disease recurrence in PCa, and more recently for assessment for treatment eligibility to PSMA radioligand therapy (RLT). Harmonization of PSMA-PET interpretation and synoptic reports are needed to communicate concisely and reproducibly PSMA-PET/CT to referring physicians and to support clinician therapeutic management decisions in various stages of the disease. Uniform image interpretation is also important to provide comparable data between clinical trials and to translate such data from research to daily practice. This review provides an overview of the value of PSMA-PET across the different clinical stages of PCa, discusses published reporting criteria for PSMA-PET, identifies pitfalls in reporting PSMA, and provides recommendations for synoptic reports.

Future Imaging of Prostate Cancer: Do We Need More Than PSMA PET/CT?

In the setting of prostate cancer (PCa), many different imaging modalities are available to correctly assess staging, restaging, treatment response and radio-ligand therapy recruitment. The introduction of fluoride or gallium-labelled prostate specific membrane antigen (PSMA) made a revolution in PCa management, also due to its possible theragnostic use. Nowadays PSMA-PET/CT is a fundamental tool for staging and restaging PCa. This review discusses the latest findings in PSMA imaging in PCa patients and the impact of PSMA imaging on the patients' management in primary staging, biochemical recurrence and in advanced prostate cancer, always keeping in mind the important theragnostic role of PSMA. This review tries also to assess the current role of other radiopharmaceuticals as Choline, FACBC or other radiotracers like gastrin-releasing peptide receptor targeting tracers and FAPI in different PCa settings.

Preclinical Evaluation of a Novel High-Affinity Radioligand [99mTc]Tc-BQ0413 Targeting Prostate-Specific Membrane Antigen (PSMA)

Radionuclide imaging using radiolabeled inhibitors of prostate-specific membrane antigen (PSMA) can be used for the staging of prostate cancer. Previously, we optimized the Glu-urea-Lys binding moiety using a linker structure containing 2-napththyl-L-alanine and L-tyrosine. We have now designed a molecule that contains mercaptoacetyl-triglutamate chelator for labeling with Tc-99m (designated as BQ0413). The purpose of this study was to evaluate the imaging properties of [99mTc]Tc-BQ0413. PSMA-transfected PC3-pip cells were used to evaluate the specificity and affinity of [99mTc]Tc-BQ0413 binding in vitro. PC3-pip tumor-bearing BALB/C nu/nu mice were used as an in vivo model. [99mTc]Tc-BQ0413 bound specifically to PC3-pip cells with an affinity of 33 ± 15 pM. In tumor-bearing mice, the tumor uptake of [99mTc]Tc-BQ0413 (38 ± 6 %IA/g in PC3-pip 3 h after the injection of 40 pmol) was dependent on PSMA expression (3 ± 2 %IA/g and 0.9 ± 0.3 %IA/g in PSMA-negative PC-3 and SKOV-3 tumors, respectively). We show that both unlabeled BQ0413 and the commonly used binder PSMA-11 enable the blocking of [99mTc]Tc-BQ0413 uptake in normal PSMA-expressing tissues without blocking the uptake in tumors. This resulted in an appreciable increase in tumor-to-organ ratios. At the same injected mass (5 nmol), the use of BQ0413 was more efficient in suppressing renal uptake than the use of PSMA-11. In conclusion, [99mTc]Tc-BQ0413 is a promising probe for the visualization of PSMA-positive lesions using single-photon emission computed tomography (SPECT).

The diagnosis and treatment of castrate-sensitive oligometastatic prostate cancer: A review

BACKGROUND

Oligometastatic prostate cancer (OMPCa) is emerging as a transitional disease state between localized and polymetastatic disease. This review will assess the current knowledge of castrate-sensitive OMPCa.

METHODS

A review of the current literature was performed to summarize the definition and classification of OMPCa, assess the diagnostic methods and imaging modalities utilized, and to review the treatment options and outcomes. We further identify gaps in knowledge and areas for future research.

RESULTS

Currently there is no unified definition of OMPCa. National guidelines mostly recommend systemic therapies without distinguishing oligometastatic and polymetastatic disease. Next generation imaging is more sensitive than conventional imaging and has led to early detection of metastases at initial diagnosis or recurrence. While mostly retrospective in nature, recent studies suggest that treatment (surgical or radiation) of the primary tumor and/or metastatic sites might delay initiation of androgen deprivation therapy while increasing survival in selected patients.

CONCLUSIONS

Prospective data are required to better assess the incremental improvement in survival and quality of life achieved with various treatment strategies in patients with OMPCa.

177Lu-labeled PSMA targeting therapeutic with optimized linker for treatment of disseminated prostate cancer; evaluation of biodistribution and dosimetry

Introduction

Prostate specific membrane antigen (PSMA), highly expressed in metastatic castration-resistant prostate cancer (mCRPC), is an established therapeutic target. Theranostic PSMA-targeting agents are widely used in patient management and has shown improved outcomes for mCRPC patients. Earlier, we optimized a urea-based probe for radionuclide visualization of PSMA-expression in vivo using computer modeling. With the purpose to develop a targeting agent equally suitable for radionuclide imaging and therapy, the agent containing DOTA chelator was designed (BQ7876). The aim of the study was to test the hypothesis that 177Lu-labeled BQ7876 possesses target binding and biodistribution properties potentially enabling its use for radiotherapy.

Methods

BQ7876 was synthesized and labeled with Lu-177. Specificity and affinity of [177Lu]Lu-BQ7876 to PSMA-expressing PC3-pip cells was evaluated and its processing after binding to cells was studied. Animal studies in mice were performed to assess its biodistribution in vivo, target specificity and dosimetry. [177Lu]Lu-PSMA-617 was simultaneously evaluated for comparison.

Results

BQ7876 was labeled with Lu-177 with radiochemical yield >99%. Its binding to PSMA was specific in vitro and in vivo when tested in antigen saturation conditions as well as in PSMA-negative PC-3 tumors. The binding of [177Lu]Lu-BQ7876 to living cells was characterized by rapid association, while the dissociation included a rapid and a slow phase with affinities KD1 = 3.8 nM and KD2 = 25 nM. The half-maximal inhibitory concentration for natLu-BQ7876 was 59 nM that is equal to 61 nM for natLu-PSMA-617. Cellular processing of [177Lu]Lu-BQ7876 was accompanied by slow internalization. [177Lu]Lu-BQ7876 was cleared from blood and normal tissues rapidly. Initial elevated uptake in kidneys decreased rapidly, and by 3 h post injection, the renal uptake (13 ± 3%ID/g) did not differ significantly from tumor uptake (9 ± 3%ID/g). Tumor uptake was stable between 1 and 3 h followed by a slow decline. The highest absorbed dose was in kidneys, followed by organs and tissues in abdomen.

Discussion

Biodistribution studies in mice demonstrated that targeting properties of [177Lu]Lu-BQ7876 are not inferior to properties of [177Lu]Lu-PSMA-617, but do not offer any decisive advantages.

Predictors of PSMA PET Positivity: Analysis in a Selected Cohort of Biochemical Recurrence Prostate Cancer Patients after Radical Prostatectomy

Localized prostate cancer (PCa) can be treated with radical prostatectomy (RP). Up to 30% of patients undergoing this procedure experience biochemical recurrence (BCR), namely the rise in serum prostate-specific antigen (PSA) levels during the post-surgical follow-up, requiring further treatments and with the risk of severe disease progression. Currently, the most accurate imaging technique to confirm, detect, and locate disease relapses in BCR patients is prostate-specific membrane antigen (PSMA)-targeted PET, as recommended by international clinical guidelines. The aim of the study was to investigate potential clinical and pathological predictors of PSMA PET positivity, validated by clinical and instrumental follow-up or histopathological data. In this study, a selected cohort of BCR patients after RP and no other PCa-related therapy who underwent either PSMA PET/CT or PSMA PET/MRI has been analysed. Among the considered predictors, both pathological staging after RP equal or higher than pT3a and higher PSA levels at the time of the scan were significantly correlated with PSMA PET positivity on multivariate logistic regression analysis. As expected, PSMA PET confirmed its role as an accurate imaging technique in the setting of BCR in PCa. These findings may inform appropriate and tailored patient selection and scan timing to optimize and fully exploit this powerful diagnostic tool.

[Systemic therapy for mHSPC: doublet or triplet therapy - who, when and how?]

At present, androgen deprivation therapy (ADT) as monotherapy for metastatic hormone-sensitive prostate cancer (mHSPC) should be an exception. The new standard of care is a doublet combination consisting of ADT + a new hormonal agent (NHA) or ADT + chemotherapy. Contemporary investigations even recommend a triplet therapy consisting of ADT + NHA + chemotherapy for selected mHSPC patients. The current evolution of mHSPC therapy demands a pretherapeutic classification of mHSPC: "low" vs. "high risk", "low" vs. "high volume" and synchronous vs. metachronous mHSPC. Additionally, attention should be paid to the drug specific side effects and especially whether the patient is fit for chemotherapy. This article gives a concise overview of the key clinical trials, current guideline recommendations and drug approvals for Germany.