Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography and (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for recurrent prostate carcinoma: results of a prospective clinical trial

Positron Emission Tomography Radiotracers for Identification of Site of Recurrence in Prostate Cancer After Primary Treatment Failure

Despite substantial improvement in the definitive management of primary prostate cancer, a significant number of patients experience biochemical recurrence-a clinical state in which serum prostate-specific antigen (PSA) levels rise prior to the development of physical signs or symptoms. The early detection and localization of biochemical recurrence may confer eligibility for salvage therapy; therefore, imaging techniques that provide accurate disease visualization are imperative. In this review, we discuss various imaging methods for localizing disease in the context of biochemical recurrence in prostate cancer. Particularly, we describe available or investigational positron emission tomography (PET) radiotracers, such as 18F-FDG, 18F-NaF, choline (both 18F and 11C), the 18F-labeled amino acid derivative fluciclovine, prostate-specific membrane antigen (PSMA) radioligands, and the short peptide compound bombesin. Generally, PET radiotracers such as 18F-FDG, 18F-NaF, and 18F/11C choline have fallen out of favor because of their inferior sensitivity and/or specificity in relation to more recently developed radiotracers. 18F-fluciclovine has addressed these shortcomings by exploiting the upregulation of amino acid transporters in tumors; however, PSMA-targeting agents have significantly advanced the management of biochemical recurrence of prostate cancer through their high sensitivity and specificity, enabling the identification of candidates for radionuclide therapy. Investigational agents, such as bombesin-based radiotracers, may address the shortcomings of treating prostate cancer with little to no PSMA expression.

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.

Initial Experience with the Radiotracer 18F-Fluciclovine PET/CT in Ovarian Cancer

OBJECTIVE

Early and accurate staging of ovarian cancer is paramount to disease survival. Conventional imaging including FDG PET/CT are limited in the evaluation of small metastatic lesions. 18F-Fluciclovine has minimal urine and bowel excretion allowing optimal visualization of the abdomen and pelvis. This study examines 18F-fluciclovine uptake in known primary and recurrent ovarian cancer.

METHODS

Seven patients with a confirmed diagnosis of epithelial ovarian cancer underwent 18F-fluciclovine PET/CT imaging. Forty-one (41) lesions were identified with 18F-fluciclovine and confirmed to be true positive (n = 41). We aim to explore if 18F-fluciclovine uptake in ovarian lesions were greater than background uptake of bone marrow, blood pool, and bladder. Quantification analysis was performed to determine max and mean standard uptake values (SUVmax and SUVmean) of known and suspected lesions compared to SUVmean uptake of background structures.

RESULTS

18F-Fluciclovine demonstrated 100% sensitivity (41/41) for uptake in known ovarian lesions. The average SUVmax (±SD) uptake of known ovarian lesions was 5.9 (±2.6) and 5.1 (±2.0) on early and delayed images, respectively. The average tumor SUVmax to SUVmean of background (±SD) (T:B) ratios on early and delay were 1.9 (±0.8), 2.1 (±0.9) for marrow; 3.8 (±1.8), 3.4 (±1.5) for aorta; and 8.4 (±4.3), 1.5 (±1.7) for bladder, respectively.

CONCLUSION

18F-Fluciclovine uptake in malignant ovarian lesions was above background levels suggesting its feasibility in the imaging of ovarian cancer. Due to increasing tracer washout via the urinary bladder over time, early imaging at 4 min post injection is favorable.

An 18F-MD-PSMA (Multi-dentate PMSA Imaging Agent) PET/CT in Prostate Cancer Relapse: Results of a Retrospective Trial

PURPOSE

This study aimed to evaluate the performance of 18F-MD-PSMA PET/CT in patients previously treated for prostate cancer by either surgery or therapy, but later relapsed biochemically.

METHODS

This retrospective study enrolled 213 patients in sequence previously treated for prostate cancer by either surgery or therapy, but later PSA relapsed. A total of 191 of these 213 patients were included in this analysis. All patients were biochemically relapsed after radical prostatectomy or therapy, had 18F-MD-PSMA PET/CT scan within 1 week, and were off hormonal therapy at the time of the scans. The new tracer was compared directly with 11C-choline in sensitivity.

RESULTS

In 3 patients, a side-by-side comparison between 18F-MD-PSMA and 11C-choline was performed, and it was found that the former was about 3 times more sensitive than the latter. The analysis of PET imaging using 18F-MD-PSMA in 191 relapsed patients showed that less than 10% of patients showed the disease limited in the prostate. Among the remote lesions, the number in decreasing order was bone, followed by lymph nodes and other organs. The maximal SUV in lesions in each patient followed an exponential decay, with SUV inclined to the lower end. The Gleason score measured at the diagnosis showed no correlation with the average number of lesions in each patient, the average maximal SUV values among this cohort of patients, and the PSA values measured at the time of PET imaging. The number of lesions observed in each patient has no correlation with the PSA value measured at the time of PET imaging. When PSA value was measured as an independent biomarker at the time of PET imaging, the positivity of PET imaging using 18F-MD-PSMA increased along with an increase in PSA value, but with exceptions where PSMA expression was low or negative. From the PET imaging of this radioligand, the majority of patients showed oligo-metastasis, favoring using local therapy to manage the disease.

CONCLUSION

An 18F-MD-PSMA as a radioligand was found to be superior to 11C-choline in the setting of patients with biochemical relapse after previous treatment. Its PET imaging results matched those of established PSMA radioligands, but its chemical structure was found to have added features to conjugate with other functional molecules, such as those with therapeutic properties. This radioligand lays the foundation for our further work.

Precision strikes: PSMA-targeted radionuclide therapy in prostate cancer - a narrative review

Introduction

Radio-ligand targeted therapy is a new and promising concept of treatment Castration resistant prostate cancer (CRPC). Only a few radio-pharmaceutics were approved for usage in treating prostate cancer, among the multiple others tested. We aimed to review and summarize the literature on the therapeutic isotopes specific for PSMA.

Methods

We performed a scoping literature review of PubMed from January 1996 to December 2022.

Results

98 publications were selected for inclusion in this review. The studies contained in publications allowed to summarize the data on pharmacokinetics, therapeutic effects, side effects and the medical use of 225Ac and 177Lu radionuclides. The review also presents new research directions for specific PSMA radionuclides.

Conclusion

Radioligand targeted therapy is a new and promising concept where Lu-177-PSMA-617 have promising outcomes in treatment according to standard of care.

Traditional and novel imaging modalities for advanced prostate cancer: A critical review

Accurate detection of metastatic prostate cancer in the setting of preoperative staging as well as posttreatment recurrence is crucial to provide patients with appropriate and timely treatment of their disease. This has traditionally been accomplished with a combination of computed tomography, magnetic resonance imaging, and bone scan. Recently, more novel imaging techniques have been developed to help improve the detection of advanced and metastatic prostate cancer. This review discusses the efficacy of the traditional imaging modalities as well as the novel imaging techniques in detecting metastatic prostate cancer. Articles discussed were gathered through a formal PubMed search.

Challenges in diagnosis and therapeutic options for metastatic prostate cancer to the right ventricle

Our patient presented with right-sided heart failure symptoms and found to have a large mass protruding into the heart's right ventricle. Cardiac MRI delineated the morphological and tissue characteristics of the tumour. Although 18-fluorodeoxyglucose positron emission tomography (PET) did not reveal an intracardiac mass, the lesion was well demonstrated by Fluciclovine F18 PET/CT.

Contemporary Review of Multimodality Imaging of the Prostate Gland

Tissue changes and the enlargement of the prostate, whether benign or malignant, are among the most common groups of diseases that affect men and can have significant impacts on length and quality of life. The prevalence of benign prostatic hyperplasia (BPH) increases significantly with age and affects nearly all men as they grow older. Other than skin cancers, prostate cancer is the most common cancer among men in the United States. Imaging is an essential component in the diagnosis and management of these conditions. Multiple modalities are available for prostate imaging, including several novel imaging modalities that have changed the landscape of prostate imaging in recent years. This review will cover the data relating to commonly used standard-of-care prostate imaging modalities, advances in newer technologies, and newer standards that impact prostate gland imaging.

Management of Advanced Prostate Cancer in the Precision Oncology Era

Prostate cancer (PC) is the second leading cause of cancer death in men in the United States. While diversified and improved treatment options for aggressive PC have improved patient outcomes, metastatic castration-resistant prostate cancer (mCRPC) remains incurable and an area of investigative therapeutic interest. This review will cover the seminal clinical data supporting the indication of new precision oncology-based therapeutics and explore their limitations, present utility, and potential in the treatment of PC. Systemic therapies for high-risk and advanced PC have experienced significant development over the past ten years. Biomarker-driven therapies have brought the field closer to the goal of being able to implement precision oncology therapy for every patient. The tumor agnostic approval of pembrolizumab (a PD-1 inhibitor) marked an important advancement in this direction. There are also several PARP inhibitors indicated for patients with DNA damage repair deficiencies. Additionally, theranostic agents for both imaging and treatment have further revolutionized the treatment landscape for PC and represent another advancement in precision medicine. Radiolabeled prostate-specific membrane antigen (PSMA) PET/CT is rapidly becoming a standard of care for diagnosis, and PSMA-targeted radioligand therapies have gained recent FDA approval for metastatic prostate cancer. These advances in precision-based oncology are detailed in this review.

Prostate Cancer-PET Imaging Update

Prostate cancer is the most common non-dermatologic cancer in men, and one of the leading causes of cancer-related mortality. The incidence of prostate cancer increases precipitously after the age of 65 and demonstrates variable aggressiveness, depending on its grade and stage at diagnosis. Despite recent advancements in prostate cancer treatment, recurrence is seen in 25% of patients. Advancements in prostate cancer Positron Emission Tomography (PET) molecular imaging and recent United States Food and Drug Administration (FDA) approvals have led to several new options for evaluating prostate cancer. This manuscript will review the commonly used molecular imaging agents, with an emphasis on Fluorine-18 fluciclovine (Axumin) and PSMA-ligand agents, including their protocols, imaging interpretation, and pitfalls.

The Value of Phenotypic Precision Medicine in Prostate Cancer

Prostate cancer is the most common cancer among men and the second leading cause of cancer-related death. For patients who develop metastatic disease, tissue-based and circulating-tumor-based molecular and genomic biomarkers have emerged as a means of improving outcomes through the application of precision medicine. However, the benefit is limited to a minority of patients. An additional approach to further characterize the biology of advanced prostate cancer is through the use of phenotypic precision medicine, or the identification and targeting of phenotypic features of an individual patient's cancer. In this review article, we will discuss the background, potential clinical benefits, and limitations of genomic and phenotypic precision medicine in prostate cancer. We will also highlight how the emergence of image-based phenotypic medicine may lead to greater characterization of advanced prostate cancer disease burden and more individualized treatment approaches in patients.

Effect of Androgen Deprivation Therapy on the Results of PET/CT with 18F-Fluciclovine in Patients with Metastatic Prostate Cancer

Background: 18F-fluciclovine is a positron emission tomography (PET) radiotracer approved for the detection of prostate cancer recurrence. No effect of androgen deprivation therapy (ADT) on its performance has been established. Purpose: To study the impact of concurrent ADT on disease detection with 18F-fluciclovine PET in patients with prostate cancer. Materials and Methods: Data from patients with prostate cancer who had been receiving ADT for ≥3 months at the time of undergoing an 18F-fluciclovine PET/CT at our institution were retrospectively reviewed. Seventy-three scans from 71 patients were included. The scans indicated rising prostate-specific antigen (n = 58), staging advanced disease (n = 4) or therapeutic monitoring (n = 9). Patients’ medical records provided baseline clinical data and post-scan outcomes (median follow-up 40 months). Results: Malignant lesions with increased uptake of 18F-fluciclovine were detected in 60/73 (82%) scans; 33 (45%) had lesions in the prostate/bed and 46 (63%) in extraprostatic sites. Patients received ADT for a median of 2 years (range 3 months to >10 years) pre-scan. The time on ADT did not influence detection; the detection rates were 89% for patients who had received ADT for <1 year, 63% for a treatment period of 1−<2 years, 83% for 2−4 years, 78% for >4−10 years, and 67% for a treatment period of >10 years. Conclusion: 18F-fluciclovine detected recurrent or metastatic lesions in 82% of patients with prostate cancer receiving ADT. The rates achieved in the present study are consistent with widely reported data for 18F-fluciclovine PET/CT, suggesting that withdrawal of ADT before scanning is not necessary.

[18F]Fluciclovine PET/CT Improves the Clinical Management of Early Recurrence Prostate Cancer Patients

Simple Summary

In the challenge between increasingly sensitive PET radiopharmaceuticals for the evaluation of prostate cancer patient in biochemical relapse, the choice of the most accurate PET tracer must be guided by literature data, but above all tailored to the patient’s profile. In describing our single-center experience, we aimed to identify biochemical and clinical–histological factors to be considered in patient selection and the semiquantitative parameters that can help the interpretation of malignant from benign lesions, in order to optimize the performance of this imaging method. These data in combination with a significant impact on therapeutic decision making can be useful to further validate the [¹⁸F]Fluciclovine PET/CT clinical application.

Abstract

We investigated the [¹⁸F]Fluciclovine PET/CT reliability in the early detection of recurrent prostate cancer (PCa) and its impact on therapeutic decision making. We retrospectively analyzed 58 [¹⁸F]Fluciclovine PET/CT scans performed to identify early PCa recurrence. Detection rate (DR) and semiquantitative analysis were evaluated in relation to biochemical and clinical–histological features. Clinical follow-up data were collected and considered as gold standard to evaluate sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV). The impact of [¹⁸F]Fluciclovine PET/CT on clinical management was also assessed. Overall DR resulted as 66%, while DR was 53%, 28%, and 7% in prostate/bed, lymph nodes, and bone, respectively. DR significantly increased with higher PSA values (p = 0.009) and 0.45 ng/mL was identified as the optimal cut-off value. Moreover, SUVmax and SUVmean resulted significant parameters in interpreting malignant from benign findings. [¹⁸F]Fluciclovine PET/CT reached a sensitivity, specificity, PPV, NPV, and accuracy of 87.10%, 80.00%, 87.10%, 80.00%, and 84.31%, respectively. Therapeutic strategy was changed in 51% of patients. Our results support [¹⁸F]Fluciclovine PET/CT as a reliable tool for early restaging of PCa patients, especially for local recurrence detection, leading to a significant impact on clinical management. Semiquantitative analysis could improve specificity in interpreting malignant from benign lesions.

Gadolinium and Polythiophene Functionalized Polyurea Polymer Dots as Fluoro-Magnetic Nanoprobes

A rapid and one-pot synthesis of poly 3-thiopheneacetic acid (PTAA) functionalized polyurea polymer dots (Pdots) using polyethyleneimine and isophorone diisocyanate is reported. The one-pot mini-emulsion polymerization technique yielded Pdots with an average diameter of ~20 nm. The size, shape, and concentration of the surface functional groups could be controlled by altering the synthesis parameters such as ultrasonication time, concentration of the surfactant, and crosslinking agent, and the types of isocyanates utilized for the synthesis. Colloidal properties of Pdots were characterized using dynamic light scattering and zeta potential measurements. The spherical geometry of Pdots was confirmed by scanning electron microscopy. The Pdots were post-functionalized by 1,4,7,10 tetraazacyclododecane-1,4,7,10-tetraacetic acid for chelating gadolinium nanoparticles (Gd³⁺) that provide magnetic properties to the Pdots. Thus, the synthesized Pdots possess fluorescent and magnetic properties, imparted by PTAA and Gd³⁺, respectively. Fluorescence spectroscopy and microscopy revealed that the synthesized dual-functional Gd³⁺-Pdots exhibited detectable fluorescent signals even at lower concentrations. Magnetic levitation experiments indicated that the Gd³⁺-Pdots could be easily manipulated via an external magnetic field. These findings illustrate that the dua- functional Gd³⁺-Pdots could be potentially utilized as fluorescent reporters that can be magnetically manipulated for bioimaging applications.

18F-Fluciclovine PET/CT performance in biochemical recurrence of prostate cancer: a systematic review

BACKGROUND

A systematic literature review of the performance of 18Fluorine-fluciclovine PET/CT for imaging of men with recurrent prostate cancer was performed.

METHODS

Scientific literature databases (MEDLINE, ScienceDirect and Cochrane Libraries) were searched systematically during Oct 2020 using PRISMA criteria. No limit was put on the date of publication. Prospective studies reporting a patient-level 18F-fluciclovine detection rate (DR) from ≥25 patients with recurrent prostate cancer were sought. Proceedings of relevant meetings held from 2018 through Oct 2020 were searched for abstracts meeting criteria.

RESULTS

Searches identified 321 unique articles. In total, nine articles (six papers and three conference abstracts), comprising a total of 850 patients met inclusion criteria. Most studies (n = 6) relied on ASTRO-Phoenix Criteria, EAU-ESTRO-SIOG, and/or ASTRO-AUA guidelines to identify patients with biochemical recurrence. Patients' PSA levels ranged from 0.02-301.7 ng/mL (median level per study, 0.34-4.10 ng/mL [n = 8]). Approximately 64% of patients had undergone prostatectomy, but three studies focused solely on post-prostatectomy patients. Adherence to imaging protocol guidelines was heterogeneous, with variance seen in administered activity, uptake and scan times. Overall patient-level DR varied between studies from 26% to 83%, with 78% of studies reporting a DR > 50%. DR was proportional to PSA, but even at PSA < 0.5 ng/mL DR of up to 53% were reported. Prostate/bed DR (n = 7) ranged from 18% to 78% and extra-prostatic rates (n = 6) from 8% to 72%. Pelvic node and bone lesion DR ranged from 8% to 47% and 0% to 26%, respectively (n = 5). 18F-Fluciclovine PET/CT was shown to impact patient management and outcomes. Two studies reported 59-63% of patients to have a management change post-scan. A further study showed significant increase in failure-free survival following 18F-fluciclovine-guided compared with conventional imaging-guided radiotherapy planning.

CONCLUSIONS

18F-Fluciclovine PET/CT shows good performance in patients with recurrent prostate cancer leading to measurable clinical benefits. Careful adherence to recommended imaging protocols may help optimize DR.

Radionuclide-Based Imaging of Breast Cancer: State of the Art

Simple Summary

Breast cancer is one of the most commonly diagnosed malignant tumors, possessing high incidence and mortality rates that threaten women’s health. Thus, early and effective breast cancer diagnosis is crucial for enhancing the survival rate. Radionuclide molecular imaging displays its advantages for detecting breast cancer from a functional perspective. Noninvasive visualization of biological processes with radionuclide-labeled small metabolic compounds helps elucidate the metabolic state of breast cancer, while radionuclide-labeled ligands/antibodies for receptor-targeted radionuclide molecular imaging is sensitive and specific for visualization of the overexpressed molecular markers in breast cancer. This review focuses on the most recent developments of novel radiotracers as promising tools for early breast cancer diagnosis.

Abstract

Breast cancer is a malignant tumor that can affect women worldwide and endanger their health and wellbeing. Early detection of breast cancer can significantly improve the prognosis and survival rate of patients, but with traditional anatomical imagine methods, it is difficult to detect lesions before morphological changes occur. Radionuclide-based molecular imaging based on positron emission tomography (PET) and single-photon emission computed tomography (SPECT) displays its advantages for detecting breast cancer from a functional perspective. Radionuclide labeling of small metabolic compounds can be used for imaging biological processes, while radionuclide labeling of ligands/antibodies can be used for imaging receptors. Noninvasive visualization of biological processes helps elucidate the metabolic state of breast cancer, while receptor-targeted radionuclide molecular imaging is sensitive and specific for visualization of the overexpressed molecular markers in breast cancer, contributing to early diagnosis and better management of cancer patients. The rapid development of radionuclide probes aids the diagnosis of breast cancer in various aspects. These probes target metabolism, amino acid transporters, cell proliferation, hypoxia, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), gastrin-releasing peptide receptor (GRPR) and so on. This article provides an overview of the development of radionuclide molecular imaging techniques present in preclinical or clinical studies, which are used as tools for early breast cancer diagnosis.

Localization of primary prostate cancer: FACBC PET/CT compared with multiparametric MRI using histopathology as reference standard

FACBC (anti-1-amino-3-¹⁸F-fluorocyclobutane-1-carboxylic acid) is a FDA-approved PET-tracer in patients with suspected recurrent prostate cancer. In the diagnostic work-up of primary prostate cancer, accurate localization of the index tumor is needed for image-guidance of biopsies. We therefore assessed the performance of FACBC PET/CT to detect and localize the index tumor and compared it to multiparametric MRI (mpMRI) using whole-mount histopathology as reference standard. Twenty-three patients with biopsy-proven prostate cancer had FACBC PET/CT and mpMRI within two weeks prior to prostatectomy. FACBC PET/CT was acquired as 14 minutes list-mode and re-binned into seven 2-minutes intervals. Static FACBC was the acquired data from 4-6 minutes, whereas the dynamic FACBC included all seven intervals. Two radiologists and two nuclear medicine physicians independently interpreted the images and consensus was reached in case of discrepancy. Static PET detected 15 of 23 (65%) of the index tumors, dynamic PET detected 14 of 22 (64%), and MRI detected 20 of 23 (87%). To assess the extent of the tumor, the interpreters delineated the tumor in a 12-regions sector-based template. True positive, true negative, false positive and false negative sectors were recorded based on the template drawings and whole-mount histopathology. Both static and dynamic FACBC PET had sensitivity of 40% and specificity of 99%, whereas MRI had sensitivity of 81% and specificity of 100%. Our data indicate that FACBC PET/CT may be useful but that mpMRI is better for localizing the index tumor in patients with prostate cancer.

Diagnostic Accuracy of 68Ga-PSMA-11 PET for Pelvic Nodal Metastasis Detection Prior to Radical Prostatectomy and Pelvic Lymph Node Dissection: A Multicenter Prospective Phase 3 Imaging Trial

Importance

The presence of pelvic nodal metastases at radical prostatectomy is associated with biochemical recurrence after prostatectomy.

Objective

To assess the accuracy of prostate-specific membrane antigen (PSMA) 68Ga-PSMA-11 positron emission tomographic (PET) imaging for the detection of pelvic nodal metastases compared with histopathology at time of radical prostatectomy and pelvic lymph node dissection.

Design, Setting, and Participants

This investigator-initiated prospective multicenter single-arm open-label phase 3 imaging trial of diagnostic efficacy enrolled 764 patients with intermediate- to high-risk prostate cancer considered for prostatectomy at University of California, San Francisco and University of California, Los Angeles from December 2015 to December 2019. Data analysis took place from October 2018 to July 2021.

Interventions

Imaging scan with 3 to 7 mCi of 68Ga-PSMA-11 PET.

Main Outcomes and Measures

The primary end point was the sensitivity and specificity for the detection pelvic lymph nodes compared with histopathology on a per-patient basis using nodal region correlation. Each scan was read centrally by 3 blinded independent central readers, and a majority rule was used for analysis.

Results

A total of 764 men (median [interquartile range] age, 69 [63-73] years) underwent 1 68Ga-PSMA-11 PET imaging scan for primary staging, and 277 of 764 (36%) subsequently underwent prostatectomy with lymph node dissection (efficacy analysis cohort). Based on pathology reports, 75 of 277 patients (27%) had pelvic nodal metastasis. Results of 68Ga-PSMA-11 PET were positive in 40 of 277 (14%), 2 of 277 (1%), and 7 of 277 (3%) of patients for pelvic nodal, extrapelvic nodal, and bone metastatic disease. Sensitivity, specificity, positive predictive value, and negative predictive value for pelvic nodal metastases were 0.40 (95% CI, 0.34-0.46), 0.95 (95% CI, 0.92-0.97), 0.75 (95% CI, 0.70-0.80), and 0.81 (95% CI, 0.76-0.85), respectively. Of the 764 patients, 487 (64%) did not undergo prostatectomy, of which 108 were lost to follow-up. Patients with follow-up instead underwent radiotherapy (262 of 379 [69%]), systemic therapy (82 of 379 [22%]), surveillance (16 of 379 [4%]), or other treatments (19 of 379 [5%]).

Conclusions and Relevance

This phase 3 diagnostic efficacy trial found that in men with intermediate- to high-risk prostate cancer who underwent radical prostatectomy and lymph node dissection, the sensitivity and specificity of 68Ga-PSMA-11 PET were 0.40 and 0.95, respectively. This academic collaboration is the largest known to date and formed the foundation of a New Drug Application for 68Ga-PSMA-11.

Trial Registration

ClinicalTrials.gov Identifiers: NCT03368547, NCT02611882, and NCT02919111.

Positivity Rate of [18F]Fluciclovine PET/CT in Patients with Suspected Prostate Cancer Recurrence at PSA Levels Below 1 ng/mL

PURPOSE

Early and precise localization of recurrent prostate cancer lesions after local therapy facilitates optimal disease management. Here, we present results from a single-center study to evaluate the utility of [¹⁸F]fluciclovine PET/CT to localize prostate cancer recurrence in patients with PSA <1 ng/mL.

PROCEDURES

Data from men who underwent [¹⁸F]fluciclovine PET/CT (August 2016-March 2020) for suspected recurrent prostate cancer and who had a PSA value <1ng/mL were retrospectively reviewed. The number of positive scans (positivity rates, PR) was calculated for the whole body, prostate/bed, and extraprostatic regions (pelvic or extrapelvic lymph nodes, bones, and soft tissue). PR were stratified by pre-scan PSA.

RESULTS

Data from 113 patients were included. In total, 98 (87%) were post-prostatectomy and 15 (13%) had received non-surgical primary therapy. Twenty patients (18%) were receiving ADT at the time of the scan, 91 (81%) were not, and ADT status was not known for 2 (1.8%) patients. The overall PR at PSA <1ng/mL was 59% (67/113). For the prostate/bed, it was 35% (40/113), and for extraprostatic locations, it was 37% (42/113). At PSA >0-<0.2, 0.2-<0.5, and 0.5-<1 ng/mL, the overall PR was 43% (10/23), 70% (35/50), and 55% (22/40), respectively. In the prostate/bed, these were 13% (3/23), 50% (25/50), and 30% (12/40), respectively, and in extraprostatic lesions were 30% (7/23), 44% (22/50), and 33% (13/40), respectively. Pelvic lymph nodes were the most common site for extraprostatic lesions (29/113, 26%). PR in extrapelvic lymph nodes, bone, and soft tissue were 8.0%, 12%, and 3.5%, respectively. Soft tissue lesions comprised lung nodules (n=3) and a perirectal mass implant (n=1).

CONCLUSIONS

Despite low PSA values, more than half of patients had positive [¹⁸F]fluciclovine PET/CT findings. Patients with low PSA levels may demonstrate suspicious findings outside of the pelvis, including abdominal lymph nodes and metastatic disease to bones and lungs.

Prostate cancer: Molecular imaging and MRI

The role of molecular imaging in initial evaluation of men with presumed or established diagnosis of prostate cancer and work up of biochemical recurrence and metastatic disease is rapidly evolving due to superior diagnostic performance compared to anatomic imaging. However, variable tumor biology and expression of transmembrane proteins or metabolic alterations poses a challenge. We review the evidence and controversies with emphasis on emerging PET radiopharmaceuticals and experience on clinical utility of PET/CT and PET/MRI in diagnosis and management of prostate cancer.

Salvage Radiotherapy Management Decisions in Postprostatectomy Patients with Recurrent Prostate Cancer Based on 18F-Fluciclovine PET/CT Guidance

Imaging with novel PET radiotracers has significantly influenced radiotherapy decision making and radiation planning in patients with recurrent prostate cancer (PCa). The purpose of this analysis was to report the final results for management decision changes based on 18F-fluciclovine PET/CT findings and determine whether the decision change trend remained after completion of accrual. Methods: Patients with detectable prostate-specific antigen (PSA) after prostatectomy were randomized to undergo either conventional imaging (CI) only (arm A) or CI plus 18F-fluciclovine PET/CT (arm B) before radiotherapy. In arm B, positivity rates on CI and 18F-fluciclovine PET/CT for detection of recurrent PCa were determined. Final decisions on whether to offer radiotherapy and whether to include only the prostate bed or also the pelvis in the radiotherapy field were based on 18F-fluciclovine PET/CT findings. Radiotherapy decisions before and after 18F-fluciclovine PET/CT were compared. The statistical significance of decision changes was determined using the Clopper-Pearson (exact) binomial method. Prognostic factors were compared between patients with and without decision changes. Results: All 165 patients enrolled in the study had standard-of-care CI and were initially planned to receive radiotherapy. Sixty-three of 79 (79.7%) patients (median PSA, 0.33 ng/mL) who underwent 18F-fluciclovine PET/CT (arm B) had positive findings. 18F-Fluciclovine PET/CT had a significantly higher positivity rate than CI did for the whole body (79.7% vs. 13.9%; P < 0.001), prostate bed (69.6% vs. 5.1%; P < 0.001), and pelvic lymph nodes (38.0% vs. 10.1%; P < 0.001). Twenty-eight of 79 (35.4%) patients had the overall radiotherapy decision changed after 18F-fluciclovine PET/CT; in 4 of 79 (5.1%), the decision to use radiotherapy was withdrawn because of extrapelvic disease detected on 18F-fluciclovine PET/CT. In 24 of 75 (32.0%) patients with a final decision to undergo radiotherapy, the radiotherapy field was changed. Changes in overall radiotherapy decisions and radiotherapy fields were statistically significant (P < 0.001). Overall, the mean PSA at PET was significantly different between patients with and without radiotherapy decision changes (P = 0.033). Conclusion:18F-Fluciclovine PET/CT significantly altered salvage radiotherapy decisions in patients with recurrent PCa after prostatectomy. Further analysis to determine the impact of 18F-fluciclovine PET/CT guidance on clinical outcomes after radiotherapy is in progress.

Diagnostic Performance of 18F-DCFPyL-PET/CT in Men with Biochemically Recurrent Prostate Cancer: Results from the CONDOR Phase III, Multicenter Study

PURPOSE

Current FDA-approved imaging modalities are inadequate for localizing prostate cancer biochemical recurrence (BCR). 18F-DCFPyL is a highly selective, small-molecule prostate-specific membrane antigen-targeted PET radiotracer. CONDOR was a prospective study designed to determine the performance of 18F-DCFPyL-PET/CT in patients with BCR and uninformative standard imaging.

EXPERIMENTAL DESIGN

Men with rising PSA ≥0.2 ng/mL after prostatectomy or ≥2 ng/mL above nadir after radiotherapy were eligible. The primary endpoint was correct localization rate (CLR), defined as positive predictive value with an additional requirement of anatomic lesion colocalization between 18F-DCFPyL-PET/CT and a composite standard of truth (SOT). The SOT consisted of, in descending priority (i) histopathology, (ii) subsequent correlative imaging findings, or (iii) post-radiation PSA response. The trial was considered a success if the lower bound of the 95% confidence interval (CI) for CLR exceeded 20% for two of three 18F-DCFPyL-PET/CT readers. Secondary endpoints included change in intended management and safety.

RESULTS

A total of 208 men with a median baseline PSA of 0.8 ng/mL (range: 0.2-98.4 ng/mL) underwent 18F-DCFPyL-PET/CT. The CLR was 84.8%-87.0% (lower bound of 95% CI: 77.8-80.4). A total of 63.9% of evaluable patients had a change in intended management after 18F-DCFPyL-PET/CT. The disease detection rate was 59% to 66% (at least one lesion detected per patient by 18F-DCFPyL-PET/CT by central readers).

CONCLUSIONS

Performance of 18F-DCFPyL-PET/CT achieved the study's primary endpoint, demonstrating disease localization in the setting of negative standard imaging and providing clinically meaningful and actionable information. These data further support the utility of 18F-DCFPyL-PET/CT to localize disease in men with recurrent prostate cancer.See related commentary by True and Chen, p. 3512.

Review of commonly used prostate specific PET tracers used in prostate cancer imaging in current clinical practice

¹⁸F-Fluorodeoxyglucose positron emission tomography (FDG-PET) underperforms in detecting prostate cancer (PCa) due to inherent characteristics of primary and metastatic tumors, including relatively low rate of glucose utilization. Consequently, alternate PCa PET imaging agents targeting other aspects of PCa cell biology have been developed for clinical practice. The most common dedicated PET imaging tracers include ⁶⁸Ga/¹⁸F prostate-specific membrane antigen (PSMA), ¹¹C-Choline, and ¹⁸F-fluciclovine (Axumin™). This review will describe how these agents target specific inherent characteristics of PCa and explore the current literature for these agents for both primary and recurrent PCa, comparing the advantages and limitations of each tracer. Both ¹¹C-Choline and ¹⁸F-Fluciclovine PET have been shown to detect nodal and osseous disease at higher rates compared to FDG-PET but offer no additional benefit in detecting prostate disease, especially in primary staging. As a result, PSMA PET, specifically ⁶⁸Ga-PSMA-11, has emerged as a key imaging option for both primary and recurrent cancer. PSMA PET may be more sensitive than MRI at the local level and more sensitive than ¹¹C-Choline and ¹⁸F-Fluciclovine PET for distant disease. Furthermore, compared to ¹¹C-Choline and ¹⁸F-Fluciclovine PET, ⁶⁸Ga-PSMA-11 PET has higher detection rates at low PSA levels (<2 ng/dL). With improved delineation of disease, PSMA imaging has influenced treatment planning; radiation fields can be narrowed, and patients with isolated or oligo-metastatic disease can be spared systemic therapy. The retrospective nature of many of the studies describing these PCa imaging modalities complicates their assessment and comparison.

Exploratory study of 18F-fluciclovine pet/ct for response assessment to docetaxel in patients with metastatic castration-resistant prostate cancer

Monitoring therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC) can be challenging. We set out to determine if ¹⁸F-fluciclovine PET/CT could be a useful imaging biomarker for response to docetaxel chemotherapy in patients with mCRPC. Seven patients with mCRPC had ¹⁸F-fluciclovine PET/CT scheduled at baseline and after 1 and 6 cycles of chemotherapy. The sum of SUVmax from the prostate/bed and up to 5 metastatic bone and soft tissue/visceral lesions were recorded. The SUVpeak of the hottest lesion (PERCIST-like) was also recorded. In comparison to the baseline scan, a decrease of ≥30% was considered response; new lesions or >30% increase was progressive disease; change of <30% was stable disease. Bone scintigraphy and CT were acquired at baseline and after the 6th cycle. Response assessment was based on the Prostate Cancer Clinical Trial Working Group 3 recommendations. All (7/7) enrolled patients completed the 1^st and 2^nd scans, while 4/7 patients completed all 3 scans. PET response correlated with PSA response in 3/7 (42.9%) patients after 1 cycle of docetaxel, and 3/4 (75%) patients after 6 cycles of docetaxel, respectively. Bone scan and CT correlated with PSA response in 1/4 (25%) patients. There was no significant correlation between baseline ¹⁸F-fluciclovine PET parameters or changes in PET parameters and time to PSA progression. In conclusion, this exploratory study showed that ¹⁸F-fluciclovine PET/CT has better correlation with PSA response than CT or bone scan in patients with mCRPC treated with docetaxel. ¹⁸F-fluciclovine PET/CT however did not predict time to PSA progression.

A bicentric retrospective analysis of clinical utility of 18F-fluciclovine PET in biochemically recurrent prostate cancer following primary radiation therapy: is it helpful in patients with a PSA rise less than the Phoenix criteria?

PURPOSE

¹⁸F-Fluciclovine PET imaging has been increasingly used in the restaging of prostate cancer patients with biochemical recurrence (BCR); however, its clinical utility in patients with low prostate-specific antigen (PSA) levels following primary radiation therapy has not been well-studied. This study aims to determine the detection rate and diagnostic accuracy of ¹⁸F-fluciclovine PET and the patterns of prostate cancer recurrence in patients with rising PSA after initial radiation therapy, particularly in patients with PSA levels below the accepted Phoenix definition of BCR (PSA nadir +2 ng/mL).

METHODS

This retrospective study included patients from two tertiary institutions who underwent ¹⁸F-fluciclovine PET scans for elevated PSA level following initial external beam radiation therapy, brachytherapy, and/or proton therapy. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to determine the diagnostic accuracy of ¹⁸F-fluciclovine PET and associations of PSA kinetic parameters with ¹⁸F-fluciclovine PET outcome.

RESULTS

One hundred patients were included in this study. The overall detection rate on a patient-level was 79% (79/100). ¹⁸F-Fluciclovine PET was positive in 62% (23/37) of cases with PSA below the Phoenix criteria. The positive predictive value of ¹⁸F-fluciclovine PET was 89% (95% CI: 80-94%). In patients with PSA below the Phoenix criteria, the PSA velocity had the highest predictive value of ¹⁸F-fluciclovine PET outcome. PSA doubling time (PSADT) and PSA velocity were associated with the presence of extra-pelvic metastatic disease.

CONCLUSION

¹⁸F-Fluciclovine PET can identify recurrent disease at low PSA level and PSA rise below accepted Phoenix criteria in patients with suspected BCR after primary radiation therapy, particularly in patients with low PSADT or high PSA velocity. In patients with low PSADT or high PSA velocity, there is an increased probability of extra-pelvic metastases. Therefore, these patients are more likely to benefit from PET/CT or PET/MRI than pelvic MRI alone.

18F-fluciclovine-PET/CT imaging versus conventional imaging alone to guide postprostatectomy salvage radiotherapy for prostate cancer (EMPIRE-1): a single centre, open-label, phase 2/3 randomised controlled trial

BACKGROUND

Molecular imaging is increasingly used to guide treatment decisions and planning in prostate cancer. We aimed to evaluate the role of ¹⁸F-fluciclovine-PET/CT in improving cancer control compared with conventional imaging (bone scan and either CT or MRI) alone for salvage postprostatectomy radiotherapy.

METHODS

In EMPIRE-1, a single-centre, open-label, phase 2/3 randomised controlled trial, patients with prostate cancer with detectable PSA after prostatectomy and negative conventional imaging (no extrapelvic or bone findings) were randomly assigned in a 1:1 ratio to radiotherapy directed by conventional imaging alone or to conventional imaging plus ¹⁸F-fluciclovine-PET/CT. Computer-generated randomisation was stratified by PSA concentration, adverse pathology indicators, and androgen deprivation therapy intent. In the ¹⁸F-fluciclovine-PET/CT group, radiotherapy decisions were rigidly determined by PET findings, which were also used for target delineation. The primary endpoint was 3 year event-free survival, with events defined as biochemical or clinical recurrence or progression, or initiation of systemic therapy, using univariate and multivariable analyses in patients who received radiotherapy. This trial is registered with ClinicalTrials.gov, NCT01666808 and is closed to new participants.

FINDINGS

From Sept 18, 2012, to March 4, 2019, 165 patients were randomly assigned, with median follow-up of 3·52 years (95% CI 2·98-3·95). PET findings resulted in four patients in the ¹⁸F-fluciclovine-PET/CT group having radiotherapy aborted; these patients were excluded from survival analyses. Median survival was not reached (95% CI 35·2-not reached; 33% of 81 patients had events) in the conventional imaging group compared with not reached (95% CI not reached-not reached; 20% of 76 patients) in the ¹⁸F-fluciclovine-PET/CT group, and 3 year event-free survival was 63·0% (95% CI 49·2-74·0) in the conventional imaging group versus 75·5% (95% CI 62·5-84·6) for ¹⁸F-fluciclovine-PET/CT (difference 12·5; 95% CI 4·3-20·8; p=0·0028). In adjusted analyses, study group (hazard ratio 2·04 [95% CI 1·06-3·93], p=0·0327) was significantly associated with event-free survival. Toxicity was similar in both study groups, with the most common adverse events being late urinary frequency or urgency (37 [46%] of 81 patients in the conventional imaging group and 31 [41%] of 76 in the PET group), and acute diarrhoea (11 [14%] in the conventional imaging group and 16 [21%] in the PET group).

INTERPRETATION

Inclusion of ¹⁸F-fluciclovine-PET into postprostatectomy radiotherapy decision making and planning significantly improved survival free from biochemical recurrence or persistence. Integration of novel PET radiotracers into radiotherapy decisions and planning for prostate cancer patients warrants further study.

FUNDING

National Institutes of Health/National Cancer Institute, Blue Earth Diagnostics, and Winship Cancer Institute of Emory University.

Molecular Imaging of Newly Diagnosed Prostate Cancer

Positron emission tomography (PET) is a valuable imaging in evaluating many malignancies. There are various molecular imaging tracers that are currently being utilized with prostate cancer (PC). Several PET agents imaging different molecular processes in PC have reached the clinic. While all of these agents have demonstrated an advantage over conventional imaging, there are considerable differences in the performance of each in staging newly diagnosed PC. In this article, we review the current updates available of different PET tracers, with a strong focus on the emerging role of prostate-specific membrane antigen PET in the management of newly diagnosed PC.

Prostate-Specific Membrane Antigen (PSMA)-Targeted Radionuclide Therapies for Prostate Cancer

PURPOSE OF REVIEW

Prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy (TRT) is a promising investigational treatment for metastatic castration-resistant prostate cancer (mCRPC). This review describes the available data with PSMA TRT.

RECENT FINDINGS

Conjugates used for PSMA TRT include antibodies or small molecules PSMA-radiolabeled with beta (most commonly 177Lu) or alpha emitters (commonly 225Ac). 177Lu-J591 demonstrated accurate targeting of known metastatic sites, based on post-treatment scintigraphy, in study populations that were not selected for PSMA expression, with evidence of dose-response and dose-limiting myelosuppression. Early phase studies of 177Lu-PSMA-617 have demonstrated favorable adverse event profiles and signs of clinical activity as evidenced by PSA responses and other short-term outcomes. A phase II randomized study of 177Lu-PSMA-617 showed a superior PSA50 response rate (66 vs 37%) over cabazitaxel in patients with docetaxel-pretreated, progressive mCRPC selected by PSMA and FDG PET/CT scans. PSMA TRT is emerging as a promising investigational therapy for mCRPC. The first randomized data with 177Lu-PSMA-617 (phase 2) have been presented, and the first phase 3 trial has completed accrual with radiographic progression-free and overall survival as dual primary endpoints. Multiple additional phase 3 trials of PSMA-TRT are starting and studies investigating optimal patient selection and combination therapy continue.

18F-Fluciclovine PET/CT in Therapeutic Decision Making for Prostate Cancer: A Large Single-Center Practice-Based Analysis

METHODS

We carried out a retrospective cohort study of patients with BR after primary treatment of PC who received imaging with 18F-fluciclovine PET/CT at our institution between January 2010 and January 2019. PET/CT results were compared with biopsy, conventional imaging results, and/or response to PC therapy. 18F-Fluciclovine PET/CT performance statistics and effects on treatment planning were calculated.

RESULTS

A total of 328 patients with a median age of 71 years (range, 47-90 years) and median serum prostate-specific antigen level of 1.6 ng/mL (0.02-186.7 ng/mL) were included. Three hundred thirty-six 18F-fluciclovine PET/CT scans were analyzed and classified as positive (65%), negative (25%), or equivocal (10%) based on radiology reports. Sensitivity was 93% (95% confidence interval, 86%-96%) and specificity was 63% (95% confidence interval, 45%-77%). Of patients with known management recommendations post-PET/CT, scan results changed or influenced pre-PET/CT management plans in 73%, and 58% of recommendations involved treatment modality decisions. Overall, 82% of patients' actual management was concordant with post-PET/CT recommendations. Of evaluable patients, 116 (35%) had some form of post-PET radiotherapy included in their care plans, with 95% receiving radiotherapy at a PET-avid target.

CONCLUSIONS

In the largest single-institutional cohort to date, 18F-fluciclovine PET/CT showed value in the workup of PC in the setting of BR, with noteworthy influence over clinical management decisions. Further studies are needed to evaluate whether PET/CT-based changes in management are associated with improved outcomes.

18F-Fluciclovine Positron Emission Tomography in Prostate Cancer: A Systematic Review and Diagnostic Meta-Analysis

Background: to explore the diagnostic accuracy of 18F-Fluciclovine positron-emission tomography (PET) in prostate cancer (PCa), considering both primary staging prior to radical therapy, biochemical recurrence, and advanced setting. Methods: A systematic web search through Embase and Medline was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies performed from 2011 to 2020 were evaluated. The terms used were “PET” or “positron emission tomography” or “positron emission tomography/computed tomography” or “PET/CT” or “positron emission tomography-computed tomography” or “PET-CT” and “Fluciclovine” or “FACBC” and “prostatic neoplasms” or “prostate cancer” or “prostate carcinoma”. Only studies reporting about true positive (TP), true negative (TN), false positive (FP) and false negative (FN) findings of 18F-fluciclovine PET were considered eligible. Results: Fifteen out of 283 studies, and 697 patients, were included in the final analysis. The pooled sensitivity for 18F-Fluciclovine PET/CT for diagnosis of primary PCa was 0.83 (95% CI: 0.80–0.86), the specificity of 0.77 (95% CI: 0.74–0.80). The pooled sensitivity for preoperative LN staging was 0.57 (95% CI: 0.39–0.73) and specificity of 0.99 (95% CI: 0.94–1.00). The pooled sensitivity for the overall detection of recurrence in relapsed patients was 0.68 (95% CI: 0.63–0.73), and specificity of 0.68 (95% CI: 0.60–0.75). Conclusion: This meta-analysis showed promising results in term of sensitivity and specificity for 18F-Fluciclovine PET/CT to stage the primary lesion and in the assessment of nodal metastases, and for the detection of PCa locations in the recurrent setting. However, the limited number of studies and the broad heterogeneity in the selected cohorts and in different investigation protocols are limitation affecting the strength of these results.

Role of 18F-Fluciclovine and Prostate-Specific Membrane Antigen PET/CT in Guiding Management of Oligometastatic Prostate Cancer: AJR Expert Panel Narrative Review

Twenty-five years ago, oligometastatic disease was proposed as an intermediary clinical state of cancer with unique implications for therapies that may impact cancer evolution and patient outcome. Identification of limited metastases that are potentially amenable to targeted therapies fundamentally depends on the sensitivity of diagnostic tools, including new-generation imaging methods. For men with biochemical recurrence after definitive therapy of the primary prostate cancer, PET/CT using either the FDA-approved radiolabeled amino acid analogue ¹⁸F-fluciclovine or investigational radiolabeled agents targeting prostate-specific membrane antigen (PSMA) enables identification of early metastases at lower serum PSA levels than was previously feasible using conventional imaging. Evidence supports PSMA PET/CT as the most sensitive imaging modality available for identifying disease sites in oligometastatic prostate cancer. PSMA PET/CT will likely become the modality of choice after regulatory approval and will drive the development of trials of emerging metastasis-directed therapies such as stereotactic ablative body radiation and radioguided surgery. Indeed, numerous ongoing or planned clinical trials are studying advances in management of oligometastatic prostate cancer based on this heightened diagnostic capacity. In this rapidly evolving clinical environment, radiologists and nuclear medicine physicians will play major roles in facilitating clinical decision making and management of patients with oligometastatic prostate cancer.

The Clinical Utility of 18F-Fluciclovine PET/CT in Biochemically Recurrent Prostate Cancer: an Academic Center Experience Post FDA Approval

PURPOSE

To evaluate the diagnostic performance and clinical utility of ¹⁸F-fluciclovine PET/CT in patients with biochemical recurrence (BCR) of prostate cancer (PC).

METHODS

¹⁸F-Fluciclovine scans of 165 consecutive men with BCR after primary definitive treatment with prostatectomy (n = 102) or radiotherapy (n = 63) were retrospectively evaluated. Seventy patients had concurrent imaging with at least one other conventional modality (CT (n = 31), MRI (n = 31), or bone scan (n = 26)). Findings from ¹⁸F-fluciclovine PET were compared with those from conventional imaging modalities. The positivity rate and impact of ¹⁸F-fluciclovine PET on patient management were recorded. In 33 patients who underwent at least one other PET imaging (¹⁸F-NaF PET/CT (n = 12), ⁶⁸Ga-PSMA11 PET/CT (n = 5), ¹⁸F-DCFPyL PET/CT (n = 20), and ⁶⁸Ga-RM2 PET/MRI (n = 5)), additional findings were evaluated.

RESULTS

The overall positivity rate of ¹⁸F-fluciclovine PET was 67 %, which, as expected, increased with higher prostate-specific antigen (PSA) levels (ng/ml): 15 % (PSA < 0.5), 50 % (0.5 ≤ PSA < 1), 56 % (1 ≤ PSA < 2), 68 % (2 ≤ PSA < 5), and 94 % (PSA ≥ 5), respectively. One hundred and two patients (62 %) had changes in clinical management based on ¹⁸F-fluciclovine PET findings. Twelve of these patients (12 %) had lesion localization on ¹⁸F-fluciclovine PET, despite negative conventional imaging. Treatment plans of 14 patients with negative ¹⁸F-fluciclovine PET were changed based on additional PET imaging with a different radiopharmaceutical.

CONCLUSION

¹⁸F-Fluciclovine PET/CT remains a useful diagnostic tool in the workup of patients with BCR PC, changing clinical management in 62 % of participants in our cohort.

Detection of Recurrent Prostate Cancer With 18F-Fluciclovine PET/MRI

OBJECTIVE

Simultaneous PET/MRI combines soft-tissue contrast of MRI with high molecular sensitivity of PET in one session. The aim of this prospective study was to evaluate detection rates of recurrent prostate cancer by 18F-fluciclovine PET/MRI.

METHODS

Patients with biochemical recurrence (BCR) or persistently detectable prostate specific antigen (PSA), were examined with simultaneous 18F-fluciclovine PET/MRI. Multiparametric MRI (mpMRI) and PET/MRI were scored on a 3-point scale (1-negative, 2-equivocal, 3-recurrence/metastasis) and detection rates (number of patients with suspicious findings divided by total number of patients) were reported. Detection rates were further stratified based on PSA level, PSA doubling time (PSAdt), primary treatment and inclusion criteria (PSA persistence, European Association of Urology (EAU) Low-Risk BCR and EAU High-Risk BCR). A detailed investigation of lesions with discrepancy between mpMRI and PET/MRI scores was performed to evaluate the incremental value of PET/MRI to mpMRI. The impact of the added PET acquisition on further follow-up and treatment was evaluated retrospectively.

RESULTS

Among patients eligible for analysis (n=84), 54 lesions were detected in 38 patients by either mpMRI or PET/MRI. Detection rates were 41.7% for mpMRI and 39.3% for PET/MRI (score 2 and 3 considered positive). There were no significant differences in detection rates for mpMRI versus PET/MRI. Disease detection rates were higher in patients with PSA≥1ng/mL than in patients with lower PSA levels but did not differ between patients with PSAdt above versus below 6 months. Detection rates in patients with primary radiation therapy were higher than in patients with primary surgery. Patients categorized as EAU Low-Risk BCR had a detection rate of 0% both for mpMRI and PET/MRI. For 15 lesions (27.8% of all lesions) there was a discrepancy between mpMRI score and PET/MRI score. Of these, 10 lesions scored as 2-equivocal by mpMRI were changed to a more definite score (n=4 score 1 and n=6 score 3) based on the added PET acquisition. Furthermore, for 4 of 10 patients with discrepancy between mpMRI and PET/MRI scores, the added PET acquisition had affected the treatment choice.

CONCLUSION

Combined 18F-fluciclovine PET/MRI can detect lesions suspicious for recurrent prostate cancer in patients with a range of PSA levels. Combined PET/MRI may be useful to select patients for appropriate treatment, but is of limited use at low PSA values or in patients classified as EAU Low-Risk BCR, and the clinical value of 18F-fluciclovine PET/MRI in this study was too low to justify routine clinical use.

Incidental Detection of Lung Adenocarcinoma Presenting as an Anterior Mediastinal Mass on 18F-Fluciclovine PET/CT in a Patient With Primary Prostate Cancer

F-fluciclovine is a PET radiotracer approved for detection of recurrent prostate cancer, with utility in other malignancies being investigated. We present the case of a 71-year-old man with high-risk primary prostate cancer (Gleason score 9, prostate-specific antigen 34 ng/mL) and newly diagnosed lung adenocarcinoma. As part of a clinical trial (NCT03081884), preoperative F-fluciclovine PET/CT showed localized abnormal uptake in the prostate gland with extracapsular extension. Additionally, an incidental anterior mediastinal mass measuring 2.2 × 1.8 cm demonstrated abnormal radiotracer uptake. Biopsy of the mediastinal mass confirmed invasive lung adenocarcinoma with solid and acinar patterns and high programmed death 1 ligand expression.

Imaging assessment of local recurrence of prostate cancer after radical prostatectomy

Definitive therapy for prostate cancer includes radical prostatectomy and radiation therapy. Treatment is elected based on patient preference, biological tumor factors, and underlying health. Post prostatectomy, men are surveyed for disease recurrence with serial PSA measurements, digital rectal exam, and imaging studies depending on nomogram predicted risk of local disease recurrence and distant metastasis. In men with rising PSA levels, pathologically incomplete surgical margins or, if symptoms of metastasis develop, imaging may be obtained to localize disease. In cases of known biochemical recurrence, imaging is used to target biopsy, to contour in salvage radiation therapy and to assess disease response. For local disease recurrence, the most commonly performed exams are pelvic MRI and transrectal US. CT can evaluate for lymph node metastasis, but is suboptimal in the evaluation of the prostatectomy bed. PET/CT and PET/MRI have been used successfully to evaluate for local disease recurrence. The PI-RADSv2.1 manual provides a risk level and lexicon for use in description of prostate carcinoma prior to prostatectomy, but does not address imaging features post-surgery. A detailed description of nodal, bony, and visceral metastasis is given elsewhere. This manuscript outlines the context in which appropriate imaging exams may be obtained and focuses on imaging findings concerning for local disease recurrence after prostatectomy on various imaging modalities including CT, US, MRI, and PET.

Assessment of Postprostatectomy Radiotherapy as Adjuvant or Salvage Therapy in Patients With Prostate Cancer: A Systematic Review

Importance

After radical prostatectomy, adverse pathologic features and postoperative prostate-specific antigen (PSA) levels can herald disease recurrence or progression. Postoperative radiotherapy (RT) remains beneficial in this setting.

Objective

To examine the evidence supporting the use of postoperative RT as well as recent advances that help determine timing, scope, and use in combination with androgen deprivation therapy (ADT) with or without lymphatic irradiation.

Evidence Review

A search was conducted of MEDLINE (Ovid), Embase (Elsevier), and the Cochrane Library (Wiley) databases, in addition to clinical trial registries. The reference list of included studies was reviewed for relevant articles. The search was limited to studies published between January 1, 2014, and December 31, 2019.

Findings

After 548 citations were screened, 27 articles were selected for inclusion. In addition to conventional imaging, positron-emission tomographic (PET)-based radiotracers can aid in disease localization. While PET imaging may influence management with RT, studies are underway examining this issue, and several limitations must be considered, such as limited detectability at lower PSA levels and regional sensitivity. Available genomic classifiers can risk stratify patients or assess potential added benefit of RT. Prospective validation is underway with cooperative group trials. Adjuvant RT, on the basis of adverse pathologic features (such as extraprostatic extension or positive margins) is beneficial in terms of disease control, but it is unclear whether this therapy translates into more meaningful clinical benefit (eg, improved overall survival and a reduction in metastasis), which has been demonstrated by only 1 older, prospective randomized study. Preliminary data suggest that for a relatively favorable-risk population (low Gleason score but with positive margins), PSA monitoring may be a reasonable alternative in some men. Use of androgen deprivation therapy and lymphatic irradiation should be considered in higher-risk cohorts (those with high PSA, high Gleason score, seminal vesicle invasion or node positivity) in conjunction with postoperative RT.

Conclusions and Relevance

The findings of this review suggest that postprostatectomy RT should be considered for men with prostate cancer in the setting of adverse pathologic features; in carefully selected patients with favorable characteristics, close PSA monitoring is an option. Androgen deprivation therapy and pelvic lymphatic irradiation should be considered for higher risk cohorts (eg, higher PSA values, higher Gleason score). PET imaging and molecular studies remain unproven as decision tools.

Current Status of MRI and PET in the NCCN Guidelines for Prostate Cancer

Prostate cancer (PCa) represents a significant source of morbidity and mortality for men in the United States, with approximately 1 in 9 being diagnosed with PCa in their lifetime. The role of imaging in the evaluation of men with PCa has evolved and currently plays a central role in diagnosis, treatment planning, and evaluation of recurrence. Appropriate use of multiparametric MRI (mpMRI) and MRI-guided transrectal ultrasound (MR-TRUS) biopsy increases the detection of clinically significant PCa while decreasing the detection of clinically insignificant PCa. This process may help patients with clinically insignificant PCa avoid the adverse effects of unnecessary therapy. In the setting of a known PCa, patients with low-grade disease can be observed using active surveillance, which often includes a combination of prostate-specific antigen (PSA) testing, serial mpMRI, and, if indicated, follow-up systematic and targeted TRUS-guided tissue sampling. mpMRI can provide important information in the posttreatment setting, but PET/CT is creating a paradigm shift in imaging standards for patients with locally recurrent and metastatic PCa. This article examines the strengths and limitations of mpMRI for initial PCa diagnosis, active surveillance, recurrent disease evaluation, and image-guided biopsies, and the use of PET/CT imaging in men with recurrent PCa. The goal of this review is to provide a rational basis for current NCCN Clinical Practice Guidelines in Oncology for PCa as they pertain to the use of these advanced imaging modalities.

The Role of PET-CT Imaging in Prostate Cancer

Prostate cancer is the commonest malignancy to affect men in the United Kingdom. Extraprostatic disease detection at staging and in the setting of biochemical recurrence is essential in determining treatment strategy. Conventional imaging including computed tomography and bone scintigraphy are limited in their ability to detect sites of loco-regional nodal and metastatic bone disease, particularly at clinically relevant low prostate-specific antigen levels. The use of positron emission tomography-computed tomography has helped overcome these deficiencies and is leading a paradigm shift in the management of prostate cancer using a wide range of radiopharmaceuticals. Their mechanisms of action, utility in both staging and biochemical recurrence, and comparative strengths and weaknesses will be covered in this article.

Novel PET imaging methods for prostate cancer

INTRODUCTION

Prostate cancer is a common neoplasm but conventional imaging methods such as CT and bone scan are often insensitive. A new class of PET agents have emerged to diagnose and manage prostate cancer.

METHODS

The relevant literature on PET imaging agents for prostate cancer was reviewed.

RESULTS

This review shows a broad range of PET imaging agents, the most successful of which is prostate specific membrane antigen (PSMA) PET. Other agents either lack the sensitivity or specificity of PSMA PET.

CONCLUSION

Among the available PET agents for prostate cancer, PSMA PET has emerged as the leader. It is likely to have great impact on the diagnosis, staging and management of prostate cancer patients.

Utility of 18F-Fluciclovine PET/CT for Detecting Prostate Cancer Recurrence in Patients With Low (< 1 ng/mL) or Very Low (< 0.3 ng/mL) Prostate-Specific Antigen Levels

OBJECTIVE. We reviewed a retrospective series of 126 ¹⁸F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that ¹⁸F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that ¹⁸F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.

Fluorine-18-Labeled Fluciclovine PET/CT in Primary and Biochemical Recurrent Prostate Cancer Management

OBJECTIVE. The purpose of this article is to review the utility of ¹⁸F-fluciclovine PET/CT in the evaluation of recurrent prostate cancer. CONCLUSION. Fluorine-18-labeled fluciclovine PET/CT has shown promise in the evaluation of recurrent prostate cancer. Its performance has been superior to that of other imaging modalities. It has had good diagnostic accuracy, especially in the detection of extra-prostatic disease recurrence, and the findings have an impact on treatment planning. Gallium-68-labeled prostate-specific membrane antigen PET/CT has also had excellent performance in the detection of biochemically recurrent prostate cancer with detection rates superior to those of fluciclovine PET/CT.

Non-metastatic castration-resistant prostate cancer: current status and future directions

INTRODUCTION

The emergence of novel hormonal therapies and the increase availability of sensitive next-generation imaging techniques has significantly changed the management of recurrent prostate cancer.

AREAS COVERED

In this review, we summarize the definition, diagnosis, treatment, and ongoing clinical trials in non-metastatic castration resistant prostate cancer (M0CRPC). We have also discussed the role of newer imaging modalities in the detection of advanced prostate cancer.

EXPERT OPINION

M0CRPC is a disease state in prostate cancer when serologic progression (PSA only disease) occurs despite castrated levels of testosterone and imaging shows no evidence of metastasis. With the availability of next-generation imaging, more patients are migrating from M0CRPC to mCRPC space. This stage migration impacts the treatment options currently available in clinical practice and requires the integration of novel imaging in prospective studies moving forward. Until that data become available men with M0CRPC should be considered for therapy with any of these three novel oral AR inhibitors, with a positive impact in metastasis-free and overall survival. Treatment selection should be based on Quality of Life, side effects, and drug-drug interactions.

Effect of 18F-Fluciclovine Positron Emission Tomography on the Management of Patients With Recurrence of Prostate Cancer: Results From the FALCON Trial

PURPOSE

Early and accurate localization of lesions in patients with biochemical recurrence (BCR) of prostate cancer may guide salvage therapy decisions. The present study, 18F-Fluciclovine PET/CT in biochemicAL reCurrence Of Prostate caNcer (FALCON; NCT02578940), aimed to evaluate the effect of 18F-fluciclovine on management of men with BCR of prostate cancer.

METHODS AND MATERIALS

Men with a first episode of BCR after curative-intent primary therapy were enrolled at 6 UK sites. Patients underwent 18F-fluciclovine positron emission tomography/computed tomography (PET/CT) according to standardized procedures. Clinicians documented management plans before and after scanning, recording changes to treatment modality as major and changes within a modality as other. The primary outcome measure was record of a revised management plan postscan. Secondary endpoints were evaluation of optimal prostate specific antigen (PSA) threshold for detection, salvage treatment outcome assessment based on 18F-fluciclovine-involvement, and safety.

RESULTS

18F-Fluciclovine was well tolerated in the 104 scanned patients (median PSA = 0.79 ng/mL). Lesions were detected in 58 out of 104 (56%) patients. Detection was broadly proportional to PSA level; ≤1 ng/mL, 1 out of 3 of scans were positive, and 93% scans were positive at PSA >2.0 ng/mL. Sixty-six (64%) patients had a postscan management change (80% after a positive result). Major changes (43 out of 66; 65%) were salvage or systemic therapy to watchful waiting (16 out of 66; 24%); salvage therapy to systemic therapy (16 out of 66; 24%); and alternative changes to treatment modality (11 out of 66, 17%). The remaining 23 out of 66 (35%) management changes were modifications of the prescan plan: most (22 out of 66; 33%) were adjustments to planned brachytherapy/radiation therapy to include a 18F-fluciclovine-guided boost. Where 18F-fluciclovine guided salvage therapy, the PSA response rate was higher than when 18F-fluciclovine was not involved (15 out of 17 [88%] vs 28 out of 39 [72%]).

CONCLUSIONS

18F-Fluciclovine PET/CT located recurrence in the majority of men with BCR, frequently resulting in major management plan changes. Incorporating 18F-fluciclovine PET/CT into treatment planning may optimize targeting of recurrence sites and avoid futile salvage therapy.

Comparison of cross-sectional imaging techniques for the detection of prostate cancer lymph node metastasis: a critical review

Conventional staging for prostate cancer (PCa) is performed for men diagnosed with unfavorable-intermediate or higher risk disease. Computed tomography (CT) of the abdomen and pelvis and whole body bone scan remains the standard of care for the detection of visceral, nodal, and bone metastasis. The implementation of the 2012 United States Preventive Services Task Force recommendation against routine prostate specific antigen (PSA) screening resulted in a rise of metastatic PCa at the time of diagnosis, emphasizing the importance of effective imaging modalities for evaluating metastatic disease. CT plays a major role in clinical staging at the time of PCa diagnosis, but multi-parametric magnetic resonance imaging (MRI) is now integrated into many prostate biopsy protocols for the detection of primary PCa, and may be a surrogate for CT for nodal staging. Current guidelines incorporate both CT and MRI as appropriate cross-sectional imaging modalities for the identification of nodal metastasis in indicated patients. There is an ongoing debate about the utility of traditional cross-sectional imaging modalities as well as advanced imaging modalities in detection of both organ-confined PCa detection and nodal involvement.

[18F]Fluciclovine Positron Emission Tomography/Computerized Tomography for Preoperative Staging in Patients with Intermediate to High Risk Primary Prostate Cancer

PURPOSE

Accurate preoperative staging of prostate cancer is essential for treatment planning. Conventional imaging is limited in detection of metastases. Our primary aim was to determine if [¹⁸F]fluciclovine positron emission tomography/computerized tomography is an early indicator of subclinical metastasis among patients with high risk prostate cancer.

MATERIALS AND METHODS

A total of 68 patients with unfavorable intermediate to very high risk prostate cancer without systemic disease on conventional imaging were recruited before robotic radical prostatectomy with extended pelvic lymph node dissection. Diagnostic performance of [¹⁸F]fluciclovine positron emission tomography/computerized tomography and conventional imaging for detection of metastatic disease, and correlation of positivity to node and metastatic deposit size were determined.

RESULTS

Overall 57 of 68 patients completed the protocol, of whom 31 had nodal metastasis on histology. [¹⁸F]Fluciclovine positron emission tomography/computerized tomography sensitivity and specificity in detecting nodal metastasis was 55.3% and 84.8% per patient, and 54.8% and 96.4% per region (right and left pelvis, presacral and nonregional), respectively. Compared with conventional imaging [¹⁸F]Fluciclovine positron emission tomography/computerized tomography had significantly higher sensitivity on patient based (55.3% vs 33.3%, p <0.01) and region based (54.8% vs 19.4%, p <0.01) analysis, detecting metastasis in 7 more patients and 22 more regions, with similar high specificity. Four additional patients had distant disease or other cancer detected on [¹⁸F] fluciclovine positron emission tomography/computerized tomography which precluded surgery. Detection of metastasis was related to size of metastatic deposits within lymph nodes and overall metastatic burden.

CONCLUSIONS

[¹⁸F]Fluciclovine positron emission tomography/computerized tomography detects occult metastases not identified on conventional imaging and may help guide treatment decisions and lymph node dissection due to high specificity for metastatic disease.