Theragnostic Aspects and Radioimmunotherapy in Pediatric Tumors

Brain metastasis: An insight into novel molecular targets for theranostic approaches

Brain metastases (BrM) are common malignant lesions in the central nervous system, and pose a significant threat in advanced-stage malignancies due to delayed diagnosis and limited therapeutic options. Their distinct genomic profiles underscore the need for molecular profiling to tailor effective treatments. Recent advances in cancer biology have uncovered molecular drivers underlying tumor initiation, progression, and metastasis. This, coupled with the advances in molecular imaging technology and radiotracer synthesis, has paved the way for the development of innovative radiopharmaceuticals with enhanced specificity and affinity for BrM specific targets. Despite the challenges posed by the blood-brain barrier to effective drug delivery, several radiolabeled compounds have shown promise in detecting and targeting BrM. This manuscript provides an overview of the recent advances in molecular biomarkers used in nuclear imaging and targeted radionuclide therapy in both clinical and preclinical settings. Additionally, it explores potential theranostic applications addressing the unique challenges posed by BrM.

Functional Imaging in Musculoskeletal Disorders in Menopause

Menopause-related musculoskeletal (MSK) disorders include osteoporosis, osteoarthritis (OA), sarcopenia and sarco-obesity. This review focuses on the applications of nuclear medicine for the functional imaging of the aforementioned clinical conditions. Bone Scan (BS) with 99mTc-labeled phosphonates, alone or in combination with MRI, can identify "fresh" vertebral collapse due to age-associated osteoporosis and provides quantitative parameters characterized by a good correlation with radiological indices in patients with OA. 18F-NaF PET, particularly when performed by dynamic scan, has given encouraging results for measuring bone turnover in osteoporosis and allows the evaluation of subchondral bone metabolic activity in OA. FDG PET can help discriminate between pathological and nonpathological vertebral fractures, especially by applying appropriate SUV-based thresholds. In OA, it can effectively image inflamed joints and support appropriate clinical management. Preliminary evidences suggest a possible application of FDG in sarco-obesity for the detection and quantification of visceral adipose tissue (VAT). Further studies are needed to better define the role of nuclear medicine in menopause-related MSK disease, especially as regards the possible impact of new radiopharmaceuticals (ie, FAPI and RGD peptides) and recent technological advances (eg, total-body PET/CT scanners).

NECTIN-4 targeted theranostics for urothelial cancer: getting ready for primetime?

Locally advanced and metastatic urothelial carcinoma (UC) presents a bleak prognosis, with limited treatment options. NECTIN-4, an overexpressed protein in UC, has become a target for therapy. Enfortumab vedotin (EV) gained Food and Drug Administration approval for advanced UC treatment, but patient selection based on NECTIN-4 expression remains challenging. In the study under evaluation, Duan et al. introduced a novel PET/CT imaging approach using 68Ga-N188, a molecular probe, to visualize NECTIN-4 expression in UC. Their study encompassed preclinical evaluations and translational assessments in both healthy individuals and UC patients. Results demonstrated the potential of 68Ga-N188 in identifying NECTIN-4 expression in UC lesions. Additionally, the study utilized long axial field-of-view (LAFOV) PET/CT, enhancing sensitivity and enabling dynamic studies for improved radiopharmaceutical evaluation. In summary, the study from Duan and colleagues introduces a promising molecular imaging technique that could aid in patient selection for EV therapy and the development of targeted drugs for UC. It also highlights the potential of LAFOV PET/CT in enhancing imaging precision and expanding future therapeutic possibilities for UC.

Radiometals in Imaging and Therapy: Highlighting Two Decades of Research

The present article highlights the important progress made in the last two decades in the fields of molecular imaging and radionuclide therapy. Advancements in radiometal-based positron emission tomography, single photon emission computerized tomography, and radionuclide therapy are illustrated in terms of their production routes and ease of radiolabeling. Applications in clinical diagnostic and radionuclide therapy are considered, including human studies under clinical trials; their current stages of clinical translations and findings are summarized. Because the metalloid astatine is used for imaging and radionuclide therapy, it is included in this review. In regard to radionuclide therapy, both beta-minus (β-) and alpha (α)-emitting radionuclides are discussed by highlighting their production routes, targeted radiopharmaceuticals, and current clinical translation stage.

Nuclear Medicine and Cancer Theragnostics: Basic Concepts

Cancer theragnostics is a novel approach that combines diagnostic imaging and radionuclide therapy. It is based on the use of a pair of radiopharmaceuticals, one optimized for positron emission tomography imaging through linkage to a proper radionuclide, and the other bearing an alpha- or beta-emitter isotope that can induce significant damage to cancer cells. In recent years, the use of theragnostics in nuclear medicine clinical practice has increased considerably, and thus investigation has focused on the identification of novel radionuclides that can bind to molecular targets that are typically dysregulated in different cancers. The major advantages of the theragnostic approach include the elimination of multi-step procedures, reduced adverse effects to normal tissues, early diagnosis, better predictive responses, and personalized patient care. This review aims to discuss emerging theragnostic molecules that have been investigated in a series of human malignancies, including gliomas, thyroid cancer, neuroendocrine tumors, cholangiocarcinoma, and prostate cancer, as well as potent and recently introduced molecular targets, like cell-surface receptors, kinases, and cell adhesion proteins. Furthermore, special reference has been made to copper radionuclides as theragnostic agents and their radiopharmaceutical applications since they present promising alternatives to the well-studied gallium-68 and lutetium-177.

[18F]-FDHT PET for the Imaging of Androgen Receptor in Prostate and Breast Cancer: A Systematic Review

The aim of this systematic review is to provide a comprehensive overview of the role of fluoro-5α-dihydrotestosterone ([18F]-FDHT) for the in vivo imaging of androgen receptors (AR) through positron emission tomography (PET) in metastatic breast (mBC) and metastatic castration-resistant prostate cancer (mCRPC). Relevant studies published from 2013 up to May 2023 were selected by searching Scopus, PubMed and Web of Science. The selected imaging studies were analyzed using a modified version of the critical Appraisal Skills Programme (CASP). Eleven studies encompassing 321 patients were selected. Seven of the eleven selected papers included 266 subjects (82.2%) affected by mCRPC, while four encompassed 55 (17.2%) patients affected by mBC. [18F]-FDHT PET showed a satisfying test/retest reproducibility, and when compared to a histochemical analysis, it provided encouraging results for in vivo AR quantification both in mCRPC and mBC. [18F]-FDHT PET had a prognostic relevance in mCRPC patients submitted to AR-targeted therapy, while a clear association between [18F]-FDHT uptake and the bicalutamide response was not observed in women affected by AR-positive mBC. Further studies are needed to better define the role of [18F]-FDHT PET, alone or in combination with other tracers (i.e., [18F]-FDG/[18F]-FES), for patients' selection and monitoring during AR-targeted therapy, especially in the case of mBC.

The new bone WB-SPECT/CT: hybrid, from head-to-toe and digital! Is it worth the effort?

INTRODUCTION

A bone scan (BS) plays a pivotal role in many oncological and non-oncological conditions. The planar BS is characterized by high sensitivity but low specificity. With respect to planar imaging, the implementation of single-photon emission computed tomography (SPECT) has allowed increased image contrast and more accurate tracer localization.

AREAS COVERED

Recent technological innovations in the field of BS are treated, with a particular focus on multi-field-of-view devices allowing to cover the entire scan length with a 3D acquisition (WB-SPECT/CT). In addition, the applications of cadmium zinc telluride/CzT detectors capable of converting gamma photons directly into electrical impulses (i.e. 'digital SPECT') are discussed.

EXPERT OPINION

Initial clinical experiences indicate that WB-SPECT/CT is characterized by higher sensitivity, diagnostic accuracy, and increased confidence in image interpretation with respect to the 'old-fashioned' BS (planar images with or without a single field-of-view SPECT). Furthermore, CzT-based detectors, thanks to their superior sensitivity, might be helpful to implement fast acquisition protocols. Further studies are needed to better define the clinical impact of bone CzT WB-SPECT/CT on patients' management and outcome, as well as its cost-benefit ratio.

Head-to-Head Comparison between FDG and 11C-Methionine in Multiple Myeloma: A Systematic Review

The aim of this systematic review is to provide a comprehensive overview of the existing literature, comparing ¹⁸F-fluorodeoxyglucose (FDG) and ¹¹C-methionine (MET) for the imaging of multiple myeloma (MM) with positron emission computed tomography (PET/CT). Relevant studies published from 2013 up to March 2023 were selected by searching Scopus, PubMed, and Web of Science. Selected imaging studies were analyzed using a modified version of the critical Appraisal Skills Programme (CASP). Ten studies encompassing 335 patients were selected. On a patient-based analysis, MET sensitivity ranged between 75.6% and 100%, resulting higher than that measured for FDG (0-100%). MET outperformed FDG for the detection of focal lesions, diffuse bone marrow involvement and mixed patterns. PET-derived parameters resulted higher for MET than for FDG, with a strong correlation with clinical variables (e.g., monoclonal component and beta-2-microglobulin levels, bone marrow infiltration, etc.), although FDG maintained a prognostic impact on outcome prediction. When compared to other tracers or imaging modalities, MET showed stronger correlation and inter-observer agreement than FDG. Although biased by the small cohorts and requiring confirmation through multicenter studies, preliminary findings suggest that MET-PET should be preferred to FDG for PET imaging of MM, or alternatively used as a complementary imaging modality. Some issues, such as tracer availability and the role of MET with respect to other emerging tracers (i.e., ⁶⁸Ga-pentixafor, ¹⁸F-FACBC and ¹⁸F-FET), should be the topic of further investigations.

Clinical Applications of TSPO PET for Glioma Imaging: Current Evidence and Future Perspective-A Systematic Review

Our aim was to provide a comprehensive overview of the existing literature concerning the clinical applications of positron emission computed tomography (PET) with radiopharmaceuticals targeting the translocator protein (TSPO) in gliomas. A literature search for studies about TSPO PET in the last 10 years (from 2013 to February 2023) was carried out on PubMed, Scopus, and Web of Science using the following keywords: "PET" AND "Gliomas" AND "TSPO". The Critical Appraisal Skills Program checklist for diagnostic test studies was used for testing the quality of selected papers. Ten articles were selected, encompassing 314 glioma patients submitted to PET/CT (9/10) or PET/MRI (1/10) with TSPO ligands. Among the various available TSPO tracers, the most frequently used was the third-generation ligand, [¹⁸F]-GE-180. TSPO PET results were useful to identify anaplastic transformation in gliomas and for the prognostic stratification of patients bearing homogeneous genetic alterations. When compared to amino-acid PET, TSPO PET with [¹⁸F]-GE-180 presented superior image quality and provided larger and only partially overlapping PET-based volumes. Although biased by some issues (i.e., small sample size, most of the studies coming from the same country), preliminary applications of TSPO PET were encouraging. Further studies are needed to define implications in clinical practice and shape the role of TSPO PET for patients' selection for potential TSPO-targeted molecular therapies.

Novel Theranostic Approaches Targeting CCR4-Receptor, Current Status and Translational Prospectives: A Systematic Review

Background: With the high mortality rate of malignant tumors, there is a need to find novel theranostic approaches to provide an early diagnosis and targeted therapy. The chemokine receptor 4 (CCR4) is highly expressed in various tumors and plays an important role in tumor pathogenesis. This systematic review aims to provide a complete overview on clinical and preclinical applications of the CCR4 receptor as a target for theranostics, using a systematic approach to classify and assemble published studies performed on humans and animals, sorted by field of application and specific tumor. Methods: A systematic literature search of articles suiting the inclusion criteria was conducted on Pubmed, Scopus, Central, and Web of Science databases, including papers published from January 2006 to November 2022. Eligible studies had to be performed on humans and/or in vivo/in vitro studying CCR4 expression in tumors. The methodological quality was assessed through the Critical Appraisal Skills Programme (CASP) assessing only the studies performed on humans. Results: A total of 17 articles were screened. The articles were assessed for eligibility with the exclusion of 4 articles. Ultimately, 13 articles were selected for the qualitative analysis, and six articles were selected for the critical appraisal skills program. Conclusions: The development of new radionuclides and radiopharmaceuticals targeting CCR4 show promising results in the theranostics of CCR4 sensible tumors. Although to widen its use in clinical practice, further translation of preclinical to clinical data is needed.

Fibroblast Activation Protein Inhibitor (FAPI)-Based Theranostics-Where We Are at and Where We Are Heading: A Systematic Review

Cancer is the leading cause of death around the globe, followed by heart disease and stroke, with the highest mortality to this day. We have reached great levels of understanding of how these various types of cancer operate at a cellular level and this has brought us to what we call "precision medicine" where every diagnostic examination and the therapeutic procedure is tailored to the patient. FAPI is among the new tracers that can be used to assess and treat many types of cancer. The aim of this review was to gather all the known literature on FAPI theranostics. A MEDLINE search was conducted on four web libraries, PUBMED, Cochrane, Scopus, and Web of Sciences. All of the available articles that included both diagnoses and therapy with FAPI tracers were collected and put through the CASP (Critical Appraisal Skills Programme) questionnaire for systematic reviewing. A total of 8 records were deemed suitable for CASP review, ranging from 2018 to November 2022. These studies were put through the CASP diagnostic checklist, in order to assess the goal of the study, diagnostic and reference tests, results, descriptions of the patient sample, and future applications. Sample sizes were heterogeneous, both for size as well as for tumor type. Only one author studied a single type of cancer with FAPI tracers. Progression of disease was the most common outcome, and no relevant collateral effects were noted. Although FAPI theranostics is still in its infancy and lacks solid grounds to be brought into clinical practice, it does not show any collateral effects that prohibit administration to patients, thus far, and has good tolerability profiles.

DNA Damage Repair Defects and Targeted Radionuclide Therapies for Prostate Cancer: Does Mutation Really Matter? A Systematic Review

The aim of the present review was to assess the impact of DNA damage repair (DDR) mutations on response and outcome of patients (pts) affected by advanced prostate cancer (PCa) submitted to radionuclide therapies with [223Ra]RaCl2 (223Ra-therapy) or prostate specific membrane antigen (PSMA) ligands. A systematic literature search according to PRISMA criteria was made by using two main databases. Only studies published up until to October 2022 in the English language with ≥10 enrolled patients were selected. Seven studies including 326 pts, of whom 201 (61.6%) harboring DDR defects, were selected. The majority of selected papers were retrospective and four out of seven (57.1%) had small sample size (<50 pts). Three out of seven (42.8%) studies reported a more favorable outcome (overall or progression free survival) after therapy with alpha emitters (223Ra-therapy or [225Ac]Ac-PSMA-617) in subjects with DDR defects with respect to those without mutations. In two studies employing alpha or beta emitters ([177Lu]/[225Ac]-PMSA), no significant benefit was registered in pts harboring DDR defects. In all but one paper, no significant difference in response rate was reported among pts with or without DDR mutations. Although preliminary and biased by the retrospective design, preliminary data suggest a trend towards a longer survival in PCa pts harboring DDR defects submitted to radionuclide targeted therapy with alpha emitters.

Prostate-specific membrane antigen-directed imaging and radioguided surgery with single-photon emission computed tomography: state of the art and future outlook

INTRODUCTION

Prostate-specific membrane antigen (PSMA) has emerged as a highly relevant target for prostate cancer (PC) diagnosis and therapy. PSMA inhibitors targeting PSMA-enzymatic domain have been successfully labeled with radionuclides emitting positrons or gamma-photons, thus obtaining tracers suitable for imaging with positron emission computed tomography (PET/CT) or single-photon emission tomography (SPECT).

AREAS COVERED

The different approaches for obtaining PSMA-ligands labeled with gamma-emitting nuclides (^99mTc or¹¹¹In) are reviewed. Furthermore, the applications of ^99mTc/¹¹¹In-PSMA SPECT for the imaging of PC patients in different clinical settings (staging or biochemical recurrence) are covered. Lastly, the employment of PSMA-targeted SPECT tracers for radioguided surgery (RGS) during primary or salvage lymphadenectomy is discussed.

EXPERT OPINION

RGS provided satisfying preliminary results in both primary and salvage lymphadenectomy, allowing to discriminate between pathological and non-pathological nodes with high accuracy, although prospective studies with larger cohorts are needed to further validate this surgical approach. The potential of PSMA-targeted SPECT/CT has not been fully explored yet, but it might represent a relatively cost-effective alternative to PSMA PET/CT in limited resource environments. In this perspective, the implementation of novel SPECT technologies or algorithms, such as semiconductor-ionization detectors or resolution recovery reconstruction, will be topic of future investigation.

Advanced Neuroimaging Approaches to Pediatric Brain Tumors

Simple Summary

After leukemias, brain tumors are the most common cancers in children, and early, accurate diagnosis is critical to improve patient outcomes. Beyond the conventional imaging methods of computed tomography (CT) and magnetic resonance imaging (MRI), advanced neuroimaging techniques capable of both structural and functional imaging are moving to the forefront to improve the early detection and differential diagnosis of tumors of the central nervous system. Here, we review recent developments in neuroimaging techniques for pediatric brain tumors.

Abstract

Central nervous system tumors are the most common pediatric solid tumors; they are also the most lethal. Unlike adults, childhood brain tumors are mostly primary in origin and differ in type, location and molecular signature. Tumor characteristics (incidence, location, and type) vary with age. Children present with a variety of symptoms, making early accurate diagnosis challenging. Neuroimaging is key in the initial diagnosis and monitoring of pediatric brain tumors. Conventional anatomic imaging approaches (computed tomography (CT) and magnetic resonance imaging (MRI)) are useful for tumor detection but have limited utility differentiating tumor types and grades. Advanced MRI techniques (diffusion-weighed imaging, diffusion tensor imaging, functional MRI, arterial spin labeling perfusion imaging, MR spectroscopy, and MR elastography) provide additional and improved structural and functional information. Combined with positron emission tomography (PET) and single-photon emission CT (SPECT), advanced techniques provide functional information on tumor metabolism and physiology through the use of radiotracer probes. Radiomics and radiogenomics offer promising insight into the prediction of tumor subtype, post-treatment response to treatment, and prognostication. In this paper, a brief review of pediatric brain cancers, by type, is provided with a comprehensive description of advanced imaging techniques including clinical applications that are currently utilized for the assessment and evaluation of pediatric brain tumors.

Emerging Role and Mechanism of circRNAs in Pediatric Malignant Solid Tumors

Circular RNAs (circRNAs) are non-coding RNAs with covalent closed-loop structures and are widely distributed in eukaryotes, conserved and stable as well as tissue-specific. Malignant solid tumors pose a serious health risk to children and are one of the leading causes of pediatric mortality. Studies have shown that circRNAs play an important regulatory role in the development of childhood malignant solid tumors, hence are potential biomarkers and therapeutic targets for tumors. This paper reviews the biological characteristics and functions of circRNAs as well as the research progress related to childhood malignant solid tumors.

Role of Precision Medicine in Pediatric Oncology

Childhood cancer is the leading cause of nonaccidental death in children and adolescents. Over the past 50 years, development of novel therapies and improvements in supportive care have led to improvements in long-term survival rates. However, there remains great morbidity associated with cancer treatment among childhood cancer survivors, and the outcomes for patients who relapse remain poor. The introduction of precision medicine, an approach that uses the understanding of genetic and biochemical profiles of a disease (as enabled by next-generation sequencing) to tailor treatment to a patient, has quickly started to change the diagnostic and therapeutic landscape of pediatric oncology. With its use, a better understanding of tumor biology, improved classification systems for various cancers, and genetically and molecularly targeted therapeutic strategies have been developed. We review the implementation of precision medicine in pediatric oncology and its effect on diagnosis, management, and treatment of pediatric cancers. [Pediatr Ann. 2022;51(1):e8-e14.].

Peptide Receptor Radionuclide Therapy and Primary Brain Tumors: An Overview

Primary brain tumors (PBTs) are some of the most difficult types of cancer to treat, and despite advancements in surgery, chemotherapy and radiotherapy, new strategies for the treatment of PBTs are needed, especially for those with poor prognosis such as inoperable/difficult-to-reach lesions or relapsing disease. In regard to the last point, malignant primary brain tumors remain some of the most lethal types of cancer. Nuclear medicine may provide exciting new weapons and significant contributions in the treatment of PBTs. In this review, we performed literature research in order to highlight the possible role of peptide receptor radionuclide therapy (PRRT) in the treatment of PBTs with radiolabeled molecules that bind with high-affinity transmembrane receptors such as somatostatin receptors (SSTRs), neurokinin type-1 receptor and prostate-specific membrane antigen (PSMA). These receptors are overexpressed in some cancer types such as gliomas, meningiomas, pituitary tumors and medulloblastomas. A comprehensive overview of possible applications in this field will be shown, providing knowledge about benefits, feasibility, developments and limitations of PRRT in this type of tumor, also revealing new advantages in the management of the disease.

Medical Imaging in the Diagnosis of Schistosomiasis: A Review

Schistosomiasis is one of the most important parasitic diseases and it is endemic in tropical and subtropical areas. Clinical and laboratory data are fundamental for the diagnosis of schistosomiasis, but diagnostic imaging techniques such as x-rays, ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) may be helpful in the evaluation of disease severity and complications. In this context, the aim of this review is to explore the actual role of diagnostic imaging in the diagnosis of schistosomiasis, underlining advantages and drawbacks providing information about the utilization of diagnostic imaging techniques in this context. Furthermore, we aim to provide a useful guide regarding imaging features of schistosomiasis for radiology and nuclear medicine physicians of non-endemic countries: in fact, in the last years non-endemic countries have experienced important flows of migrants from endemic areas, therefore it is not uncommon to face cases of this disease in daily practice.

Interventional Techniques for Bone and Musculoskeletal Soft Tissue Tumors: Current Practices and Future Directions - Part II. Stabilization

Percutaneous image-guided oncologic interventions have rapidly evolved over the last two decades as an independent strategy or used within a first-, second-, or even third-line strategy in the treatment of musculoskeletal (MSK) tumors. Abundant mostly nonrandomized publications have described the safety, efficacy, and reproducibility of implementing percutaneous therapies both with curative and palliative intent. In this article, we continue to share our experience in bone and MSK soft tissue interventions focusing on stabilization and combined ablation and stabilization. We propose a pathway and explore future directions of image-guided interventional oncology related to skeletal disease. We reflect on the advantages and limitations of each technique and offer guidance and pearls to improve outcomes. Representing patterns from our practices, we demonstrate the role of collaborative working within a multidisciplinary team, ideally within a dedicated tumor treatment center, to deliver patient-specific therapy plans that are value based and favored by patients when given the choice.