How We Do It: A Multidisciplinary Approach to 177Lu DOTATATE Peptide Receptor Radionuclide Therapy

Quarter Century PET/Computed Tomography Transformation of Oncology: Neuroendocrine Tumors

Significant improvement in molecular imaging and theranostics in the management of neuroendocrine tumors (NETs) has been made in the last few decades. Somatostatin receptor-targeted PET imaging outperforms conventional, planar, and single-photon emission computed tomography imaging and is indicated in the evaluation of these patients when available, resulting in a significant impact on staging, treatment response assessment, and restaging of these patients. Radionuclide therapy can have an impact on patient outcome in metastatic disease when not many treatment options are available.

Establishing a robust radioligand therapy program: A practical approach for North American centers

Radioligand therapy (RLT) is a targeted approach to treating cancer that has been shown to be safe and effective in a variety of disease states, including gastroenteropancreatic neuroendocrine tumors, lymphoma, and most recently, advanced prostate cancer. In the United States, patient access to this therapy is currently variable. Implementation of new RLT programs and expansion of existing programs are needed to broaden patient access to and standardize the delivery of RLT, especially as new therapies are introduced into clinical practice. Drawing from experience in establishing RLT programs in different settings, we have developed practical recommendations for building and implementing a robust RLT program. In this review, we present our recommendations for minimal requirements and optimal requirements, as well as system considerations, and special issues associated with implementing an RLT program in North American centers.

Need for enrichment of lutetium isotope and design of a laser based separator module

Lutetium-177 radio-pharmaceutical has become an important theranostic candidate in cancer treatment. Its availability from bench-to-bed requires strategic implementation of isotope-enrichment, neutron-irradiation and radio-chemical techniques. In this paper, the need for enrichment of lutetium-176 is emphasized by estimating specific activity of lutetium-177 as a function of enrichment percentage for typical neutron flux available at Dhruva reactor, India. A novel Atomic Vapour Laser Isotope Separation (AVLIS) module for lutetium-176 enrichment is designed to meet the above requirement. The paper documents its characteristics and production estimates. The design is carried out after critical assessment and evaluation of available AVLIS-infrastructure in the country. Outline of lutetium-177 enrichment, capable of producing non-carrier-added lutetium is also provided. This work concludes that India has taken a step forward towards self-reliance (Atmanirbhar Bharat) in securing the supply chain of lutetium-177.

A Review of Theranostics: Perspectives on Emerging Approaches and Clinical Advancements

Theranostics is the combination of two approaches-diagnostics and therapeutics-applied for decades in cancer imaging using radiopharmaceuticals or paired radiopharmaceuticals to image and selectively treat various cancers. The clinical use of theranostics has increased in recent years, with U.S. Food and Drug Administration (FDA) approval of lutetium 177 (177Lu) tetraazacyclododecane tetraacetic acid octreotate (DOTATATE) and 177Lu-prostate-specific membrane antigen vector-based radionuclide therapies. The field of theranostics has imminent potential for emerging clinical applications. This article reviews critical areas of active clinical advancement in theranostics, including forthcoming clinical trials advancing FDA-approved and emerging radiopharmaceuticals, approaches to dosimetry calculations, imaging of different radionuclide therapies, expanded indications for currently used theranostic agents to treat a broader array of cancers, and emerging ideas in the field. Keywords: Molecular Imaging, Molecular Imaging-Cancer, Molecular Imaging-Clinical Translation, Molecular Imaging-Target Development, PET/CT, SPECT/CT, Radionuclide Therapy, Dosimetry, Oncology, Radiobiology © RSNA, 2023.

Integrating Theranostics Into Patient Care Pathways: AJR Expert Panel Narrative Review

Theranostics describes the coupling of a diagnostic biomarker and a therapeutic agent (i.e., a theranostic pair) that have a common target in tumor cells or their microenvironment. The term is increasingly associated with in vivo nuclear medicine oncologic applications that couple diagnostic imaging by means of gamma radiation with concomitant localized high-energy particulate radiation to a tissue expressing the common target. Several theranostic pairs have been translated into clinical practice in the United States and are poised to become a mainstay of cancer treatment. The purposes of this article are to review experience with theranostics for solid-organ malignancies and to address the practical integration into care pathways of β-emitting therapies that include somatostatin analogue radioligands for neuroendocrine tumors, PSMA-directed therapy for prostate cancer, and 131I-MIBG therapy for tumors of neural crest origin. Toxicities related to theranostics administration and indications for cessation of therapy in patients who experience adverse events are also discussed. A multidisciplinary team-based approach for identifying patients most likely to respond to these agents, determining the optimal time for therapy delivery, and managing patient care throughout the therapeutic course is critical to the success of a radiotheranostic program.

Lutetium177-Labeled DOTA-Ibandronate: A Novel Radiopharmaceutical for Targeted Treatment of Bone Metastases

Bone metastases of malignant tumors significantly threaten the patient survival and quality of life. We designed and synthesized a novel bisphosphonate radiopharmaceutical [⁶⁸Ga- or ¹⁷⁷Lu-labeled DOTA-Ibandronate(⁶⁸Ga/¹⁷⁷Lu-DOTA-IBA)] for targeted diagnosis and treatment of bone metastases. This study explored the basic biological characteristics of ¹⁷⁷Lu-DOTA-IBA, guiding clinical translation and providing evidence for future clinical applications. The control variable method was used to optimize the optimal labeling conditions. The in vitro properties, biological distribution, and toxicity of ¹⁷⁷Lu-DOTA-IBA were studied. Normal mice and tumor-bearing mice were imaged using micro SPECT/CT. With Ethics Committee approval, five volunteers were recruited for a preliminary clinical translation study. ¹⁷⁷Lu-DOTA-IBA has a radiochemical purity of more than 98%, with good biological properties and safety. Blood clearance is fast and soft tissue uptake is low. Tracers are excreted mainly through the urinary system, targeting and continuously concentrating in the bones. Three patients experienced significant pain relief within 3 days after ¹⁷⁷Lu-DOTA-IBA treatment (740-1110 MBq), lasting more than 2 months, with no toxic side effects. ¹⁷⁷Lu-DOTA-IBA is easy to prepare and exhibits good pharmacokinetic characteristics. Low-dose ¹⁷⁷Lu-DOTA-IBA is effective, well tolerated, and was associated with no significant adverse reactions. It is a promising radiopharmaceutical for the targeted treatment of bone metastases, controlling the progress of bone metastasis and improving survival and quality of life of patients with advanced bone metastasis.

Incorporating radioligand therapy in clinical practice in the United States for patients with prostate cancer

Prostate cancer (PC) is the second most commonly diagnosed cancer in the United States. Advanced PC evolves to metastatic castration-resistant PC (mCRPC). Theranostics combining prostate-specific membrane antigen-targeted positron emission tomography imaging and radioligand therapy (RLT) represents a precision medicine approach to PC treatment. With the recent approval of lutetium Lu 177 (¹⁷⁷Lu) vipivotide tetraxetan for men with mCRPC, the utilization of RLT will increase. In this review, we suggest a framework for incorporating RLT for PC into clinical practice. A search of PubMed and Google Scholar was performed using keywords related to PC, RLT, prostate-specific membrane antigen, and novel RLT centers. The authors also provided opinions based on their clinical experience. The setup and operation of an RLT center requires the diligence and cooperation of a well-trained multidisciplinary team committed to patient safety and clinical efficacy. Administrative systems should ensure that treatment scheduling, reimbursement, and patient monitoring are efficient. For optimal outcomes, the clinical care team must have an organizational plan that delineates the full range of required tasks. Establishing new RLT centers for treatment of PC is possible with appropriate multidisciplinary planning. We provide an overview of the key elements to consider when establishing a safe, efficient, and high-quality RLT center.

Ga-68 DOTATATE PET/CT in a patient with Zollinger-Ellison syndrome

This case report follows a 70-year-old male patient with Zollinger-Ellison syndrome undergoing computed tomography (CT) for weight loss and surveillance of bilateral adrenal nodules. Incidentally, diffuse gastric and duodenal wall thickening was noted on CT. The patient underwent esophagogastroduodenoscopy with biopsy results showing well-differentiated neuroendocrine tumors (NET) in the stomach and duodenum. Subsequent imaging with gallium-68 DOTATATE PET/CT showed intense tracer uptake in the stomach and proximal duodenum with liver and regional nodal metastases around the superior mesenteric artery. This case outlines the utility of Ga-68 DOTATATE PET/CT in diagnosing, localizing, and staging NET such as gastrinomas.

Gastric neuroendocrine neoplasms: a primer for radiologists

Gastric neuroendocrine neoplasms are uncommon tumors with variable differentiation and malignant potential. Three main subtypes are recognized: type 1, related to autoimmune atrophic gastritis; type 2, associated with Zollinger-Ellison and MEN1 syndrome; and type 3, sporadic. Although endoscopy alone is often sufficient for diagnosis and management of small, indolent, multifocal type 1 tumors, imaging is essential for evaluation of larger, high-grade, and type 2 and 3 neoplasms. Hypervascular intraluminal gastric masses are typically seen on CT/MRI, with associated perigastric lymphadenopathy and liver metastases in advanced cases. Somatostatin receptor nuclear imaging (such as Ga-68-DOTATATE PET/CT) may also be used for staging and assessing candidacy for peptide receptor radionuclide therapy. Radiotracer uptake is more likely in well-differentiated, lower-grade tumors, and less likely in poorly differentiated tumors, for which F-18-FDG-PET/CT may have additional value. Understanding disease pathophysiology and evolving histologic classifications is particularly useful for radiologists, as these influence tumor behavior, preferred imaging, therapy options, and patient prognosis.

Addressing Challenges and Controversies in the Management of Prostate Cancer with Multidisciplinary Teams

The diagnostic and treatment landscapes of prostate cancer are rapidly evolving. This has led to several challenges and controversies regarding optimal management of the disease that outpace guidelines and clinical data. Multidisciplinary teams (MDTs) can be used to engage the array of specialists that collaborate to treat complex malignancies such as prostate cancer. While the rationale for the use of MDTs in prostate cancer is well known, ways to optimally use MDTs to address the challenges and controversies associated with prostate cancer management are less well understood. One area of MDT care that remains undefined is how MDTs can most effectively provide guidance on clinical decision-making in situations in which information from novel diagnostic testing (genetic testing, molecular imaging) is substantially different from the established clinical risk factors. In this review, we provide a clinical perspective on ways that MDTs can be used to address this and other challenges and controversies across the prostate cancer disease continuum, from diagnosis to end-of-life considerations. Beyond clinical scenarios, we also review ways in which MDTs can mitigate disparities of care in prostate cancer. Overall, MDTs play a central role in helping to address the daily vexing issues faced by clinicians related to diagnosis, risk stratification, and treatment. Given the accelerating advances in precision medicine and targeted therapy, and the new questions and controversies these will bring, the value of MDTs for prostate cancer management will only increase in the future.

High-Contrast Detection of Somatostatin Receptor Subtype-2 for Fluorescence-Guided Surgery

Dye design can influence the ability of fluorescently labeled imaging agents to generate tumor contrast and has become an area of significant interest in the field of fluorescence-guided surgery (FGS). Here, we show that the charge-balanced near-infrared fluorescent (NIRF) dye FNIR-Tag enhances the imaging properties of a fluorescently labeled somatostatin analogue. In vitro studies showed that the optimized fluorescent conjugate MMC(FNIR-Tag)-TOC bound primarily via somatostatin receptor subtype-2 (SSTR2), whereas its negatively charged counterpart with IRDye 800CW had higher off-target binding. NIRF imaging in cell line- and patient-derived xenograft models revealed markedly higher tumor contrast with MMC(FNIR-Tag)-TOC, which was attributed to increased tumor specificity. Ex vivo staining of surgical biospecimens from primary and metastatic tumors, as well as involved lymph nodes, demonstrated binding to human tumors. Finally, in an orthotopic tumor model, a simulated clinical workflow highlighted our unique ability to use standard preoperative nuclear imaging for selecting patients likely to benefit from SSTR2-targeted FGS. Our findings demonstrate the translational potential of MMC(FNIR-Tag)-TOC for intraoperative imaging and suggest broad utility for using FNIR-Tag in fluorescent probe development.

Molecular imaging in oncology: Current impact and future directions

The authors define molecular imaging, according to the Society of Nuclear Medicine and Molecular Imaging, as the visualization, characterization, and measurement of biological processes at the molecular and cellular levels in humans and other living systems. Although practiced for many years clinically in nuclear medicine, expansion to other imaging modalities began roughly 25 years ago and has accelerated since. That acceleration derives from the continual appearance of new and highly relevant animal models of human disease, increasingly sensitive imaging devices, high-throughput methods to discover and optimize affinity agents to key cellular targets, new ways to manipulate genetic material, and expanded use of cloud computing. Greater interest by scientists in allied fields, such as chemistry, biomedical engineering, and immunology, as well as increased attention by the pharmaceutical industry, have likewise contributed to the boom in activity in recent years. Whereas researchers and clinicians have applied molecular imaging to a variety of physiologic processes and disease states, here, the authors focus on oncology, arguably where it has made its greatest impact. The main purpose of imaging in oncology is early detection to enable interception if not prevention of full-blown disease, such as the appearance of metastases. Because biochemical changes occur before changes in anatomy, molecular imaging-particularly when combined with liquid biopsy for screening purposes-promises especially early localization of disease for optimum management. Here, the authors introduce the ways and indications in which molecular imaging can be undertaken, the tools used and under development, and near-term challenges and opportunities in oncology.

Preliminary experience with a new institutional tumor board dedicated to patients with neuroendocrine neoplasms

PURPOSE

To determine the decision patterns of a neuroendocrine neoplasm (NEN) tumor board (TB) and the factors behind those.

METHODS

We retrospectively reviewed all NEN-TB recommendations from 07/2018 to 12/2021 and recorded patient characteristics, TB outcomes and associations between them.

RESULTS

A total of 652 patient entries were identified. Median age of participants was 61 years and an equal number of men and women were presented. Most patients (33.4%) had tumors originating in the small bowel with 16.8% of high grade and 25.9% of pancreatic origin. Imaging was reviewed 97.2% of the time, with most frequently reviewed modalities being PET (55.3%) and CT (44.3%). Imaging review determined that there was no disease progression 20.8% of the time and significant treatment changes were recommended in 36.1% of patients. Major pathology amendments occurred in 3.7% of cases and a clinical trial was identified in 2.6%. There was no association between patient or disease presentation with the tumor board outcomes. There was a slight decrease in number of patients discussed per session, from 10.0 to 8.2 (p < 0.001) when the TB transitioned to a virtual format during the COVID-19 pandemic but all other factors remained unchanged.

CONCLUSION

NEN-TB relies heavily on image review, can impact significant treatment changes in patients with rare tumors like NENs, and was not affected by the switch to a virtual format. Finally, none of the examined factors were predictive of the tumor board recommendations.

Peptide receptor radionuclide therapy with [177Lu]Lu-DOTA-TATE

This continuing education aims to present in a clear and easy-to-understand way, the biology of neuroendocrine tumors (NETs), the characteristics of somatostatin receptors, the selection of patients for radiolabelled peptide therapy (PRRT), the inclusion criteria to benefit from treatment with the minimum possible adverse effects, the administration protocol, follow-up and response evaluation. The functional imaging studies necessary to explore the biology of the tumor and to individualize the treatment are also carried out, and constitute the cornerstone for the development of teragnosis. Clinical trials are being developed to better define the position of PRRT within the broad therapeutic options, and among the future perspectives, there are several lines of research to improve the objective response rate and survival with PRRT, focused on the development of new agonists and somatostatin receptor antagonists, new radionuclides and radiosensitizing combination therapies. In conclusion, PRRT is a great therapeutic, well-tolerated and safe tool with generally mild and self-limited acute side effects, that must be sequenced at the best moment of the evolution of the disease of patients with NET. Candidate patients for PRRT should always be evaluated by a multidisciplinary clinical committee.

Building the Bridge: Molecular Imaging Biomarkers for 21st Century Cancer Therapies

Precision medicine, where the molecular underpinnings of the disease are assessed for tailored therapies, has greatly impacted cancer care. In parallel, a new pillar of therapeutics has emerged with profound success, including immunotherapies such as checkpoint inhibitors and cell-based therapies. Nonetheless, it remains essential to develop paradigms to predict and monitor for therapeutic response. Molecular imaging has the potential to add substantially to all phases of cancer patient care: predicative, companion diagnostics can illuminate therapeutic target density within a tumor, and pharmacodynamic imaging biomarkers can complement traditional modalities to judge a favorable treatment response. This "Focus on Molecular Imaging" article discusses the current role of molecular imaging in oncology and highlights an additional step in clinical paradigm termed a "therapeutic biomarker," which serves to assess whether next generation drugs reach their target to elicit a favorable clinical response.

Role of PET/CT and Therapy Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine neoplasms (panNENs) are heterogeneous neoplasms with neuroendocrine differentiation that show peculiar clinical and histomorphological features, with variable prognosis. In recent years, advances in knowledge regarding the pathophysiology and heterogeneous clinical presentation, as well as the availability of different diagnostic procedures for panNEN diagnosis and novel therapeutic options for patient clinical management, has led to the recognition of the need for an active multidisciplinary discussion for optimal patient care. Molecular imaging with positron emission tomography/computed tomography (PET/CT) has become indispensable for the management of panNENs. Several PET radiopharmaceuticals can be used to characterize either panNEN receptor expression or metabolism. The aim of this review is to offer an overview of all the currently used radiopharmaceuticals and of the new upcoming tracers for pancreatic neuroendocrine tumors (panNETs), and their clinical impact on therapy management. [⁶⁸Ga]Ga-DOTA-peptide PET/CT (SSA-PET/CT) has high sensitivity, specificity, and accuracy and is recommended for the staging and restaging of any non-insulinoma well-differentiated panNEN cases to carry out detection of unknown primary tumor sites or early relapse and for evaluation of in vivo somatostatin receptors expression (SRE) to select patient candidates for peptide receptor radiometabolic treatment (PRRT) with ⁹⁰Y or ¹⁷⁷Lu and/or cold analogs. SSA-PET/CT also has a strong impact on clinical management, leading to a change in treatment in approximately a third of the cases. Its role for treatment response assessment is still under debate due to the lack of standardized criteria, even though some semiquantitative parameters seem to be able to predict response. [¹⁸F]FDG PET/CT generally shows low sensitivity in small growing and well-differentiated neuroendocrine tumors (NET; G1 and G2), while it is of utmost importance in the evaluation and management of high-grade NENs and also provides important prognostic information. When positive, [¹⁸F]FDG PET/CT impacts therapeutical management, indicating the need for a more aggressive treatment regime. Although FDG positivity does not exclude the patient from PRRT, several studies have demonstrated that it is certainly useful to predict response, even in this setting. The role of [¹⁸F]FDOPA for the study of panNET is limited by physiological uptake in the pancreas and is therefore not recommended. Moreover, it provides no information on SRE that has crucial clinical management relevance. Early acquisition of the abdomen and premedication with carbidopa may be useful to increase the accuracy, but further studies are needed to clarify its utility. GLP-1R agonists, such as exendin-4, are particularly useful for benign insulinoma detection, but their accuracy decreases in the case of malignant insulinomas. Being a whole-body imaging technique, exendin-PET/CT gives important preoperative information on tumor size and localization, which is fundamental for surgical planning as resection (enucleation of the lesion or partial pancreatic resection) is the only curative treatment. New upcoming tracers are under study, such as promising SSTR antagonists, which show a favorable biodistribution and higher tumor-to-background ratio that increases tumor detection, especially in the liver. [⁶⁸Ga]pentixafor, an in vivo marker of CXCR4 expression associated with the behavior of more aggressive tumors, seems to only play a limited role in detecting well-differentiated NET since there is an inverse expression of SSTR2 and CXCR4 in G1 to G3 NETs with an elevation in CXCR4 and a decrease in SSTR2 expression with increasing grade. Other tracers, such as [⁶⁸Ga]Ga-PSMA, [⁶⁸Ga]Ga-DATA-TOC, [¹⁸F]SiTATE, and [¹⁸F]AlF-OC, are also under investigation.