Joint EANM, SNMMI and IAEA enabling guide: how to set up a theranostics centre

Ethical principles for practice building in the era of targeted radioligand therapy

Theranostics is emerging as a critical pillar of oncologic management, as exemplified by the success of Lu-177-PSMA-617 for the treatment of castration-resistant prostate cancer. The emergence of such theranostic agents represents an opportunity to reconsider facets of nuclear medicine practice that will enable its engagement in high-volume radioligand delivery. In this article, we aim to explore simple ethical principles that can guide the development of theranostics programs as radiopharmaceutical agents proliferate and the typical nuclear medicine physician transitions from a primarily diagnostic role to a mixed diagnostic and therapeutic role. Such a mixed role will demand all the attendant competencies of direct patient care. We argue that restructuring nuclear medicine practice to meet this challenge involves developing processes for promoting the principle of fairness in patient selection for theranostic agents and for promoting the principle of responsibility during the administration of theranostic agents. We further specify that this responsibility extends to the patient receiving the therapy, the local community of the patient, and the general community exposed to the population of patients receiving theranostic agents. PRéCIS: The expansion of radioligand therapy requires promoting the ethical principle of fairness in patient selection and the ethical principle of responsibility in the delivery of radioligand therapy.

Radiotherapy and theranostics: a Lancet Oncology Commission

Following on from the 2015 Lancet Oncology Commission on expanding global access to radiotherapy, Radiotherapy and theranostics: a Lancet Oncology Commission was created to assess the access and availability of radiotherapy to date and to address the important issue of access to the promising field of theranostics at a global level. A marked disparity in the availability of radiotherapy machines between high-income countries and low-income and middle-income countries (LMICs) has been identified previously and remains a major problem. The availability of a suitably trained and credentialled workforce has also been highlighted as a major limiting factor to effective implementation of radiotherapy, particularly in LMICs. We investigated initiatives that could mitigate these issues in radiotherapy, such as extended treatment hours, hypofractionation protocols, and new technologies. The broad implementation of hypofractionation techniques compared with conventional radiotherapy in prostate cancer and breast cancer was projected to provide radiotherapy for an additional 2·2 million patients (0·8 million patients with prostate cancer and 1·4 million patients with breast cancer) with existing resources, highlighting the importance of implementing new technologies in LMICs. A global survey undertaken for this Commission revealed that use of radiopharmaceutical therapy-other than 131I-was highly variable in high-income countries and LMICs, with supply chains, workforces, and regulatory issues affecting access and availability. The capacity for radioisotope production was highlighted as a key issue, and training and credentialling of health professionals involved in theranostics is required to ensure equitable access and availability for patient treatment. New initiatives-such as the International Atomic Energy Agency's Rays of Hope programme-and interest by international development banks in investing in radiotherapy should be supported by health-care systems and governments, and extended to accelerate the momentum generated by recognising global disparities in access to radiotherapy. In this Commission, we propose actions and investments that could enhance access to radiotherapy and theranostics worldwide, particularly in LMICs, to realise health and economic benefits and reduce the burden of cancer by accessing these treatments.

Best Patient Care Practices for Administering PSMA-Targeted Radiopharmaceutical Therapy

Optimal patient management protocols for metastatic castration-resistant prostate cancer (mCRPC) are poorly defined and even further complexified with new therapy approvals, such as radiopharmaceuticals. The prostate-specific membrane antigen (PSMA)-targeted agent 177Lu vipivotide tetraxetan ([177Lu]Lu-PSMA-617), approved after the phase III VISION study, presents physicians with additional aspects of patient management, including specific adverse event (AE) monitoring and management, as well as radiation safety. Drawing on our experience as VISION study investigators, here we provide guidance on best practices for delivering PSMA-targeted radiopharmaceutical therapy (RPT) to patients with mCRPC. After a comprehensive review of published evidence and guidelines on RPT management in prostate cancer, we identified educational gaps in managing the radiation safety and AEs associated with [177Lu]Lu-PSMA-617. Our results showed that providing sufficient education on AEs (e.g., fatigue and dry mouth) and radiation safety principles is key to effective delivery and management of patient expectations. Patient counseling by health care professionals, across disciplines, is a cornerstone of optimal patient management during PSMA-targeted RPT. Multidisciplinary collaboration is crucial, and physicians must adhere to radiation safety protocols and counsel patients on radiation safety considerations. Treatment with [177Lu]Lu-PSMA-617 is generally well tolerated; however, additional interventions may be required, such as dosing modification, medications, or transfusions. Urinary incontinence can be challenging in the context of radiation safety. Multidisciplinary collaboration between medical oncologists and nuclear medicine teams ensures that patients are monitored and managed safely and efficiently. In clinical practice, the benefit-to-risk ratio should always be evaluated on a case-by-case basis.

Recommendations from the Galician Oncological Society and the Galician Society of Nuclear Medicine for the use of 177Lu-PSMA-617 radioligand-therapy in prostate cancer

Theragnostic is a type of precision medicine that uses molecules linked to radioactive isotopes for the diagnosis and treatment of diseases. In recent years, it has gained significant importance to treat neuroendocrine tumors and is currently being used in prostate cancer. Various radiopharmaceuticals have emerged for diagnosing and detecting lesions showing prostate-specific membrane antigen (PSMA) positivity on the Positron emission tomography/computed tomography scan, being the most widely used labeled with [68Ga] and [18F]. Its use as therapy in prostate cancer (PC) has been assessed in the VISION, TheraP, and PSMAfore clinical trials conducted with the radioligand [177Lu]Lu-PSMA-617, demonstrating significant antitumor activity. The aim of this article is to present practical recommendations, based on current available scientific evidence and on a multidisciplinary consensus, for the diagnosis and treatment with [177Lu]Lu-PSMA-617 in patients with PC.

Survey of Clinical Protocols for the Use of 177Lu-PSMA-617 in the United States

Although guidelines for the use of 177Lu-PSMA-617 published by various organizations are important, they do not include all the essential, practical points necessary for a complete institutional protocol. Therefore, a brief survey was performed to assess key components of the 177Lu-PSMA-617 protocol before, during, and after delivery of therapy. This survey demonstrated the wide variability in many aspects of institutional protocols regarding determination of eligibility for and administration of 177Lu-PSMA-617 therapy. The real-world protocol details provided here from a variety of institutions may help new and established theranostic programs.

Translating the theranostic concept to neuro-oncology: disrupting barriers

Theranostics integrate molecular imaging and targeted radionuclide therapy for personalised cancer therapy. Theranostic treatments have shown meaningful efficacy in randomised clinical trials and are approved for clinical use in prostate cancer and neuroendocrine tumours. Brain tumours represent an unmet clinical need and theranostics might offer effective treatment options, although specific issues need to be considered for clinical development. In this Policy Review, we discuss opportunities and challenges of developing targeted radionuclide therapies for the treatment of brain tumours including glioma, meningioma, and brain metastasis. The rational choice of molecular treatment targets is highlighted, including the potential relevance of different types of targeted radionuclide therapeutics, and the role of the blood-brain barrier and blood-tumour barrier. Furthermore, we discuss considerations for effective clinical trial design and conduct, as well as logistical and regulatory challenges for implementation of radionuclide therapies into neuro-oncological practice. Rational development will foster successful translation of the theranostic concept to brain tumours.

Imaging and therapy in prostate cancer using prostate specific membrane antigen radioligands

Prostate specific membrane antigen (PSMA) directed PET imaging has rapidly transformed prostate cancer workup over the past decade and paved the way for a theranostic approach using 177Lu-labelled PSMA radioligand therapy (RLT). This review gives an overview of the underlying principles behind PSMA as a target; the current use of PSMA PET in prostate cancer imaging and benefits compared to conventional imaging; and therapeutic applications including optimisation of patient selection. It also explores the evidence base of PSMA PET for other indications not in routine clinical use and the future of PSMA-directed RLT.

Guiding principles on the education and practice of theranostics

PURPOSE

The recent development and approval of new diagnostic imaging and therapy approaches in the field of theranostics have revolutionised nuclear medicine practice. To ensure the provision of these new imaging and therapy approaches in a safe and high-quality manner, training of nuclear medicine physicians and qualified specialists is paramount. This is required for trainees who are learning theranostics practice, and for ensuring minimum standards for knowledge and competency in existing practising specialists.

METHODS

To address the need for a training curriculum in theranostics that would be utilised at a global level, a Consultancy Meeting was held at the IAEA in May 2023, with participation by experts in radiopharmaceutical therapy and theranostics including representatives of major international organisations relevant to theranostics practice.

RESULTS

Through extensive discussions and review of existing curriculum and guidelines, a harmonised training program for theranostics was developed, which aims to ensure safe and high quality theranostics practice in all countries.

CONCLUSION

The guiding principles for theranostics training outlined in this paper have immediate relevance for the safe and effective practice of theranostics.

Radiotheranostics Global Market and Future Developments

Radiotheranostics, a combination of diagnostic and therapeutic approaches, was first utilized in cancer management using radiopharmaceuticals to both image and selectively treat specific cancer subtypes nearly a century ago. Radiotheranostic strategies rooted in nuclear medicine have revolutionized the treatment landscape for individuals diagnosed with prostate cancer and neuroendocrine tumors in the past 10 years. In specific contexts, these approaches have emerged as the prevailing standard, yielding numerous positive results. The field of radiotheranostics shows great potential for future clinical applications. This article aims to examine the key factors that will contribute to the success of radiotheranostics in the future, as well as the current challenges and potential strategies to overcome them, with insight into the global radiotheranostic market.

The synergy of 177Lu-FAPI-46 with tyrosine kinase inhibitor in a sarcoma patient-derived xenograft mouse model

BACKGROUND

Given the heterogeneity and high mortality associated with metastatic soft tissue sarcoma, this study aims to evaluate the therapeutic efficacy of combining 177Lu-FAPI-46 with Pazopanib against this malignancy.

METHODS

Patient-derived xenograft (PDX)-bearing mice were randomly divided into three groups: the control group, the 177Lu-FAPI-46 monotherapy group, and the 177Lu-FAPI-46 combined with Pazopanib therapy group. Therapeutic efficacy was regularly monitored.

RESULTS

The microPET imaging showed a 0.84-fold decrease in the T/M ratio of 68Ga-FAPI-46 on day 7/8 post combination therapy, while the control group exhibited a 1.23-fold increase. Combination therapy significantly inhibited tumor proliferation, as evidenced by reduced Ki-67 and increased caspase 3 expressions. Notably, there was no significant body weight loss observed in any group.

CONCLUSION

This study successfully demonstrated the reduction in FAP expression and suppression of tumor volume in sarcoma PDX following the combination therapy of 177Lu-FAPI-46 with Pazopanib.

Production and regulatory issues for theranostics

Theranostics has become a major area of innovation and progress in cancer care over the last decade. In view of the introduction of approved therapeutics in neuroendocrine tumours and prostate cancer in the last 10 years, the ability to provide access to these treatments has emerged as a key factor in ensuring global benefits from this cancer therapy approach. In this Series paper we explore the issues that affect access to and availability of theranostic radiopharmaceuticals, including supply and regulatory issues that might affect the availability of theranostic treatments for patients with cancer.

Guardians of precision: advancing radiation protection, safety, and quality systems in nuclear medicine

BACKGROUND

In the rapidly evolving field of nuclear medicine, the paramount importance of radiation protection, safety, and quality systems cannot be overstated. This document provides a comprehensive analysis of the intricate regulatory frameworks and guidelines, meticulously crafted and updated by national and international regulatory bodies to ensure the utmost safety and efficiency in the practice of nuclear medicine.

METHODS

We explore the dynamic nature of these regulations, emphasizing their adaptability in accommodating technological advancements and the integration of nuclear medicine with other medical and scientific disciplines.

RESULTS

Audits, both internal and external, are spotlighted for their pivotal role in assessing and ensuring compliance with established standards, promoting a culture of continuous improvement and excellence. We delve into the significant contributions of entities like the International Atomic Energy Agency (IAEA) and relevant professional societies in offering universally applicable guidelines that amalgamate the latest in scientific research, ethical considerations, and practical applicability.

CONCLUSIONS

The document underscores the essence of international collaborations in pooling expertise, resources, and insights, fostering a global community of practice where knowledge and innovations are shared. Readers will gain an in-depth understanding of the practical applications, challenges, and opportunities presented by these regulatory frameworks and audit processes. The ultimate goal is to inspire and inform ongoing efforts to enhance safety, quality, and effectiveness in nuclear medicine globally.

Leveraging Programmatic Collaboration for a Radiopharmaceutical Clinic

Radiation oncologists, radiopharmacists, nuclear medicine physicians, and medical oncologists have seen a renewed clinical interest in radiopharmaceuticals for the curative or the palliative treatment of cancer. To allow for the discovery and the clinical advancement of targeted radiopharmaceuticals, these stakeholders have reformed their trial efforts and remodeled their facilities to accommodate the obligations of a program centered upon radioactive investigational drug products. Now considered informally as drugs and not beam radiotherapy, radiopharmaceuticals can be more easily studied in the traditional clinical trial enterprise ranging from phase 0-I to phase III studies. Resources and physical facilities allocated to radiopharmaceuticals have brought forth new logistics and patient experience for safe and satisfactory drug delivery. The clinical use of theranostic agents-that is, diagnostic and therapeutic radionuclide pairs-has accelerated radiopharmaceutical development.

Differences and Common Ground in 177Lu-PSMA Radioligand Therapy Practice Patterns: International Survey of 95 Theranostic Centers

177Lu-labeled prostate-specific membrane antigen (PSMA) radioligand therapy effectively treats metastatic castration-resistant prostate cancer. Patients requiring treatment, and consequently the number of theranostic centers, are expected to increase significantly after Food and Drug Administration and European Medicines Agency approval. This requires standardization or harmonization among theranostic centers. The aim of this study was to assess operational differences and similarities among 177Lu-PSMA treatment centers. Methods: A questionnaire comprising 62 items, designed by a core team of 5 physicians and externally reviewed by international experts, was developed. Study participants were asked to provide answers about their center, patient selection, radiopharmaceuticals, clinical assessment before and after 177Lu-PSMA treatments, laboratory values, treatment discontinuation, posttreatment imaging, and general information. An invitation e-mail to participate in the study was sent in June 2022. Duplicates were removed to allow for only one valid response per center. Results: Ninety-five of 211 (45%) contacted centers completed the questionnaire. Most participating centers were in Europe (51%), followed by America (22%) and Asia (22%). During the 12 mo before this study, a total of 5,906 patients received 177Lu-PSMA therapy at the 95 participating centers. Most of these patients were treated in Europe (2,840/5,906; 48%), followed by Asia (1,313/5,906; 22%) and Oceania (1,225/5,906; 21%). PSMA PET eligibility for 177Lu-PSMA was determined most frequently using 68Ga-PSMA-11 (77%). Additional pretherapy imaging included 18F-FDG PET/CT, CT, renal scintigraphy, and bone scintigraphy at 41 (49%), 27 (32%), 25 (30%), and 13 (15%), respectively, of the 84 centers for clinical standard of care, compassionate care, or local research protocols and 11 (26%), 25 (60%), 9 (21%), and 28 (67%), respectively, of the 42 centers for industry-sponsored trials. PSMA PET eligibility criteria included subjective qualitative assessment of PSMA positivity at 33% of centers, VISION criteria at 23%, and TheraP criteria at 13%. The mean standard injected activity per cycle was 7.3 GBq (range, 5.5-11.1 GBq). Sixty-two (65%) centers applied standardized response assessment criteria, and PSMA PET Progression Criteria were the most applied (37%). Conclusion: Results from this international survey revealed interinstitutional differences in several aspects of 177Lu-PSMA radionuclide therapy, including patient selection, administered activity, and the response assessment strategy. Standardization or harmonization of protocols and dedicated training are desirable in anticipation of increasing numbers of patients and theranostic centers.

Reliability and practicability of PSMA-RADS 1.0 for structured reporting of PSMA-PET/CT scans in prostate cancer patients

OBJECTIVES

As structured reporting is increasingly used in the evaluation of prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT) for prostate cancer, there is a need to assess the reliability of these frameworks. This study aimed to evaluate the intra- and interreader agreement among readers with varying levels of experience using PSMA-RADS 1.0 for interpreting PSMA-PET/CT scans, even when blinded to clinical data, and therefore to determine the feasibility of implementing this reporting system in clinical practice.

METHODS

PSMA-PET/CT scans of 103 patients were independently evaluated by 4 readers with different levels of experience according to the reporting and data system (RADS) for PSMA-PET/CT imaging PSMA-RADS 1.0 at 2 time points within 6 weeks. For each scan, a maximum of five target lesions were freely chosen and stratified according to PSMA-RADS 1.0. Overall scan score and compartment-based scores were assessed. Intra- and interreader agreement was determined using the intraclass correlation coefficient (ICC).

RESULTS

PSMA-RADS 1.0 demonstrated excellent interreader agreement for both overall scan scores (ICC ≥ 0.91) and compartment-based scores (ICC ≥ 0.93) across all four readers. The framework showed excellent intrareader agreement for overall scan scores (ICC ≥ 0.86) and compartment-based scores (ICC ≥ 0.95), even among readers with varying levels of experience.

CONCLUSIONS

PSMA-RADS 1.0 is a reliable method for assessing PSMA-PET/CT with strong consistency and agreement among readers. It shows great potential for establishing a standard approach to diagnosing and planning treatment for prostate cancer patients, and can be used confidently even by readers with less experience.

CLINICAL RELEVANCE STATEMENT

This study underlines that PSMA-RADS 1.0 is a valuable and highly reliable scoring system for PSMA-PET/CT scans of prostate cancer patients and can be used confidently by radiologists with different levels of experience in routine clinical practice.

KEY POINTS

PSMA-RADS version 1.0 is a scoring system for PSMA-PET/CT scans. Its reproducibility needs to be analyzed in order to make it applicable to clinical practice. Excellent interreader and intrareader agreement for overall scan scores and compartment-based scores using PSMA-RADS 1.0 were seen in readers with varying levels of experience. PSMA-RADS 1.0 is a reliable tool for accurately diagnosing and planning treatment for prostate cancer patients, and can be used confidently in clinical routine.

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.

Estrada FG, Barrenechea EA, San Luis, Jr TO. Formulating a national position statement and guide on modern theranostics in the Philippines

Barriers to the establishment of advanced technologies in developing countries were overcome when modern theranostics pertaining to the use of Ga-68 and Lu-177 PSMA and DOTATATE were first offered to patients in the Philippines in early 2018. However, significant growth was not experienced at St. Luke's Medical Center for five years and lutetium was not yet distributed to other institutions by a radiopharmaceutical supplier. Due to the relative novelty and rapid expansion of theranostics worldwide, position statements were released by the Australasian Association of Nuclear Medicine Specialists, European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and International Atomic Energy Agency primarily to uphold patient safety and ensure a level of standard among its practitioners. Subsequently in the latter half of 2022, these were adopted and modified according to what is feasible and applicable locally within the Philippine Society of Nuclear Medicine, considering the current status and future possibilities. Different representatives were involved, and several groups were mobilized for successful implementation. A liability clause was incorporated to discourage unprofessional acts.

EANM enabling guide: how to improve the accessibility of clinical dosimetry

Dosimetry can be a useful tool for personalization of molecular radiotherapy (MRT) procedures, enabling the continuous development of theranostic concepts. However, the additional resource requirements are often seen as a barrier to implementation. This guide discusses the requirements for dosimetry and demonstrates how a dosimetry regimen can be tailored to the available facilities of a centre. The aim is to help centres wishing to initiate a dosimetry service but may not have the experience or resources of some of the more established therapy and dosimetry centres. The multidisciplinary approach and different personnel requirements are discussed and key equipment reviewed example protocols demonstrating these factors are given in the supplementary material for the main therapies carried out in nuclear medicine, including [131I]-NaI for benign thyroid disorders, [177Lu]-DOTATATE and 131I-mIBG for neuroendocrine tumours and [90Y]-microspheres for unresectable hepatic carcinoma.

Safety and Therapeutic Optimization of Lutetium-177 Based Radiopharmaceuticals

Peptide receptor radionuclide therapy (PRRT) using Lutetium-177 (¹⁷⁷Lu) based radiopharmaceuticals has emerged as a therapeutic area in the field of nuclear medicine and oncology, allowing for personalized medicine. Since the first market authorization in 2018 of [¹⁷⁷Lu]Lu-DOTATATE (Lutathera®) targeting somatostatin receptor type 2 in the treatment of gastroenteropancreatic neuroendocrine tumors, intensive research has led to transfer innovative ¹⁷⁷Lu containing pharmaceuticals to the clinic. Recently, a second market authorization in the field was obtained for [¹⁷⁷Lu]Lu-PSMA-617 (Pluvicto®) in the treatment of prostate cancer. The efficacy of ¹⁷⁷Lu radiopharmaceuticals are now quite well-reported and data on the safety and management of patients are needed. This review will focus on several clinically tested and reported tailored approaches to enhance the risk-benefit trade-off of radioligand therapy. The aim is to help clinicians and nuclear medicine staff set up safe and optimized procedures using the approved ¹⁷⁷Lu based radiopharmaceuticals.

Main challenges in radiation protection with emerging radionuclide therapies

The recent development of radionuclide therapy and radioligand therapy has raised a call for achieving the highest quality standards, for either radiopharmacy or radiation protection. Novel radionuclides are now being used, either under the form of in-house production radiopharmaceuticals or available from companies. Over the last 20 years, they include radiolabeled microspheres for selective internal radiotherapy (SIRT), the introduction of the first commercially available alpha emitter radiopharmaceutical, ²²³Ra, and the radiosynoviorthesis which is highly variable across Europe. More important is the development of radioligand therapy, often called theranostics. In this concept, a diagnostic radiopharmaceutical can determine the chance of success of a therapeutic one. Typically, diagnostic radiopharmaceuticals for positron emission tomography, are labeled with ¹⁸F or ⁶⁸Ga, such as the PSMA ligands or somatostatin analogs, and the therapeutic radiopharmaceutical is labeled with ¹⁷⁷Lu. This has revolutionized the world of Nuclear Medicine, but also all concepts that shall be applied to properly apply quality assurance and radiation protection in the field. This article will follow the example of ¹³¹I as the main used radionuclide for therapy during the last 80 years. Proposals can be general, and in parallel expert's articles will give specific guidance on issues with particular radionuclides, i.e., alpha emitters and ¹⁷⁷Lu. This article will also give insight in the radiation protection issues related to the use of microspheres radiolabeled with either ⁹⁰Y or ¹⁶⁶Ho.

Philosophy of Cancer Theranostics

Imagine a theranostic nuclear physician oncologist engaged in a Socratic philosophic dialogue. Questions that may be posed include the status of our current knowledge base of radiomolecular tumor biology, the meaning of precision in personalized dosimetry, the nature of responsibility for direct patient care, and the moral and ethical dimensions of individual quality of life (QOL) when survival is prolonged. This review invites reflective enquiry into one's personal practice of theranostics in cancer care, with the objective of optimizing clinical outcomes, not only in terms of prolonged survival but also individual QOL, in respect of its meaning for each patient, both physically and emotionally.

A Primer on Radiopharmaceutical Therapy

The goal of this article is to serve as a primer for the United States-based radiation oncologist who may be interested in learning more about radiopharmaceutical therapy (RPT). Specifically, we define RPT, review the data behind its current and anticipated indications, and discuss important regulatory considerations for incorporating it into clinical practice. RPT represents an opportunity for radiation oncologists to leverage 2 key areas of expertise, namely therapeutic radiation therapy and oncology, and apply them in a distinct context in collaboration with nuclear medicine and medical oncology colleagues. Although not every radiation oncologist will incorporate RPT into their day-to-day practice, it is important to understand the role for this modality and how it can be appropriately used in select patients.

Albumin-Mediated Size Exclusion Chromatography: The Apparent Molecular Weight of PSMA Radioligands as Novel Parameter to Estimate Their Blood Clearance Kinetics

A meticulously adjusted pharmacokinetic profile and especially fine-tuned blood clearance kinetics are key characteristics of therapeutic radiopharmaceuticals. We, therefore, aimed to develop a method that allowed the estimation of blood clearance kinetics in vitro. For this purpose, ¹⁷⁷Lu-labeled PSMA radioligands were subjected to a SEC column with human serum albumin (HSA) dissolved in a mobile phase. The HSA-mediated retention time of each PSMA ligand generated by this novel 'albumin-mediated size exclusion chromatography' (AMSEC) was converted to a ligand-specific apparent molecular weight (MW_app), and a normalization accounting for unspecific interactions between individual radioligands and the SEC column matrix was applied. The resulting normalized MW_app,norm. could serve to estimate the blood clearance of renally excreted radioligands by means of their influence on the highly size-selective process of glomerular filtration (GF). Based on the correlation between MW and the glomerular sieving coefficients (GSCs) of a set of plasma proteins, GSC_calc values were calculated to assess the relative differences in the expected GF/blood clearance kinetics in vivo and to select lead candidates among the evaluated radioligands. Significant differences in the MW_app,norm. and GSC_calc values, even for stereoisomers, were found, indicating that AMSEC might be a valuable and high-resolution tool for the preclinical selection of therapeutic lead compounds for clinical translation.