Advanced tissue engineering processes and regenerative medicine provide modern strategies for fabricating 3D spheroids. Several different 3D cancer models are being developed to study a variety of cancers. Three-dimensional spheroids can correctly replicate some features of solid tumors (such as the secretion of soluble mediators, drug resistance mechanisms, gene expression patterns and physiological responses) better than 2D cell cultures or animal models. Tumor spheroids are also helpful for precisely reproducing the three-dimensional organization and microenvironmental factors of tumors. Because of these unique properties, the potential of 3D cell aggregates has been emphasized, and they have been utilized in in vitro models for the detection of novel anticancer drugs. This review discusses applications of 3D spheroid models in nuclear medicine for diagnosis and therapy, immunotherapy, and stem cell and photodynamic therapy and also discusses the establishment of the anticancer activity of nanocarriers.

Following previously published systematic reviews on the diagnostic use of nanoparticles (NPs), in this manuscript, we report published methods for radiolabeling nanoparticles with therapeutic alpha-emitting, beta-emitting, or Auger’s electron-emitting isotopes. After analyzing 234 papers, we found that different methods were used with the same isotope and the same type of nanoparticle. The most common type of nanoparticles used are the PLGA and PAMAM nanoparticles, and the most commonly used therapeutic isotope is ¹⁷⁷Lu. Regarding labeling methods, the direct encapsulation of the isotope resulted in the most reliable and reproducible technique. Radiolabeled nanoparticles show promising results in metastatic breast and lung cancer, although this field of research needs more clinical studies, mainly on the comparison of nanoparticles with chemotherapy.

Inter- or intra-tumor heterogeneity refers to the genetic, epigenetic, and phenotypic variability that characterizes tumor cells. Regardless of its nature, this complexity represents a great challenge for diagnosis and treatment, since cells with different characteristics may respond differently to therapies, resulting in drug resistance and/or relapses. Furthermore, it has emerged that this heterogeneity can change over time or following a stimulus, such as a treatment. Molecular imaging is an essential tool in oncology. By enabling the identification of specific metabolic or receptor alterations of tumor cells, it provides a more accurate diagnosis, prognosis, and allows personalizing treatments. To date, addressing these challenges may be crucial for accurate diagnosis and therapeutic choice. In recent years, the design, synthesis, and characterization of bispecific radioligands (BRLs) with dual targeting capacity has emerged. In this review, we discuss the in vitro and in vivo studies of this new class of radiopharmaceuticals conducted so far, while assessing their potential advantages over traditional single-target radiopharmaceuticals.

Background: G-protein-coupled receptors (GPCRs) play pivotal roles in tumor growth and progression. Among these, the luteinizing hormone-releasing hormone receptor (LHRH-R) and follicle-stimulating hormone receptor (FSH-R) represent promising translational targets, unlike luteinizing hormone receptors (LH-Rs). Indeed, both LHRH-R and FSH-R are selectively expressed in various cancers and their vasculature, offering opportunities for receptor-mediated imaging and therapy. Objectives: This systematic review aims to evaluate radiolabeled LHRH- and FSH-derivative biomolecules, including peptides, monoclonal antibodies and nanocarriers, for their applications in cancer diagnosis and treatment. Methods: The systematic review was conducted following PRISMA 2020 guidelines. A systematic search of PubMed, Scopus and Web of Science was conducted for studies published between 2005 and 2025. A total of 248 records were identified, and 156 articles were screened after removing duplicate records. Two authors independently selected eligible studies. Quality of evidence was assessed by the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) approach. Results: A total of 25 studies met the inclusion criteria and were included in the final review. Radiolabeled LHRH and FSH derivatives showed receptor-specific tumor localization in both preclinical and clinical applications. FSH-R expression in tumor blood vessels supports its potential as a biomarker for early cancer diagnosis. FSHβ-derived peptides exhibit improved pharmacokinetics compared to monoclonal antibodies in PET imaging. LHRH analogues, particularly D-Lys⁶-modified peptides, proved effective for SPECT, PET and therapeutic applications, particularly in breast and prostate cancer. The integration of radiolabeled LHRH and FSH derivatives with nanocarriers further enhanced probe stability and tumor targeting, increasing tumor accumulation and image contrast compared to free peptide. Conclusions: Radiopharmaceuticals targeting LHRH-R and FSH-R are promising tools for cancer imaging and treatment. Advances in nanotechnology enhance delivery precision and reduce systemic toxicity, thereby increasing its translational promise in oncology.

Tumor associated fibroblasts (TAFs) play a key role in tumor growth and metastatization. TAFs overexpress different biomarkers that are usually expressed at low levels in physiological conditions. Among them are the fibroblast growth factor receptors (FGFRs) that bind the fibroblast growth factors (FGFs). In particular, the overexpression of FGFR-2c in tumors has been associated with advanced clinical stages and increased metastatization. Here, we developed a non-invasive tool to evaluate, in vivo, the expression of FGFR-2c in metastatic cancer. This is based on ^99mTc-labelled FGF-2. Methods: ^99mTc-FGF-2 was tested in vitro and in vivo in mice bearing allografts of sarcoma cells. Images of ^99mTc-FGF-2 were acquired using a new portable high-resolution ultra-sensitive gamma camera for small animal imaging. Results: FGF-2 was labeled with high specific activity but low labelling efficiency, thus requiring post-labeling purification by gel-filtration chromatography. In vitro binding to 2C human keratinocytes showed a Kd of 3.36 × 10⁻⁹ M. In mice bearing J774A.1 cell allografts, we observed high and rapid tumor uptake of ^99mTc-FGF-2 with a high Tumor/Blood ratio at 24 h post-injection (26.1 %ID/g and 12.9 %ID) with low kidney activity and moderate liver activity. Conclusions: we labeled FGF-2 with ^99mTc and showed nanomolar Kd in vitro with human keratinocytes expressing FGF-2 receptors. In mice, ^99mTc-FGF-2 rapidly and efficiently accumulated in tumors expressing FGF-2 receptors. This new radiopharmaceutical could be used in humans to image TAFs.

Background/Objectives: Radiolabeled interleukin-2 (IL2) could allow for imaging activated T-lymphocytes in the tumor microenvironment (TME). The aims of this study were to assess the shelf life of a lyophilized kit containing THP-desIL2 to allow for the labeling of IL2 with ⁶⁸Ga at room temperature and to test the in vitro binding of ⁶⁸Ga-THP-desIL2 on different T-cell populations in order to determine which specific T-cell subset expresses the CD25 subunit of the IL2 receptor (IL2R). Methods: desIL2 was conjugated with THP and lyophilized. ⁶⁸Ga labeling was performed and several quality controls, including HPLC, iTLC and SDS-PAGE, were carried out at different storage times (1, 3 and 6 months) and temperatures (4 °C and −80 °C). Moreover, flow cytometric analysis on different T-cell populations and the in vitro and competitive binding of ⁶⁸Ga-THP-desIL2 were performed. Results: The lyophilized kit of THP-desIL2 was stable up to 6 months at −80 °C, preserving its sterility, integrity and acceptable values of labeling yield (51.80 ± 3.74%), radiochemical purity (>96%) and specific activity (5.59 ± 0.40 MBq/µg). Binding of ⁶⁸Ga-THP-desIL2 on activated lymphocytes was specific and exhibited a low dissociation constant from IL2R on stimulated Tregs (Kd: 10⁻⁹–10⁻¹⁰ mol/L). Conclusions: We assessed the shelf life of a lyophilized kit containing THP-desIL2 for the easy labeling of IL2 with ⁶⁸Ga at room temperature. The kit can be stored at −80 °C up to 6 months, thus facilitating the adoption of ⁶⁸Ga-THP-desIL2 into clinical practice. ⁶⁸Ga-THP-desIL2 showed high affinity and specificity for CD25 on activated T-lymphocytes, particularly Tregs, thus opening new opportunities for imaging immune cells trafficking in the TME.