Receptor-Targeted Fluorescence-Guided Surgery With Low Molecular Weight Agents

Generation and Characterization of Novel Pan-Cancer Anti-uPAR Fluorescent Nanobodies as Tools for Image-Guided Surgery

Fluorescence molecular imaging plays a vital role in image-guided surgery. In this context, the urokinase plasminogen activator receptor (uPAR) is an interesting biomarker enabling the detection and delineation of various tumor types due to its elevated expression on both tumor cells and the tumor microenvironment. In this study, anti-uPAR Nanobodies (Nbs) are generated through llama immunization with human and murine uPAR protein. Extensive in vitro characterization and in vivo testing with radiolabeled variants are conducted to assess their pharmacokinetics and select lead compounds. Subsequently, the selected Nbs are converted into fluorescent agents, and their application for fluorescence-guided surgery is evaluated in various subcutaneous and orthotopic tumor models. The study yields a panel of high-affinity anti-uPAR Nbs, showing specific binding across multiple types of cancer cells in vitro and in vivo. Lead fluorescently-labeled compounds exhibit high tumor uptake with high contrast at 1 h after intravenous injection across all assessed uPAR-expressing tumor models, outperforming a non-targeting control Nb. Additionally, rapid and accurate tumor localization and demarcation are demonstrated in an orthotopic human glioma model. Utilizing these Nbs can potentially enhance the precision of surgical tumor resection and, consequently, improve survival rates in the clinic.

What defines the "value" of robotic surgery for patients with gastrointestinal cancers? Perspectives from a U.S. Cancer Center

The use of robotic surgery has experienced rapid growth across diverse medical conditions, with a notable emphasis on gastrointestinal cancers. The advanced technologies incorporated into robotic surgery platforms have played a pivotal role in enabling the safe performance of complex procedures, including gastrectomy and pancreatectomy, through a minimally invasive approach. However, there exists a noteworthy gap in high-level evidence demonstrating that robotic surgery for gastric and pancreatic cancers has substantial benefits compared to traditional open or laparoscopic methods. The primary impediment hindering the broader implementation of robotic surgery is its cost. The escalating healthcare expenses in the United States have prompted healthcare providers and payors to explore patient-centered, value-based healthcare models and reimbursement systems that embrace cost-effectiveness. Thus, it is important to determine what defines the value of robotic surgery. It must either maintain or enhance oncological quality and improve complication rates compared to open procedures. Moreover, its true value should be apparent in patients' expedited recovery and improved quality of life. Another essential aspect of robotic surgery's value lies in minimizing or even eliminating opioid use, even after major operations, offering considerable benefits to the broader public health landscape. A quicker return to oncological therapy has the potential to improve overall oncological outcomes, while a speedier return to work not only alleviates individual financial distress but also positively impacts societal productivity. In this article, we comprehensively review and summarize the current landscape of health economics and value-based care, with a focus on robotic surgery for gastrointestinal cancers.

Translocator Protein 18 kDa (TSPO): A Promising Molecular Target for Image-Guided Surgery of Solid Cancers

The translocator protein 18-kDa (TSPO) is a mitochondrial membrane protein that is previously identified as the peripheral benzodiazepine receptor (PBR). Furthermore, it plays a significant role in a diverse range of biochemical processes, including steroidogenesis, mitochondrial cholesterol transport, cell survival and death, cell proliferation, and carcinogenesis. Several investigations also reported its roles in various types of cancers, including colorectal, brain, breast, prostate, and lung cancers, as well as melanoma. According to a previous study, the expression of TSPO was upregulated in cancer cells, which corresponds to an aggressive phenotype and/or poor prognosis. Consequently, the potential for crafting diagnostic and prognostic tools with a focus on TSPO holds great potential. In this context, several radioligands designed to target this protein have been identified, and some of the candidates have advanced to clinical trials. In recent years, the use of hybrid probes with radioactive and fluorescence molecules for image-guided surgery has exhibited promising results in animal and human studies. This indicates that the approach can serve as a valuable surgical navigator during cancer surgery. The current hybrid probes are built from various molecular platforms, including small molecules, nanoparticles, and antibodies. Although several TSPO-targeted imaging probes have been developed, their development for image-guided surgery of cancers is still limited. Therefore, this review aims to highlight recent findings on the involvement of TSPO in carcinogenesis, as well as provide a new perspective on the potential application of TSPO-targeted hybrid probes for image-guided surgery.

Improving oral squamous cell carcinoma diagnosis and treatment with fluorescence molecular imaging

Timely identification and complete removal of oral squamous cell carcinoma (OSCC) through surgery is crucial for effective treatment. However, current diagnostic methods that rely on physical abnormalities are not very informative and practical in clinical settings, leading to the late detection of oral cancer. Furthermore, no dependable intraoperative tools available for assessing surgical margins in real-time. Fluorescence imaging allows the visualization of biological processes occurring in the early stages of cancer, and as a result, small tumors can be detected at an early stage. Fluorescence imaging can effectively aid in assessing excised edges during surgery for OSCC as it possesses high sensitivity and spatial resolution. This review focuses on tongue cancer as a representation of OSCC and delves into various fluorescence techniques that can aid in early diagnosis and surgical guidance. The review also discusses the potential clinical applications of these techniques in the future.

Biodistributions and Imaging of Poly(ethylene glycol)-Conjugated Silicon Quantum Dot Nanoparticles in Osteosarcoma Models via Intravenous and Intratumoral Injections

Osteosarcoma is a malignant tumor with relatively high mortality rates in children and adolescents. While nanoparticles have been widely used in assisting the diagnosis and treatment of cancers, the biodistributions of nanoparticles in osteosarcoma models have not been well studied. Herein, we synthesize biocompatible and highly photoluminescent silicon quantum dot nanoparticles (SiQDNPs) and investigate their biodistributions in osteosarcoma mouse models after intravenous and intratumoral injections by fluorescence imaging. The bovine serum albumin (BSA)-coated and poly(ethylene glycol) (PEG)-conjugated SiQDNPs, when dispersed in phosphate-buffered saline (PBS), can emit red photoluminescence with the photoluminescence quantum yield more than 30% and have very low in vitro and in vivo toxicity. The biodistributions after intravenous injections reveal that the SiQDNPs are mainly metabolized through the livers in mice, while only slight accumulation in the osteosarcoma tumor is observed. Furthermore, the PEG conjugation can effectively extend the circulation time. Finally, a mixture of SiQDNPs and indocyanine green (ICG), which complement each other in the spectral range and diffusion length, is directly injected into the tumor for imaging. After the injection, the SiQDNPs with relatively large particle sizes stay around the injection site, while the ICG molecules diffuse over a broad range, especially in the muscular tissue. By taking advantage of this property, the difference between the osteosarcoma tumor and normal muscular tissue is demonstrated.

A translational blueprint for developing intraoperative imaging agents via radiopharmaceutical-guided drug design

Cancer imaging is a rapidly evolving field due to the discovery of novel molecular targets and the availability of corresponding techniques to detect them with high precision, accuracy, and sensitivity. Nuclear medicine is the most widely used molecular imaging modality and has a growing toolkit of clinically used radiopharmaceuticals that enable whole-body tumor visualization, staging, and treatment monitoring for a variety of tumors in a non-invasive manner. The need for similar imaging capabilities in the operating room has led to the emergence of fluorescence-guided surgery (FGS) as a powerful technique that gives surgeons unprecedented ability to distinguish tumors from healthy tissues. While a variety of strategies have been used to develop contrast agents for FGS, the use of radiopharmaceuticals as models brings exceptional translational potential and has increasingly been explored. Here, we review strategies used to convert clinically used radiopharmaceuticals into fluorescent and multimodal counterparts. Unique preclinical and clinical capabilities stemming from radiopharmaceutical-based agent design are also discussed to illustrate the advantages of this approach.

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.

Bioinspired large Stokes shift small molecular dyes for biomedical fluorescence imaging

Long Stokes shift dyes that minimize cross-talk between the excitation source and fluorescent emission to improve the signal-to-background ratio are highly desired for fluorescence imaging. However, simple small molecular dyes with large Stokes shift (more than 120 nanometers) and near-infrared (NIR) emissions have been rarely reported so far. Here, inspired by the chromophore chemical structure of fluorescent proteins, we designed and synthesized a series of styrene oxazolone dyes (SODs) with simple synthetic methods, which show NIR emissions (>650 nanometers) with long Stokes shift (ranged from 136 to 198 nanometers) and small molecular weight (<450 daltons). The most promising SOD9 shows rapid renal excretion and blood-brain barrier passing properties. After functioning with the mitochondrial-targeted triphenylphosphonium (TPP) group, the resulting SOD9-TPP can be engineered for head-neck tumor imaging, fluorescence image-guided surgery, brain neuroimaging, and on-site pathologic analysis. In summary, our findings add an essential small molecular dye category to the classical dyes.

Targeted Dual-Modal PET/SPECT-NIR Imaging: From Building Blocks and Construction Strategies to Applications

Molecular imaging is an emerging non-invasive method to qualitatively and quantitively visualize and characterize biological processes. Among the imaging modalities, PET/SPECT and near-infrared (NIR) imaging provide synergistic properties that result in deep tissue penetration and up to cell-level resolution. Dual-modal PET/SPECT-NIR agents are commonly combined with a targeting ligand (e.g., antibody or small molecule) to engage biomolecules overexpressed in cancer, thereby enabling selective multimodal visualization of primary and metastatic tumors. The use of such agents for (i) preoperative patient selection and surgical planning and (ii) intraoperative FGS could improve surgical workflow and patient outcomes. However, the development of targeted dual-modal agents is a chemical challenge and a topic of ongoing research. In this review, we define key design considerations of targeted dual-modal imaging from a topological perspective, list targeted dual-modal probes disclosed in the last decade, review recent progress in the field of NIR fluorescent probe development, and highlight future directions in this rapidly developing field.