A Novel Tumor-Specific Agent for Intraoperative Near-Infrared Fluorescence Imaging: A Translational Study in Healthy Volunteers and Patients with Ovarian Cancer

The Application of Nanoparticle-Based Imaging and Phototherapy for Female Reproductive Organs Diseases

Various female reproductive disorders affect millions of women worldwide and bring many troubles to women's daily life. Let alone, gynecological cancer (such as ovarian cancer and cervical cancer) is a severe threat to most women's lives. Endometriosis, pelvic inflammatory disease, and other chronic diseases-induced pain have significantly harmed women's physical and mental health. Despite recent advances in the female reproductive field, the existing challenges are still enormous such as personalization of disease, difficulty in diagnosing early cancers, antibiotic resistance in infectious diseases, etc. To confront such challenges, nanoparticle-based imaging tools and phototherapies that offer minimally invasive detection and treatment of reproductive tract-associated pathologies are indispensable and innovative. Of late, several clinical trials have also been conducted using nanoparticles for the early detection of female reproductive tract infections and cancers, targeted drug delivery, and cellular therapeutics. However, these nanoparticle trials are still nascent due to the body's delicate and complex female reproductive system. The present review comprehensively focuses on emerging nanoparticle-based imaging and phototherapies applications, which hold enormous promise for improved early diagnosis and effective treatments of various female reproductive organ diseases.

Preoperative [18F]fluoro-PEG-folate PET/CT in advanced stage epithelial ovarian cancer: A safety and feasibility study

PURPOSE

The selection for either primary or interval cytoreductive surgery (CRS) in patients with epithelial ovarian cancer (EOC) is currently based on imaging techniques like computed tomography (CT), [18F]fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET), diffusion-weighted magnetic resonance imaging (DW-MRI) and/or diagnostic laparoscopy, but these have limitations. Folate receptor (FR)-targeted PET/CT imaging, using [18F]fluoro-PEG-folate, could improve preoperative assessment, potentially reducing unnecessary laparotomies. This paper presents the first experience with [18F]fluoro-PEG-folate PET/CT imaging in advanced stage EOC, focusing on safety, tolerability, and feasibility for reflecting the extent of disease.

METHODS

Tolerability and safety were monitored after administration of the [18F]fluoro-PEG-folate tracer by measurements of vital function parameters (blood pressure, heart rate, peripheral oxygen saturation, respiratory rate, and temperature). In addition, (serious) adverse events were recorded. Disease burden was quantified using the Peritoneal Cancer Index (PCI) score on preoperative [18F]fluoro-PEG-folate PET/CT and during surgery. PCI scores were compared with intraoperative findings, considering histopathologic results as the gold standard. Tissue specimens were stained for FRα and FRβ. Relative uptake of the radiotracer by EOC lesions and other tissues was quantified using body weighted standardized uptake values (SUV).

RESULTS

The study was terminated prematurely during the interim analysis after inclusion of eight patients of whom five had completed the study protocol. Although [18F]fluoro-PEG-folate demonstrated safety, efficacy for tumor-specific imaging was limited. Despite clear FRα overexpression, low tracer uptake was observed in EOC lesions, contrasting with high uptake in healthy tissues, posing challenges in specificity and accurately assessing tumor burden.

CONCLUSIONS

Overall, while [18F]fluoro-PEG-folate was well-tolerated, its clinical utility in the preoperative assessment of the extent of disease in EOC was limited. This highlights the need for further research in developing targeted imaging agents for optimal detection of EOC metastases.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT05215496. Registered 31 January 2022.

Synthesis and Characterization of Folic Acid-Conjugated Terbium Complexes as Luminescent Probes for Targeting Folate Receptor-Expressing Cells

Several conjugates between folic acid and a series of kinetically stable lanthanide complexes have been synthesized, using amide coupling and azide-alkyne cycloaddition methodologies to link the metal-binding domain to folate through a variety of spacer groups. While all these complexes exhibit affinity for the folate receptor, it is clear that the point of attachment to folate is essential, with linkage through the γ-carboxylic acid giving rise to significantly enhanced receptor affinity. All the conjugates studied show affinities consistent with displacing biological circulating folate derivatives, 5-methyltetrahydrofolate, from folate receptors. All the complexes exhibit luminescence with a short-lived component arising from ligand fluorescence overlaid on a much longer lived terbium-centered component. These can be separated using time-gating methods. From the results obtained, the most promising approach to achieve sensitized luminescence in these systems requires incorporating a sensitizing chromophore close to the lanthanide.

Molecular image-guided surgery in gynaecological cancer: where do we stand?

PURPOSE

The aim of this review is to give an overview of the current status of molecular image-guided surgery in gynaecological malignancies, from both clinical and technological points of view.

METHODS

A narrative approach was taken to describe the relevant literature, focusing on clinical applications of molecular image-guided surgery in gynaecology, preoperative imaging as surgical roadmap, and intraoperative devices.

RESULTS

The most common clinical application in gynaecology is sentinel node biopsy (SNB). Other promising approaches are receptor-target modalities and occult lesion localisation. Preoperative SPECT/CT and PET/CT permit a roadmap for adequate surgical planning. Intraoperative detection modalities span from 1D probes to 2D portable cameras and 3D freehand imaging.

CONCLUSION

After successful application of radio-guided SNB and SPECT, innovation is leaning towards hybrid modalities, such as hybrid tracer and fusion of imaging approaches including SPECT/CT and PET/CT. Robotic surgery, as well as augmented reality and virtual reality techniques, is leading to application of these innovative technologies to the clinical setting, guiding surgeons towards a precise, personalised, and minimally invasive approach.

Polymer-Tethered Quenched Fluorescent Probes for Enhanced Imaging of Tumor-Associated Proteases

Fluorescence-based contrast agents enable real-time detection of solid tumors and their neovasculature, making them ideal for use in image-guided surgery. Several agents have entered late-stage clinical trials or secured FDA approval, suggesting they are likely to become the standard of care in cancer surgeries. One of the key parameters to optimize in contrast agents is molecular size, which dictates much of the pharmacokinetic and pharmacodynamic properties of the agent. Here, we describe the development of a class of protease-activated quenched fluorescent probes in which a N-(2-hydroxypropyl)methacrylamide copolymer is used as the primary scaffold. This copolymer core provides a high degree of probe modularity to generate structures that cannot be achieved with small molecules and peptide probes. We used a previously validated cathepsin substrate and evaluated the effects of length and type of linker, as well as the positioning of the fluorophore/quencher pair on the polymer core. We found that the polymeric probes could be optimized to achieve increased overall signal and tumor-to-background ratios compared to the reference small molecule probe. Our results also revealed multiple structure-activity relationship trends that can be used to design and optimize future optical imaging probes. Furthermore, they confirm that a hydrophilic polymer is an ideal scaffold for use in optical imaging contrast probes, allowing a highly modular design that enables efficient optimization to maximize probe accumulation and overall biodistribution properties.

Fluorescent imaging probes for in vivo ovarian cancer targeted detection and surgery

Ovarian cancer is the most lethal gynecological cancer, with a survival rate of approximately 40% at five years from the diagno. The first-line treatment consists of cytoreductive surgery combined with chemotherapy (platinum- and taxane-based drugs). To date, the main prognostic factor is related to the complete surgical resection of tumor lesions, including occult micrometastases. The presence of minimal residual diseases not detected by visual inspection and palpation during surgery significantly increases the risk of disease relapse. Intraoperative fluorescence imaging systems have the potential to improve surgical outcomes. Fluorescent tracers administered to the patient may support surgeons for better real-time visualization of tumor lesions during cytoreductive procedures. In the last decade, consistent with the discovery of an increasing number of ovarian cancer-specific targets, a wide range of fluorescent agents were identified to be employed for intraoperatively detecting ovarian cancer. Here, we present a collection of fluorescent probes designed and developed for fluorescence-guided ovarian cancer surgery. Original articles published between 2011 and November 2022 focusing on fluorescent probes, currently under preclinical and clinical investigation, were searched in PubMed. The keywords used were targeted detection, ovarian cancer, fluorescent probe, near-infrared fluorescence, fluorescence-guided surgery, and intraoperative imaging. All identified papers were English-language full-text papers, and probes were classified based on the location of the biological target: intracellular, membrane, and extracellular.

Polymer-tethered quenched fluorescent probes for enhanced imaging of tumor associated proteases

Fluorescence-based contrast agents enable real-time detection of solid tumors and their neovasculature, making them ideal for use in image-guided surgery. Several agents have entered late-stage clinical trials or secured FDA approval, suggesting they are likely to become standard of care in cancer surgeries. One of the key parameters to optimize in contrast agent is molecular size, which dictates much of the pharmacokinetic and pharmacodynamic properties of the agent. Here, we describe the development of a class of protease-activated quenched fluorescent probes in which a N-(2-hydroxypropyl)methacrylamide copolymer is used as the primary scaffold. This copolymer core provides a high degree of probe modularity to generate structures that cannot be achieved with small molecules and peptide probes. We used a previously validated cathepsin substrate and evaluated the effects of length and type of linker as well as positioning of the fluorophore/quencher pair on the polymer core. We found that the polymeric probes could be optimized to achieve increased over-all signal and tumor-to-background ratios compared to the reference small molecule probe. Our results also revealed multiple structure-activity relationship trends that can be used to design and optimize future optical imaging probes. Furthermore, they confirm that a hydrophilic polymer is an ideal scaffold for use in optical imaging contrast probes, allowing a highly modular design that enables efficient optimization to maximize probe accumulation and overall biodistribution properties.

Precise and safe pulmonary segmentectomy enabled by visualizing cancer margins with dual-channel near-infrared fluorescence

BACKGROUND

Segmentectomy is a type of limited resection surgery indicated for patients with very early-stage lung cancer or compromised function because it can improve quality of life with minimal removal of normal tissue. For segmentectomy, an accurate detection of the tumor with simultaneous identification of the lung intersegment plane is critical. However, it is not easy to identify both during surgery. Here, the authors report dual-channel image-guided lung cancer surgery using renally clearable and physiochemically stable targeted fluorophores to visualize the tumor and intersegmental plane distinctly with different colors; cRGD-ZW800 (800 nm channel) targets tumors specifically, and ZW700 (700 nm channel) simultaneously helps discriminate segmental planes.

METHODS

The near-infrared (NIR) fluorophores with 700 nm and with 800 nm channels were developed and evaluated the feasibility of dual-channel fluorescence imaging of lung tumors and intersegmental lines simultaneously in mouse, rabbit, and canine animal models. Expression levels of integrin αvβ3, which is targeted by cRGD-ZW800-PEG, were retrospectively studied in the lung tissue of 61 patients who underwent lung cancer surgery.

RESULTS

cRGD-ZW800-PEG has clinically useful optical properties and outperforms the FDA-approved NIR fluorophore indocyanine green and serum unstable cRGD-ZW800-1 in multiple animal models of lung cancer. Combined with the blood-pooling agent ZW700-1C, cRGD-ZW800-PEG permits dual-channel NIR fluorescence imaging for intraoperative identification of lung segment lines and tumor margins with different colors simultaneously and accurately.

CONCLUSION

This dual-channel image-guided surgery enables complete tumor resection with adequate negative margins that can reduce the recurrence rate and increase the survival rate of lung cancer patients.

Activity-Based Fluorescence Diagnostics for Cancer

Fluorescence imaging is one of the most promising approaches to achieve intraoperative assessment of the tumor/normal tissue margins during cancer surgery. This is critical to improve the patients' prognosis, and therefore various molecular fluorescence imaging probes have been developed for the identification of cancer lesions during surgery. Among them, "activatable" fluorescence probes that react with cancer-specific biomarker enzymes to generate fluorescence signals have great potential for high-contrast cancer imaging due to their low background fluorescence and high signal amplification by enzymatic turnover. Over the past two decades, activatable fluorescence probes employing various fluorescence control mechanisms have been developed worldwide for this purpose. Furthermore, new biomarker enzymatic activities for specific types of cancers have been identified, enabling visualization of various types of cancers with high sensitivity and specificity. This Review focuses on recent advances in the design, function and characteristics of activatable fluorescence probes that target cancer-specific enzymatic activities for cancer imaging and also discusses future prospects in the field of activity-based diagnostics for cancer.

Unfolded Protein-Based Sandwich AIE Probe Imparts High Fluorescent Contrast for Pan-Cancer Surgical Navigation

Fluorescence imaging-guided navigation for cancer surgery has a promising clinical application. However, pan-cancer encompasses a wide variety of cancer types with significant heterogeneity, resulting in the lack of universal and highly contrasted fluorescent probes for surgical navigation. Here, we developed an aggregation-induced emission (AIE) probe (MI-AIE-TsG, MAT) with dual activation for pan-cancer surgical navigation. MAT weakly activates fluorescence by targeting the SUR1 protein on the endoplasmic reticulum (ER) through the TsG group. Subsequently, the sulfhydryl groups on the unfolded proteins, which are highly enriched in cancer ER, react with the maleimide (MI) of MAT through the thiol-ene click reaction, further enhancing the fluorescence. The formation of a SUR1-MAT-unfolded protein sandwich complex reinforces the restriction of intramolecular motion and eliminates photoinduced electron transfer of MAT, leading to high signal-to-noise (9.2) fluorescence imaging and use for surgical navigation of pan-cancer. The generally high content of unfolded proteins in cancer cells makes MAT imaging generalizable, and it currently has proven feasibility in ovarian, cervical, and breast cancers. Meanwhile, MAT promotes cellular autophagy by hindering protein folding, thereby inhibiting cancer cell proliferation. This generalizable, high-contrast AIE fluorescent probe spans the heterogeneity of pancreatic cancer, enabling precise pancreatic cancer surgery navigation and treatment.

The utilization of nanotechnology in the female reproductive system and related disorders

The health of the reproductive system is intricately linked to female fertility and quality of life. There has been a growing prevalence of reproductive system disorders among women, particularly in younger age groups, resulting in significant adverse effects on their reproductive health. Consequently, there is an urgent need for effective treatment modalities. Nanotechnology, as an advanced discipline, provides innovative avenues for managing and treating diseases of the female reproductive system by enabling precise manipulation and regulation of biological molecules and cells. By utilizing nanodelivery systems, drugs can be administered with pinpoint accuracy, leading to reduced side effects and improved therapeutic efficacy. Moreover, nanomaterial imaging techniques enhance diagnostic precision and sensitivity, aiding in the assessment of disease severity and progression. Furthermore, the implementation of nanobiosensors facilitates early detection and prevention of ailments. This comprehensive review aims to summarize recent applications of nanotechnology in the treatment of female reproductive system diseases. The latest advancements in drug delivery, diagnosis, and treatment approaches will be discussed, with an emphasis on the potential of nanotechnology to improve treatment outcomes and overall quality of life.

Nanocarrier systems loaded with IR780, iron oxide nanoparticles and chlorambucil for cancer theragnostics

Theragnostics has become a popular term nowadays, since it enables both diagnosis and therapy at the same time while only using one carrier platform. Therefore, formulating a nanocarrier system that could serve as theragnostic agent by using simple techniques would be an advantage during production. In this project, we aimed to develop a nanocarrier that can be loaded with the chemotherapeutic medication chlorambucil and magnetic resonance imaging agents (e.g., iron oxide nanoparticles and near-infrared fluorophore IR780) for theragnostics. Poly(lactic-co-glycolic acid) was combined with the aforementioned ingredients to generate poly(vinyl alcohol)-based nanoparticles (NPs) using the single emulsion technique. Then the NPs were coated with F127 and F127-folate by simple incubation for five days. The nanoparticles have the hydrodynamic size of approx. 250 nm with negative charge. Similar to chlorambucil and IR780, iron oxide loadings were observed for all three kinds of NPs. The release of chlorambucil was quicker at pH 5.4 than at pH 7.4 at 37 °C. The F127@NPs and F127-folate@NPs demonstrated much greater cell uptake and toxicity up to 72 h after incubation. Our in vitro results of F127@NPs and F127-folate@NPs have demonstrated the ability of these systems to serve as medication and imaging agent carriers for cancer treatment and diagnostics, respectively.

Membrane cholesterol enrichment and folic acid functionalization lead to increased accumulation of erythrocyte-derived optical nano-constructs within the ovarian intraperitoneal tumor implants in mice

Cytoreductive surgery remains as the gold standard to treat ovarian cancer, but with limited efficacy since not all tumors can be intraoperatively visualized for resection. We have engineered erythrocyte-derived nano-constructs that encapsulate the near infrared (NIR) fluorophore, indocyanine green (ICG), as optical probes for NIR fluorescence imaging of ovarian tumors. Herein, we have enriched the membrane of these nano-constructs with cholesterol, and functionalized their surface with folic acid (FA) to target the folate receptor-α. Using a mouse model, we show that the average fraction of the injected dose per tumor mass for nano-constructs with both membrane cholesterol enrichment and FA functionalization was ~ sixfold higher than non-encapsulated ICG, ~ twofold higher than nano-constructs enriched with cholesterol alone, and 33 % higher than nano-constructs with only FA functionalization at 24-h post-injection. These results suggest that erythrocyte-derived nano-constructs containing both cholesterol and FA present a platform for improved fluorescence imaging of ovarian tumors.

A follicle-stimulating hormone receptor-targeted near-infrared fluorescent probe for tumor-selective imaging and photothermal therapy

Late detection, peritoneal dissemination, chemoresistance and weak response to targeted therapeutics lead to high mortality in ovarian cancer. More efficient and specific tumor imaging and therapeutic agents are needed to improve the resection rate of surgery and to eliminate residual disease. The expression patterns of follicle-stimulating hormone (FSH) receptor make it a suitable target for ovarian cancer. Here, we report a strategy to develop an organic near-infrared probe for FSH receptor-targeted tumor imaging and photothermal therapy. The FSH-Rh760 probe was conjugated from the Rh760 fluorophore with the FSH β subunit 33-53 peptide. FSH-Rh760 specifically distinguished peritoneal metastatic ovarian cancerous foci from surrounding normal tissues with a high tumor-to-background ratio. The fluorescence signals in tumors peaked at 2 h and were cleared at 120 h postinjection. FSH-Rh760 treatment rapidly increased the abdomen temperature of mice up to ∼43 °C upon exposure to a near-infrared laser and effectively suppressed peritoneal tumor growth with tumor specificity. No significant systemic toxicities were observed. This study demonstrates the targeting ability and biocompatibility of FSH receptor-targeted theranostics and highlights its potential for clinical application in imaging-guided precision tumor resection and photothermal therapy to eliminate cancer lesions intraoperatively and postoperatively.

Discovery of novel tumor-targeted near-infrared probes with 6-substituted pyrrolo[2,3-d]pyrimidines as targeting ligands

Since the overexpression of folate receptors (FRs) in certain types of cancers, a variety of FR-targeted fluorescent probes for tumor detection have been developed. However, the reported probes almost all have the same targeting ligand of folic acid with various fluorophores and/or linkers. In the present study, a series of novel tumor-targeted near-infrared (NIR) molecular fluorescent probes were designed and synthesized based on previously reported 6-substituted pyrrolo[2,3-d]pyrimidine antifolates. All newly synthesized probes showed specific FR binding in vitro, whereas GT-NIR-4 and GT-NIR-5 with a benzene and a thiophene ring, respectively, on the side chain of pyrrolo[2,3-d]pyrimidine exhibited better FR binding affinity than that of GT-NIR-6 with folic acid as targeting ligand. GT-NIR-4 also showed high tumor uptake in KB tumor-bearing mice with good pharmacokinetic properties and biological safety. This work demonstrates the first attempt to replace folic acid with antifolates as targeting ligands for tumor-targeted NIR probes.

Fluorescence lifetime of injected indocyanine green as a universal marker of solid tumours in patients

The surgical resection of solid tumours can be enhanced by fluorescence-guided imaging. However, variable tumour uptake and incomplete clearance of fluorescent dyes reduces the accuracy of distinguishing tumour from normal tissue via conventional fluorescence intensity-based imaging. Here we show that, after systemic injection of the near-infrared dye indocyanine green in patients with various types of solid tumour, the fluorescence lifetime (FLT) of tumour tissue is longer than the FLT of non-cancerous tissue. This tumour-specific shift in FLT can be used to distinguish tumours from normal tissue with an accuracy of over 97% across tumour types, and can be visualized at the cellular level using microscopy and in larger specimens through wide-field imaging. Unlike fluorescence intensity, which depends on imaging-system parameters, tissue depth and the amount of dye taken up by tumours, FLT is a photophysical property that is largely independent of these factors. FLT imaging with indocyanine green may improve the accuracy of cancer surgeries.

Fluorescent Probes for Imaging in Humans: Where Are We Now?

Optical imaging has become an indispensable technology in the clinic. The molecular design of cell-targeted and highly sensitive materials, the validation of specific disease biomarkers, and the rapid growth of clinically compatible instrumentation have altogether revolutionized the way we use optical imaging in clinical settings. One prime example is the application of cancer-targeted molecular imaging agents in both trials and routine clinical use to define the margins of tumors and to detect lesions that are "invisible" to the surgeons, leading to improved resection of malignant tissues without compromising viable structures. In this Perspective, we summarize some of the key research advances in chemistry, biology, and engineering that have accelerated the translation of optical imaging technologies for use in human patients. Finally, our paper comments on several research areas where further work will likely render the next generation of technologies for translational optical imaging.

Lymph node metastasis in cancer progression: molecular mechanisms, clinical significance and therapeutic interventions

Lymph nodes (LNs) are important hubs for metastatic cell arrest and growth, immune modulation, and secondary dissemination to distant sites through a series of mechanisms, and it has been proved that lymph node metastasis (LNM) is an essential prognostic indicator in many different types of cancer. Therefore, it is important for oncologists to understand the mechanisms of tumor cells to metastasize to LNs, as well as how LNM affects the prognosis and therapy of patients with cancer in order to provide patients with accurate disease assessment and effective treatment strategies. In recent years, with the updates in both basic and clinical studies on LNM and the application of advanced medical technologies, much progress has been made in the understanding of the mechanisms of LNM and the strategies for diagnosis and treatment of LNM. In this review, current knowledge of the anatomical and physiological characteristics of LNs, as well as the molecular mechanisms of LNM, are described. The clinical significance of LNM in different anatomical sites is summarized, including the roles of LNM playing in staging, prognostic prediction, and treatment selection for patients with various types of cancers. And the novel exploration and academic disputes of strategies for recognition, diagnosis, and therapeutic interventions of metastatic LNs are also discussed.

Safety assessment of fluorescently labeled anti-EGFR Nanobodies in healthy dogs

Introduction: Surgical resection is one of the main treatment options for several types of cancer, the desired outcome being complete removal of the primary tumor and its local metastases. Any malignant tissue that remains after surgery may lead to relapsing disease, negatively impacting the patient's quality of life and overall survival. Fluorescence imaging in surgical oncology aims to facilitate full resection of solid tumors through the visualization of malignant tissue during surgery, following the administration of a fluorescent contrast agent. An important class of targeting molecules are Nanobodies® (Nbs), small antigen-binding fragments derived from camelid heavy chain only antibodies. When coupled with a fluorophore, Nbs can bind to a specific receptor and demarcate tumor margins through a fluorescence camera, improving the accuracy of surgical intervention. A widely investigated target for fluorescence-guided surgery is the epidermal growth factor receptor (EGFR), which is overexpressed in several types of tumors. Promising results with the fluorescently labeled anti-EGFR Nb 7D12-s775z in murine models motivated a project employing the compound in a pioneering study in dogs with spontaneous cancer. Methods: To determine the safety profile of the study drug, three healthy purpose-bred dogs received an intravenous injection of the tracer at 5.83, 11.66, and 19.47 mg/m2, separated by a 14-day wash-out period. Physical examination and fluorescence imaging were performed at established time points, and the animals were closely monitored between doses. Blood and urine values were analyzed pre- and 24 h post administration. Results: No adverse effects were observed, and blood and urine values stayed within the reference range. Images of the oral mucosa, acquired with a fluorescence imaging device (Fluobeam®), suggest rapid clearance, which was in accordance with previous in vivo studies. Discussion: These are the first results to indicate that 7D12-s775z is well tolerated in dogs and paves the way to conduct clinical trials in canine patients with EGFR-overexpressing spontaneous tumors.

A first-in-class fully modified version of miR-34a with outstanding stability, activity, and anti-tumor efficacy

Altered by defects in p53, epigenetic silencing, and genomic loss, the microRNA miR-34a represents one of the most clinically relevant tumor-suppressive microRNAs. Without question, a striking number of patients with cancer would benefit from miR-34a replacement, if poor miR-34a stability, non-specific delivery, and delivery-associated toxicity could be overcome. Here, we highlight a fully modified version of miR-34a (FM-miR-34a) that overcomes these hurdles when conjugated to a synthetically simplistic ligand. FM-miR-34a is orders of magnitude more stable than a partially modified version, without compromising its activity, leading to stronger repression of a greater number of miR-34a targets. FM-miR-34a potently inhibited proliferation and invasion, and induced sustained downregulation of endogenous target genes for >120 h following in vivo delivery. In vivo targeting was achieved through conjugating FM-miR-34a to folate (FM-FolamiR-34a), which inhibited tumor growth leading to complete cures in some mice. These results have the ability to revitalize miR-34a as an anti-cancer agent, providing a strong rationale for clinical testing.

Synthetic Approaches to the New Drugs Approved During 2021

Each year, new drugs are introduced to the market, representing structures that have affinity for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates, provide insight into molecular recognition and serve as potential leads for the design of future medicines. This annual review is part of a continuing series highlighting the most likely process-scale synthetic approaches to 35 NCEs that were first approved anywhere in the world during 2021.

Intraoperative Molecular Imaging of Lung Cancer

Intraoperative molecular imaging innovations have been propelled by the development of fluorescent contrast agents that specifically target tumor tissues and advanced camera systems that can detect the specified fluorescence. The most promising agent to date is OTL38, a targeted and near-infrared agent that was recently approved by the Food and Drug Administration for intraoperative imaging for lung cancer.

Evaluation of Potential Targets for Fluorescence-Guided Surgery in Pediatric Ewing Sarcoma: A Preclinical Proof-of-Concept Study

Fluorescence-guided surgery (FGS), based on fluorescent tracers binding to tumor-specific biomarkers, could assist surgeons to achieve complete tumor resections. This study evaluated potential biomarkers for FGS in pediatric Ewing sarcoma (ES). Immunohistochemistry (IHC) was performed to assess CD99, CXCR4, CD117, NPY-R-Y1, and IGF-1R expression in ES biopsies and resection specimens. LINGO-1 and GD2 evaluation did not work on the acquired tissue. Based on the immunoreactive scores, anti-CD99 and anti-CD117 were evaluated for binding specificity using flow cytometry and immunofluorescence microscopy. Anti-GD2, a tracer in the developmental phase, was also tested. These three tracers were topically applied to a freshly resected ES tumor and adjacent healthy tissue. IHC demonstrated moderate/strong CD99 and CD117 expression in ES tumor samples, while adjacent healthy tissue had limited expression. Flow cytometry and immunofluorescence microscopy confirmed high CD99 expression, along with low/moderate CD117 and low GD2 expression, in ES cell lines. Topical anti-CD99 and anti-GD2 application on ES tumor showed fluorescence, while anti-CD117 did not show fluorescence for this patient. In conclusion, CD99-targeting tracers hold promise for FGS of ES. CD117 and GD2 tracers could be potential alternatives. The next step towards development of ES-specific FGS tracers could be ex vivo topical application experiments on a large cohort of ES patients.

Safety and anti-tumour activity of the IgE antibody MOv18 in patients with advanced solid tumours expressing folate receptor-alpha: a phase I trial

All antibodies approved for cancer therapy are monoclonal IgGs but the biology of IgE, supported by comparative preclinical data, offers the potential for enhanced effector cell potency. Here we report a Phase I dose escalation trial (NCT02546921) with the primary objective of exploring the safety and tolerability of MOv18 IgE, a chimeric first-in-class IgE antibody, in patients with tumours expressing the relevant antigen, folate receptor-alpha. The trial incorporated skin prick and basophil activation tests (BAT) to select patients at lowest risk of allergic toxicity. Secondary objectives were exploration of anti-tumour activity, recommended Phase II dose, and pharmacokinetics. Dose escalation ranged from 70 μg-12 mg. The most common toxicity of MOv18 IgE is transient urticaria. A single patient experienced anaphylaxis, likely explained by detection of circulating basophils at baseline that could be activated by MOv18 IgE. The BAT assay was used to avoid enrolling further patients with reactive basophils. The safety profile is tolerable and maximum tolerated dose has not been reached, with evidence of anti-tumour activity observed in a patient with ovarian cancer. These results demonstrate the potential of IgE therapy for cancer.

Dispersion Performances of Naphthalimides Doped in Dual Temperature- and pH-Sensitive Poly (N-Isopropylacrylamide-co-acrylic Acid) Shell Assembled with Vinyl-Modified Mesoporous SiO2 Core for Fluorescence Cell Imaging

Developing effective intelligent nanocarriers is highly desirable for fluorescence imaging and therapeutic applications but remains challenging. Using a vinyl-grafted BMMs (bimodal mesoporous SiO₂ materials) as a core and PAN ((2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione))-dispersed dual pH/thermal-sensitive poly(N-isopropylacrylamide-co-acrylic acid) as a shell, PAN@BMMs with strong fluorescence and good dispersibility were prepared. Their mesoporous features and physicochemical properties were extensively characterized via XRD patterns, N₂ adsorption-desorption analysis, SEM/TEM images, TGA profiles, and FT-IR spectra. In particular, their mass fractal dimension (d_m) features based on SAXS patterns combined with fluorescence spectra were successfully obtained to evaluate the uniformity of the fluorescence dispersions, showing that the d_m values increased from 2.49 to 2.70 with an increase of the AN-additive amount from 0.05 to 1%, along with the red shifting of their fluorescent emission wavelength from 471 to 488 nm. The composite (PAN@BMMs-I-0.1) presented a densification trend and a slight decrease in peak (490 nm) intensity during the shrinking process. Its fluorescent decay profiles confirmed two fluorescence lifetimes of 3.59 and 10.62 ns. The low cytotoxicity obtained via in vitro cell survival assay and the efficient green imaging performed via HeLa cell internalization suggested that the smart PAN@BMM composites are potential carriers for in vivo imaging and therapy.

First-in-patient study of OTL78 for intraoperative fluorescence imaging of prostate-specific membrane antigen-positive prostate cancer: a single-arm, phase 2a, feasibility trial

BACKGROUND

Targeted real-time imaging during robot-assisted radical prostatectomy provides information on the localisation and extent of prostate cancer. We assessed the safety and feasibility of the prostate-specific membrane antigen (PSMA)-targeted fluorescent tracer OTL78 in patients with prostate cancer.

METHODS

In this single-arm, phase 2a, feasibility trial with an adaptive design was carried out in The Netherlands Cancer Institute, Netherlands. Male patients aged 18 years or older, with PSMA PET-avid prostate cancer with an International Society of Urological Pathology (ISUP) grade group of 2 or more, who were scheduled to undergo robot-assisted radical prostatectomy with or without extended pelvic lymph node dissection were eligible. All patients had a robot-assisted radical prostatectomy using OTL78. Based on timing and dose, patients received a single intravenous infusion of OTL78 (0·06 mg/kg 1-2 h before surgery [dose cohort 1], 0·03 mg/kg 1-2 h before surgery [dose cohort 2], or 0·03 mg/kg 24 h before surgery [dose cohort 3]). The primary outcomes, assessed in all enrolled patients, were safety and pharmacokinetics of OTL78. This study is completed and is registered in the European Trial Database, 2019-002393-31, and the International Clinical Trials Registry Platform, NL8552, and is completed.

FINDINGS

Between June 29, 2020, and April 1, 2021, 19 patients were screened for eligibility, 18 of whom were enrolled. The median age was 69 years (IQR 64-70) and median prostate-specific antigen concentration was 15 ng/mL (IQR 9·3-22·0). In 16 (89%) of 18 patients, robot-assisted radical prostatectomy was accompanied by an extended pelvic lymph node dissection. Three serious adverse events occurred in one (6%) patient: an infected lymphocele, a urosepsis, and an intraperitoneal haemorrhage. These adverse events were considered unrelated to the administration of OTL78 or intraoperative fluorescence imaging. No patient died, required a dose reduction, or required discontinuation due to drug-related toxicity. The dose-normalised maximum serum concentration (C_max/dose) in patients was 84·1 ng/mL/mg for the 0·03 mg/kg dose and 79·6 ng/mL/mg for the 0·06 mg/kg dose, the half-life was 5·1 h for the 0·03 mg/kg dose and 4·7 h for the 0·06 mg/kg dose, the volume of distribution was 22·9 L for the 0·03 mg/kg dose and 19·5 L for the 0·06 mg/kg dose, and the clearance was 3·1 L/h for the 0·03 mg/kg dose and 3·0 L/h for the 0·06 mg/kg dose.

INTERPRETATION

This first-in-patient study showed that OTL78 was well tolerated and had the potential to improve prostate cancer detection. Optimal dosing was 0·03 mg/kg, 24 h preoperatively. PSMA-directed fluorescence imaging allowed real-time identification of visually occult prostate cancer and might help to achieve complete oncological resections.

FUNDING

On Target Laboratories.

Non-invasive molecular imaging for precision diagnosis of metastatic lymph nodes: opportunities from preclinical to clinical applications

Lymph node metastasis is an indicator of the invasiveness and aggressiveness of cancer. It is a vital prognostic factor in clinical staging of the disease and therapeutic decision-making. Patients with positive metastatic lymph nodes are likely to develop recurrent disease, distant metastasis, and succumb to death in the coming few years. Lymph node dissection and histological analysis are needed to detect whether regional lymph nodes have been infiltrated by cancer cells and determine the likely outcome of treatment and the patient's chances of survival. However, these procedures are invasive, and tissue biopsies are prone to sampling error. In recent years, advanced molecular imaging with novel imaging probes has provided new technologies that are contributing to comprehensive management of cancer, including non-invasive investigation of lymphatic drainage from tumors, identifying metastatic lymph nodes, and guiding surgeons to operate efficiently in patients with complex lesions. In this review, first, we outline the current status of different molecular imaging modalities applied for lymph node metastasis management. Second, we summarize the multi-functional imaging probes applied with the different imaging modalities as well as applications of cancer lymph node metastasis from preclinical studies to clinical translations. Third, we describe the limitations that must be considered in the field of molecular imaging for improved detection of lymph node metastasis. Finally, we propose future directions for molecular imaging technology that will allow more personalized treatment plans for patients with lymph node metastasis.

Comparison of Five Near-Infrared Fluorescent Folate Conjugates in an Ovarian Cancer Model

PURPOSE

Fluorescence imaging (FLI) using targeted near-infrared (NIR) conjugates aids the detection of tumour lesions pre- and intraoperatively. The optimisation of tumour visualisation and contrast is essential and can be achieved through high tumour-specificity and low background signal. However, the choice of fluorophore is recognised to alter biodistribution and clearance of conjugates and is therefore a determining factor in the specificity of target binding. Although ZW800-1, IRDye® 800CW and ICG are the most commonly employed NIR fluorophores in clinical settings, the fluorophore with optimal in vivo characteristics has yet to be determined. Therefore, we aimed to characterise the impact the choice of fluorophore has on the biodistribution, specificity and contrast, by comparing five different NIR fluorophores conjugated to folate, in an ovarian cancer model.

PROCEDURES

ZW800-1, ZW800-1 Forte, IRDye® 800CW, ICG-OSu and an in-house synthesised Cy7 derivative were conjugated to folate through an ethylenediamine linker resulting in conjugates 1-5, respectively. The optical properties of all conjugates were determined by spectroscopy, the specificity was assessed in vitro by flow cytometry and FLI, and the biodistribution was studied in vivo and ex vivo in a subcutaneous Skov-3 ovarian cancer model.

RESULTS

We demonstrated time- and receptor-dependent binding of folate conjugates in vitro and in vivo. Healthy tissue clearance characteristics and tumour-specific signal varied between conjugates 1-5. ZW800-1 Forte (2) revealed the highest contrast in folate receptor alpha (FRα)-positive xenografts and showed statistically significant target specificity. While conjugates 1, 2 and 3 are renally cleared, hepatobiliary excretion and no or very low accumulation in tumours was observed for 4 and 5.

CONCLUSIONS

The choice of fluorophore has a significant impact on the biodistribution and tumour contrast. ZW800-1 Forte (2) exhibited the best properties of those tested, with significant specific fluorescence signal.

Can fluorescence-guided surgery improve optimal surgical treatment for ovarian cancer? A systematic scoping review of clinical studies

BACKGROUND

The predicament of achieving optimal surgical intervention faced by surgeons in treating ovarian cancer has driven research into improving intra-operative detection of cancer using fluorescent materials.

OBJECTIVE

To provide a literature overview on the clinical use of intra-operative fluorescence-guided surgery for ovarian cancer, either for cytoreductive surgery or sentinel lymph node (SLN) biopsy.

METHODS

The systematic review included studies from June 2002 until October 2021 from PubMed, Web of Science, and Scopus as well as those from a search of related literature. Studies were included if they investigated the use of fluorescence-guided surgery in patients with a diagnosis of ovarian cancer. Authors charted variables related to study characteristics, patient demographics, baseline clinical characteristics, fluorescence-guided surgery material, and treatment details, and surgical, oncological, and survival outcome variables. After screening 2817 potential studies, 24 studies were included.

RESULTS

Studies investigating the role of fluorescence-guided surgery to visualize tumor deposits or SLN biopsy included the data of 410 and 118 patients, respectively. Six studies used indocyanine green tracer with a mean SLN detection rate of 92.3% with a pelvic and para-aortic detection rate of 94.8% and 96.7%, respectively. The sensitivity, specificity, and positive predictive value for micrometastases detection of OTL38 and 5-aminolevulinc acid at time of cytoreduction were 92.2% vs 79.8%, 67.3% vs 94.8%, and 55.8% vs 95.8%, respectively.

CONCLUSION

Fluorescence -guided surgery is a technique that may improve the detection rate of micrometastases and SLN identification in ovarian cancer. Further research is needed to establish whether this will lead to improved patient outcomes.

A Phase III Study of Pafolacianine Injection (OTL38) for Intraoperative Imaging of Folate Receptor-Positive Ovarian Cancer (Study 006)

PURPOSE

The adjunctive use of intraoperative molecular imaging (IMI) is gaining acceptance as a potential means to improve outcomes for surgical resection of targetable tumors. This confirmatory study examined the use of pafolacianine for real-time detection of folate receptor-positive ovarian cancer.

METHODS

This phase III, open-label, 11-center study included subjects with known or suspected ovarian cancer, scheduled to undergo cytoreductive surgery. The objectives were to confirm safety and efficacy of pafolacianine (0.025 mg/kg IV), given ≥ 1 hour before intraoperative near-infrared imaging to detect macroscopic lesions not detected by palpation and normal white light.

RESULTS

From March 2018 through April 2020, 150 patients received a single infusion of pafolacianine (safety analysis set); 109 patients with folate receptor-positive ovarian cancer comprised the full analysis set for efficacy. In 33.0% of patients (95% CI, 24.3 to 42.7; P < .001), pafolacianine with near-infrared imaging identified additional cancer on tissue not planned for resection and not detected by white light assessment and palpation, exceeding the prespecified threshold of 10%. Among patients who underwent interval debulking surgery, the rate was 39.7% (95% CI, 27.0 to 53.4; P < .001). The sensitivity to detect ovarian cancer was 83%, and the patient false-positive rate was 24.8%. Investigators reported achieving complete R0 resection in 62.4% (68 of 109) of patients. Drug-related adverse events were reported by 30% of patients (45 of 150) and most commonly included nausea, vomiting, and abdominal pain. No drug-related serious adverse events or deaths were reported.

CONCLUSION

This phase III study of pafolacianine met its primary efficacy end point, identifying additional cancers not otherwise identified or planned for resection. Pafolacianine may offer an important real-time adjunct to current surgical approaches for ovarian cancer.

Future in precise surgery: Fluorescence-guided surgery using EVs derived fluorescence contrast agent

Surgery is the only cure for many solid tumors, but positive resection margins, damage to vital nerves, vessels and organs during surgery, and the range and extent of lymph node dissection are significant concerns which hinder the development of surgery. The emergence of fluorescence-guided surgery (FGS) means a farewell to the era when surgeons relied only on visual and tactile feedback, and it gives surgeons another eye to distinguish tumors from normal tissues for precise resection and helps to find a balance between complete tumor lesions removal and maximal organ function conservation. However, the existing synthetic fluorescence contrast agent has flaws in safety, specificity and biocompatibility to various extents. Extracellular vesicles (EVs) are a group of heterogeneous types of cell-derived membranous structures present in all biological fluids. EVs, especially engineered targeting EVs, play an increasingly important role in drug delivery because of their good biocompatibility, validated safety and targeting ability. Nevertheless, few studies have employed EVs loaded with fluorophores to construct fluorescence contrast agents and used them in FGS. Here, we systematically reviewed the current state of knowledge regarding FGS, fundamental characteristics of EVs, and the development of engineered targeting EVs, and put forward a novel strategy and procedures to produce EVs-based fluorescence contrast agent used in fluorescence-guided surgery.

Unraveling the Chemistry of meso-Cl Tricarbocyanine Dyes in Conjugation Reactions for the Creation of Peptide Bonds

Tricarbocyanine dyes have become popular tools in life sciences and medicine. Their near-infrared (NIR) fluorescence makes them ideal agents for imaging of thick specimens or in vivo imaging, e.g., in fluorescence-guided surgery. Among other types of cyanine dyes, meso-Cl tricarbocyanine dyes have received a surge of interest, as it emerged that their high reactivity makes them inherently tumor-targeting. As such, significant research efforts have focused on conjugating these to functional moieties. However, the syntheses generally suffer from low yields. Hereby, we report on the reaction of meso-Cl dyes with a small selection of coupling reagents to give the corresponding keto-polymethines, potentially explaining low yields and the prevalence of monofunctionalized cyanine conjugates in the current state of the art of functional near-infrared dyes. We present the synthesis and isolation of the first keto-polymethine-based conjugate and present preliminary investigation in the prostate cancer cell lines PC3 and DU145 by confocal microscopy and discuss changes to optical properties in biological media.

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.

Updates on fluorescent probes and open-field imaging methods for fluorescence-guided cytoreductive surgery for epithelial ovarian cancer: A review

Fluorescence-guided surgery has emerged as a promising imaging technique for real-time intraoperative tumour delineation and visualisation of submillimetre tumour masses in cytoreductive surgery for epithelial ovarian cancer (EOC). Researchers have developed several EOC-targeted fluorescent probes, most of which are currently in the preclinical stage. Interestingly, imaging devices designed for open surgery are proof of concept. This review summarises the recent advances in EOC-targeted fluorescent probes and open-field fluorescence imaging strategies and discusses the challenges and potential solutions for clinical translation.

Intraoperative Tumor Detection Using Pafolacianine

Cancer is a leading cause of death worldwide, with increasing numbers of new cases each year. For the vast majority of cancer patients, surgery is the most effective procedure for the complete removal of the malignant tissue. However, relapse due to the incomplete resection of the tumor occurs very often, as the surgeon must rely primarily on visual and tactile feedback. Intraoperative near-infrared imaging with pafolacianine is a newly developed technology designed for cancer detection during surgery, which has been proven to show excellent results in terms of safety and efficacy. Therefore, pafolacianine was approved by the U.S. Food and Drug Administration (FDA) on 29 November 2021, as an additional approach that can be used to identify malignant lesions and to ensure the total resection of the tumors in ovarian cancer patients. Currently, various studies have demonstrated the positive effects of pafolacianine’s use in a wide variety of other malignancies, with promising results expected in further research. This review focuses on the applications of the FDA-approved pafolacianine for the accurate intraoperative detection of malignant tissues. The cancer-targeting fluorescent ligands can shift the paradigm of surgical oncology by enabling the visualization of cancer lesions that are difficult to detect by inspection or palpation. The enhanced detection and removal of hard-to-detect cancer tissues during surgery will lead to remarkable outcomes for cancer patients and society, specifically by decreasing the cancer relapse rate, increasing the life expectancy and quality of life, and decreasing future rates of hospitalization, interventions, and costs.

An Acid Response IR780-Based Targeted Nanoparticle for Intraoperative Near-Infrared Fluorescence Imaging of Ovarian Cancer

INTRODUCTION

Complete resection of all visible disease (R0 resection) is critical for the treatment of ovarian cancer patients, and accurate real-time guidance provided by intraoperative near-infrared (NIR) fluorescence images is beneficial for achieving complete resection of all visible disease.

METHODS

Based on the optical properties of IR780 and the characteristics of the acidic tumor microenvironment, we develop a new smart nanoparticle (eg, FA-IR780&PFOB-SNPs) by using the pH response nano framework (FA-PEG-PLGA-PEOz) and adjusting the amount of IR780. The FA-IR780&PFOB-SNPs was characterized for morphology, microstructure, particle size, pH-response, drug-loading efficiency and biological safety. The ultraclear fluorescence Navigation Endoscopy System was applied to evaluate the tumor recognition of FA-IR780&PFOB-SNPs in vivo.

RESULTS

The structure of FA-IR780&PFOB-SNPs was stable in a neutral environment, and the near-infrared (NIR) fluorescence was turned off, while the structure of FA-IR780&PFOB-SNPs was degraded in the acidic tumour microenvironment, and the NIR fluorescence was turned on. Through the ovarian subcutaneous xenograft tumour and ovarian intraperitoneal xenograft tumour models, it was confirmed that FA-IR780&PFOB-SNPs could clearly display the boundaries of abdominal micron-sized tumours through near-infrared fluorescence imaging, with a TBR greater than 5.

CONCLUSION

The FA-IR780&PFOB-SNPs have the potential to provide to ovarian cancer intraoperative near infrared fluorescence navigation during precision tumour resection to achieve R0 and improve the prognosis of ovarian cancer patients.

In vivo fluorescence imaging: success in preclinical imaging paves the way for clinical applications

Advances in diagnostic imaging have provided unprecedented opportunities to detect diseases at early stages and with high reliability. Diagnostic imaging is also crucial to monitoring the progress or remission of disease and thus is often the central basis of therapeutic decision-making. Currently, several diagnostic imaging modalities (computed tomography, magnetic resonance imaging, and positron emission tomography, among others) are routinely used in clinics and present their own advantages and limitations. In vivo near-infrared (NIR) fluorescence imaging has recently emerged as an attractive imaging modality combining low cost, high sensitivity, and relative safety. As a preclinical tool, it can be used to investigate disease mechanisms and for testing novel diagnostics and therapeutics prior to their clinical use. However, the limited depth of tissue penetration is a major challenge to efficient clinical use. Therefore, the current clinical use of fluorescence imaging is limited to a few applications such as image-guided surgery on tumors and retinal angiography, using FDA-approved dyes. Progress in fluorophore development and NIR imaging technologies holds promise to extend their clinical application to oncology, cardiovascular diseases, plastic surgery, and brain imaging, among others. Nanotechnology is expected to revolutionize diagnostic in vivo fluorescence imaging through targeted delivery of NIR fluorescent probes using antibody conjugation. In this review, we discuss the latest advances in in vivo fluorescence imaging technologies, NIR fluorescent probes, and current and future clinical applications.

DNA Framework-Programmed Ligand Positioning to Modulate the Targeting Performance

Effective targeting of nanomedicine is still an intricacy since unsatisfactory clinical trial feedback demonstrated their inadequate concentration at the desired area. However, the regulatory effect of ligand-modification patterns on the targeting effect has not been surveyed yet. Based on the superior spatial addressability of DNA frame structures, herein DNA tetrahedrons were used as templates for site-specific modification of targeting ligands. In this work, nanovectors with homogeneous ligand-modification patterns, including various valence of ligands and the precisely controlled distance between ligands at the nanoscale, were established for the first time. In vitro and in vivo targeting performance studies found that merely relying on the augment of the ligand quantity exhibited a confined promotion effect on the targeting efficiency. Notably, the space distance between ligands displayed a more important role in reforming the targeting effect, and the largest ligand distance (approximately 156.55 Å) pattern exhibited an optimal targeting effect and prominently cytostatic activity toward tumor cells. Generally, the survey of ligand-modification patterns on nanovectors provided a valid guidance to direct the optimization of nanomedicine.

PET/NIR-II fluorescence imaging and image-guided surgery of glioblastoma using a folate receptor α-targeted dual-modal nanoprobe

PURPOSE

The surgery of glioblastoma (GBM) requires a maximal resection of the tumor when it is safe and feasible. The infiltrating growth property of the GBM makes it a challenge for neurosurgeons to identify the tumor tissue even with the assistance of the surgical microscope. This highlights the urgent requirement for imaging techniques that can differentiate tumor tissues during surgery in real time. Fluorescence image-guided surgery of GBM has been investigated using several non-specific fluorescent probes that emit light in the visible and the first near-infrared window (NIR-I, 700-900 nm), which limit the detection accuracy because of the non-specific targeting mechanism and spectral characteristics. Targeted NIR-II (1000-1700 nm) fluorescent probes for GBM are thus highly desired. The folate receptor (FR) has been reported to be upregulated in GBM, which renders it to be a promising target for specific tumor imaging.

METHODS

In this study, the folic acid (FA) that can target the FR was conjugated with the clinically approved indocyanine green (ICG) dye and DOTA chelator for radiolabeling with ⁶⁴Cu to achieve targeted positron emission tomography (PET) and fluorescence imaging of GBM.

RESULTS

Surprisingly it was found that the resulted bioconjugate, DOTA-FA-ICG and non-radioactive ^natCu-DOTA-FA-ICG, were both self-assembled into nanoparticles with NIR-II emission signal. The radiolabeled DOTA-FA-ICG, ⁶⁴Cu-DOTA-FA-ICG, was found to specifically accumulate in the orthotopic GBM models using in vivo PET, NIR-II, and NIR-I fluorescence imaging. The best time window of fluorescence imaging was demonstrated to be 24 h after DOTA-FA-ICG injection. NIR-II fluorescence image-guided surgery was successfully conducted in the orthotopic GBM models using DOTA-FA-ICG. All the fluorescent tissue was removed and proved to be GBM by the H&E examination.

CONCLUSION

Overall, our study demonstrates that the probes, ⁶⁴Cu-DOTA-FA-ICG and DOTA-FA-ICG, hold promise for preoperative PET examination and intraoperative NIR-II fluorescence image-guided surgery of GBM, respectively.

EGFR-targeted fluorescent imaging using the da Vinci® Firefly™ camera for gallbladder cancer

Background

Fluorescent imaging may aid with the precise diagnosis and treatment of patients with gallbladder cancer. In this study, we sought to demonstrate whether the da Vinci® surgical system and Firefly™ camera could detect EGFR-targeted fluorescent images in orthotopic mouse models of gallbladder cancer.

Methods

An orthotopic mouse model of gallbladder cancer was created by injecting NOZ gallbladder cancer cells mixed with Matrigel into the gallbladder. In vivo imaging of subcutaneous and orthotopic gallbladder tumors was performed after the injection of DyLight 650- or 800-conjugated EGFR antibody.

Results

Western blotting, flow cytometry, and confocal microscopy showed the presence of EGFR in NOZ cells, but not in HEK293 cells. Subcutaneous NOZ cell tumors fluoresced after injection with fluorescent EGFR antibody, but subcutaneous HEK293 tumors did not. Fluorescent EGFR antibody made orthotopic NOZ tumors fluoresce, with an intensity stronger than that in the surrounding normal tissues. Histochemical examination confirmed the location of the tumors inside the gallbladder and adjacent liver parenchyma. Fluorescent signal was also detected in orthotopic gallbladder tumors with Firefly™ camera.

Conclusion

Our study showed that fluorescent EGFR antibodies and the Firefly camera in the da Vinci system can detect fluorescing gallbladder tumors, which demonstrates their potential use for molecular imaging-based prevision surgery in the near future.

First Clinical Results of Fluorescence Lifetime-enhanced Tumor Imaging Using Receptor-targeted Fluorescent Probes

PURPOSE

Fluorescence molecular imaging, using cancer-targeted near infrared (NIR) fluorescent probes, offers the promise of accurate tumor delineation during surgeries and the detection of cancer specific molecular expression in vivo. However, nonspecific probe accumulation in normal tissue results in poor tumor fluorescence contrast, precluding widespread clinical adoption of novel imaging agents. Here we present the first clinical evidence that fluorescence lifetime (FLT) imaging can provide tumor specificity at the cellular level in patients systemically injected with panitumumab-IRDye800CW, an EGFR-targeted NIR fluorescent probe.

EXPERIMENTAL DESIGN

We performed wide-field and microscopic FLT imaging of resection specimens from patients injected with panitumumab-IRDye800CW under an FDA directed clinical trial.

RESULTS

We show that the FLT within EGFR-overexpressing cancer cells is significantly longer than the FLT of normal tissue, providing high sensitivity (>98%) and specificity (>98%) for tumor versus normal tissue classification, despite the presence of significant nonspecific probe accumulation. We further show microscopic evidence that the mean tissue FLT is spatially correlated (r > 0.85) with tumor-specific EGFR expression in tissue and is consistent across multiple patients. These tumor cell-specific FLT changes can be detected through thick biological tissue, allowing highly specific tumor detection and noninvasive monitoring of tumor EFGR expression in vivo.

CONCLUSIONS

Our data indicate that FLT imaging is a promising approach for enhancing tumor contrast using an antibody-targeted NIR probe with a proven safety profile in humans, suggesting a strong potential for clinical applications in image guided surgery, cancer diagnostics, and staging.

Fluorescence guided surgery to improve peritoneal cytoreduction in epithelial ovarian cancer: A systematic review of available data

During surgery for advanced epithelial ovarian cancer (EOC), the most important prognostic factor is the absence of residual tumor. Invisible microscopic peritoneal metastasis (mPM) are not removed during surgery and can be responsible of peritoneal recurrences. The aim of this current systematic review is to assess the role of fluorescence in evaluating mPM in EOC. We performed a systematic review using bibliographic citations from PubMed, Clinical Trials.gov, Embase, Cochrane Library, and Web of Science databases. MeSH terms for fluorescence, EOC and peritoneal carcinomatosis were combined and not restricted to the English language. The final search was performed on September 1rst, 2021. The primary outcome was to determine the diagnostic accuracy of fluorescence. We also reviewed the different techniques used. Eighty-seven studies were identified. Of these, 10 were included for analysis. The sensitivity and specificity of fluorescence ranged between 66.7-100% and 54.2-100%, respectively. Most importantly, the negative predictive value (NPV) ranged from 90 to 100% Due to the heterogeneity of the studies, no consensus was reached concerning the optimal use of fluorescence in terms of type of dye, type and timing of injection and imager to use. No adverse event was reported. Fluorescence can safely be used in EOC to evaluate mPM with a high NPV. However, a randomized controlled trial is needed to homogenize current practice.

Peptide-decorated nanocarriers penetrating the blood-brain barrier for imaging and therapy of brain diseases

Blood-Brain Barrier (BBB) is one of the most important physiological barriers strictly restricting the substance exchange between blood and brain tissues. While the BBB protects the brain from infections and toxins and maintains brain homeostasis, it is also recognized as the main obstacle to the penetration of therapeutics and imaging agents into the brain. Due to high specificity and affinity, peptides are frequently exploited to decorate nanocarriers across the BBB for diagnosis and/or therapy purposes. However, there are still some challenges that restrict their clinical application, such as stability, safety and immunocompatibility. In this review, we summarize the biological and pathophysiological characteristics of the BBB, strategies across the BBB, and recent progress on peptide decorated nanocarriers for brain diseases diagnosis and therapy. The challenges and opportunities for their translation are also discussed.

Design, Synthesis and In Vivo Fluorescence Imaging Study of a Cytochrome P450 1B1 Targeted NIR Probe Containing a Chelator Moiety

Cytochrome P450 (CYP) 1B1 has been found to be overexpressed specifically in tumor tissues at early stage, which makes it a potential cancer biomarker for molecular imaging of cancer. Multimodal imaging combines different imaging modalities and offers more comprehensive information. Thus, imaging probes bearing more than one kind of signal fragment have been extensively explored and displayed great promise. Herein, we developed a near infrared (NIR) probe with a chelator moiety targeting CYP1B1 by conjugating α-naphthoflavone (ANF) derivatives with both a NIR dye and a chelator for potential application in bimodal imaging. Enzymatic inhibitory studies demonstrated inhibitory activity against CYP1B1 and selectivity among CYP1 were successfully retained after chemical modification. Cell-based saturation study indicated nanomolar range binding affinity between the probe and CYP1B1 overexpressed cancer cells. In vitro competitive binding assay monitored by confocal microscopy revealed that the probe could specifically accumulate in tumor cells. In vivo and ex vivo imaging studies demonstrated the probe could effectively lighten up the tumor tissues as early as 2 hours post injection. Besides, the fluorescence was significantly blocked by co-injection of CYP1B1 inhibitor, which indicated the probe accumulation in tumor sites was due to specific binding towards CYP1B1.

Fast and Durable Intraoperative Near-infrared Imaging of Ovarian Cancer Using Ultrabright Squaraine Fluorophores

The residual tumor after surgery is the most significant prognostic factor of patients with epithelial ovarian cancer. Near-infrared (NIR) fluorescence-guided surgery is actively utilized for tumor localization and complete resection during surgery. However, currently available contrast-enhancing agents display low on-target binding, unfavorable pharmacokinetics, and toxicity, thus not ideal for clinical use. Here we report ultrabright and stable squaraine fluorophores with optimal pharmacokinetics by introducing an asymmetric molecular conformation and surface charges for rapid transporter-mediated cellular uptake. Among the tested, OCTL14 shows low serum binding and rapid distribution into cancer tissue via organic cation transporters (OCTs). Additionally, the charged squaraine fluorophores are retained in lysosomes, providing durable intraoperative imaging in a preclinical murine model of ovarian cancer up to 24 h post-injection. OCTL14 represents a significant departure from the current bioconjugation approach of using a non-targeted fluorophore and would provide surgeons with an indispensable tool to achieve optimal resection.

The use of biomarkers to stratify surgical care in women with ovarian cancer: Scientific Impact Paper No. 69 March 2022: Scientific Impact Paper No. 69 May 2022

Biomarkers may offer unforeseen insights into clinical diagnosis, as well as the likely course and outcome of a condition. In this paper, the focus is on the use of biological molecules found in body fluids or tissues for diagnosis and prediction of outcome in ovarian cancer patients. In cancer care, biomarkers are being used to develop personalised treatment plans for patients based on the unique characteristics of their tumour. This tailoring of care can be used to pursue specific targets identified by biomarkers, or treat the patient according to specific tumour characteristics. Surgery is one of the core treatments for ovarian cancer, whether it is offered in primary surgery or following chemotherapy in delayed surgery. Biomarkers already exist to guide the treatment of tumours with chemotherapy, but very little research has determined the value of biomarkers in tailoring surgical care for ovarian cancer. Such research is required to identify new biomarkers and assess their effectiveness in a clinical setting as well as to help identify specific tumour types to guide surgery. Biomarkers could help to determine the success of removing the disease surgically, or help to identify tumour deposits that persist after chemotherapy. All of these aspects would improve current practice. This Scientific Impact Paper highlights research that may pave the way towards bespoke surgery according to the biological characteristics of a tumour and aid gynaecological oncologists to provide surgical treatment according to individual need, rather than a blanket approach for all.

Near-Infrared Fluorescence Imaging of EGFR-Overexpressing Tumors in the Mouse Xenograft Model Using scFv-IRDye800CW and Cetuximab-IRDye800CW

EGFR (epidermal growth factor receptor) is overexpressed in a variety of human cancers (including squamous cell carcinoma of head and neck, colon cancer, and some breast cancers) and therefore is regarded as an ideal target for cancer therapy or imaging purposes. In the current study, we produced a scFv-based near-infrared probe (called cet.Hum.scFv-IRDye-800CW) and evaluated its ability in recognizing and imaging of EGFR-overexpressing tumors in a mouse model. Like the molecular probe consisting of its parental antibody (cetuximab, an FDA-approved monoclonal antibody) and IRD800CW, cet.Hum.scFv-IRDye-800CW was able to recognize EGFR-overexpressing tumors in mice. cet.Hum.scFv-IRDye-800CW was found to be superior to the cetuximab-based probe in imaging of mouse tumors. The tumor-to-background ratio and blood clearance rate were higher when cet.Hum.scFv-IRDye-800CW was used as an imaging probe.

Optical Imaging of Epigenetic Modifications in Cancer: A Systematic Review

Increasing evidence has demonstrated that abnormal epigenetic modifications are strongly related to cancer initiation. Thus, sensitive and specific detection of epigenetic modifications could markedly improve biological investigations and cancer precision medicine. A rapid development of molecular imaging approaches for the diagnosis and prognosis of cancer has been observed during the past few years. Various biomarkers unique to epigenetic modifications and targeted imaging probes have been characterized and used to discriminate cancer from healthy tissues, as well as evaluate therapeutic responses. In this study, we summarize the latest studies associated with optical molecular imaging of epigenetic modification targets, such as those involving DNA methylation, histone modification, noncoding RNA regulation, and chromosome remodeling, and further review their clinical application on cancer diagnosis and treatment. Lastly, we further propose the future directions for precision imaging of epigenetic modification in cancer. Supported by promising clinical and preclinical studies associated with optical molecular imaging technology and epigenetic drugs, the central role of epigenetics in cancer should be increasingly recognized and accepted.

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.