Imaging of intraperitoneal tumors with technetium-99m GSA

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.

Artificial Glycoproteins as a Scaffold for Targeted Drug Therapy

Akin to a cellular "fingerprint," the glycocalyx is a glycan-enriched cellular coating that plays a crucial role in mediating cell-to-cell interactions. To gain a better understanding of the factors that govern in vivo recognition, artificial glycoproteins were initially created to probe changes made to the accumulation and biodistribution of specific glycan assemblies through biomimicry. As a result, the organ-specific accumulation for a variety of glycoproteins decorated with simple and/or complex glycans was identified. Additionally, binding trends with regard to cancer cell selectivity were also investigated. To exploit the knowledge gained from these studies, numerous groups thus became engaged in developing targeted drug methodologies based on the use of artificial glycoproteins. This has either been done through adopting the glycoprotein scaffold as a drug carrier, or to directly glycosylate therapeutic proteins/enzymes to localize their biological activity. The principle aim of this Review is to present the foundational research that has driven artificial glycoprotein-based targeting and subsequent adaptations with potential therapeutic applications.

Coil-like Enzymatic Biohybrid Structures Fabricated by Rational Design: Controlling Size and Enzyme Activity over Sequential Nanoparticle Bioconjugation and Filtration Steps

Well-defined enzymatic biohybrid structures (BHS) composed of avidin, biotinylated poly(propyleneimine) glycodendrimers, and biotinylated horseradish peroxidase were fabricated by a sequential polyassociation reaction to adopt directed enzyme prodrug therapy to protein-glycopolymer BHS for potential biomedical applications. To tailor and gain fundamental insight into pivotal properties such as size and molar mass of these BHS, the dependence on the fabrication sequence was probed and thoroughly investigated by several complementary methods (e.g., UV/vis, DLS, cryoTEM, AF4-LS). Subsequent purification by hollow fiber filtration allowed us to obtain highly pure and well-defined BHS. Overall, by rational design and control of preparation parameters, e.g., fabrication sequence, ligand-receptor stoichiometry, and degree of biotinylation, well-defined BHS with stable and even strongly enhanced enzymatic activities can be achieved. Open coil-like structures of BHS with few branches are available by the sequential bioconjugation approach between synthetic and biological macromolecules possessing similar size dimensions.

Radiosynthesis, biodistribution and micro-SPECT imaging study of dendrimer-avidin conjugate

Partially acetylated generation five polyamidoamine (PAMAM) dendrimer (G5-Ac) was reacted with biotin and 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetria minepentaacetic acid (1B4M-DTPA), respectively to form the complex Bt-G5-Ac-1B4M which was further conjugated with avidin to give the conjugate Av-G5-Ac-1B4M. Then both of the conjugates were radiolabeled with technetium-99m ((99m)Tc), respectively. Their in vitro cellular uptake study shows that the conjugate of Av-G5-Ac-1B4M-(99m)Tc exhibits much higher cellular uptake in HeLa cells than that of Bt-G5-Ac-1B4M-(99m)Tc. Accordingly the following evaluation such as in vitro/in vivo stability, biodistribution and micro-SPECT imaging was observed only for the conjugate of Av-G5-Ac-1B4M-(99m)Tc.

Steroid-coupled liposomes for targeted delivery to tumor

The steroidal receptors play a key role in protein synthesis and maintain the homeostasis in normal and diseased state, including tumorigenesis at the target tissues when overactivated. Thus steroidal receptors may act as potential targets for selective delivery of different therapeutic agents as they are overexpressed by a number of endocrinal tumors. The selective delivery of these agents may be a better treatment strategy for endocrinal cancer as it may also result in cytosolic and nuclear delivery of cytotoxic agents. In this review, the targeting potential of steroidal receptors for the drug or bioactive(s) delivery is discussed. The ligands that have been proven to be effective for specific steroidal receptors can be used as vectors for carrying the drug or drug-delivery system to the desired site of drug action in an optimum concentration. This strategy will not only minimize the undesired side effects associated with nonspecific delivery of drug, but will also maximize the drug utilization. Ligand-conjugated liposomes as a carrier of bioactives prevent passive diffusion of the encapsulated drug to normal cells, increase the time of circulation and reduce the undesirable side effects of a drug.

Functional L-lysine dendritic macromolecules as liver-imaging probes

Liver-imaging probes are prepared through the conjugation of Gd chelates and galactosyl moieties to peptide dendrimers. The dendritic probes possessing highly controlled structures and a single molecular weight have a two-fold increase in T(1) relaxivity to 9.1 x 10(3) (Gd M)(-1) s(-1) compared to Gd-DTPA. No obvious cytotoxicity of this multifunctional dendritic agent is discovered in vitro. The dendrimer bearing galactosyl moieties leads to a much-higher hepatocyte-cell uptake in vitro and provides good signal-intensity enhancement (35%) of mouse liver in vivo especially at 60 min after intravenous injection. In comparison, non-targeting Gd dendrimers provide only an 11% enhancement of imaging contrast at the same time point. Overall, the dendrimers bearing galactosyl moieties may be used as liver-imaging probes.

Sensitive and selective tumor imaging with novel and highly activatable fluorescence probes

Selective and sensitive tumor imaging in vivo is one of the most requested methodologies in medical sciences. Although several imaging modalities have been developed including positron emission tomography (PET) and magnetic resonance (MR) imaging for the detection of tumors, none of these modalities can activate the signals upon being accumulated or uptaken to tumor sites. Among these modalities, only optical fluorescence imaging has a marked advantage, that is, their signals can be dramatically increased upon detecting some biological features. In this short review, I will introduce some recent strategies for activatable optical fluorescence imaging of tumors, and discuss their advantages over other modalities.

D-galactose receptor-targeted in vivo spectral fluorescence imaging of peritoneal metastasis using galactosamin-conjugated serum albumin-rhodamine green

The wavelength resolved spectral fluorescence imaging technique using a fluorescein-conjugated avidin has been reported to visualize submillimeter implants of ovarian cancer because of its highly targeted and quickly cleared pharmacokinetics. However, clinical application of avidin was hampered by its strong immunogenicity. As a clinically feasible alternative to avidin, which targets the same D-galactose receptor but is made from a nonimmunogenic source, with even better binding capability by multiplying binding sites but still maintaining a favorable characteristic of high isoelectric point, a serum albumin conjugated with 23 galactosamine and 2 rhodamine green molecules (GmSA-RhodG) was designed and synthesized. GmSA-RhodG showed more than 10-fold rapid and higher uptake by SHIN3 ovarian cancer cells than both avidin- and no galactosamine-conjugated albumin (bovine serum)-RhodG. Sensitivity and specificity of GmSA-RhodG to detect red fluorescence labeled peritoneal cancer foci in mouse cancer model were 100%/99% (n=566), respectively for approximately 1-mm lesions and even smaller lesions were detected in vivo. These results indicate that GmSA-RhodG is not only a clinically feasible alternative but more efficient targeting reagent for D-galactose receptors than avidin-RhodG.

In vivo spectral fluorescence imaging of submillimeter peritoneal cancer implants using a lectin-targeted optical agent

Intraperitoneal metastases commonly recur after surgery because small tumor foci escape detection within the complex anatomy of the peritoneal cavity and mesentery. Accurate localization of peritoneal implants during surgery could improve the resection of ovarian cancer and other malignancies, but few practical techniques to enhance detectability are currently available. Here, we describe a targeted molecular imaging method that employs fluorescently labeled avidin to detect submillimeter peritoneal implants of ovarian cancer in mice. After binding to surface lectins on the tumor, fluorescein-conjugated avidin enabled the spectral fluorescence imaging of disseminated peritoneal implants. High spatial resolution and high tumor-to-background ratio allowed the visualization of implants as small as 0.3 mm (with 100% sensitivity and specificity; n = 150) and the identification of even smaller lesions ex vivo. These results suggest that targeted molecular imaging with a fluorescence-labeled lectin-ligand system is a promising technique for the detection of disseminated submillimeter foci of cancer.

Targeted optical imaging of cancer cells using lectin-binding BODIPY conjugated avidin

Lectins (asialo-receptor family) are expressed on a number of tumors that develop peritoneal metastases. To demonstrate that fluorescence imaging based on lectin binding is applicable for a variety of tumors, we conjugated BODIPY to avidin (avidin-BODIPY), and studied the efficacy of tumor targeting in 9 cancer cell lines in vitro and an ovarian cancer cell line in vivo using a murine peritoneal cancer model. All 9 cell lines showed specific intracellular accumulation with avidin-BODIPY on fluorescence microscopy and flow cytometry. In vivo spectral molecular imaging clearly visualized the peritoneal tumor foci with avidin-BODIPY, whereas, deglycosylated avidin-BODIPY (neutravidin-BODIPY) showed only minimal fluorescence from the tumor foci and was accompanied by higher background signals. These results suggest the lectin-targeted molecular imaging technique using a targeted green fluorescence probe is potentially useful in a wide variety of cancers with a proclivity for dissemination in the peritoneal space.