Role of Albumin in Accumulation and Persistence of Tumor-Seeking Cyanine Dyes

A near-infrared superoxide generator based on a biocompatible indene-bearing heptamethine cyanine dye

One of the most significant limitations of photodynamic therapy is its reduced efficacy in hypoxic microenvironments, which are typical of the majority of tumors. This work demonstrates that indolenine heptamethine cyanines with different substituents in the polymethine chain and at the terminal heterocycles are effective superoxide generators that can be activated in the near-infrared range. The introduction of an indene moiety into the polymethine chain results in a significant enhancement in photostability compared to dyes with a cyclohexene moiety or an unsubstituted polymethine chain. A hydrophilic indene-bearing heptamethine cyanine dye is shown to be efficiently internalized by Vero E6 cells and to give bright intracellular fluorescence in the 700-850 nm range. Furthermore, the dye generates superoxide anion radicals and induces severe oxidative stress in cells upon activation in the near-infrared range (∼750 nm), ultimately resulting in cell death. The capacity of heptamethine cyanines to generate a superoxide anion radical may prove advantageous for enhancing the efficacy of photodynamic therapy under hypoxic conditions.

A pan-cancer dye for solid-tumour screening, resection and wound monitoring via short-wave and near-infrared fluorescence imaging

The efficacy of fluorescence-guided surgery in facilitating the real-time delineation of tumours depends on the optical contrast of tumour tissue over healthy tissue. Here we show that CJ215-a commercially available, renally cleared carbocyanine dye sensitive to apoptosis, and with an absorption and emission spectra suitable for near-infrared fluorescence imaging (wavelengths of 650-900 nm) and shortwave infrared (SWIR) fluorescence imaging (900-1,700 nm)-can facilitate fluorescence-guided tumour screening, tumour resection and the assessment of wound healing. In tumour models of either murine or human-derived breast, prostate and colon cancers and of fibrosarcoma, and in a model of intraperitoneal carcinomatosis, imaging of CJ215 with ambient light allowed for the delineation of nearly all tumours within 24 h after intravenous injection of the dye, which was minimally taken up by healthy organs. At later timepoints, CJ215 provided tumour-to-muscle contrast ratios up to 100 and tumour-to-liver contrast ratios up to 18. SWIR fluorescence imaging with the dye also allowed for quantifiable non-contact wound monitoring through commercial bandages. CJ215 may be compatible with existing and emerging clinical solutions.

Structure-Inherent Tumor-Targeted IR-783 for Near-Infrared Fluorescence-Guided Photothermal Therapy

IR-783, a commercially available near-infrared (NIR) heptamethine cyanine dye, has been used for selective tumor imaging in breast, prostate, cervical, and brain cancers in vitro and in vivo. Although the molecular mechanism behind the structure-inherent tumor targeting of IR-783 has not been well-demonstrated, IR-783 has unique properties such as a good water solubility and low cytotoxicity compared with other commercial heptamethine cyanine dyes. The goal of this study is to evaluate the phototherapeutic efficacy of IR-783 as a tumor-targeted photothermal agent in human colorectal cancer xenografts. The results demonstrate that IR-783 shows both the subcellular localization in HT-29 cancer cells and preferential accumulation in HT-29 xenografted tumors 24 h after its intravenous administration. Furthermore, the IR-783 dye reveals the superior capability to convert NIR light into heat energy under 808 nm NIR laser irradiation in vitro and in vivo, thereby inducing cancer cell death. Taken together, these findings suggest that water-soluble anionic IR-783 can be used as a bifunctional phototherapeutic agent for the targeted imaging and photothermal therapy (PTT) of colorectal cancer. Therefore, this work provides a simple and effective approach to develop biocompatible, hydrophilic, and tumor-targetable PTT agents for targeted cancer phototherapy.

Water-Soluble Small Organic Fluorophores for Oncological Theragnostic Applications: Progress and Development

Cancer is one of the major noncommunicable diseases, responsible for millions of deaths every year worldwide. Though various cancer detection and treatment modalities are available today, many deaths occur owing to its late-stage detection and metastatic nature. Noninvasive detection using luminescence-based imaging tools is considered one of the promising techniques owing to its low cost, high sensitivity, and brightness. Moreover, these tools are unique and valuable as they can detect even the slightest changes in the cellular microenvironment. To achieve this, a fluorescent probe with strong tumor uptake and high spatial and temporal resolution, especially with high water solubility, is highly demanded. Recently, several water-soluble molecules with emission windows in the visible (400-700 nm), first near-infrared (NIR-I, 700-1000 nm), and second near-infrared (NIR-II, 1000-1700 nm) windows have been reported in literature. This review highlights recently reported water-soluble small organic fluorophores/dyes with applications in cancer diagnosis and therapeutics. We systematically highlight and describe the key concepts, structural classes of fluorophores, strategies for imparting water solubility, and applications in cancer therapy and diagnosis, i.e., theragnostics. We discuss examples of water-soluble fluorescent probes based on coumarin, xanthene, boron-dipyrromethene (BODIPY), and cyanine cores. Some other emerging classes of dyes based on carbocyclic and heterocyclic cores are also discussed. Besides, emerging molecular engineering methods to obtain such fluorophores are discussed. Finally, the opportunities and challenges in this research area are also delineated.

Albumin-seeking dyes with adjustable assemblies in situ enable programmable imaging windows and targeting tumor imaging

Cyanine dyes are widely used organic probes for in vivo imaging due to their tunable fluorescence. They can form complexes with endogenous albumin, resulting in enhanced brightness and photostability. However, this binding is uncontrollable and irreversible, leading to considerable nonspecific background signals and unregulated circulation time. Methods: Here, we connect varying numbers of 4-(4-iodophenyl) butanoic acid (IP) as albumin-binding moieties (ABM) to the cyanine dye, enabling dynamic and controllable binding with albumin. Meanwhile, we provide a blocking method to completely release the dye from covalent capture with albumin, resulting in specific targeting fluorescence. Furthermore, we evaluate the pharmacokinetics and tumor targeting of the developed dyes. Results: The engineered dyes can dynamically and selectively bind with multiple albumins to change the in situ size of assemblies and circulation time, providing programmable regulation over the imaging time window. The nucleophilic substitution of meso-Cl with water-soluble amino acids or targeting peptides for IP-engineered dye further addresses the nonspecific signals caused by albumin, allowing for adjustable angiography time and efficient tumor targeting. Conclusion: This study rationalizes the binding modes of dyes and proteins, applicable to a wide range of near-infrared (NIR) dyes for improving their in vivo molecular imaging.

Site-specific albumin tagging with NIR-II fluorogenic dye for high-performance and super-stable bioimaging

Synthetic near-infrared-II (NIR-II) dyes are promising for deep tissue imaging, yet they are generally difficult to target a given biomolecule with high specificity. Furthermore, the interaction mechanism between albumin and cyanine molecules, which is usually regarded as uncertain "complexes" such as crosslinked nanoparticles, remains poorly understood. Methods: Here, we propose a new class of NIR-II fluorogenic dyes capable of site-specific albumin tagging for in situ albumin seeking/targeting or constructing high-performance cyanine@albumin probes. We further investigate the interaction mechanism between NIR-II fluorogenic dyes and albumin. Results: We identify CO-1080 as an optimal dye structure that produces a stable/bright NIR-II cyanine@albumin probe. CO-1080 exhibits maximum supramolecular binding affinity to albumin while catalyzing their covalent attachment. The probe shows exact binding sites located on Cys476 and Cys101, as identified by proteomic analysis and docking modeling. Conclusion: Our cyanine@albumin probe substantially improves the pharmacokinetics of its free dye counterpart, enabling high-performance NIR-II angiography and lymphography. Importantly, the site-specific labeling tags between NIR-II fluorogenic dyes and albumin occur under mild conditions, offering a specific and straightforward synthesis strategy for NIR-II fluorophores in the fields of targeting bioimaging and imaging-guided surgery.

A pan-cancer agent for screening, resection and wound monitoring via NIR and SWIR imaging

Fluorescence guided surgery (FGS) facilitates real time tumor delineation and is being rapidly established clinically. FGS efficacy is tied to the utilized dye and provided tumor contrast over healthy tissue. Apoptosis, a cancer hallmark, is a desirable target for tumor delineation. Here, we preclinically in vitro and in vivo, validate an apoptosis sensitive commercial carbocyanine dye (CJ215), with absorption and emission spectra suitable for near infrared (NIR, 650-900nm) and shortwave infrared (SWIR, 900-1700nm) fluorescence imaging (NIRFI, SWIRFI). High contrast SWIRFI for solid tumor delineation is demonstrated in multiple murine and human models including breast, prostate, colon, fibrosarcoma and intraperitoneal colorectal metastasis. Organ necropsy and imaging highlighted renal clearance of CJ215. SWIRFI and CJ215 delineated all tumors under ambient lighting with a tumor-to-muscle ratio up to 100 and tumor-to-liver ratio up to 18, from 24 to 168 h post intravenous injection with minimal uptake in healthy organs. Additionally, SWIRFI and CJ215 achieved non-contact quantifiable wound monitoring through commercial bandages. CJ215 provides tumor screening, guided resection, and wound healing assessment compatible with existing and emerging clinical solutions.

Applications of human and bovine serum albumins in biomedical engineering: A review

Serum albumin, commonly recognized as a predominant major plasma protein, is ubiquitously distributed among vertebrates, demonstrating versatility and widespread accessibility. Numerous studies have discussed the composition and attributes of human and bovine serum albumin; nonetheless, few systematic and comprehensive summaries on human and bovine serum albumin exist. This paper reviews the applications of human and bovine serum albumin in biomedical engineering. First, we introduce the differences in the structure of human and bovine serum albumin. Next, we describe the extraction methods for human and bovine serum albumin (fractionation process separation, magnetic adsorption, reverse micellar (RM) extraction, and genetic engineering) and the advantages and disadvantages of recently developed extraction methods. The characteristics of different processing forms of human and bovine serum albumin are also discussed, concomitantly elucidating their intrinsic properties, functions, and applications in biomedicine. Notably, their pivotal functions as carriers for drugs and tissue-engineered scaffolds, as well as their contributions to cell reproduction and bioimaging, are critically examined. Finally, to provide guidance for researchers in their future work, this review summarizes the current state of human and bovine serum albumin research and outlines potential future research topics.

HSA-ZW800-PEG for Enhanced Optophysical Stability and Tumor Targeting

Small molecule fluorophores often face challenges such as short blood half-life, limited physicochemical and optical stability, and poor pharmacokinetics. To overcome these limitations, we conjugated the zwitterionic near-infrared fluorophore ZW800-PEG to human serum albumin (HSA), creating HSA-ZW800-PEG. This conjugation notably improves chemical, physical, and optical stability under physiological conditions, addressing issues commonly encountered with small molecules in biological applications. Additionally, the high molecular weight and extinction coefficient of HSA-ZW800-PEG enhances biodistribution and tumor targeting through the enhanced permeability and retention effect. The unique distribution and elimination dynamics, along with the significantly extended blood half-life of HSA-ZW800-PEG, contribute to improved tumor targetability in both subcutaneous and orthotopic xenograft tumor-bearing animal models. This modification not only influences the pharmacokinetic profile, affecting retention time and clearance patterns, but also enhances bioavailability for targeting tissues. Our study guides further development and optimization of targeted imaging agents and drug-delivery systems.

PET/NIR Fluorescence Bimodal Imaging for Targeted Tumor Detection

Cancer is one of the greatest threats to human health due to late diagnosis and incomplete resection. The bimodal probe combines positron emission tomography (PET) imaging for noninvasive whole-body scanning with intraoperative near-infrared fluorescence (NIRF) surgical guidance for preoperative tumor detection, tumor resection during surgery, and postoperative monitoring. We developed a new PET/NIRF bimodal imaging agent, [68Ga]Ga-DOTA-NPC, covalently coupled to DCDSTCY and DOTA via ethylenediamine and radiolabeled with gallium-68, and investigated it in vitro and in vivo. The probe was found to be preferential for colon cancer cells due to the organic anion-transporting polypeptide1B3 (OATP1B3). PET/NIRF imaging allowed us to confirm [68Ga]Ga-DOTA-NPC as a promising probe for tumor detection, as it provides good biosafety and high-contrast tumor accumulation. Orthotopic and subcutaneous colon tumors were successfully resected under real-time NIRF guidance. [68Ga]Ga-DOTA-NPC provides highly sensitive and unlimited tissue-penetrating PET/NIRF imaging, helping to visualize and differentiate tumors from adjacent tissue.

Cyanine Dye Conjugation Enhances Crizotinib Localization to Intracranial Tumors, Attenuating NF-κB-Inducing Kinase Activity and Glioma Progression

Glioblastoma (GBM) is a highly aggressive form of brain cancer with a poor prognosis and limited treatment options. The ALK and c-MET inhibitor Crizotinib has demonstrated preclinical therapeutic potential for newly diagnosed GBM, although its efficacy is limited by poor penetration of the blood brain barrier. Here, we identify Crizotinib as a novel inhibitor of nuclear factor-κB (NF-κB)-inducing kinase, which is a key regulator of GBM growth and proliferation. We further show that the conjugation of Crizotinib to a heptamethine cyanine dye, or a near-infrared dye (IR-Crizotinib), attenuated glioma cell proliferation and survival in vitro to a greater extent than unconjugated Crizotinib. Moreover, we observed increased IR-Crizotinib localization to orthotopic mouse xenograft GBM tumors, which resulted in impaired tumor growth in vivo. Overall, IR-Crizotinib exhibited improved intracranial chemotherapeutic delivery and tumor localization with concurrent inhibition of NIK and noncanonical NF-κB signaling, thereby reducing glioma growth in vitro, as well as in vivo, and increasing survival in a preclinical rodent model.

Site-specific albumin tagging with chloride-containing near-infrared cyanine dyes: molecular engineering, mechanism, and imaging applications

Near-infrared dyes, particularly cyanine dyes, have shown great potential in biomedical imaging due to their deep tissue penetration, high resolution, and minimal tissue autofluorescence/scattering. These dyes can be adjusted in terms of absorption and emission wavelengths by modifying their chemical structures. The current issues with cyanine dyes include aggregation-induced quenching, poor photostability, and short in vivo circulation time. Encapsulating cyanine dyes with albumin, whether exogenous or endogenous, has been proven to be an effective strategy for improving their brightness and pharmacokinetics. In detail, the chloride-containing (Cl-containing) cyanine dyes have been found to selectively bind to albumin to achieve site-specific albumin tagging, resulting in enhanced optical properties and improved biosafety. This feature article provides an overview of the progress in the covalent binding of Cl-containing cyanine dyes with albumin, including molecular engineering methods, binding sites, and the selective binding mechanism. The improved optical properties of cyanine dyes and albumin complexes have led to cutting-edge applications in biological imaging, such as tumor imaging (diagnostics) and imaging-guided surgery.

Multifunctional Near-Infrared Dye IR-817 Encapsulated in Albumin Nanoparticles for Enhanced Imaging and Photothermal Therapy in Melanoma

Background

Near-infrared cyanine dyes have high sensitivity and spatial resolution imaging capabilities, but they also have unavoidable drawbacks such as photobleaching, low water solubility, fluorescence quenching, and toxic side effects. As an effective biologic drug carrier, albumin combines with cyanine dyes to form albumin@dye nanoparticles. These nanoparticles can alleviate the aforementioned issues and are widely used in tumor imaging and photothermal therapy.

Methods

Herein, a newly synthesized near-infrared dye IR-817 was combined with bovine serum albumin (BSA) to create BSA@IR-817 nanoparticles. Through the detection of fluorescence emission and absorption, the optimal concentration and ratio of BSA and IR-817 were determined. Subsequently, dynamic light scattering (DLS) measurements and scanning electron microscopy (SEM) were used for the physical characterization of the BSA@IR-817 nanoparticles. Finally, in vitro and in vivo experiments were conducted to assess the fluorescence imaging and photothermal therapeutic potential of BSA@IR-817 nanoparticles.

Results

IR-817 was adsorbed onto the BSA carrier by covalent conjugation and supramolecular encapsulation, resulting in the formation of dispersed, homogeneous, and stable nanoparticles with a particle size range of 120-220 nm. BSA@IR-817 not only improved the poor water solubility, fluorescence quenching, and toxic side effects of IR-817 but also enhanced the absorption and fluorescence emission peaks in the near-infrared region, as well as the fluorescence in the visible spectrum. In addition, BSA@IR-817 combined with laser 808 irradiation was able to convert light energy into heat energy with temperatures exceeding 50 °C. By creating a mouse model of subcutaneous melanoma, it was discovered that the tumor inhibition rate of BSA@IR-817 was greater than 99% after laser irradiation and that it achieved nearly complete tumor ablation without causing significant toxicity.

Conclusion

Our research, therefore, proposes the use of safe and effective photothermal nanoparticles for the imaging, diagnosis, and treatment of melanoma, and offers a promising strategy for future biomedical applications.

Three-Dimensional Histological Electrophoresis for High-Throughput Cancer Margin Detection in Multiple Types of Tumor Specimens

Accurate identification of tumor margins during cancer surgeries relies on a rapid detection technique that can perform high-throughput detection of multiple suspected tumor lesions at the same time. Unfortunately, the conventional histopathological analysis of frozen tissue sections, which is considered the gold standard, often demonstrates considerable variability, especially in many regions without adequate access to trained pathologists. Therefore, there is a clinical need for a multitumor-suitable complementary tool that can accurately and high-throughput assess tumor margins in every direction within the surgically resected tissue. We herein describe a high-throughput three-dimensional (3D) histological electrophoresis device that uses tumor-specific proteins to identify and contour tumor margins intraoperatively. Testing on seven cell-line xenograft models and human cervical cancer models (representing five types of tissues) demonstrated the high-throughput detection utility of this approach. We anticipate that the 3D histological electrophoresis device will improve the accuracy and efficiency of diagnosing a wide range of cancers.

Three-dimensional histological electrophoresis enables fast automatic distinguishment of cancer margins and lymph node metastases

Tissue diagnosis is important during surgical excision of solid tumors for margin evaluation. Conventional histopathologic methods rely heavily on image-based visual diagnosis by specialized pathologists, which can be time-consuming and subjective. We report a three-dimensional (3D) histological electrophoresis system for rapid labeling and separation of the proteins within tissue sections, providing a more precise assessment of tumor-positive margin in surgically resected tissues. The 3D histological electrophoresis system uses a tumor-seeking dye labeling strategy to visualize the distribution of tumor-specific proteins within sections and a tumor finder that automatically predicts the tumor contour. We successfully demonstrated the system's capability to predict the tumor contours from five murine xenograft models and distinguish the tumor-invaded region of sentinel lymph nodes. Specifically, we used the system to accurately assess tumor-positive margins from 14 patients with cancer. Our 3D histological electrophoresis system serves as an intraoperative tissue assessment technology for more accurate and automatic pathologic diagnosis.

Ready vascular permeability of a near-infrared fluorescent agent ASP5354 for intraoperative ureteral identification enables imaging of carcinoma tissues

This study investigates the ability of a near-infrared fluorescence (NIRF) imaging agent, ASP5354, for in vivo fluorescence imaging of esophageal squamous cell carcinoma (ESCC) tissues. The ability of ASP5354 was evaluated using a single dose of ASP5354 or indocyanine green (ICG), which was intravenously administered to a KYSE850 human ESCC xenograft mouse model. Subsequently, in vivo NIRF images of the mouse were obtained using a clinically available camera system. ASP5354-specific NIRF signals were strongly detectable in KYSE850 carcinoma tissues immediately (30 s) following ASP5354 administration compared with normal tissues. Meanwhile, ICG could not distinguish between normal and carcinomatous tissues. To elucidate the associated imaging mechanisms, the vascular permeability of ASP5354 and ICG was investigated in rat back dermis treated with saline or histamine, which enhances vascular permeability, using in vivo NIRF imaging. ASP5354 exhibited higher vascular permeability in histamine-treated skin than in normal skin. KYSE850 carcinoma tissues can be distinguished from normal tissues based on the measurement of ASP5354-specific NIRF signals, and the mechanism that enables imaging relies on the specific and rapid leakage of ASP5354 from the capillaries into the stroma of carcinoma tissues.

Tetrazine-Derived Near-Infrared Dye for Targeted Photoacoustic Imaging of Bone

A near-infrared photoacoustic probe was used to image bone in vivo through active and bioorthogonal pretargeting strategies that utilized coupling between a tetrazine-derived cyanine dye and a trans-cyclooctene-modified bisphosphonate. In vitro hydroxyapatite binding of the probe via active and pretargeting strategies showed comparable increases in percent binding vs a nontargeted control. Intrafemoral injection of the bisphosphonate-dye conjugate showed retention out to 24 h post-injection, with a 14-fold increase in signal over background, while the nontargeted dye exhibited negligible binding to bone and signal washout by 4 h post-injection. Intravenous injection, using both active and pretargeting strategies, demonstrated bone accumulation as earlier as 4 h post-injection, where the signal was found to be 3.6- and 1.5-fold higher, respectively, than the signal from the nontargeted dye. The described bone-targeted dye enabled in vivo photoacoustic imaging, while the synthetic strategy provides a convenient building block for developing new targeted photoacoustic probes.

In vivo near-infrared fluorescence imaging of gastric cancer in an MKN-45 gastric cancer xenograft mouse model using intraoperative ureteral identification agent ASP5354

Accurate intraoperative identification of gastric cancer lesions and determination of the extent of resection are important for curability and function preservation. This study aimed to investigate the potential of the near-infrared fluorescence (NIRF) imaging agent ASP5354 for in vivo fluorescence imaging of gastric cancer. The capability of ASP5354 was evaluated using an MKN-45 human gastric cancer xenograft mouse model. A single dose of ASP5354 was intravenously administered to the mice at a concentration of 120 nmol (0.37 mg)/kg body weight. In vivo NIRF images of the mouse backs were obtained using an NIRF camera system. Moreover, the cancer tissues were dissected, and the NIRF intensity in the tissue sections was measured using the NIRF camera system. ASP5354 uptake in MKN-45 cells was assessed in vitro using the NIRF microscope. The NIRF signal of ASP5354 was selectively detected in gastric cancer tissues immediately after the intravenous administration of ASP5354. The cancer tissues emitted stronger NIRF signals than adjacent normal tissues. The difference in the NIRF intensity between the normal and cancer tissues was clearly observed at the boundary between them in the macrolevel NIRF images. Cancer tissues can be distinguished from normal tissues based on the measurement of the NIRF of ASP5354, using an NIRF camera system. ASP5354 is a promising agent for NIRF imaging of gastric cancer tissues.

Cytotoxicities of Tumor-Seeking Dyes: Impact on Future Clinical Trials

Heptamethine (Cy7) dyes with meso-Cl substituents injected intravenously (iv) into mice accumulate in tumors and persist there over several days. We believe this occurs via meso-Cl displacement by the only free cysteine residues of albumin; therefore, conjugating tumor-seeking dyes with fragments can increase selective therapeutic delivery to tumors and drug residence. This strategy has elevated significance recently because the first tumor-seeking dye-drug conjugate has moved into clinical trials. Options for further clinical research include modifying the dye, and use of preformed albumin adducts instead of dyes alone. Herein we show correlations of cytotoxicities, lipophilicities, organelle localization, apoptosis, cell-cycle arrest, wound healing/migration assays, and reactivities/affinities with human serum albumin are difficult to observe. However, our studies arrived at an important conclusion: preformed dye-drug-HSA adducts are less cytotoxic, and therefore preferable for subsequent clinical work, relative to direct injection of meso-Cl-containing forms.

Elucidating the cellular uptake mechanisms of heptamethine cyanine dye analogues for their use as an anticancer drug-carrier molecule for the treatment of glioblastoma

The development of chemotherapies for glioblastoma is hindered by their limited bioavailability and toxicity on normal brain function. To overcome these limitations, we investigated the structure-dependent activity of heptamethine cyanine dyes (HMCD), a group of tumour-specific and BBB permeable near-infrared fluorescent dyes, in both commercial (U87MG) and patient-derived GBM cell lines. HMCD analogues with strongly ionisable sulphonic acid groups were not taken up by patient-derived GBM cells, but were taken up by the U87MG cell line. HMCD uptake relies on a combination of transporter uptake through organic anion-transporting polypeptides (OATPs) and endocytosis into GBM cells. The uptake of HMCDs was not affected by p-glycoprotein efflux in GBM cells. Finally, we demonstrate structure-dependent cytotoxic activity at high concentrations (EC₅₀ : 1-100 μM), likely due to mitochondrial damage-induced apoptosis. An in vivo orthotopic glioblastoma model highlights tumour-specific accumulation of our lead HMCD, MHI-148, for up to 7 days following a single intraperitoneal injection. These studies suggest that strongly ionisable groups like sulphonic acids hamper the cellular uptake of HMCDs in patient-derived GBM cell lines, highlighting cell line-specific differences in HMCD uptake. We envisage these findings will help in the design and structural modifications of HMCDs for drug-delivery applications for glioblastoma.

Fluorescence-based methods for studying activity and drug-drug interactions of hepatic solute carrier and ATP binding cassette proteins involved in ADME-Tox

In humans, approximately 70% of drugs are eliminated through the liver. This process is governed by the concerted action of membrane transporters and metabolic enzymes. Transporters mediating hepatocellular uptake of drugs belong to the SLC (Solute carrier) superfamily of transporters. Drug efflux either toward the portal vein or into the bile is mainly mediated by active transporters of the ABC (ATP Binding Cassette) family. Alteration in the function and/or expression of liver transporters due to mutations, disease conditions, or co-administration of drugs or food components can result in altered pharmacokinetics. On the other hand, drugs or food components interacting with liver transporters may also interfere with liver function (e.g., bile acid homeostasis) and may even cause liver toxicity. Accordingly, certain transporters of the liver should be investigated already at an early stage of drug development. Most frequently radioactive probes are applied in these drug-transporter interaction tests. However, fluorescent probes are cost-effective and sensitive alternatives to radioligands, and are gaining wider application in drug-transporter interaction tests. In our review, we summarize our current understanding about hepatocyte ABC and SLC transporters affected by drug interactions. We provide an update of the available fluorescent and fluorogenic/activable probes applicable in in vitro or in vivo testing of these ABC and SLC transporters, including near-infrared transporter probes especially suitable for in vivo imaging. Furthermore, our review gives a comprehensive overview of the available fluorescence-based methods, not directly relying on the transport of the probe, suitable for the investigation of hepatic ABC or SLC-type drug transporters.

Design and Evaluation of a Carrier-Free Prodrug-Based Palmitic-DEVD-Doxorubicin Conjugate for Targeted Cancer Therapy

In the development of new drugs, typical polymer- or macromolecule-based nanocarriers suffer from manufacturing process complexity, unwanted systematic toxicity, and low loading capacity. However, carrier-free nanomedicines have made outstanding progress in drug delivery and pharmacokinetics, demonstrating most of the advantages associated with nanoparticles when applied in targeted anticancer therapy. Here, to overcome the problems of nanocarriers and conventional cytotoxic drugs, we developed a novel, carrier-free, self-assembled prodrug consisting of a hydrophobic palmitic (16-carbon chain n-hexadecane chain) moiety and hydrophilic group (or moiety) which is included in a caspase-3-specific cleavable peptide (Asp-Glu-Val-Asp, DEVD) and a cytotoxic drug (doxorubicin, DOX). The amphiphilic conjugate, the palmitic-DEVD-DOX, has the ability to self-assemble into nanoparticles in saline without the need for any carriers or nanoformulations. Additionally, the inclusion of doxorubicin is in its prodrug form and the apoptosis-specific DEVD peptide lead to the reduced side effects of doxorubicin in normal tissue. Furthermore, the carrier-free palmitic-DEVD-DOX nanoparticles could passively accumulate in the tumor tissues of tumor-bearing mice due to an enhanced permeation and retention (EPR) effect. As a result, the palmitic-DEVD-DOX conjugate showed an enhanced therapeutic effect compared with the unmodified DEVD-DOX conjugate. Therefore, this carrier-free palmitic-DEVD-DOX prodrug has great therapeutic potential to treat solid tumors, overcoming the problems of conventional chemotherapy and nanoparticles.

In Vivo Evaluation of a Gallium-68-Labeled Tumor-Tracking Cyanine Dye for Positron Emission Tomography/Near-Infrared Fluorescence Carcinoma Imaging, Image-Guided Surgery, and Photothermal Therapy

Positron emission tomography (PET)/near-infrared fluorescence (NIRF) dual-modal imaging presents an enticing prospect for tumor diagnosis and surgical navigation. In this study, we developed a novel probe IR808-DOTA for tumor-targeted PET/NIRF imaging, image-guided surgery, and photothermal therapy. This construct had better water solubility and pharmacokinetics than IR808 and had similar photophysical properties, tumor targeting ability, and photothermal anticancer effect to IR808. By a simple labeling process, IR808-DOTA was labeled with gallium-68 and applied as a PET probe for tumor imaging in MCF-7 tumor xenografted mice. IR808-DOTA itself acted as an NIRF imaging agent in the following surgery for intraoperative navigation to aid surgeons in the delineation of tumor margins and visualizing sentinel lymph nodes to facilitate a more thorough tumor resection. Irradiation by laser, IR808-DOTA could prominently inhibit tumor growth in MCF-7 subcutaneous tumor model mice by directly ablating tumor cells, inhibiting tumor proliferation, and promoting tumor cell apoptosis. In summary, ⁶⁸Ga-DOTA-IR808 could enable a convenient and user-friendly workflow for tumor imaging and guided surgery, and therefore, it may have great prospects for clinical translation as a PET/NIRF dual-modal probe.

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.

J-Aggregates Formed by NaCl Treatment of Aza-Coating Heptamethine Cyanines and Their Application to Monitoring Salt Stress of Plants and Promoting Photothermal Therapy of Tumors

The cationic nature of heptamethine cyanines gives them the capacity to form aggregates with salts by electrostatic interactions. In this work, NaCl promoted J-aggregate formation of aza-coating heptamethine cyanines is explored. NaCl can induce the N-benzyloxycarbonyl Cy-CO₂ Bz to assemble into a J-aggregate having an absorption at 890 nm. Its excellent fluorescence response to NaCl implies that it has great potential for use as a probe for tracing salt stress in plants. Moreover, NaCl also promotes formation of J-aggregates from the N-ethyloxycarbonyl Cy-CO₂ Et. The aggregate shows an intense absorption at 910 nm compared to the monomer which absorbs at 766 nm. Its J-aggregated form can serve as a photothermal agent. And the photothermal conversion efficiency is increased from 29.37 % to 57.59 %. This effort leads to the development of two applications of new cyanine J-aggregates including one for tracing salt stress of plants and the other for promoting photothermal therapy of tumors.

Enhanced Tumor Uptake and Retention of Cyanine Dye-Albumin Complex for Tumor-Targeted Imaging and Phototherapy

Heptamethine cyanine dyes are widely used for in vivo near-infrared (NIR) fluorescence imaging and NIR laser-induced cancer phototherapy due to their good optical properties. Since most of heptamethine cyanine dyes available commercially are highly hydrophobic, they can usually be used for in vivo applications after formation of complexes with blood plasma proteins, especially serum albumin, to increase aqueous solubility. The complex formation between cyanine dyes and albumin improves the chemical stability and optical property of the hydrophobic cyanine dyes, which is the bottom of their practical use. In this study, the complexes between three different heptamethine cyanine dyes, namely clinically available indocyanine green (ICG), commercially available IR-786 and zwitterionic ZW800-Cl, and bovine serum albumin (BSA), were prepared to explore the effect of cyanine dyes on their tumor uptake and retention. Among the three complexes, IR-786©BSA exhibited increased tumor accumulation with prolonged tumor retention, compared to other complexes. Moreover, IR-786 bound to BSA played an important role in tumor growth suppression due to its cytotoxicity. To achieve complete tumor ablation, the tumor targeted by IR-786©BSA was further exposed to 808 nm laser irradiation for effective photothermal cancer treatment.

D. Medeiros H, Bates M, Roshanzadeh A, Thing Teoh S, P. Ogrodzinski M, Borhan B, Lunt RR, Lunt SY. Counterion Tuning of Near-Infrared Organic Salts Dictates Phototoxicity to Inhibit Tumor Growth

Photodynamic therapy (PDT) has the potential to improve cancer treatment by providing dual selectivity through the use of both photoactive agent and light, with the goal of minimal harmful effects from either the agent or light alone. However, current PDT is limited by insufficient photosensitizers (PSs) that can suffer from low tissue penetration, insufficient phototoxicity (toxicity with light irradiation), or undesirable cytotoxicity (toxicity without light irradiation). Recently, we reported a platform for decoupling optical and electronic properties with counterions that modulate frontier molecular orbital levels of a photoactive ion. Here, we demonstrate the utility of this platform in vivo by pairing near-infrared (NIR) photoactive heptamethine cyanine cation (Cy⁺), which has enhanced optical properties for deep tissue penetration, with counterions that make it cytotoxic, phototoxic, or nontoxic in a mouse model of breast cancer. We find that pairing Cy⁺ with weakly coordinating anion FPhB^- results in a selectively phototoxic PS (CyFPhB) that stops tumor growth in vivo with minimal side effects. This work provides proof of concept that our counterion pairing platform can be used to generate improved cancer PSs that are selectively phototoxic to tumors and nontoxic to normal healthy tissues.

Molecular Tuning of IR-786 for Improved Brown Adipose Tissue Imaging

To overcome the limitations of brown adipose tissue (BAT) imaging with MRI and PET/CT, near-infrared (NIR) fluorescence imaging has been utilized in living animals because it is highly sensitive, noninvasive, nonradioactive, and cost-effective. To date, only a few NIR fluorescent dyes for detecting BAT have been reported based on the structure-inherent targeting strategy. Among them, IR-786, a commercial cyanine dye, was used firstly for quantitative NIR imaging of BAT perfusion in 2003. Owing to the high cytotoxicity, poor water solubility, and strong nonspecific background uptake of IR-786, the chemical structure of IR-786 should be redesigned to be more hydrophilic and less toxic so that it can show more BAT-specific accumulation. Here, we developed a BAT-specific NIR dye, BF800-AM, by incorporating the tyramine linker in the original structure of IR-786. After modifying the physicochemical properties of IR-786, in vivo results showed significant uptake of the newly designed BF800-AM in the BAT with improved signal-to-background ratio. Additional in vivo studies using mouse tumor models revealed that BF800-AM targeting to BAT is independent of tumor tissues, as distinct from IR-786 showing uptake in both tissues. Therefore, BF800-AM can be used for improved noninvasive visualization of BAT mass and activity in living animals.

Affinity probes based on small-molecule inhibitors for tumor imaging

Methods for molecular imaging of target areas, including optical imaging, radionuclide imaging, magnetic resonance imaging and other imaging technologies, are helpful for the early diagnosis and precise treatment of cancers. In addition to cancer management, small-molecule inhibitors are also used for developing cancer target probes since they act as the tight-binding ligands of overexpressed proteins in cancer cells. This review aims to summarize the structural designs of affinity probes based on small-molecule inhibitors from the aspects of the inhibitor, linker, dye and radionuclide, and discusses the influence of the modification of these structures on affinity and pharmacokinetics. We also present examples of inhibitor affinity probes in clinical applications, and these summaries will provide insights for future research and clinical translations.

Ultrabright Renal-Clearable Cyanine-Protein Nanoprobes for High-Quality NIR-II Angiography and Lymphography

The renal-clearable aspect of imaging agent with minimum toxicity issues and side effects is essential for clinical translation, yet clinical near-infrared-I/II (NIR-I/II) fluorophores with timely renal-clearance pathways are very limited. Herein, we rationally develop the cyanine-protein composite strategy through covalent bonding of β-lactoglobulin (β-LG) and chloride-cyanine dye to produce a brilliant and stable NIR-I/II fluorophore (e.g., β-LG@IR-780). The β-LG acts as a protecting shell with small molecular weight (18.4 kDa) and ultrasmall size (<5 nm), thus endowing the β-LG@IR-780 with excellent biocompatibility and renal excretion. Our β-LG@IR-780 probe enables noninvasive and precise NIR-II visualization of the physiological and pathological conditions of the vascular and lymphatic drainage system, facilitating intraoperative imaging-guided surgery and postoperative noninvasive monitoring. The minimum accumulation of our probes in the main organs improves the overall biosafety. This study provides a facile methodology for new-generation NIR-II fluorophores and largely improves the brightness and pharmacokinetics of small molecular dyes.

Synthesis and Study on Aggregation Behaviors in Liquid Phase of Three Prepared Cyanine Dyes

Here we investigate the aggregation behaviors of three prepared dyes in the liquid phase to pick out one possessing J-aggregation characteristic which is of significant interest for organic materials used in multiple bio-applications. The self-assembly of dyes usually leads to various forms of aggregates, for example, H-aggregates or J-aggregates and it is easy to distinguish bathochromic J-aggregation from hypsochromic H-aggregation by UV/Vis spectroscopy. Enlightened by the cyanine dyes which have shown a great tendency to self-associate, we designed and synthesized three cyanine dyes: Cy7-Ph, DCy7-Ph, SN-Cy7-Ph, followed by the study of the influence of multiple factors to their aggregation behaviors, including solvent polarity, ionic strength and temperature. Finally, we found that only SN-Cy7-Ph of the three molecules can self-assemble into J-aggregates conveniently and stably in the aqueous phase under normal conditions.

Topical pH Sensing NIR Fluorophores for Intraoperative Imaging and Surgery of Disseminated Ovarian Cancer

Fluorescence-guided surgery (FGS) aids surgeons with real-time visualization of small cancer foci and borders, which improves surgical and prognostic efficacy of cancer. Despite the steady advances in imaging devices, there is a scarcity of fluorophores available to achieve optimal FGS. Here, 1) a pH-sensitive near-infrared fluorophore that exhibits rapid signal changes in acidic tumor microenvironments (TME) caused by the attenuation of intramolecular quenching, 2) the inherent targeting for cancer based on chemical structure (structure inherent targeting, SIT), and 3) mitochondrial and lysosomal retention are reported. After topical application of PH08 on peritoneal tumor regions in ovarian cancer-bearing mice, a rapid fluorescence increase (< 10 min), and extended preservation of signals (> 4 h post-topical application) are observed, which together allow for the visualization of submillimeter tumors with a high tumor-to-background ratio (TBR > 5.0). In addition, PH08 is preferentially transported to cancer cells via organic anion transporter peptides (OATPs) and colocalizes in the mitochondria and lysosomes due to the positive charges, enabling a long retention time during FGS. PH08 not only has a significant impact on surgical and diagnostic applications but also provides an effective and scalable strategy to design therapeutic agents for a wide array of cancers.

Tailoring Multifunctional Small Molecular Photosensitizers to In Vivo Self-Assemble with Albumin to Boost Tumor-Preferential Accumulation, NIR Imaging, and Photodynamic/Photothermal/Immunotherapy

Cancer immunotherapy has great potential in tumor eradication and metastasis suppression. However, systemic administration of immune adjuvants and inadequate specificity in cancer treatment, lead to restricted therapeutic benefits and potential immune-related side effects in clinical settings. In this report, the synthesis of various lengths of heptamethine cyanine small molecules to act as multifunctional photosensitizers (PS) for tumor-specific accumulation, near-infrared (NIR) fluorescent imaging, and photodynamic/photothermal/immunotherapy is optimized. In particular, it is demonstrated that C8, which contains eight carbons on two N-alkyl side chains, efficiently self-assembles with albumin to form nanosized dye-albumin complexes. This feature facilitates C8 in vivo self-assembly to remarkably improve its water-solubility, NIR fluorescent emission, long-term blood circulation, as well as tumor-specific accumulation. More importantly, C8 not only exhibits a superior phototherapeutic effect on primary tumors, but also elicits secretion of damage associated molecular patterns, cytokine secretion, dendritic cell maturation, and cytotoxic T lymphocytes activation, ultimately triggering a sufficient antitumor immune response to suppress growths of distant and metastatic tumors. Hence, this multifunctional small molecular PS is characterized with excellent tumor-preferential accumulation, imaging-guided laser irradiation, and phototherapy-induced in situ antitumor immune response, providing a prospective future of its use in tumor-targeting immunotherapy.

Effect of Trimethine Cyanine Dye- and Folate-Conjugation on the In Vitro Biological Activity of Proapoptotic Peptides

Despite continuous advances, anticancer therapy still faces several technical hurdles, such as selectivity on cellular and subcellular targets of therapeutics. Toward addressing these limitations, we have combined the use of proapoptotic peptides, trimethine cyanine dye, and folate to target the mitochondria of tumor cells. A series of proapoptotic peptides and their conjugates with a cyanine dye and/or folate were synthesized in the solid phase, and their toxicity in different human cell lines was assessed. Cyanine-bearing conjugates were found to be up to 100-fold more cytotoxic than the parent peptides and to localize in mitochondria. However, the addition of a folate motif did not enhance the potency or selectivity of the resulting conjugates toward tumor cells that overexpress folate receptor α. Furthermore, while dual-labeled constructs were also found to localize within the target organelle, they were not generally selective towards folate receptor α-positive cell lines in vitro.

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.

Molecular Tuning of IR-786 for Improved Tumor Imaging and Photothermal Therapy

A tumor-targeted near-infrared (NIR) fluorophore CA800Cl was developed based on commercially available IR-786 by modulating its physicochemical properties. IR-786, a hydrophobic cationic heptamethine cyanine fluorophore, was previously recognized as a mitochondria-targeting NIR agent with excellent optical properties. Owing to the poor tumor specificity of IR-786 itself, in vivo studies on tumor-targeted imaging have not yet been investigated. A chloro-cyclohexene ring and indolium side groups on the heptamethine chain are key structural features that improve tumor targetability, owing to better biodistribution and clearance. Thus, IR-786 should be designed to be more soluble in aqueous solutions so that it can preferentially accumulate in the tumor based on the structure-inherent targeting strategy. In this study, we developed a bifunctional NIR fluorophore CA800Cl by incorporating carboxylate moieties in the basic structure of IR-786. This improved its tumor targetability and water solubility, thereby enabling the use of CA800Cl for enhanced photothermal cancer therapy.

QuatCy-I2 and MHI-I2 in Photodynamic Therapy

MHI-I2 (1) and QuatCy-I2 (2) were compared in terms of properties important for early-stage photodynamic therapy preclinical candidates. Thus, experiments were performed to monitor dark cytotoxicities, light/dark cytotoxicity ratios, selectivity of localization in tumors over other organs, and clearance from the plasma.

Effect of morpholine and charge distribution of cyanine dyes on cell internalization and cytotoxicity

To improve the potency of Heptamethine cyanines (Hcyanines) in cancer research, we designed and synthesized two novel Hcyanines based theranostic probes, IR794-Morph and IR794-Morph-Mpip, to enhance cancer cell internalization and targeting. In acidic conditions that resemble to tumour environment, both IR794 derivatives exhibited broad NIR absorption band (704‒794 nm) and fluorescence emission (798‒828 nm) that is suitable for deep seated tumour imaging. Moreover, in vitro study revealed that IR794-Morph-Mpip exhibited better cancer targetability towards various cancer cell lines under physiological and slightly acidic conditions compared to normal cells. IR794-Morph-Mpip was fast internalized into the cancer cells within the first 5 min and mostly localized in lysosomes and mitochondria. In addition, the internalized signal was brighter when the cells were in the hypoxic environment. Furthermore, cellular uptake mechanism of both IR794 dyes, investigated via flow cytometry, revealed that endocytosis through OATPs receptors and clathrin-mediated endocytosis were the main routes. Moreover, IR794-Morph-Mpip, displayed anti-cancer activity towards all tested cancer cell types with IC50 below 7 μM (at 6 h incubation), which is approximately three times lower than that of the normal cells. Therefore, increasing protonated cites in tumour environment of Hcyanines together with incorporating morpholine in the molecule can enhance structure-inherent targeting of these dyes.

Tumor-Associated Immune-Cell-Mediated Tumor-Targeting Mechanism with NIR-II Fluorescence Imaging

The strategy of structure-inherent tumor targeting (SITT) with cyanine-based fluorophores is receiving more attention because no chemical conjugation of targeting moieties is required. However, the targeting mechanism behind SITT has not yet been well explained. Here, it is demonstrated that heptamethine-cyanine-based fluorophores possess not only targetability of tumor microenvironments without the need for additional targeting ligands but also second near-infrared spectral window (NIR-II) imaging capabilities, i.e., minimum scattering and ultralow autofluorescence. The new SITT mechanism suggests that bone-marrow-derived and/or tissue-resident/tumor-associated immune cells can be a principal target for cancer detection due to their abundance in tumoral tissues. Among the tested, SH1 provides ubiquitous tumor targetability and a high tumor-to-background ratio (TBR) ranging from 9.5 to 47 in pancreatic, breast, and lung cancer mouse models upon a single bolus intravenous injection. Furthermore, SH1 can be used to detect small cancerous tissues smaller than 2 mm in diameter in orthotopic lung cancer models. Thus, SH1 could be a promising cancer-targeting agent and have a bright future for intraoperative optical imaging and image-guided cancer surgery.

Fibrinogen/Albumin Ratio (FAR) in Patients with Triple Negative Breast Cancer and Its Relationship with Epidermal Growth Factor Receptor Expression

OBJECTIVE

To investigate the potential prognostic significance of fibrinogen/albumin ratio (FAR) in triple negative breast cancer (TNBC) patients and its relationship with epidermal growth factor receptor (EGFR) expression.

METHODS

There were 164 patients with TNBC enrolled in this study in our hospital from January 2010 to December 2015. The optimal cutoff value of FAR was evaluated by the receiver operating characteristic curve (ROC). The associations between TNBC and clinicopathological variables by FAR were performed by Chi-square test. Kaplan-Meier method and Log rank test were used for survival analysis. The independent prognostic factors were determined by univariate and multivariate Cox's proportional hazards regression model. The EGFR expression was analyzed by the immunohistochemistry assay.

RESULTS

One hundred and sixty-four TNBC patients were divided into: low FAR group (FAR < 0.08) and high FAR group (FAR ≥ 0.08) by ROC. The preoperative FAR was associated to BMI, menopause, red blood cell, albumin, fibrinogen (P < 0.05). FAR was an independent prognostic factor for TNBC. In low FAR group, the mean disease-free survival (DFS) and overall survival (OS) were 33.62 months and 52.99 months; in high FAR group, the mean DFS and OS were 30.18 months and 48.27 months, respectively. The DFS and OS survival curve were performed by Log rank assay and were statistically significant (P < 0.05). The mean DFS and OS after operation in patients with EGFR negative expression were longer than that in patients with EGFR positive expression. In EGFR positive group, the mean DFS and OS of low FAR group were higher than that of high FAR group, and the difference was statistically significant (P < 0.05).

CONCLUSION

Pretreatment FAR is the independent prognostic factor in TNBC, and with low cost, strong repeatability, and high safety. It can be acted as an effective indicator to predict the prognosis of TNBC.

Systematic interaction of plasma albumin with the efficacy of chemotherapeutic drugs

Albumin, as the most abundant plasma protein, plays an integral role in the transport of a variety of exogenous and endogenous ligands in the bloodstream and extravascular spaces. For exogenous drugs, especially chemotherapeutic drugs, binding to and being delivered by albumin can significantly affect their efficacy. Meanwhile, albumin can also bind to many endogenous ligands, such as fatty acids, with important physiological significance that can affect tumor proliferation and metabolism. In this review, we summarize how albumin with unique properties affects chemotherapeutic drugs efficacy from the aspects of drug outcome in blood, toxicity, tumor accumulation and direct or indirect interactions with fatty acids, plus application of albumin-based carriers for anti-tumor drug delivery.

Effects of Human Serum Albumin on the Fluorescence Intensity and Tumor Imaging Properties of IR-780 Dye

IR-780 is a lipophilic dye with excellent optical and tumor imaging properties for early tumor diagnostics. Although the mechanism of tumor targeting has not been fully identified, the view that serum albumin plays an important role in tumor accumulation has been recognized. Here, the mechanism of the interaction between IR-780 and HSA was studied to explore the effect of albumin on its tumor targeting properties. Data demonstrate that IR-780 can be tightly adsorbed by HSA at a ratio of 1:1 to form a noncovalent complex, which exhibits significant improvement in the near-infrared fluorescence imaging and tumor diagnosis capacity. During this process, the endogenous fluorescence and esterase activity of HSA are both partially inhibited by IR-780, and the α-helical content of HSA slightly increases. Molecular docking simulation displays that the binding site of IR-780 on HSA is between subdomains IIA and IIB. These results indicate that HSA is an important factor to mediate the optical performance of IR-780, giving it higher tumor diagnosis capability.

Cytoprotective agent troxipide-cyanine dye conjugate with cytotoxic and antiproliferative activity in patient-derived glioblastoma cell lines

Cytoprotective agents are mainly used to protect the gastrointestinal tract linings and in the treatment of gastric ulcers. These agents are devoid of appreciable cytotoxic or cytostatic effects, and medicinal chemistry efforts to modify them into anticancer agents are rare. A drug repurposing campaign initiated in our laboratory with the primary focus of discovering brain cancer drugs resulted in drug-dye conjugate 1, a combination of the cytoprotective agent troxipide and heptamethine cyanine dye MHI 148. The drug-dye conjugate 1 was evaluated in three different patient-derived adult glioblastoma cell lines, commercially available U87 glioblastoma, and one paediatric glioblastoma cell line. In all cases, the conjugate 1 showed potent cytotoxic activity with nanomolar potency (EC₅₀: 267 nM). Interestingly, troxipide alone does not show any cytotoxic and cytostatic activity in the above cell lines. We also observe a synergistic effect of 1 with temozolomide (TMZ), the standard drug used for glioblastoma treatment, even though the cell lines we used in this study were resistant to TMZ treatment. Herein we disclose the synthesis and in vitro activity of drug-dye conjugate 1 for treatment of difficult-to-treat brain cancers such as glioblastoma.

How Different Albumin-Binders Drive Probe Distribution of Fluorescent RGD Mimetics

The biodistribution of medical imaging probes depends on the chemical nature of the probe and the preferred metabolization and excretion routes. Especially targeted probes, which have to reach a certain (sub)cellular destination, have to be guided to the tissue of interest. Therefore, small molecular probes need to exhibit a well-balanced polarity and lipophilicity to maintain an advantageous bioavailability. Labelled antibodies circulate for several days due to their size. To alter the biodistribution behavior of probes, different strategies have been pursued, including utilizing serum albumin as an inherent transport mechanism for small molecules. We describe here the modification of an existing fluorescent RGD mimetic probe targeted to integrin α_vβ₃ with three different albumin binding moieties (ABMs): a diphenylcyclohexyl (DPCH) group, a p-iodophenyl butyric acid (IPBA) and a fatty acid (FA) group with the purpose to identify an optimal ABM for molecular imaging applications. All three modifications result in transient albumin binding and a preservation of the target binding capability. Spectrophotometric measurements applying variable amounts of bovine serum albumin (BSA) reveal considerable differences between the compounds concerning their absorption and emission characteristics and hence their BSA binding mode. In vivo the modified probes were investigated in a murine U87MG glioblastoma xenograft model over the course of 1 wk by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT). While the unmodified probe was excreted rapidly, the albumin-binding probes were accumulating in tumor tissue for at least 5 days. Considerable differences between the three probes in biodistribution and excretion characteristics were proved, with the DPCH-modified probe showing the highest overall signal intensities, while the FA-modified probe exhibits a low but more specific fluorescent signal. In conclusion, the modification of small molecular RGD mimetics with ABMs can precisely fine-tune probe distribution and offers potential for future clinical applications.

Fluorescent kinase inhibitors as probes in cancer

Fluorescent dyes attached to kinase inhibitors (KIs) can be used to probe kinases in vitro, in cells, and in vivo. Ideal characteristics of the dyes vary with their intended applications. Fluorophores used in vitro may inform on kinase active site environments, hence the dyes used should be small and have minimal impact on modes of binding. These probes may have short wavelength emissions since blue fluorophores are perfectly adequate in this context. Thus, for instance, KI fragments that mimic nucleobases may be modified to be fluorescent with minimal perturbation to the kinase inhibitor structure. However, progressively larger dyes, that emit at longer wavelengths, are required for cellular and in vivo work. In cells, it is necessary to have emissions above autofluorescence of biomolecules, and near infrared dyes are needed to enable excitation and observation through tissue in vivo. This review is organized to describe probes intended for applications in vitro, in cells, then in vivo. The readers will observe that the probes featured tend to become larger and responsive to the near infared end of the spectrum as the review progresses. Readers may also be surprised to realize that relatively few dyes have been used for fluorophore-kinase inhibitor conjugates, and the area is open for innovations in the types of fluorophores used.

Preoperative Serum Hypersensitive-c-Reactive-Protein (Hs-CRP) to Albumin Ratio Predicts Survival in Patients with Luminal B Subtype Breast Cancer

Objective

To evaluate the clinical prognostic significance of preoperative serum hypersensitive-c-reactive-protein (Hs-CRP) to albumin ratio (CAR) in patients with luminal B subtype breast cancer.

Methods

A total of 199 patients with luminal B subtype breast cancer enrolled in this study were analyzed retrospectively. The optimal cutoff value of CAR was performed by the receiver operating characteristic curve (ROC). The associations between luminal B subtype breast cancer and clinicopathological variables by CAR were performed by chi-square test. Kaplan–Meier and log rank method were used for survival analysis. The independent prognostic factors were determined by univariate and multivariate Cox’s proportional hazards regression model.

Results

The patients were divided into low CAR group (CAR<0.044) and high CAR group (CAR≥0.044) by ROC. CAR was the independent factor by univariate and multivariate analysis, and the mean DFS and OS in the low CAR group survived longer than those in the high CAR group (p<0.05). According to the endocrine therapy with aromatase inhibitors, the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Moreover, patients with pathological I+II stage survived longer than those with pathological III stage, and the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Patients without lymph vessel invasion survived longer than those with lymph vessel invasion (p<0.05), and the mean survival time of DFS and OS in low the CAR group was significantly higher than that in the high CAR group (p<0.05).

Conclusion

Preoperative CAR was significantly associated with survival and prognosis of breast cancer, and it can be used as a routine prognostic indicator to predict the prognosis of luminal B subtype breast cancer.