Drug Conjugation Affects Pharmacokinetics and Specificity of Kidney-Targeted Peptide Carriers

Protein and peptide-based renal targeted drug delivery systems

Renal diseases have become an increasingly concerned public health problem in the world. Kidney-targeted drug delivery has profound transformative potential on increasing renal efficacy and reducing extra-renal toxicity. Protein and peptide-based kidney targeted drug delivery systems have garnered more and more attention due to its controllable synthesis, high biocompatibility and low immunogenicity. At the same time, the targeting methods based on protein/peptide are also abundant, including passive renal targeting based on macromolecular protein and active targeting mediated by renal targeting peptide. Here, we review the application and the drug loading strategy of different proteins or peptides in targeted drug delivery, including the ferritin family, albumin, low molecular weight protein (LMWP), different peptide sequence and antibodies. In addition, we summarized the factors influencing passive and active targeting in drug delivery system, the main receptors related to active targeting in different kidney diseases, and a variety of nano forms of proteins based on the controllable synthesis of proteins.

Water-soluble chromenylium dyes for shortwave infrared imaging in mice

In vivo imaging using shortwave infrared light (SWIR, 1000-2000 nm) benefits from deeper penetration and higher resolution compared to using visible and near-infrared wavelengths. However, the development of biocompatible SWIR contrast agents remains challenging. Despite recent advancements, small molecule SWIR fluorophores are often hindered by their significant hydrophobicity. We report a platform for generating a panel of soluble and functional dyes for SWIR imaging by late-stage functionalization of a versatile fluorophore intermediate, affording water-soluble dyes with bright SWIR fluorescence in serum. Specifically, a tetra-sulfonate derivative enables clear video-rate imaging of vasculature with only 0.05 nmol dye, and a tetra-ammonium dye shows strong cellular retention for tracking of tumor growth. Additionally, incorporation of phosphonate functionality enables imaging of bone in awake mice. This modular design provides insights for facile derivatization of existing SWIR fluorophores to introduce both solubility and bioactivity towards in vivo bioimaging.

Biopolymer-Based Nanosystems: Potential Novel Carriers for Kidney Drug Delivery

Kidney disease has become a serious public health problem throughout the world, and its treatment and management constitute a huge global economic burden. Currently, the main clinical treatments are not sufficient to cure kidney diseases. During its development, nanotechnology has shown unprecedented potential for application to kidney diseases. However, nanotechnology has disadvantages such as high cost and poor bioavailability. In contrast, biopolymers are not only widely available but also highly bioavailable. Therefore, biopolymer-based nanosystems offer new promising solutions for the treatment of kidney diseases. This paper reviews the biopolymer-based nanosystems that have been used for renal diseases and describes strategies for the specific, targeted delivery of drugs to the kidney as well as the physicochemical properties of the nanoparticles that affect the targeting success.

Comparison of low-molecular-weight ligand and whole antibody in prostate-specific membrane antigen targeted near-infrared photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a cancer phototherapy that uses antibody-IR700 conjugate (Ab-IR700) and NIR light. Ab-IR700 forms aggregates on the plasma membranes of targeted cancer cells after light exposure, inducing lethal physical damage within the membrane. Low-molecular-weight (LMW) ligands are candidate targeting moieties instead of antibodies, but whether LMW-IR700 conjugates induce cell death by aggregation, the same mechanism as Ab-IR700, is unknown. Thus, we investigated differences in cytotoxicity and mechanisms between LMW-IR700 and Ab-IR700 targeting prostate-specific membrane antigen (PSMA). Both conjugates decreased cell viability to the same degree after light irradiation, but different morphological changes were observed in PSMA-positive LNCaP cells by microscopy. Cell swelling and bleb formation were induced by Ab-IR700, but only swelling was observed in cells treated with LMW-IR700, suggesting the cells were damaged via different cytotoxic mechanisms. However, LMW-IR700 induced bleb formation, a hallmark of NIR-PIT with Ab-IR700, when singlet oxygen was quenched or LMW-IR700 was localized only on the plasma membrane. Moreover, the water-soluble axial ligands of LMW-IR700 were cleaved, consistent with previous reports on Ab-IR700. Thus, the main cytotoxic mechanisms of Ab-IR700 and LMW-IR700 differ, although LMW-IR700 on the plasma membrane can cause aggregation-mediated cytotoxicity as well as Ab-IR700.

Targeted Drug Delivery Systems for Kidney Diseases

Kidney diseases have gradually become a global health burden. Along with the development of nanotechnology, many hybrids or nanomaterials have been utilized to promote treatment efficiency with negligible side effects. These therapeutic agents have been successfully applied in many fields. In particular, some efforts have also been made to ameliorate the treatment of kidney diseases through targeted delivery nanomaterials. Though most of the delivery systems have not yet been transmitted into clinical use or even still at an early stage, they have shown great potential in carrying immunosuppressants like tacrolimus and triptolide, antioxidants, or siRNAs. Excitingly, some of them have achieved significant treatment effectiveness and reduced systemic side effect in kidney disease animal models. Here, we have reviewed the recent advances and presented nanotherapeutic devices designed for kidney targeted delivery.

A Pretargeted Imaging Strategy for EGFR-Positive Colorectal Carcinoma via Modulation of Tz-Radioligand Pharmacokinetics

PURPOSE

Previously, we successfully developed a pretargeted imaging strategy (atezolizumab-TCO/[^99mTc]HYNIC-PEG₁₁-Tz) for evaluating programmed cell death ligand-1 (PD-L1) expression in xenograft mice. However, the surplus unclicked [^99mTc]HYNIC-PEG₁₁-Tz is cleared somewhat sluggishly through the intestines, which is not ideal for colorectal cancer (CRC) imaging. To shift the excretion of the Tz-radioligand to the renal system, we developed a novel Tz-radioligand by adding a polypeptide linker between HYNIC and PEG₁₁.

PROCEDURES

Pretargeted molecular probes [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz and cetuximab-TCO were synthesized. [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz was evaluated for in vitro stability and in vivo blood pharmacokinetics. In vitro ligation reactivity of [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz towards cetuximab-TCO was also tested. Biodistribution assay and imaging of [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz were performed to observe its excretion pathway. Pretargeted biodistribution was measured at three different accumulation intervals to determine the optimal pretargeted interval time. Pretargeted (cetuximab-TCO 48 h/[^99mTc]HYNIC-PEG₁₁-Tz 6 h) and (cetuximab-TCO 48 h/[^99mTc]HYNIC-Polypeptide-PEG₁₁-Tz 6 h) imagings were compared to examine the effect of the excretion pathway on tumor imaging.

RESULTS

[^99mTc]HYNIC-polypeptide-PEG₁₁-Tz showed favorable in vitro stability and rapid blood clearance in mice. SEC-HPLC revealed almost complete reaction between cetuximab-TCO and [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz in vitro, with the 8:1 Tz-to-mAb reaction providing a conversion yield of 87.83 ± 3.27 %. Biodistribution and imaging analyses showed that the Tz-radioligand was cleared through the kidneys. After 24, 48, and 72 h of accumulation in HCT116 tumor, the tumor-to-blood ratio of cetuximab-TCO was 0.83 ± 0.13, 1.40 ± 0.31, and 1.15 ± 0.21, respectively. Both pretargeted (cetuximab-TCO 48 h/[^99mTc]HYNIC-PEG₁₁-Tz 6 h) and (cetuximab-TCO 48 h/[^99mTc]HYNIC-polypeptide-PEG₁₁-Tz 6 h) clearly delineated HCT116 tumor. Pretargeted imaging strategy using cetuximab-TCO/[^99mTc]HYNIC-polypeptide-PEG₁₁-Tz could be used for diagnosing CRC, as the surplus unclicked [^99mTc]HYNIC-polypeptide-PEG₁₁-Tz was cleared through the urinary system, leading to low abdominal uptake background.

CONCLUSION

Our novel pretargeted imaging strategy (cetuximab-TCO/[^99mTc]HYNIC-polypeptide-PEG₁₁-Tz) was useful for imaging CRC, broadening the application scope of pretargeted imaging strategy. The pretargeted imaging strategy clearly delineated HCT116 tumor, showing that its use could be extended to selection of internalizing antibodies.

Restoration of renal TIMP3 levels via genetics and pharmacological approach prevents experimental diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN), one of the major complications of diabetes, is characterized by albuminuria, glomerulosclerosis, and progressive loss of renal function. Loss of TIMP3, an Extracellular Matrix bound protein affecting both inflammation and fibrosis, is a hallmark of DN in human subjects and mouse models.

METHODS

This study was designed to provide evidences that the modulation of the system involving TIMP3 and its target A Disintegrin And Metalloproteinase 17 (ADAM17), may rescue kidney pathology in diabetic mice. Mice with cell-targeted overexpression of TIMP3 in myeloid cells (MacT3), podocyte-specific ADAM17 knockout mice (∆PodA17), and DBA/2J mice, were rendered diabetic at 8 weeks of age with a low-dose streptozotocin protocol. DBA/2J mice were administered new peptides based on the human TIMP3 N-terminal domain, specifically conjugated with G3C12, a carrier peptide highly selective and efficient for transport to the kidney. Twelve weeks after Streptozotocin injections, 24-hour albuminuria was determined by ELISA, kidney morphometry was analyzed by periodic acid-shift staining, and Real Time-PCR and western blot analysis were performed on mRNA and protein extracted from kidney cortex.

RESULTS

Our results showed that both genetic modifications and peptides treatment positively affect renal function and structure in diabetic mice, as indicated by a significant and consistent decline in albuminuria along with reduction in glomerular lesions, as indicated by reduced mesangial expansion and glomerular hypertrophy, decreased deposition of extracellular matrix in the mesangium, diminished protein expression of the NADPH oxidases 4 (NOX4), and the improvement of podocyte structural markers such as WT1, nephrin, and podocin. Moreover, the positive effects were exerted through a mechanism independent from glycemic control.

CONCLUSIONS

In diabetic mice the targeting of TIMP3 system improved kidney structure and function, representing a valid approach to develop new avenues to treat this severe complication of diabetes.

The effect of size, charge, and peptide ligand length on kidney targeting by small, organic nanoparticles

Chronic kidney disease (CKD) affects 15% of the US adult population. However, most clinically available drugs for CKD show low bioavailability to the kidneys and non-specific uptake by other organs which results in adverse side effects. Hence, a targeted, drug delivery strategy to enhance kidney drug delivery is highly desired. Recently, our group developed small, organic nanoparticles called peptide amphiphile micelles (PAM) functionalized with the zwitterionic peptide ligand, (KKEEE)3K, that passage through the glomerular filtration barrier for kidney accumulation. Despite high bioavailability to the kidneys, these micelles also accumulated in the liver to a similar extent. To further optimize the physicochemical properties and develop design rules for kidney-targeting micelles, we synthesized a library of PAMs of varying size, charge, and peptide repeats. Specifically, variations of the original (KKEEE)3K peptide including (KKEEE)2K, (KKEEE)K, (EEKKK)3E, (EEKKK)2E, (EEKKK)E, KKKKK, and EEEEE were functionalized onto nanoparticles, and peptide surface density and PEG linker molecular weight were altered. After characterization with transmission electron microscopy (TEM) and dynamic light scattering (DLS), nanoparticles were intravenously administered into wildtype mice, and biodistribution was assessed through ex vivo imaging. All micelles localized to the kidneys, but nanoparticles that are positively-charged, close to the renal filtration size cut-off, and consisted of additional zwitterionic peptide sequences generally showed higher renal accumulation. Upon immunohistochemistry, micelles were confirmed to bind to the multiligand receptor, megalin, and histological analyses showed no tissue damage. Our study provides insight into the design of micelle carriers for kidney targeting and their potential for future therapeutic application.

Targeting and therapeutic peptide-based strategies for polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by progressive cyst growth and is a leading cause of renal failure worldwide. Currently, there are limited therapeutic options available to PKD patients, and only one drug, tolvaptan, has been FDA-approved to slow cyst progression. Similar to other small molecule drugs, however, tolvaptan is costly, only moderately effective, and causes adverse events leading to high patient dropout rates. Peptides may mitigate many drawbacks of small molecule drugs, as they can be highly tissue-specific, biocompatible, and economically scaled-up. Peptides can function as targeting ligands that direct therapies to diseased renal tissue, or be potent as therapeutic agents themselves. This review discusses various aberrant signaling pathways in PKD and renal receptors that can be potential targets of peptide-mediated strategies. Additionally, peptides utilized in other kidney applications, but may prove useful in the context of PKD, are highlighted. Insights into novel peptide-based solutions that have potential to improve clinical management of PKD are provided.

Advances in kidney-targeted drug delivery systems

The management and treatment of kidney diseases currently have caused a huge global burden. Although the application of nanotechnology for the therapy of kidney diseases is still at an early stages, it has profound potential of development. More and more nano-based drug delivery systems provide novel solutions for the treatment of kidney diseases. This article summarizes the physiological and anatomical properties of the kidney and the biological and physicochemical characters of drug delivery systems, which affects the ability of drug to target the kidney, and highlights the prospects, opportunities, and challenges of nanotechnology in the therapy of kidney diseases.

Pretargeted Nuclear Imaging and Radioimmunotherapy Based on the Inverse Electron-Demand Diels-Alder Reaction and Key Factors in the Pretargeted Synthetic Design

The exceptional speed and biorthogonality of the inverse electron-demand Diels-Alder (IEDDA) click chemistry between 1,2,4,5-tetrazines and strained alkene dienophiles have made it promising in the realm of pretargeted imaging and therapy. During the past 10 years, the IEDDA-pretargeted strategies have been tested and have already proven capable of producing images with high tumor-to-background ratios and improving therapeutic effect. This review will focus on recent applications of click chemistry ligations in the pretargeted imaging studies of single photon emission computed tomography (SPECT), positron emission tomography (PET), and pretargeted radioimmunotherapy investigations. Additionally, the influence factors of stability, reactivity, and pharmacokinetic properties of TCO tag modified immunoconjugates and radiolabeled Tz derivatives were also summarized in this article, which should be carefully considered in the system design in order to develop a successful pretargeted methodology. We hope that this review will not only equip readers with a knowledge of pretargeted methodology based on IEDDA click chemistry but also inspire synthetic chemists and radiochemists to develop pretargeted radiopharmaceutical components in a more innovative way with various influence factors considered.

Cationic nucleopeptides as novel non-covalent carriers for the delivery of peptide nucleic acid (PNA) and RNA oligomers

Cationic nucleopeptides belong to a family of synthetic oligomers composed by amino acids and nucleobases. Their capability to recognize nucleic acid targets and to cross cellular membranes provided the basis for considering them as novel non-covalent delivery agents for nucleic acid pharmaceuticals. Herein, starting from a 12-mer nucleopeptide model, the number of cationic residues was modulated in order to obtain new nucleopeptides endowed with high solubility in acqueous medium, acceptable bio-stability, low cytotoxicity and good capability to bind nucleic acid. Two candidates were selected to further investigate their potential as nucleic acid carriers, showing higher efficiency to deliver PNA in comparison with RNA. Noteworthy, this study encourages the development of nucleopeptides as new carriers to extend the known strategies for those nucleic acid analogues, especially PNA, that still remain difficult to drive into the cells.

Site-Specifically Labeled Antibody-Drug Conjugate for Simultaneous Therapy and ImmunoPET

The conjugation of antibodies with cytotoxic drugs can alter their in vivo pharmacokinetics. As a result, the careful assessment of the in vivo behavior, and specifically the tumor-targeting properties, of antibody-drug conjugates represents a crucial step in their development. In order to facilitate this process, we have created a methodology that facilitates the dual labeling of an antibody with both a toxin and a radionuclide for positron emission tomography (PET). To minimize the impact of these modifications, this chemoenzymatic approach leverages strain-promoted azide-alkyne click chemistry to graft both cargoes to the heavy chain glycans of the immuoglobulin's F_c domain. As a proof-of-concept, a HER2-targeting trastuzumab immunoconjugate was created bearing both a monomethyl auristatin E (MMAE) toxin as well as the long-lived positron-emitting radiometal ⁸⁹Zr ( t_1/2 ≈ 3.3 days). Both the tumor targeting and therapeutic efficacy of the ⁸⁹Zr-trastuzumab-MMAE immunoconjugate were validated in vivo using a murine model of HER2-expressing breast cancer. The site-specifically dual-labeled construct enabled the clear visualization of tumor tissue via PET imaging, producing tumoral uptake of ∼70%ID/g. Furthermore, a longitudinal therapy study revealed that the immunoconjugate exerts significant antitumor activity, leading to a >90% reduction in tumor volume over the course of 20 days.

Synthesis of hydrophilic HYNIC-[1,2,4,5]tetrazine conjugates and their use in antibody pretargeting with99mTc

Pretargeted imaging is shown to be an attractive strategy to overcome disadvantages associated with traditional radioimmunoconjugates.

Exploring Structural Parameters for Pretargeting Radioligand Optimization

Pretargeting offers a way to enhance target specificity while reducing off-target radiation dose to healthy tissue during payload delivery. We recently reported the development of an ¹⁸F-based pretargeting strategy predicated on the inverse electron demand Diels-Alder reaction as well as the use of this approach to visualize pancreatic tumor tissue in vivo as early as 1 h postinjection. Herein, we report a comprehensive structure: pharmacokinetic relationship study of a library of 25 novel radioligands that aims to identify radiotracers with optimal pharmacokinetic and dosimetric properties. This investigation revealed key relationships between molecular structure and in vivo behavior and produced two lead candidates exhibiting rapid tumor targeting with high target-to-background activity concentration ratios at early time points. We believe this knowledge to be of high value for the design and clinical translation of next-generation pretargeting agents for the diagnosis and treatment of disease.

Vectorisation of agrochemicals via amino acid carriers: influence of the spacer arm structure on the phloem mobility of phenylpyrrole conjugates in the Ricinus system

BACKGROUND

Excessive agrochemical use poses significant threats to environmental safety and human health. Reducing pesticide use without reducing yield is necessary for sustainable agriculture. Therefore, we developed a vectorisation strategy to enhance agrochemical delivery through plant amino acid carriers.

RESULTS

In addition to a fenpiclonil conjugate recently described, three new amino acid conjugates were synthesised by coupling fenpiclonil to an l-α-amino acid. Phloem mobility of these conjugates, which exhibit different structures of the spacer arm introduced between fenpiclonil and the α-amino acid function, was studied using the Ricinus model. Conjugate L-14, which contains a triazole ring with the shortest amino acid chain, showed the best phloem systemicity among the four conjugates. By contrast, removing the triazole ring in the spacer arm did not improve systemicity. L-14 exhibited phloem systemicity at all reported pH values (pH values from 5.0 to 6.5) of the foliar apoplast, while acidic derivatives of fenpiclonil were translocated only at pH values near 5.0.

CONCLUSION

The conjugates were recognised by a pH-dependent transporter system and translocated at distance in the phloem. They exhibited a broader phloem systemicity than fenpiclonil acidic derivatives within the pH value range of the foliar apoplast. © 2017 Society of Chemical Industry.