Neuropilin-1-Targeted Nanomedicine for Spatiotemporal Tumor Suppression through Photodynamic Vascular Damage and Antiangiogenesis.

Antiangiogenic therapy is an effective way to disrupt nutrient supply and starve tumors, but it is restricted by poor efficacy and negative feedback-induced tumor relapse. In this study, a neuropilin-1 (NRP-1)-targeted nanomedicine (designated as FPPT@Axi) is reported for spatiotemporal tumor suppression by combining photodynamic therapy (PDT) with antiangiogenesis. In brief, FPPT@Axi is prepared by utilizing an NRP-1-targeting chimeric peptide (Fmoc-K(PpIX)-PEG8-TKPRR) to encapsulate the antiangiogenic drug Axitinib (Axi). Importantly, the NRP-1-mediated targeting property enables FPPT@Axi to selectively concentrate at vascular endothelial and breast cancer cells, facilitating the production of reactive oxygen species (ROS) in situ for specific vascular disruption and enhanced cell apoptosis under light stimulation. Moreover, the codelivered Axi can further inhibit vascular endothelial growth factor receptor (VEGFR) to impair the negative feedback of PDT-induced tumor neovascularization. Consequently, FPPT@Axi spatiotemporally restrains the tumor growth through blocking angiogenesis, destroying tumor vessels, and inducing tumor apoptosis. Such an NRP-1-mediated targeting codelivery system sheds light on constructing an appealing candidate with translational potential by using clinically approved PDT and chemotherapy.

Virtual Screening, Docking, and Designing of New VEGF Inhibitors as Anti-cancer Agents.

BACKGROUND: VEGFR-2 tyrosine kinase inhibitors are receiving a lot of attention as prospective anticancer medications in the current drug discovery process. OBJECTIVE: This work aims to explore the PubChem library for novel VEGFR-2 kinase inhibitors. 1H-Indazole-containing drug AXITINIB, or AG-013736 (FDA approved), is chosen as a rational molecule for drug design. This scaffold proved its efficiency in treating cancer and other diseases as well. METHODS: The present study used the virtual screening of the database, protein preparation, grid creation, and molecular docking analyses. RESULTS: The protein was validated on different parameters like the Ramachandran plot, the ERRAT score, and the ProSA score. The Ramachandran plot revealed that 92.1% of the amino acid residues were located in the most favorable region; this was complemented by an ERRAT score (overall quality factor) of 96.24 percent and a ProSA (Z score) of -9.24 percent. The Lipinski rule of five was used as an additional filter for screening molecules. The docking results showed values of binding affinity between -14.08 and -12.34 kcal/mol. The molecule C1 showed the highest docking value of -14.08 Kcal/mol with the maximum number of strong H-bonds by -NH of pyridine to amino acid Cys104 (4.22Å), -NH of indazole to Glu108 (4.72), and Glu70 to bridge H of -NH. These interactions are similar to Axitinib docking interactions like Glu70, Cys104, and Glu102. The docking studies revealed that pi-alkyl bonds are formed with unsubstituted pyridine, whereas important H-bonds are observed with different substitutions around -NH. Based on potential findings, we designed new molecules, and molecular docking studies were performed on the same protein along with ADMET studies. The designed molecules (M1-M4) also showed comparable docking results similar to Axitinib, along with a synthetic accessibility score of less than 4.5. CONCLUSION: The docking method employed in this work opens up new possibilities for the design and synthesis of novel compounds that can act as VEGFR-2 tyrosine kinase inhibitors and treat cancer.

An Avascular Niche Created by Axitinib-Loaded PCL/Collagen Nanofibrous Membrane Stabilized Subcutaneous Chondrogenesis of Mesenchymal Stromal Cells.

Engineered cartilage derived from mesenchymal stromal cells (MSCs) always fails to maintain the cartilaginous phenotype in the subcutaneous environment due to the ossification tendency. Vascular invasion is a prerequisite for endochondral ossification during the development of long bone. As an oral antitumor medicine, Inlyta (axitinib) possesses pronounced antiangiogenic activity, owing to the inactivation of the vascular endothelial growth factor (VEGF) signaling pathway. In this study, axitinib-loaded poly(ε-caprolactone) (PCL)/collagen nanofibrous membranes are fabricated by electrospinning for the first time. Rabbit-derived MSCs-engineered cartilage is encapsulated in the axitinib-loaded nanofibrous membrane and subcutaneously implanted into nude mice. The sustained and localized release of axitinib successfully inhibits vascular invasion, stabilizes cartilaginous phenotype, and helps cartilage maturation. RNA sequence further reveals that axitinib creates an avascular, hypoxic, and low immune response niche. Timp1 is remarkably upregulated in this niche, which probably plays a functional role in inhibiting the activity of matrix metalloproteinases and stabilizing the engineered cartilage. This study provides a novel strategy for stable subcutaneous chondrogenesis of mesenchymal stromal cells, which is also suitable for other medical applications, such as arthritis treatment, local treatment of tumors, and regeneration of other avascular tissues (cornea and tendon).

Photoswitchable Azo- and Diazocine-Functionalized Derivatives of the VEGFR-2 Inhibitor Axitinib.

In this study, we aimed at the application of the concept of photopharmacology to the approved vascular endothelial growth factor receptor (VEGFR)-2 kinase inhibitor axitinib. In a previous study, we found out that the photoisomerization of axitinib's stilbene-like double bond is unidirectional in aqueous solution due to a competing irreversible [2+2]-cycloaddition. Therefore, we next set out to azologize axitinib by means of incorporating azobenzenes as well as diazocine moieties as photoresponsive elements. Conceptually, diazocines (bridged azobenzenes) show favorable photoswitching properties compared to standard azobenzenes because the thermodynamically stable Z-isomer usually is bioinactive, and back isomerization from the bioactive E-isomer occurs thermally. Here, we report on the development of different sulfur-diazocines and carbon-diazocines attached to the axitinib pharmacophore that allow switching the VEGFR-2 activity reversibly. For the best sulfur-diazocine, we could verify in a VEGFR-2 kinase assay that the Z-isomer is biologically inactive (IC50 >> 10,000 nM), while significant VEGFR-2 inhibition can be observed after irradiation with blue light (405 nm), resulting in an IC50 value of 214 nM. In summary, we could successfully develop reversibly photoswitchable kinase inhibitors that exhibit more than 40-fold differences in biological activities upon irradiation. Moreover, we demonstrate the potential advantage of diazocine photoswitches over standard azobenzenes.

Bioanalytical assay for the new-generation ROS1/TRK/ALK inhibitor repotrectinib in mouse plasma and tissue homogenate using liquid chromatography-tandem mass spectrometry.

Repotrectinib, a next-generation ROS1/TRK/ALK tyrosine kinase inhibitor, overcomes resistance due to acquired solvent-front mutations involving ROS1, NTRK1-3, and ALK. A bioanalytical assay for quantification of repotrectinib in mouse plasma and seven tissue-related matrices (brain, liver, spleen, kidney, small intestinal tissue, small intestinal content, and testis homogenates) was developed and validated using liquid chromatography with tandem mass spectrometric detection in a high-throughput 96-well format. Protein precipitation was performed by adding acetonitrile, also containing the internal standard axitinib, to 10-µl samples for all matrices. Chromatographic separation of analytes was done on an ACQUITY UPLC® BEH C18 column by gradient elution using ammonium hydroxide in water and methanol. Compounds were monitored with positive electrospray ionization using a triple quadruple mass spectrometer in selected reaction monitoring mode. The method was successfully validated in the 1-1000 ng/ml calibration range. Precisions (intra- and interday) were in the range of 1.3-8.7% and accuracies were in between 90.5% and 107.3% for all levels in all matrices. The developed method was successfully applied to investigate the plasma pharmacokinetics and tissue accumulation of repotrectinib in wild-type mice.

Axitinib-Loaded Poly(Lactic-Co-Glycolic Acid) Nanoparticles for Age-Related Macular Degeneration: Formulation Development and In Vitro Characterization.

Despite all the research aiming to treat ocular diseases, age-related macular degeneration (AMD) remains one of the serious diseases worldwide, which needs to be treated. Neovascularization is a key factor in AMD and thus antiangiogenic therapy is beneficial in reducing the development of new abnormal blood vessels. Axitinib, multireceptor tyrosine kinase inhibitor, is a small molecule that works by blocking vascular endothelial growth factor receptors (VEGFR) and platelet-derived growth factor receptors (PDGFR) responsible for developing neovascularization. The goal of this study is to develop a sustained release formulation of axitinib-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles to minimize frequent administration of the drug by intravitreal injection. The nanoparticles were characterized for particle size and zeta potential, as well as using differential scanning calorimetry, transmission electrode microscope, and in vitro drug release profile. The cytotoxicity of the formulation was evaluated on human retinal pigmented epithelium ARPE19 cells by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide salt] assay. The cellular uptake, antimigration assay, and vascular endothelial growth factor (VEGF) expression levels were found out in vitro using cells. The optimized formulation was 131.33 ± 31.20 nm in size with -4.63 ± 0.76 mV zeta potential. Entrapment efficiency was found to be 87.9% ± 2.7%. The cytotoxicity of ARPE19 cells was <12% for nanoparticles suggesting the in vitro compatibility at 10 µM concentration of drug. Cellular uptake, antimigration assay, and VEGF expression levels for the nanoparticles suggested greater uptake, significant antiangiogenic potential, and inhibition of VEGF activity. The results showed successful development of axitinib-loaded PLGA nanoparticles as an alternative potential treatment for AMD.

Axitinib: A Photoswitchable Approved Tyrosine Kinase Inhibitor.

The goal of photopharmacology is to develop photoswitchable enzyme modulators as tunable (pro-)drugs that can be spatially and temporally controlled by light. In this context, the tyrosine kinase inhibitor axitinib, which contains a photosensitive stilbene-like moiety that allows for E/Z isomerization, is of interest. Axitinib is an approved drug that targets the vascular endothelial growth factor receptor 2 (VEGFR2) and is licensed for second-line therapy of renal cell carcinoma. The photoinduced E/Z isomerization of axitinib has been investigated to explore if its inhibitory effect can be turned "on" and "off", as triggered by light. Under controlled light conditions, (Z)-axitinib is 43 times less active than that of the E isomer in an VEGFR2 assay. Furthermore, it was proven that kinase activity in human umbilical vein cells (HUVECs) was decreased by (E)-axitinib, but only weakly affected by (Z)-axitinib. By irradiating (Z)-axitinib in vitro with UV light (λ=385 nm), it is possible to switch it almost quantitatively into the E isomer and to completely restore the biological activity of (E)-axitinib. However, switching the biological activity off from (E)- to (Z)-axitinib was not possible in aqueous solution due to a competing irreversible [2+2]-photocycloaddition, which yielded a biologically inactive axitinib dimer.

Computational assessment of thioether isosteres.

Replacement of the sulfur atom in biologically active diaryl and heteroaryl thioethers (Ar-S-Ar', HAr-S-Ar, and HAr-S-HAr') with any of several one-atom or two-atom linkers can be expected to reduce the susceptibility of the analogue to metabolic oxidation, a well-documented problem for thioethers intended for medicinal chemistry applications. Ab initio calculations indicate how well various proposed thioether isosteric groups, including some new and unusual ones, may perform structurally and electronically in replacing the bridging sulfur atom. Four of these are calculationally evaluated as proposed substructures in Axitinib analogues. The predicted binding behavior of the latter within two different previously crystallographically characterized protein-Axitinib binding sites (VEGFR2 kinase and ABL1 T315I gatekeeper mutant kinase), and an assessment of their suitability and anticipated shortcomings, are presented.