Linker Design Impacts Antibody-Drug Conjugate Pharmacokinetics and Efficacy via Modulating the Stability and Payload Release Efficiency

The development of antibody-drug conjugates (ADCs) has significantly been advanced in the past decade given the improvement of payloads, linkers and conjugation methods. In particular, linker design plays a critical role in modulating ADC stability in the systemic circulation and payload release efficiency in the tumors, which thus affects ADC pharmacokinetic (PK), efficacy and toxicity profiles. Previously, we have investigated key linker parameters such as conjugation chemistry (e.g., maleimide vs. disulfide), linker length and linker steric hindrance and their impacts on PK and efficacy profiles. Herein, we discuss our perspectives on development of integrated strategies for linker design to achieve a balance between ADC stability and payload release efficiency for desired efficacy in antigen-expressing xenograft models. The strategies have been successfully applied to the design of site-specific THIOMABTM antibody-drug conjugates (TDCs) with different payloads. We also propose to conduct dose fractionation studies to gain guidance for optimal dosing regimens of ADCs in pre-clinical models

Tissue distribution and elimination of C-14 apixaban in rats

Abbreviations used: AUC, area under the plasma concentration-time curve; BCRP, breast cancer resistance protein; BLQ, below limit of quantitation; LSC, liquid scintillation counting; LC/MS, liquid chromatography/mass spectrometry; MS/MS, tandem mass spectrometry; Mrp, multidrug resistance protein; LLOQ, low limit of quantitation; P-gp, Pglycoprotein; PK, pharmacokinetics; QWBA, Whole-body autoradiography; SD, SpragueDawley rats. ABSTRACT Apixaban, a potent and highly selective factor Xa inhibitor, is currently under development for treatment of arterial and venous thrombotic diseases. The distribution, metabolism, and elimination of C-14 apixaban were investigated in male, female, pregnant and lactating rats following single oral doses. Tissue distribution of radioactivity in rats was measured using quantitative whole-body autoradiography. Following single oral administration, radioactivity distributed quickly in rats with C max at 1 h for most tissues. The elimination t 1/2 of radioactivity in blood was 1.7 to 4.2 h. The blood AUC of radioactivity was similar between male and female rats and was slightly higher in pregnant and lower in lactating rats. The radioactivity concentration in tissues involved in elimination was greater than blood with the highest concentration in gastrointestinal tracts, liver, urinary bladder/contents, and lowest level in brains. In pregnant rats, the whole-body autoradiogram showed that low levels of radioactivity were present in fetal blood, liver, and kidney, and were much lower than the radioactivity in respective maternal organs. Fecal route was the major (74% of dose) and urinary was minor pathway (14%) for apixaban elimination. Following single oral doses of C-14 apixaban to lactating rats, apixaban exhibited extensive lacteal excretion with apixaban as the major component. In summary, tissue distribution of apixaban in rats was extensive, but with limited transfer to fetal and brain tissues and extensive secretion into rat milk with parent drug as the major component. Milk excretion could account for 10% of apixaban dose, which was comparable to urinary elimination in rats. Tissue distribution and drug excretion of apixaban are consistent with a moderately permeable drug that is a substrate for P-gp and BCRP efflux transporters

Effects of surface modification, carbon nanofiber concentration, and dispersion time on the mechanical properties of carbon-nanofiber–polycarbonate composites

The time effect of ultrasonication was investigated for dispersing carbon nanofibers (CNFs) into a polycarbonate (PC) matrix on the mechanical properties of thus-produced composites. The effects of CNF surface modification by plasma treatment and the CNF concentration in composites on their mechanical properties were also explored. The plasma coating was characterized by HRTEM and FT-IR. Furthermore, the plasma polymerization (10 w) treatment on the CNF enhanced the CNF dispersion in the polymer matrix. The mechanical properties of the CNF–PC composites varied with the dispersion time, at first increasing to a maximum value and then dropping down. After a long ultrasonic treatment (24 h), the properties increased again. At a high concentration, the CNF-PC suspension became difficult to disperse. Additionally, the possible mechanisms for these behaviors are simply proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3792–3797, 2007Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55871/1/25112_ftp.pd

In Vivo Cancer Targeting and Imaging-Guided Surgery with Near Infrared-Emitting Quantum Dot Bioconjugates

Abstract Early detection and subsequent complete surgical resection are among the most efficient methods for treating cancer. However, low detection sensitivity and incomplete tumor resection are two challenging issues. Nanoparticle-based imaging-guided surgery has proven promising for cancer-targeted imaging and subsequent debulking surgery. Particularly, the use of near infrared (NIR) fluorescent probes such as NIR quantum dots (QDs) allows deep penetration and high sensitivity for tumor detection. In this study, NIR-emitting CdTe QDs (maximum fluorescence emission peak at 728 nm) were synthesized with a high quantum yield (QY) of 38%. The tumor-specific QD bioconjugates were obtained by attaching cyclic Arg-Gly-Asp peptide (cRGD) to the surface of synthesized QDs, and then injected into U87 MG tumor-bearing mice via tail veins for tumor-targeted imaging. The tumor and its margins were visualized and distinguished by NIR QD bioconjugates, and tumor resection was successfully accomplished via NIR guidance using a Fluobeam-700 NIR imaging system. Our work indicates that the synthesized tumor-specific NIR QDs hold great promise as a potential fluorescent indicator for intraoperative tumor imaging

Title Page: Going beyond common drug metabolizing enzymes: Case studies of biotransformation involving aldehyde oxidase, gamma-glutamyl transpeptidase, cathepsin B, flavin-containing monooxygenase, and ADP-ribosyltransferase Running Title Page: Non-P450 d

adenine dinucleotide and its reduced form, NADP+/H, nicotinamide adenine dinucleotide phosphate and its reduced form, NMN, nicotinamide mononucleotide; PAB, para-aminobenzyl; Val-Cit, valine-citrulline. DMD #70169 3 Abstract The significant roles that cytochrome P450 (P450) and UDP-glucuronosyl transferase (UGT) enzymes play in drug discovery cannot be ignored, and these enzyme systems are commonly examined during drug optimization using liver microsomes or hepatocytes. At the same time, other drug metabolizing enzymes have a role in the metabolism of drugs and can lead to challenges in drug optimization that could be mitigated if the contributions of these enzymes were better understood. This paper presents examples (mostly from Genentech) of five different non-P450 and non-UGT enzymes that contribute to the metabolic clearance or bioactivation of drugs and drug candidates. Aldehyde oxidase mediates a unique amide hydrolysis of GDC-0834, leading to high clearance of the drug. Likewise, the rodent-specific ribose conjugation by ADP-ribosyltransferase leads to high clearance of an interleukin-2-inducible T-cell kinase inhibitor. Metabolic reactions by flavin-containing monooxygenases (FMO) are easily mistaken for P450-mediated metabolism such as oxidative defluorination of 4-fluoro-N-methylaniline by FMO. Gamma-glutamyl transpeptidase is involved in the initial hydrolysis of glutathione metabolites, leading to formation of proximate toxins and nephrotoxicity, as is observed with cisplatin in the clinic, or renal toxicity, as is observed with efavirenz in rodents. Finally, cathepsin B is a lysosomal enzyme that is highly expressed in human tumors and has been targeted to release potent cytotoxins, as in the case of brentuximab vedotin. These examples of non-P450-and non-UGT-mediated metabolism show that a more complete understanding of drug metabolizing enzymes allows for better insight into the fate of drugs and improved design strategies of molecules in drug discovery. DMD #70169

Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe 3 O 4 ) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe 3 O 4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent~10 nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe 3 O 4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe 3 O 4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high Néel relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems

Preclinical discovery of apixaban, a direct and orally bioavailable factor Xa inhibitor

Apixaban (BMS-562247; 1-(4-methoxyphenyl)-7-oxo-6-(4-(2-oxopiperidin-1-yl)phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxamide), a direct inhibitor of activated factor X (FXa), is in development for the prevention and treatment of various thromboembolic diseases. With an inhibitory constant of 0.08 nM for human FXa, apixaban has greater than 30,000-fold selectivity for FXa over other human coagulation proteases. It produces a rapid onset of inhibition of FXa with association rate constant of 20 μM−1/s approximately and inhibits free as well as prothrombinase- and clot-bound FXa activity in vitro. Apixaban also inhibits FXa from rabbits, rats and dogs, an activity which parallels its antithrombotic potency in these species. Although apixaban has no direct effects on platelet aggregation, it indirectly inhibits this process by reducing thrombin generation. Pre-clinical studies of apixaban in animal models have demonstrated dose-dependent antithrombotic efficacy at doses that preserved hemostasis. Apixaban improves pre-clinical antithrombotic activity, without excessive increases in bleeding times, when added on top of aspirin or aspirin plus clopidogrel at their clinically relevant doses. Apixaban has good bioavailability, low clearance and a small volume of distribution in animals and humans, and a low potential for drug–drug interactions. Elimination pathways for apixaban include renal excretion, metabolism and biliary/intestinal excretion. Although a sulfate conjugate of Ο-demethyl apixaban (O-demethyl apixaban sulfate) has been identified as the major circulating metabolite of apixaban in humans, it is inactive against human FXa. Together, these non-clinical findings have established the favorable pharmacological profile of apixaban, and support the potential use of apixaban in the clinic for the prevention and treatment of various thromboembolic diseases

Low-Temperature Preparation of Amorphous-Shell/ Nanocrystalline-Core Nanostructured Electrodes for Flexible Dye-Sensitized Solar Cells

An amorphous shell/nanocrystalline core nanostructured TiO2 electrode was prepared at low temperature, in which the mixture of TiO2 powder and TiCl4 aqueous solution was used as the paste for coating a film and in this film amorphous TiO2 resulted from direct hydrolysis of TiCl4 at 100◦C sintering was produced to connect the particles forming a thick crack-free uniform nanostructured TiO2 film (12 μm), and on which a photoelectrochemical solar cell-based was fabricated, generating a short-circuit photocurrent density of 13.58 mA/cm2, an open-circuit voltage of 0.647 V, and an overall 4.48 % light-to-electricity conversion efficiency under 1 sun illumination. Copyright © 2008 Dongshe Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1