Targeted delivery of a therapeutic agent to a site of pathology to ameliorate disease while limiting exposure at undesired tissues is an aspirational treatment scenario. Targeting diseased kidneys for pharmacologic treatment has had limited success. We designed an approach to target an extracellular matrix protein, the fibronectin extra domain A isoform (FnEDA), which is relatively restricted in distribution to sites of tissue injury. In a mouse unilateral ureteral obstruction (UUO) model of renal fibrosis, injury induced significant upregulation of FnEDA in the obstructed kidney. Using dual variable domain Ig (DVD-Ig) technology, we constructed a molecule with a moiety to target FnEDA and a second moiety to neutralize TGF- β . After systemic injection of the bispecific TGF- β + FnEDA DVD-Ig or an FnEDA mAb, chemiluminescent detection and imaging with whole-body single-photon emission computed tomography (SPECT) revealed significantly higher levels of each molecule in the obstructed kidney than in the nonobstructed kidney, the ipsilateral kidney of sham animals, and other tissues. In comparison, a systemically administered TGF- β mAb accumulated at lower concentrations in the obstructed kidney and exhibited a more diffuse whole-body distribution. Systemic administration of the bispecific DVD-Ig or the TGF- β mAb (1–10 mg/kg) but not the FnEDA mAb attenuated the injury-induced collagen deposition detected by immunohistochemistry and elevation in Col1a1, FnEDA, and TIMP1 mRNA expression in the obstructed kidney. Overall, systemic delivery of a bispecific molecule targeting an extracellular matrix protein and delivering a TGF- β mAb resulted in a relatively focal uptake in the fibrotic kidney and reduced renal fibrosis.
396 Objectives ABT-806 is a humanized antibody targeting a unique epitope on EGFR only available for binding when EGFR is overexpressed, activated, or when the EGFRvIII mutation is present. This property allows for a higher tumor to normal tissue contrast and thus enables ABT-806 for payload delivery. We have therefore developed 111In-labeled ABT-806 (ABT-806i) for SPECT imaging of EGFR positive tumors. Methods The ABT-806 antibody was conjugated with either DTPA or CHX-A’-DTPA and used to generate 111In-labeled ABT-806 (ABT-806i) which was characterized to evaluate its radiochemical features and its relative tumor-specific binding properties using nanoSPECT/CT image quantification. Results Selective tumor targeting of 111In-labeled ABT-806 (ABT-806i) was demonstrated in both wild-type EGFR overexpressing tumor xenografts (11 ± 2.1 %ID/cc) and EGFRvIII positive tumor xenografts, 21.5 ± 4.3%ID/cc in flank and 75.1 ± 11.3 %ID/cc as orthotopic glioma. The specific tumor uptake was inhibited gradually by co-dosing increasing concentrations of unlabeled ABT-806 antibody, from which a tumor occupancy curve was generated to estimate the dose for 50% tumor saturation as 13 mg/kg in flank xenografts. ABT-806 conjugated to CHX-A’-DTPA was GMP manufactured as a formulated kit. The labeling efficiency with sterile 111In was consistently higher than 95% for the instant preparation. The immunoreactive fraction was 0.8 ± 0.06 and the product is stable for 5 days and the prepared ABT-806i retained the favorable in vivo biodistribution and tumor targeting features. Conclusions These features render ABT-806i a promising imaging agent currently under clinical validation for characterization of tumor EGFR status. Research Support Abbott Labs
Despite clinical efficacy, current approved agents targeting EGFR are associated with on-target toxicities as a consequence of disrupting normal EGFR function. MAb 806 is a novel EGFR antibody that selectively targets a tumor-selective epitope suggesting that a mAb 806-based therapeutic would retain antitumor activity without the on-target toxicities associated with EGFR inhibition. To enable clinical development, a humanized variant of mAb 806 designated ABT-806 was generated and is currently in phase 1 trials. We describe the characterization of binding and functional properties of ABT-806 compared with the clinically validated anti-EGFR antibody cetuximab. ABT-806 binds the mutant EGFRvIII with high affinity and, relative to cetuximab, exhibits increased potency against glioblastoma multiforme cell line and patient-derived xenografts expressing this form of the receptor. ABT-806 also inhibits the growth of squamous cell carcinoma xenograft models expressing high levels of wild-type EGFR, associated with inhibition of EGFR signaling, although higher doses of ABT-806 than cetuximab are required for similar activity. ABT-806 enhances in vivo potency of standard-of-care therapies used to treat glioblastoma multiforme and head and neck squamous cell carcinoma. An indium-labeled version of ABT-806, [(111)In]-ABT-806, used to investigate the relationship between dose and receptor occupancy, revealed greater receptor occupancy at lowers doses in an EGFRvIII-expressing model and significant uptake in an orthotopic model. Collectively, these results suggest that ABT-806 may have antitumor activity superior to cetuximab in EGFRvIII-expressing tumors, and similar activity to cetuximab in tumors highly overexpressing wild-type EGFR with reduced toxicity.
Objectives Sarcopenia is the progressive decline in muscle mass, strength and function that is exacerbated with age. It is well known that there is an overlap between sarcopenia and osteopenia/osteoporosis in the aging population. Thus, addressing both muscle and bone loss during aging is important. Epigallocatechin gallate (EGCg) is the most abundant green tea catechin and has well established anti‐inflammatory and antioxidant benefits. Green tea consumption has also been associated with bone health. In this study we examined the impact of chronic EGCg treatment on muscle mass and bone structure in aging rats. Methods Aged male Sprague‐Dawley rats (21 months) were fed the following diets ad libitum: Control group (n=9) fed AIN93M diet, and a treatment group (n=10) fed AIN93M diet +EGCg (200 mg/kg) for 8 weeks. At the end of study, gastrocnemius muscles were weighed, and histological analysis was performed to measure muscle fiber cross sectional area (CSA) using hematoxylin & eosin staining. Bones were analyzed by MicroCT imaging (Burker) of the tibia at ~22 μm resolution and images were processed using Inveon Research Workplace software. All bone samples were analyzed for trabecular bone volume, trabecular number, trabecular spacing, trabecular thickness, trabecular pattern factor and bone density. Results Gastrocnemius muscle wet weights were significantly higher (p<0.05) and fiber CSA tended to be higher (p<0.06) in the EGCg group compared to controls. Tibia bone volume/total volume density was significantly greater (p=0.03) in animals treated with EGCg compared to control. Significant differences were found in trabecular microstructure, with a significant increase in trabecular number per given volume (p=0.01) and a corresponding significant decrease in trabecular spacing (p=0.02) in EGCg‐treated rats compared to control. No significant group differences were found in overall bone density or trabecular thickness. Differences in mean values between control and EGCg groups were determined by student’s t‐test. Conclusions These data present novel findings on the osteoprotective mechanism of EGCg on the aging bone through an increase in trabecular bone volume, trabecular number and trabecular spacing. Furthermore, the preservation of muscle mass and muscle fiber CSA suggests that the use of green tea catechin, EGCg, could be a potential nutritional therapy to prevent the progression of muscle and bone loss during sarcopenia. Support or Funding Information Abbott Nutrition
Underwater electro‐olfactogram (EOG) recordings involving 150 steroids and eight prostaglandins were used to determine which of these potential odorants are detected by the olfactory organ of an African cichlid, Haplochromis burtoni . In initial EOG tests at 10 −9 M, H. burtoni did not respond to unconjugated steroids or prostaglandins, but did respond to 17 conjugated steroids, 11 of which (17β‐oestradiol‐17β‐glucuronide; 17β‐oestradiol‐3‐sulphate; 17β‐oestradiol‐3,17β‐disulphate; epiandrosteron‐3β‐sulphate; etiocholanolone‐3α‐glucuronide; testosterone‐17β‐sulphate; dehydroepiandrosterone‐3β‐sulphate; 5α‐pregnan‐3β‐ol‐20‐one‐3β‐sulphate; 5β‐pregnan‐3α,17‐diol‐20‐one‐3α‐glucuronide; 5β‐pregnan‐3α,17,21‐triol‐11,20‐dione‐3α‐glucuronide; pregnenolone‐3β‐sulphate) were selected for EOG concentration‐response, cross‐adaptation and binary mixture tests. The EOG detection thresholds ranged from 10 −11 to 10 −9 M in all but one instance (female threshold to pregnenolone‐3β‐sulphate; 10 −8 M), and males and females exhibited only minor differences in EOG threshold or response magnitude. Results of EOG cross‐adaptation tests, which were supported by results of binary mixture tests, indicated that the response to the 11 steroid conjugates is mediated by five putative olfactory receptor mechanisms characterized by specificity for conjugate position and type: 3‐sulphate, 17‐sulphate, 3,17‐disulphate, 3‐glucuronide, 17‐glucuronide. Although there is no evidence that H. burtoni releases, or exhibits biological response to, the steroids shown to be detected in this study, the present results are suggestive of a complex pheromone system utilizing steroid conjugates.
Living in a medium that can limit visual information but readily exposes the olfactory organ to hormonal compounds released by conspecifics, fish throughout their long evolutionary history have had both clear cause and ample opportunity to evolve olfactory responsiveness to these potentially important chemical cues (hormonal pheromones). Indeed, water-borne steroids, prostaglandins, and their metabolites are detected with great sensitivity and specificity by the olfactory organs of diverse fishes, and exert important effects on reproductive behavior and physiology in major taxa including carps (goldfish), catfishes, salmon, and gobies. Best understood are goldfish, where periovulatory females sequentially release a preovulatory steroid pheromone and a postovulatory prostaglandin pheromone that dramatically affect male behavior, physiology, and reproductive fitness. Although the diverse array of hormonal products released and detected by fish indicates clear potential for species-specific hormonal pheromones, olfactory recordings showing similar patterns of hormone detection among closely related species provide little evidence of selection for specificity. By demonstrating that the actions of sex hormones and related products are not limited to reproductive synchrony within the individual, the relatively recent discovery of hormonal pheromones has considerably expanded our understanding of fish reproductive function, while providing valuable model systems for future study of olfactory function and pheromone evolution.
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