Targeting Anti-TGF-ß Therapy to Fibrotic Kidneys with a Dual Specificity Antibody Approach.

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-ß After systemic injection of the bispecific TGF-ß + 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-ß 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-ß 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-ß mAb resulted in a relatively focal uptake in the fibrotic kidney and reduced renal fibrosis.

Image quality of Zr-89 PET imaging in the Siemens microPET Focus 220 preclinical scanner.

PURPOSE: Zr-89 positron emission tomography (PET) is a valuable tool for understanding the biodistribution and pharmacokinetics of antibody-based therapeutics. We compared the image quality of Zr-89 PET and F-18 PET in the Siemens microPET Focus 220 preclinical scanner using different reconstruction methods. PROCEDURES: Image quality metrics were measured in various Zr-89 and F-18 PET phantoms, including the NEMA NU 4-2008 image quality phantom. Images were reconstructed using various algorithms. RESULTS: Zr-89 PET had greater image noise, inferior spatial resolution, and greater spillover than F-18 PET, but comparable recovery coefficients for cylinders of various diameters. Of the reconstruction methods, OSEM3D resulted in the lowest noise, highest recovery coefficients, best spatial resolution, but also the greatest spillover. Scatter correction results were found to be sensitive to varying object sizes. CONCLUSIONS: Zr-89 PET image quality was inferior to that of F-18, and no single reconstruction method was superior in all aspects of image quality.

Synthesis of [F]fallypride in a micro-reactor: rapid optimization and multiple-production in small doses for micro-PET studies.

A commercial coiled-tube micro-reactor (NanoTek; Advion) was used as a convenient platform for the synthesis of [(18)F]fallypride in small doses (0.5-1.5 mCi) for micro-PET studies of brain dopamine subtype-2 receptors in rodents. Each radiosynthesis used low amounts (20-40 mug; 39-77 nmol) of tosylate precursor and [(18)F]fluoride ion (0.5-2.5 mCi). Optimization of the labeling reaction in the apparatus, with respect to the effects of precursor amount, reaction temperature, flow rate and [(18)F]fluoride ion to precursor ratio, was achieved rapidly and the decay-corrected radiochemical yield of [(18)F]fallypride (up to 88%) was reproducible. The low amounts of material used in each radiosynthesis allowed crude [(18)F]fallypride to be purified rapidly on an analytical-size reverse phase HPLC column, preceding formulation for intravenous injection. Scale-up of the reaction was easily achieved by continuously infusing reagent precursor solutions to obtain [(18)F]fallypride in much greater quantity.