A palladium-catalyst stabilized in the chiral environment of a monoclonal antibody in water.

We report the first preparation of a monoclonal antibody (mAb) that can immobilize a palladium (Pd)-complex. The allylic amination reaction using a supramolecular catalyst consisting of the Pd-complex and mAb selectively gives the (R)-enantiomer product with an enantiomeric excess (ee) of 98 ± 2%. This is in sharp contrast to the reaction catalyzed by a conventional Pd-catalyst (ee < 2%).

ImmunoPET for assessing the differential uptake of a CD146-specific monoclonal antibody in lung cancer.

PURPOSE: Overexpression of CD146 in solid tumors has been linked to disease progression, invasion, and metastasis. We describe the generation of a 64Cu-labeled CD146-specific antibody and its use for quantitative immunoPET imaging of CD146 expression in six lung cancer models. METHODS: The anti-CD146 antibody (YY146) was conjugated to 1,4,7-triazacyclononane-triacetic acid (NOTA) and radiolabeled with 64Cu. CD146 expression was evaluated in six human lung cancer cell lines (A549, NCI-H358, NCI-H522, HCC4006, H23, and NCI-H460) by flow cytometry and quantitative western blot studies. The biodistribution and tumor uptake of 64Cu-NOTA-YY146 was assessed by sequential PET imaging in athymic nude mice bearing subcutaneous lung cancer xenografts. The correlation between CD146 expression and tumor uptake of 64Cu-NOTA-YY146 was evaluated by graphical software while ex vivo biodistribution and immunohistochemistry studies were performed to validate the accuracy of PET data and spatial expression of CD146. RESULTS: Flow cytometry and western blot studies showed similar findings with H460 and H23 cells showing high levels of expression of CD146. Small differences in CD146 expression levels were found among A549, H4006, H522, and H358 cells. Tumor uptake of 64Cu-NOTA-YY146 was highest in CD146-expressing H460 and H23 tumors, peaking at 20.1 ± 2.86 and 11.6 ± 2.34 %ID/g at 48 h after injection (n = 4). Tumor uptake was lowest in the H522 model (4.1 ± 0.98 %ID/g at 48 h after injection; n = 4), while H4006, A549 and H358 exhibited similar uptake of 64Cu-NOTA-YY146. A positive correlation was found between tumor uptake of 64Cu-NOTA-YY146 (%ID/g) and relative CD146 expression (r 2 = 0.98, p < 0.01). Ex vivo biodistribution confirmed the accuracy of the PET data. CONCLUSION: The strong correlation between tumor uptake of 64Cu-NOTA-YY146 and CD146 expression demonstrates the potential use of this radiotracer for imaging tumors that elicit varying levels of CD146. In the future, this tool may promote enhanced monitoring of therapeutic response and improved patient stratification.

Manganese and microbial pathogenesis: sequestration by the Mammalian immune system and utilization by microorganisms.

Bacterial and fungal pathogens cause a variety of infectious diseases and constitute a significant threat to public health. The human innate immune system represents the first line of defense against pathogenic microbes and employs a range of chemical artillery to combat these invaders. One important mechanism of innate immunity is the sequestration of metal ions that are essential nutrients. Manganese is one nutrient that is required for many pathogens to establish an infective lifestyle. This review summarizes recent advances in the role of manganese in the host-pathogen interaction and highlights Mn(II) sequestration by neutrophil calprotectin as well as how bacterial acquisition and utilization of manganese enables pathogenesis.

The human polynucleotide kinase/phosphatase (hPNKP) inhibitor A12B4C3 radiosensitizes human myeloid leukemia cells to Auger electron-emitting anti-CD123 ¹¹¹In-NLS-7G3 radioimmunoconjugates.

INTRODUCTION: Leukemia stem cells (LSCs) are believed to be responsible for initiating and propagating acute myeloid leukemia (AML) and for causing relapse after treatment. Radioimmunotherapy (RIT) targeting these cells may improve the treatment of AML, but is limited by the low density of target epitopes. Our objective was to study a human polynucleotide kinase/phosphatase (hPNKP) inhibitor that interferes with DNA repair as a radiosensitizer for the Auger electron RIT agent, ¹¹¹In-NLS-7G3, which recognizes the CD123⁺/CD131⁻ phenotype uniquely displayed by LSCs. METHODS: The surviving fraction (SF) of CD123⁺/CD131⁻ AML-5 cells exposed to ¹¹¹In-NLS-7G3 (33-266 nmols/L; 0.74MBq/µg) or to γ-radiation (0.25-5Gy) was determined by clonogenic assays. The effect of A12B4C3 (25 µmols/L) combined with ¹¹¹In-NLS-7G3 (16-66 nmols/L) or with γ-radiation (0.25-2Gy) on the SF of AML-5 cells was assessed. The density of DNA double-strand breaks (DSBs) in the nucleus was measured using the γ-H2AX assay. Cellular dosimetry was estimated based on the subcellular distribution of ¹¹¹In-NLS-7G3 measured by cell fractionation. RESULTS: Binding of (111)In-NLS-7G3 to AML-5 cells was reduced by 2.2-fold in the presence of an excess (1µM) of unlabeled NLS-7G3, demonstrating specific binding to the CD123⁺/CD131⁻ epitope. ¹¹¹In-NLS-7G3 reduced the SF of AML-5 cells from 86.1 ± 11.0% at 33 nmols/L to 10.5 ± 3.6% at 266 nmols/L. Unlabeled NLS-7G3 had no significant effect on the SF. Treatment of AML-5 cells with γ-radiation reduced the SF from 98.9 ± 14.9% at 0.25Gy to 0.03 ± 0.1% at 5 Gy. A12B4C3 combined with ¹¹¹In-NLS-7G3 (16-66 nmols/L) enhanced the cytotoxicity up to 1.7-fold compared to treatment with radioimmunoconjugates alone and was associated with a 1.6-fold increase in DNA DSBs in the nucleus. A12B4C3 enhanced the cytotoxicity of γ-radiation (0.25-0.5Gy) on AML-5 cells by up to 1.5-fold, and DNA DSBs were increased by 1.7-fold. Exposure to ¹¹¹In-NLS-7G3 (66 nmols/L) delivered up to 0.6Gy to AML-5 cells. CONCLUSIONS: We conclude that A12B4C3 radiosensitized AML cells to the DNA damaging effects of ¹¹¹In-NLS-7G3. Combination treatment may increase the effectiveness for Auger electron RIT of AML targeting the LSC subpopulation.