Preclinical Development of a Bispecific Antibody that Safely and Effectively Targets CD19 and CD47 for the Treatment of B-Cell Lymphoma and Leukemia

CD47, an ubiquitously expressed innate immune checkpoint receptor that serves as a universal "don't eat me" signal of phagocytosis, is often upregulated by hematologic and solid cancers to evade immune surveillance. Development of CD47-targeted modalities is hindered by the ubiquitous expression of the target, often leading to rapid drug elimination and hemotoxicity including anemia. To overcome such liabilities, we have developed a fully human bispecific antibody, NI-1701, designed to coengage CD47 and CD19 selectively on B cells. NI-1701 demonstrates favorable elimination kinetics with no deleterious effects seen on hematologic parameters following single or multiple administrations to nonhuman primates. Potent in vitro and in vivo activity is induced by NI-1701 to kill cancer cells across a plethora of B-cell malignancies and control tumor growth in xenograft mouse models. The mechanism affording maximal tumor growth inhibition by NI-1701 is dependent on the coengagement of CD47/CD19 on B cells inducing potent antibody-dependent cellular phagocytosis of the targeted cells. NI-1701-induced control of tumor growth in immunodeficient NOD/SCID mice was more effective than that achieved with the anti-CD20 targeted antibody, rituximab. Interestingly, a synergistic effect was seen when tumor-implanted mice were coadministered NI-1701 and rituximab leading to significantly improved tumor growth inhibition and regression in some animals. We describe herein, a novel bispecific antibody approach aimed at sensitizing B cells to become more readily phagocytosed and eliminated thus offering an alternative or adjunct therapeutic option to patients with B-cell malignancies refractory/resistant to anti-CD20-targeted therapy. Mol Cancer Ther; 17(8); 1739-51. ©2018 AACR.

On the interaction of oxovanadium(IV) with homocysteine

The interaction of the VO2+ cation with homocysteine was investigated by electron absorption spectroscopy in aqueous solution at different metal-to-ligand ratios. The direct reduction of vanadate(V) solutions with homocysteine was also investigated. The results suggest that the interaction is different from that found in the case of cysteine and occurs through pairs of amino and carboxylate groups of the amino acid. The interaction of VO2+ with homocystine, the oxidation product of homocysteine, was also analyzed. The interest of the results in relation to vanadium metabolism and detoxification is briefly discussed.

Reduction of vanadium(V) with ascorbic acid and isolation of the generated oxovanadium(IV) species

The interaction of sodium metavanadate and VOCl3 with ascorbic acid, one of the possible natural reducing agents of vanadium(V) to oxovanadium(IV), has been investigated. Three new VO2+ complexes could be isolated as microcrystalline powders. One of them, of composition K1.5Na0.5[VO(HAsc)(OH)3], contains ascorbic acid as a monodentate ligand. In the other two, K[VO(Diketo)(OH)] x H2O and Na3[VO(Diketo)2(OH)], the enolized form of 2,3-diketogulonic acid (one of the oxidation products of ascorbic acid), acts as a bidentate ligand. The complexes were characterized by means of electronic (absorption and reflectance) and infrared spectroscopy and magnetic susceptibility measurements. Their thermal behavior was investigated by thermogravimetric and differential thermal analyses. The interest of the investigated system in relation to vanadium detoxification is also discussed.

Synthesis, characterization and bioactivity of a new VO2+/aspirin complex

A new VO2+ complex with salicylic acid acetate (Aspirin) of formula C18H18Cl2O12V2 was synthesized and characterized. Its biological effects upon cell proliferation, differentiation and promotion of tyrosine protein phosphorylation have been tested in two lines of osteoblast-like cells in culture.

On the interaction of the VO2+ cation with cystine

The interaction between the VO2+ cation and cystine was investigated by electron absorption spectroscopy in aqueous solutions at different metal-to-ligand ratios. Reduction of NaVO3 solutions with cysteine gave similar spectra. The results suggest that interaction occurs through the carboxylate and amino groups of the ligand. The interest of the results in relation to vanadium metabolism are commented upon.

Interaction of the vanadyl (IV) cation with carnosine and related ligands

The interaction of the vanadyl (IV) (VO2+) cation with carnosine (the dipeptide beta-alanyl-histidine) has been investigated by electron absorption spectroscopy at high ligand-to-metal ratios and at different pH values. The results show that in the range 6.0-8.5, the cation interacts with the imidazole group of four different carnosine molecules and points to the presence of an axially coordinated water molecule. These suppositions were confirmed by the behavior of the VO2+/imidazole system, which was investigated under similar experimental conditions, and supported by previous ENDOR (electron-nuclear double resonance) results. The study was complemented with additional measurements using the glycylglycine, glycylglycine/imidazole, and histidine systems as ligands.

The interaction of the VO2+ cation with oxidized glutathione

The interaction of the vanadyl(IV) cation with oxidized glutathione (GSSG) in solution has been investigated using spectrophotometric techniques. Two complexes, stable at different metal-to-ligand ratios, could be identified at pH = 7. A solid 2:1 VO2+:GSSG complex could also be isolated at pH = 4.5 and characterized by chemical analysis and infrared and electronic spectroscopies. Its thermal behavior was investigated through TG and DTA measurements.

A spectrophotometric study of the VO(2+)-glutathione interactions

The interaction of the vanadyl (IV) cation with reduced glutathione (GSH) has been investigated by electronic absorption spectroscopy, at different metal-to-ligand ratios and pH values. The interaction depends strongly on the initial VO2+/GSH ratio. Starting with a tenfold GSH excess, coordination takes place through the two carboxylate groups of the ligand, generating (at pH = 7) a blue 1:2 VO2+/GSH complex; this stoichiometry could be confirmed by photometric titration experiments. Higher GSH concentrations produce a violet complex, which can also be obtained by addition of GSH to the blue species. Some measurements with the three component amino acids of GSH, as well as results obtained from the VO3-/GSH system, allowed a wider insight into the characteristics of this violet complex, in which the cation interacts with S and N atoms of the peptide.