Antibody−Dendrimer Conjugates: The Number, Not the Size of the Dendrimers, Determines the Immunoreactivity

Abstract

Radioimmunotherapy using antibodies with favorable tumor targeting properties and high binding affinity is increasingly applied in cancer therapy. The potential of this valuable cancer treatment modality could be further improved by increasing the specific activity of the labeled proteins. This can be done either by coupling a large number of chelators which leads to a decreased immunoreactivity or by conjugating a small number of multimeric chelators. In order to systematically investigate the influence of conjugations on immunoreactivity with respect to size and number of the conjugates, the anti-EGFR antibody hMAb425 was reacted with PAMAM dendrimers of different size containing up to 128 chelating agents per conjugation site. An improved dendrimer synthesis protocol was established to obtain compounds of high homogeneity suitable for the formation of defined protein conjugates. The quantitative derivatization of the PAMAM dendrimers with DOTA moieties and the characterization of the products by isotopic dilution titration using (111)In/(nat)In are shown. The DOTA-containing dendrimers were conjugated with high efficiency to hMAb425 by applying Sulfo-SMCC as cross-linking agent and a 10- to 25-fold excess of the thiol-containing dendrimers. The determination of the immunoreactivities of the antibody-dendrimer conjugates by FACS analysis revealed a median retained immunoreactivity of 62.3% for 1.7 derivatization sites per antibody molecule, 55.4% for 2.8, 27.9% for 5.3, and 17.1% for 10.0 derivatization sites per antibody but no significant differences in immunoreactivity for different dendrimer sizes. These results show that the dendrimer size does not influence the immunoreactivity of the derivatized antibody significantly over a wide molecular weight range, whereas the number of derivatization sites has a crucial effect.

Novel Nanosized Gd3+-ALGD-G2-C595: In vivo Dual Selective MUC-1 Positive Tumor Molecular MR Imaging and Therapeutic Agent

“…The outcome of the present work presents the use of antibodies such as poly or monocolonal (polyclonal goat anti-rabbit antibody, anti-EGFR antibody hmab425 or conjugated to PAMAM different generation dendrimer or C595 targeted alpha radiotherapy) as anticancer or immunological biomolecules [23][24][25][26]. As a result of observed confirmations from the present research, Gd 3+ -ALGD-G 2 -C595 nano-probe is a potential dual selective breast molecular imaging and therapeutic agents and seems to be a good functional nano-probe and it should to be further studied by clinical trials.…”

“…The advantage for the anionic linear dendrimer G 2 is regarding its PEG core which makes it mostly attractive to cancerous cells as well as anticancer effects [23][24][25][26]. The next interesting capability of anionic linear dendrimer G 2 is regarding its citric acid shell which raise potent Gd 3+ complex formation and Gd 3+ loading as well.…”

“…The complications occur while one or both biomolecule's active site (covering kinetic or dynamic active site) suffers an inactivation and this is occasional [14,[24][25][26].…”

Fungal diseases: could nanostructured drug delivery systems be a novel paradigm for therapy?

“…The compounds bound to dendrimers can improve the surface activity as well as their biological and physical properties. Several specific ligands can be adsorbed, including folic acid, 203 antibodies, 204 target cyclic peptides containing arginine-glycine-aspartic acid, 205 and PEG. Studies involving nanotechnology and medically important fungi have demonstrated improvements in the antifungal properties, such as bioavailability, toxicity, and target tissue, for some drugs, such as AmB, which can facilitate innovative therapeutic approaches.…”

Multivalent niacin nanoconjugates for delivery to cytoplasmic lipid droplets

“…It is important to follow this sequence of reactions since if BODIPY is clicked first, followed by esterification with niacin, it leads to very poor yield of the product. Dendrimer size could be an important variable in designing dendrimer based conjugates depending on their intended application [35]. For instance, smaller generations such as in 4 which is estimated to be about 3e4 nm in size [36], with tailored active sites, are in fact desirable for nanodelivery carriers targeting different intracellular locations.…”