Nir Debotton

Overcoming the formulation obstacles towards targeted chemotherapy: In vitro and in vivo evaluation of cytotoxic drug loaded immunonanoparticles

The aim of this study was to design a new one step conjugation of monoclonal antibodies (MAbs) to surface activated pegylated polyester nanoparticles (NPs) and evaluate the pharmacokinetic profile and therapeutic effect of paclitaxel palmitate (pcpl) loaded anti-HER2 immunoNPs in mice as compared to pcpl solution and NPs following IV injection. The density of the antibody conjugated to the NPs was found to be around 35 MAbs/NP (70% coupling efficiency). In vitro cell culture studies showed good binding and uptake results when immunoNPs were incubated with PC-3 and CAPAN-1 cell lines. Both pcpl NPs and immunoNPs showed significant increased t1/2, C(max) and AUC values as compared to the values of pcpl solution in mice. There was no significant difference in the C(max) and AUC values between pcpl NPs and pcpl immunoNPs. However, the immunoNPs concentrated much less in the liver and spleen than NPs. The pharmacokinetic behavior of the immunoNPs was markedly different from the pharmacokinetic profile of the naked MAb showing that the MAb lost its intrinsic molecular pharmacokinetic properties following conjugation to the NPs. The immunoNPs elicited a significant anti-tumor activity as compared to the pcpl solution and NPs, although the tumor growth was not fully inhibited.

A quantitative evaluation of the molecular binding affinity between a monoclonal antibody conjugated to a nanoparticle and an antigen by surface plasmon resonance.

We have designed a site-specific drug colloidal carrier ultimately for improving pancreatic and lung cancer treatment. It is based on a nanoparticulate drug delivery system that targets tumors overexpressing H-ferritin. A monoclonal antibody, AMB8LK, specifically recognizing H-ferritin was thiolated and conjugated to maleimide-activated polylactide nanoparticles (NPs) resulting in the formation of immunonanoparticles (immunoNPs). The AMB8LK immunoNPs exhibited a mean diameter size of 112+/-20nm and a density of 76 antibody molecules per NP. AMB8LK immunoNPs were evaluated for uptake and binding properties on CAPAN-1 and A-549 cell lines, using confocal microscopy. ImmunoNPs demonstrated specific binding and increased uptake of the desired cells by means of monoclonal antibodies (MAbs), compared to nonconjugated NPs. A lipophilic paclitaxel derivative, paclitaxel palmitate (pcpl), was encapsulated within the various NP formulations, and their cytotoxic effect was evaluated on A-549 cells using MTT assay. Pcpl-loaded AMB8LK immunoNPs showed a significantly increased cytotoxic effect when compared to pcpl solution and pcpl NPs. Surface plasmon resonance (SPR) was used to determine quantitatively the affinity constants of native AMB8LK and AMB8LK immunoNPs to gain insight on the affinity of the MAbs following the conjugation process onto NPs. The results of the association/dissociation and affinity kinetics of the interaction between H-ferritin and native AMB8LK or AMB8LK immunoNPs revealed similar constant values, showing that the conjugation process of the MAb to the NPs did not alter the intrinsic specificity and affinity of the MAb to the antigen. In conclusion, at the cellular level, AMB8LK immunoNPs may carry drugs to desired overexpressing antigen cells with adequate affinity properties, potentially leading to improved drug therapy and reduced systemic adverse effects.

Applications of Polymers as Pharmaceutical Excipients in Solid Oral Dosage Forms

Over the last few decades, polymers have been extensively used as pharmaceutical excipients in drug delivery systems. Pharmaceutical polymers evolved from being simply used as gelatin shells comprising capsule to offering great formulation advantages including enabling controlled/slow release and specific targeting of drugs to the site(s) of action (the “magic bullets” concept), hence hold a significant clinical promise.

Enhanced cutaneous bioavailability of dehydroepiandrosterone mediated by nano-encapsulation.

Polymeric nanocarriers, especially nanospheres (NSs) and nanocapsules (NCs), can promote the penetration of their cargo through the skin barrier, towards improved cutaneous bioavailability. Dehydroepiandrosterone (DHEA), an endogenous hormone exhibiting poor aqueous solubility, was shown to be effective in modulating skin-aging processes following topical application. In this study, we designed adequate DHEA preparations, in an attempt to enable local delivery of the active ingredient to the viable skin layers. In addition, the potential efficiency of DHEA NCs on dermal collagen synthesis was evaluated. Cryo-TEM observations and thermal analysis indicated that DHEA was successfully incorporated within a stable NC-based delivery system. Moreover, higher [(3)H]-DHEA levels were recorded in the viable skin layers following different incubation periods of NCs on excised pig skin specimens as compared to DHEA oil solution (free molecule). Furthermore, significantly higher (4-fold) skin flux values were observed for the DHEA NCs as compared to the values elicited by the oil control solution. Finally, collagen synthesis in human skin organ culture, assessed by the incorporation of [(3)H]-proline, was up to 42% higher for DHEA NCs 48h post-topical application than for the untreated specimens. Overall, these results suggest that poly lactic-co-glycolic acid (PLGA)-based NCs have promising potential to be used topically for various skin disorders.

Dermal absorption behavior of fluorescent molecules in nanoparticles on human and porcine skin models

The percutaneous passage of poorly skin absorbed molecules can be improved using nanocarriers, particularly biodegradable polymeric nanospheres (NSs) or nanocapsules (NCs). However, penetration of the encapsulated molecules may be affected by other factors than the nanocarrier properties. To gain insight information on the skin absorption of two fluorescent cargos, DiIC18(5) and coumarin-6 were incorporated in NSs or NCs and topically applied on various human and porcine skin samples. 3D imaging techniques suggest that NSs and NCs enhanced deep dermal penetration of both probes similarly, when applied on excised human skin irrespective of the nature of the cargo. However, when ex vivo pig skin was utilized, the cutaneous absorption of DiIC18(5) was more pronounced by means of PLGA NCs than NSs. In contrast, PLGA NSs noticeably improved the porcine skin penetration of coumarin-6, as compared to the NCs. Furthermore, the porcine skin results were reproducible when triplicated whereas from various human skin samples, as expected, the results were not sufficiently reproducible and large deviations were observed. The overall findings from this comprehensive comparison emphasize the potential of PLGA NCs or NSs to promote cutaneous bioavailability of encapsulated drugs, exhibiting different physicochemical properties but depending on the nature of the skin.