Simultaneous Delivery of Doxorubicin and Protease Inhibitor Derivative to Solid Tumors via Star-Shaped Polymer Nanomedicines Overcomes P-gp- and STAT3-Mediated Chemoresistance.

The derivative of protease inhibitor ritonavir (5-methyl-4-oxohexanoic acid ritonavir ester; RD) was recently recognized as a potent P-gp inhibitor and cancerostatic drug inhibiting the proteasome and STAT3 signaling. Therefore, we designed high-molecular-weight HPMA copolymer conjugates with a PAMAM dendrimer core bearing both doxorubicin (Dox) and RD (Star-RD + Dox) to increase the circulation half-life to maximize simultaneous delivery of Dox and RD into the tumor. Star-RD inhibited P-gp activity, potently sensitizing both low- and high-P-gp-expressing cancer cells to the cytostatic and proapoptotic activity of Dox in vitro.

Polymer-ritonavir derivate nanomedicine with pH-sensitive activation possesses potent anti-tumor activity in vivo via inhibition of proteasome and STAT3 signaling.

Drug repurposing is a promising strategy for identifying new applications for approved drugs. Here, we describe a polymer biomaterial composed of the antiretroviral drug ritonavir derivative (5-methyl-4-oxohexanoic acid ritonavir ester; RD), covalently bound to HPMA copolymer carrier via a pH-sensitive hydrazone bond (P-RD). Apart from being more potent inhibitor of P-glycoprotein in comparison to ritonavir, we found RD to have considerable cytostatic activity in six mice (IC ~ 2.

HPMA-Based Copolymers Carrying STAT3 Inhibitor Cucurbitacin-D as Stimulus-Sensitive Nanomedicines for Oncotherapy.

The study describes the synthesis, physicochemical properties, and biological evaluation of polymer therapeutics based on -(2-hydroxypropyl)methacrylamide (HPMA) copolymers intended for a tumor-targeted immuno-oncotherapy. Water-soluble linear and cholesterol-containing HPMA precursors were synthesized using controlled reversible addition-fragmentation chain transfer polymerization to reach molecular weight about 2 × 10 g·mol and low dispersity. These linear or self-assembled micellar conjugates, containing immunomodulatory agent cucurbitacin-D (CuD) or the anticancer drug doxorubicin (Dox) covalently bound by the hydrolytically degradable hydrazone bond, showed a hydrodynamic size of 10-30 nm in aqueous solutions.

Polymer nanomedicines based on micelle-forming amphiphilic or water-soluble polymer-doxorubicin conjugates: Comparative study of in vitro and in vivo properties related to the polymer carrier structure, composition, and hydrodynamic properties.

The study compared the physico-chemical and biological properties of a water-soluble star-like polymer nanomedicine with three micellar nanomedicines formed by self-assembly of amphiphilic copolymers differing in their hydrophobic part (statistical, block and thermosensitive block copolymers). All nanomedicines showed a pH-responsive release of the drug, independent on polymer structure. Significant penetration of all polymer nanomedicines into tumor cells in vitro was demonstrated, where the most pronounced effect was observed for statistical- or diblock copolymer-based micellar systems.

Bloodstream Stability Predetermines the Antitumor Efficacy of Micellar Polymer-Doxorubicin Drug Conjugates with pH-Triggered Drug Release.

Herein, the biodegradable micelle-forming amphiphilic N-(2-hydroxypropyl) methacrylamide (HPMA)-based polymer conjugates with the anticancer drug doxorubicin (Dox) designed for enhanced tumor accumulation were investigated, and the influence of their stability in the bloodstream on biodistribution, namely, tumor uptake, and in vivo antitumor efficacy were evaluated in detail. Dox was attached to the polymer carrier by a hydrazone bond enabling pH-controlled drug release. While the polymer-drug conjugates were stable in a buffer at pH 7.

Polymer donors of nitric oxide improve the treatment of experimental solid tumours with nanosized polymer therapeutics.

Polymer carriers based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers with incorporated organic nitrates as nitric oxide (NO) donors were designed with the aim to localise NO generation in solid tumours, thus highly increasing the enhanced permeability and retention (EPR) effect. The NO donors were coupled to the polymer carrier either through a stable bond or through a hydrolytically degradable, pH sensitive, bond. In vivo, the co-administration of the polymer NO donor and HPMA copolymer-bound cytotoxic drug (doxorubicin; Dox) resulted in an improvement in the treatment of murine EL4 T-cell lymphoma.

The structure of polymer carriers controls the efficacy of the experimental combination treatment of tumors with HPMA copolymer conjugates carrying doxorubicin and docetaxel.

The tumor-specific targeting of cancerostatics using polymer drug carriers represents a potential strategy to achieve an effective treatment with reduced side toxicity. Synthetic water-soluble copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are carriers with tunable architecture and drug loading, tumor-specific accumulation of the drug, and its controlled release. We describe a combination treatment of murine EL4 T cell lymphoma with HPMA-based star conjugates (M 250,000gmol) of doxorubicin (Dox) or docetaxel (Dtx) designed for enhanced tumor accumulation and combination therapy.

Overcoming multidrug resistance via simultaneous delivery of cytostatic drug and P-glycoprotein inhibitor to cancer cells by HPMA copolymer conjugate.

Multidrug resistance (MDR) is a common cause of failure in chemotherapy for malignant diseases. MDR is either acquired as a result of previous repeated exposure to cytostatic drugs (P388/MDR cells) or naturally, as some tumors are congenitally resistant to chemotherapy (CT26 cells). One of the most common mechanisms of MDR is upregulation of P-glycoprotein (P-gp) expression.

The structure-dependent toxicity, pharmacokinetics and anti-tumour activity of HPMA copolymer conjugates in the treatment of solid tumours and leukaemia.

Polymer drug carriers that are based on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers have been widely used in the development and synthesis of high-molecular-weight (HMW) drug delivery systems for cancer therapy. In this study, we compared linear (Mw ~27kDa, Rh ~4nm) and non-degradable star (Mw ~250kDa, Rh ~13nm) HPMA copolymer conjugates bearing anthracycline antibiotic doxorubicin (DOX) bound via pH-sensitive hydrazone bond. We determined the in vitro and in vivo toxicity of both conjugates and their maximum tolerated dose (MTD).

Novel IL-2-Poly(HPMA)Nanoconjugate Based Immunotherapy.

Interleukin-2 (IL-2) possesses a strong stimulatory activity for activated T and NK cells and it is an attractive molecule for immunotherapy. Nevertheless, extremely short half-life and severe toxicities associated with high-dose IL-2 treatment are serious and limiting drawbacks. In order to increase IL-2 half-life in vivo, we covalently conjugated synthetic semitelechelic polymeric carrier based on N-(2-hydroxypropyl)methacrylamide (HPMA) to IL-2.

Cancer-associated fibroblasts are not formed from cancer cells by epithelial-to-mesenchymal transition in nu/nu mice.

Cancer-associated fibroblasts are bioactive elements influencing the biological properties of malignant tumors. Their origin from different cell types has been established, and the possibility of their formation by epithelial-to-mesenchymal transition from cancer cells is under debate. This study shows that human cancer cells grafted to nu/nu mice induced formation of tumor stroma with the presence of typical smooth muscle actin-containing cancer-associated fibroblasts.

Polymer conjugates of doxorubicin bound through an amide and hydrazone bond: Impact of the carrier structure onto synergistic action in the treatment of solid tumours.

In this study, we describe the synthesis, physico-chemical characterisation and results of the in vitro and in vivo evaluation of the biological behaviour of N-(2-hydroxypropyl)methacrylamide-based (HPMA) copolymer conjugates bearing doxorubicin (DOX) partly bound via a pH-sensitive hydrazone and partly via enzymatically degradable amide bonds, each contributing to a different anti-tumour mechanism of action of the polymer-doxorubicin conjugate. The following two types of HPMA copolymer drug carriers designed for passive tumour targeting were synthesised and compared: the linear non-degradable copolymer and the biodegradable high-molecular-weight (HMW) diblock copolymer. The HMW diblock copolymer carrier containing a degradable disulphide bond between the polymer blocks showed a rapid degradation in a buffer containing glutathione within the first few hours of incubation.

HPMA copolymer conjugates of DOX and mitomycin C for combination therapy: physicochemical characterization, cytotoxic effects, combination index analysis, and anti-tumor efficacy.

The synthesis, characterization and results of evaluation of the biological behavior of HPMA copolymer conjugates bearing anti-cancer drugs doxorubicin and mitomycin C are described. Two HPMA copolymer carrier types were synthesized: the linear copolymer and the biodegradable high-molecular-weight diblock copolymer containing a degradable disulfide bond. The polymer-drug conjugates incubated in buffers modeling the intracellular environment released the drugs more rapidly than those incubated in bloodstream conditions.

Immunocompatibility evaluation of hydrogel-coated polyimide implants for applications in regenerative medicine.

Immunocompatibility of gelatin-based hydrogels to be applied as implant coatings for local regenerative treatment has been studied. First, the bio- and immuno-acceptability of the methacrylamide-modified gelatin hydrogels per se was screened. The results indicated that the hydrogels support cell growth.

Fine needle aspiration biopsy proves increased T-lymphocyte proliferation in tumor and decreased metastatic infiltration after treatment with doxorubicin bound to PHPMA copolymer carrier.

Introduction: Fine needle aspiration biopsy (FNAB) is an easy method with an option of repetitive withdrawal of cell material.

Methods: First, mice were inoculated with mouse T-lymphoma, after 10 d the samples from tumor, lymph nodes and spleen gained by FNAB and excision were analyzed by flow cytometry. Tumor progression was compared to the control group simultaneously.

Chimera of IL-2 linked to light chain of anti-IL-2 mAb mimics IL-2/anti-IL-2 mAb complexes both structurally and functionally.

IL-2/anti-IL-2 mAb immunocomplexes were described to have dramatically higher activity than free IL-2 in vivo. We designed protein chimera consisting of IL-2 linked to light chain of anti-IL-2 mAb S4B6 through flexible oligopeptide spacer (Gly(4)Ser)(3). This protein chimera mimics the structure of IL-2/S4B6 mAb immunocomplexes but eliminates general disadvantages of immunocomplexes like possible excess of either IL-2 or anti-IL-2 mAb and their dissociation to antibody and IL-2 at low concentrations.

Combination chemotherapy using core-shell nanoparticles through the self-assembly of HPMA-based copolymers and degradable polyester.

The preparation of core-shell polymeric nanoparticles simultaneously loaded with docetaxel (DTXL) and doxorubicin (DOX) is reported herein. The self-assembly of the aliphatic biodegradable copolyester PBS/PBDL (poly(butylene succinate-co-butylene dilinoleate)) and HPMA-based copolymers (N-(2-hydroxypropyl)methacrylamide-based copolymers) hydrophobically modified by the incorporation of cholesterol led to the formation of narrow-size-distributed (PDI<0.10) sub-200-nm polymeric nanoparticles suitable for passive tumor-targeting drug delivery based on the size-dependent EPR (enhanced permeability and retention) effect.

Polymer carriers for anticancer drugs targeted to EGF receptor.

A novel actively targeted polymer carrier for anticancer drugs based on an N-(2-hydroxypropyl)methacrylamide copolymer (PHPMA) is proposed. An oligopeptide sequence GE7, attached to the polymer, is a specific ligand for the EGF receptor overexpressed on most tumor cells. Co-attachment of selected chemotherapeutics will therefore lead to formation of tumor-specific polymer therapeutics, further enhanced by the EPR effect.

Dimerization of an immunoactivating peptide derived from mycobacterial hsp65 using N-hydroxysuccinimide based bifunctional reagents is critical for its antitumor properties.

We have shown previously that a short pentapeptide derived from the mycobacterial heat shock protein hsp65 can be highly activating for the immune system based on its strong reactivity with the early activation antigen of lymphocytes CD69. Here, we investigated an optimal form of presentation of this antigen to the cells of the immune system. Four different forms of the dimerized heptapeptide LELTEGY, and of the control inactive dimerized heptapeptide LELLEGY that both contained an extra UV active glycine-tyrosine sequence, were prepared using dihydroxysuccinimidyl oxalate (DSO), dihydroxysuccinimidyl tartarate (DST), dihydroxysuccinimidyl glutarate (DSG), and dihydroxysuccinimidyl suberate (DSS), respectively.

HPMA copolymer-doxorubicin conjugates: The effects of molecular weight and architecture on biodistribution and in vivo activity.

The molecular weight and molecular architecture of soluble polymer drug carriers significantly influence the biodistribution and anti-tumour activities of their doxorubicin (DOX) conjugates in tumour-bearing mice. Biodistribution of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-DOX conjugates of linear and star architectures were compared in EL4 T-cell lymphoma-bearing mice. Biodistribution, including tumour accumulation, and anti-tumour activity of the conjugates strongly depended on conjugate molecular weight (MW), polydispersity, hydrodynamic radius (R(h)) and molecular architecture.

Synergistic effect of EMF-BEMER-type pulsed weak electromagnetic field and HPMA-bound doxorubicin on mouse EL4 T-cell lymphoma.

We have investigated the effects of low-frequency pulsed electromagnetic field (LF-EMF) produced by BEMER device on experimental mouse T-cell lymphoma EL4 growing on conventional and/or athymic (nude) mice. Exposure to EMF-BEMER slowed down the growth of tumor mass and prolonged the survival of experimental animals. The effect was more pronounced in immuno-compromised nude mice compared to conventional ones.

Biodegradable star HPMA polymer-drug conjugates: Biodegradability, distribution and anti-tumor efficacy.

Herein, new biodegradable star polymer-doxorubicin conjugates designed for passive tumor targeting were investigated, and their synthesis, physico-chemical characterization, drug release, biodegradation, biodistribution and in vivo anti-tumor efficacy are described. In the conjugates, the core formed by poly(amidoamine) (PAMAM) dendrimers was grafted with semitelechelic N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers bearing doxorubicin (Dox) attached by hydrazone bonds, which enabled intracellular pH-controlled drug release. The described synthesis facilitated the preparation of biodegradable polymer conjugates in a broad range of molecular weights (200-1000g/mol) while still maintaining low polydispersity (~1.

Ellipticine-aimed polymer-conjugated auger electron emitter: multistage organelle targeting approach.

Radioactive decay of some radionuclides produces a shower of Auger electrons, potent ionizing radiation within a very short range in living tissue (typically ca. 100 nm). Therefore, they must be brought to DNA-containing cell compartments and preferentially directly to DNA to be fully biologically effective.