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Combination chemotherapeutic drugs administered via a single nanocarrier for cancer treatment provides benefits in reducing dose-limiting toxicities, improving the pharmacokinetic properties of the cargo and achieving spatial-temporal synchronization of drug exposure for maximized synergistic therapeutic effects. In an attempt to develop such a multi-drug carrier, our work focuses on functional multimodal polypeptide-based polymeric nanogels (NGs). Diblock copolymers poly (ethylene glycol)-b-poly (glutamic acid) (PEG-b-PGlu) modified with phenylalanine (Phe) were successfully synthesized and characterized. Self-assembly behavior of the resulting polymers was utilized for the synthesis of NGs with hydrophobic domains in cross-linked polyion cores coated with inert PEG chains. The resulting NGs were small (ca. 70 nm in diameter) and were able to encapsulate the combination of drugs with different physicochemical properties such as cisplatin and neratinib. Drug combination-loaded NGs exerted a selective synergistic cytotoxicity towards EGFR overexpressing ovarian cancer cells. Moreover, we developed ligand-installed EGFR-targeted NGs and tested them as an EGFR-overexpressing tumor-specific delivery system. Both in vitro and in vivo, ligand-installed NGs displayed preferential associations with EGFR (+) tumor cells. Ligand-installed NGs carrying cisplatin and neratinib significantly improved the treatment response of ovarian cancer xenografts. We also confirmed the importance of simultaneous administration of the dual drug combination via a single NG system which provides more therapeutic benefit than individual drug-loaded NGs administered at equivalent doses. This work illustrates the potential of our carrier system to mediate efficient delivery of a drug combination to treat EGFR overexpressing cancers., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Biodegradable polypeptide-based nanogels have been developed from amphiphilic block copolymers, poly(ethylene glycol)-b-poly(L-glutamic acid)-b-poly(L-phenylalanine), which effectively co-incorporate cisplatin and paclitaxel, the clinically used drug combination for the treatment of advanced ovarian cancer. In order to target both drugs selectively to the tumor cells, we explored the benefits of ligand-mediated drug delivery by targeting folate receptors, which are overexpressed in most ovarian cancers. Drug-loaded nanogels were surface-functionalized with folic acid (FA) with the help of a PEG spacer without affecting the ligand binding affinity and maintaining the stability of the carrier system. FA-decorated nanogels significantly suppressed the growth of intraperitoneal ovarian tumor xenografts outperforming their nontargeted counterparts without extending their cytotoxicity to the normal tissues. We also confirmed that synchronized co-delivery of the platinum-taxane drug combination via single carrier to the same targeted cells is more advantageous than a combination of targeted single drug formulations administered at the same drug ratio. Lastly, we demonstrated that the same platform can also be used for localized chemotherapy. Our data indicate that intraperitoneal administration can be more effective in the context of targeted combination therapy. Our findings suggest that multifunctional nanogels are promising drug delivery carriers for improvement of current treatment for ovarian cancer., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Polymer nanogels have gained considerable attention as a potential platform for drug delivery applications. Here we describe the design and synthesis of novel polypeptide-based nanogels with hydrophobic moieties in the cross-linked ionic cores. Diblock copolymer, poly(ethylene glycol)-b-poly(L-glutamic acid), hydrophobically modified with L-phenylalanine methyl ester moieties was used for controlled template synthesis of nanogels with small size (ca. 70 nm in diameter) and narrow particle size distribution. Steady-state and time-resolved fluorescence studies using coumarin C153 indicated the existence of hydrophobic domains in the ionic cores of the nanogels. Stable doxorubicin-loaded nanogels were prepared at high drug capacity (30 w/w%). We show that nanogels are enzymatically-degradable leading to accelerated drug release under simulated lysosomal acidic pH. Furthermore, we demonstrate that the nanogel-based formulation of doxorubicin is well tolerated and exhibit an improved antitumor activity compared to a free doxorubicin in an ovarian tumor xenograft mouse model. Our results signify the point to a potential of these biodegradable nanogels as attractive carriers for delivery of chemotherapeutics.

The co-delivery of drug combination at a controlled ratio via the same vehicle to the cancer cells is offering the advantages such as spatial-temporal synchronization of drug exposure, synergistic therapeutic effects and increased therapeutic potency. In an attempt to develop such multidrug vehicle this work focuses on functional biodegradable and biocompatible polypeptide-based polymeric micelles. Triblock copolymers containing the blocks of ethylene glycol, glutamic acid and phenylalanine (PEG-PGlu-PPhe) were successfully synthesized via NCA-based ring-opening copolymerization and their composition was confirmed by (1)H NMR. Self-assembly behavior of PEG-PGlu90-PPhe25 was utilized for the synthesis of hybrid micelles with PPhe hydrophobic core, cross-linked ionic PGlu intermediate shell layer, and PEG corona. Cross-linked (cl) micelles were about 90nm in diameter (ξ-potential=-20mV), uniform (narrow size distribution), and exhibited nanogels-like behavior. Degradation of cl-micelles was observed in the presence of proteolytic enzymes (cathepsin B). The resulting cl-micelles can incorporate the combination of drugs with very different physical properties such as cisplatin (15 w/w% loading) and paclitaxel (9 w/w% loading). Binary drug combination in cl-micelles exhibited synergistic cytotoxicity against human ovarian A2780 cancer cells and exerted a superior antitumor activity by comparison to individual drug-loaded micelles or free cisplatin in cancer xenograft model in vivo. Tunable composition and stability of these hybrid biodegradable micelles provide platform for drug combination delivery in a broad range of cancers., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Targeted drug delivery using multifunctional polymeric nanocarriers is a modern approach for cancer therapy. Our purpose was to prepare targeted nanogels for selective delivery of chemotherapeutic agent cisplatin to luteinizing hormone-releasing hormone (LHRH) receptor overexpressing tumor in vivo. Building blocks of such delivery systems consisted of innovative soft block copolymer nanogels with ionic cores serving as a reservoir for cisplatin (loading 35%) and a synthetic analogue of LHRH conjugated to the nanogels via poly(ethylene glycol) spacer. Covalent attachment of (D-Lys6)-LHRH to nanogels was shown to be possible without loss in either the ligand binding affinity or the nanogel drug incorporation ability. LHRH-nanogel accumulation was specific to the LHRH-receptor positive A2780 ovarian cancer cells and not toward LHRH-receptor negative SKOV-3 cells. The LHRH-nanogel cisplatin formulation was more effective and less toxic than equimolar doses of free cisplatin or untargeted nanogels in the treatment of receptor-positive ovarian cancer xenografts in mice. Collectively, the study indicates that LHRH mediated nanogel-cisplatin delivery is a promising formulation strategy for therapy of tumors that express the LHRH receptor.

Polymer micelles with cross-linked ionic cores are shown here to improve the therapeutic performance of the platinum-containing anticancer compound cisplatin. Biodistribution, antitumor efficacy, and toxicity of cisplatin-loaded core cross-linked micelles of poly(ethylene glycol)-b-poly(methacrylic acid) were evaluated in a mouse ovarian cancer xenograft model. Cisplatin-loaded micelles demonstrated prolonged blood circulation, increased tumor accumulation, and reduced renal exposure. Improved antitumor response relative to free drug was seen in a mouse model. Toxicity studies with cisplatin-loaded micelles indicate a significantly improved safety profile and lack of renal abnormalities typical of free cisplatin treatment. Overall, the study supports the fundamental possibility of improving the potential of platinum therapy using polymer micelle-based drug delivery.

Nanogels are comprised of swollen polymer networks and nearly 95% water and can entrap diverse chemical and biological agents for cancer therapy with very high loading capacities. Here we use diblock copolymer poly(ethylene oxide)-b-poly(methacrylic acid) (PEO-b-PMA) to form nanogels with the desired degree of cross-linking. The nanogels are further conjugated to folic acid (FA) and loaded with different types of drugs (cisplatin, doxorubicin). For the first time we demonstrate a tumor-specific delivery and superior anti-tumor effect in vivo of an anti-cancer drug using these polyelectrolyte nanogels decorated with folate-targeting groups. This reinforces the use of nanogels for the therapy of ovarian and other cancers, where folate receptor (FR) is overexpressed., (Copyright © 2011. Published by Elsevier Ltd.)

Novel functional polymeric nanocarriers with ionic cores containing biodegradable cross-links were developed for delivery of chemotherapeutic agents. Block ionomer complexes (BIC) of poly(ethylene oxide)-b-poly(methacylic acid) (PEO-b-PMA) and divalent metal cations (Ca(2+)) were utilized as templates. Disulfide bonds were introduced into the ionic cores by using cystamine as a biodegradable cross-linker. The resulting cross-linked micelles with disulfide bonds represented soft, hydrogel-like nanospheres and demonstrated a time-dependent degradation in the conditions mimicking the intracellular reducing environment. The ionic character of the cores allowed to achieve a very high level of doxorubicin (DOX) loading (50% w/w) into the cross-linked micelles. DOX-loaded degradable cross-linked micelles exhibited more potent cytotoxicity against human A2780 ovarian carcinoma cells as compared to micellar formulations without disulfide linkages. These novel biodegradable cross-linked micelles are expected to be attractive candidates for delivery of anticancer drugs.