Synthesis of poly(1,2-glycerol carbonate)-paclitaxel conjugates and their utility as a single high-dose replacement for multi-dose treatment regimens in peritoneal cancer

Synthesis of Amphiphilic Amino Poly-Amido-Saccharide and Poly(lactic) Acid Block Copolymers and Fabrication of Paclitaxel-Loaded Mucoadhesive Nanoparticles

Drug delivery to the esophagus through systemic administration remains challenging, as minimal drug reaches the desired target. Local delivery offers the potential for improved efficacy while minimizing off-target toxicities but necessitates bioadhesive properties for mucosal delivery. Herein, we describe the synthesis of two new mucoadhesive amphiphilic copolymers prepared by sequential ring-opening copolymerization or postpolymerization click conjugation. Both strategies yield block copolymers containing a hydrophilic amine-functionalized poly-amido-saccharide and either a hydrophobic alkyl derivatized poly-amido-saccharide or poly(lactic acid), respectively. The latter resulting copolymers readily self-assemble into spherical, ≈200 nm diameter, positively charged mucoadhesive nanoparticles. The NPs entrap ultrahigh levels of paclitaxel via encapsulation of free paclitaxel and paclitaxel conjugated to a biodegradable, biocompatible poly(1,2-glycerol carbonate). Paclitaxel-loaded NPs rapidly enter cells, release paclitaxel, are cytotoxic to esophageal OE33 and OE19 tumor cells in vitro, and, importantly, demonstrate improved mucoadhesion compared to conventional poly(ethylene glycol)-poly(lactic acid) nanoparticles to ex vivo esophageal tissue.

CO2-Sourced Polymer Dyes for Dual Information Encryption

Large amounts of small molecule dyes leak into the ecosystems annually in harmful and unsustainable ways. Polymer dyes have attracted much attention because of their high migration resistance, excellent stability, and minimized leakage. However, the complex synthesis process, high cost, and poor degradability hinder their widespread application. Herein, green and sustainable polymer dyes are prepared using natural dye quercetin (Qc) and CO2 through a one-step process. The CO2-sourced polymer dyes show strong migration resistance, high stability, and can be degraded on demand. Additionally, the CO2-sourced polymer dyes showed unique responses to Zn2+, leading to significantly enhanced fluorescence, highlighting their potential for information encryption/decryption. The CO2-sourced polymer dyes can solve the environmental hazards caused by small molecule dye leakage and promote the carbon cycle process. Meanwhile, the one-step synthesis process is expected to achieve sustainable and widespread utilization of CO2-sourced polymer dyes.

Decreased Lung Metastasis in Triple Negative Breast Cancer Following Locally Delivered Supratherapeutic Paclitaxel-Loaded Polyglycerol Carbonate Nanoparticle Therapy

Breast cancer is among the most prevalent malignancies, accounting for 685,000 deaths worldwide in 2020, largely due to its high metastatic potential. Depending on the stage and tumor characteristics, treatment involves surgery, chemotherapy, targeted biologics, and/or radiation therapy. However, current treatments are insufficient for treating or preventing metastatic disease. Herein, we describe supratherapeutic paclitaxel-loaded nanoparticles (81 wt % paclitaxel) to treat the primary tumor and reduce the risk of subsequent metastatic lesions in the lungs. Primary tumor volume and lung metastasis are reduced by day 30, compared to the paclitaxel clinical standard treatment. The ultrahigh levels of paclitaxel afford an immunotherapeutic effect, increasing natural killer cell activation and decreasing NETosis in the lung, which limits the formation of metastatic lesions.

Progress in the Treatment of Peritoneal Metastatic Cancer and the Application of Therapeutic Nanoagents

Peritoneal metastatic cancer is a cancer caused by the direct growth of cancer cells from the primary site through the bloodstream, lymph, or peritoneum, which is a difficult part of current clinical treatment. In the abdominal cavity of patients with metastatic peritoneal cancer, there are usually nodules of various sizes and malignant ascites. Among them, nodules of different sizes can obstruct intestinal movement and form intestinal obstruction, while malignant ascites can cause abdominal distension and discomfort, and even cause patients to have difficulty in breathing. The pathology and physiology of peritoneal metastatic cancer are complex and not fully understood. The main hypothesis is "seed" and "soil"; i.e., cells from the primary tumor are shed and implanted in the peritoneal cavity (peritoneal metastasis). In the last two decades, the main treatment modalities used clinically are cytoreductive surgery (CRS), systemic chemotherapy, intraperitoneal chemotherapy, and combined treatment, all of which help to improve patient survival and quality of life (QOL). However, the small-molecule chemotherapeutic drugs used clinically still have problems such as rapid drug metabolism and systemic toxicity. With the rapid development of nanotechnology in recent years, therapeutic nanoagents for the treatment of peritoneal metastatic cancer have been gradually developed, which has improved the therapeutic effect and reduced the systemic toxicity of small-molecule chemotherapeutic drugs to a certain extent. In addition, nanomaterials have been developed not only as therapeutic agents but also as imaging agents to guide peritoneal tumor CRS. In this review, we describe the etiology and pathological features of peritoneal metastatic cancer, discuss in detail the clinical treatments that have been used for peritoneal metastatic cancer, and analyze the advantages and disadvantages of the different clinical treatments and the QOL of the treated patients, followed by a discussion focusing on the progress, obstacles, and challenges in the use of therapeutic nanoagents in peritoneal metastatic cancer. Finally, therapeutic nanoagents and therapeutic tools that may be used in the future for the treatment of peritoneal metastatic cancer are prospected.

High dose, dual-release polymeric films for extended surgical bed paclitaxel delivery

While surgery represents a major therapy for most solid organ cancers, local recurrence is clinically problematic for cancers such as sarcoma for which adjuvant radiotherapy and systemic chemotherapy provide minimal local control or survival benefit and are dose-limited due to off-target side effects. We describe an implantable, biodegradable poly(1,2-glycerol carbonate) and poly(caprolactone) film with entrapped and covalently-bound paclitaxel enabling safe, controlled, and extended local delivery of paclitaxel achieving concentrations 10,000× tissue levels compared to systemic administration. Films containing entrapped and covalently-bound paclitaxel implanted in the tumor bed, immediately after resection of human cell line-derived chondrosarcoma and patient-derived xenograft liposarcoma and leiomyosarcoma in mice, improve median 90- or 200-day recurrence-free and overall survival compared to control mice. Furthermore, mice in the experimental film arm show no film-related morbidity. Continuous, extended, high-dose paclitaxel delivery via this unique polymer platform safely improves outcomes in three different sarcoma models and provides a rationale for future incorporation into human trials.

Synthesis of Polyethylene Glycol-Poly(glycerol carbonate) Block Copolymeric Micelles as Surfactant-Free Drug Delivery Systems

We report the synthesis of block copolymers of monomethoxylated polyethylene glycol and poly(glycerol carbonate) (mPEG-b-PGC) via the ring-opening polymerization of benzyl glycidyl ether, monomethoxylated polyethylene glycol, and carbon dioxide using a cobalt salen catalyst. The resulting block copolymers display high polymer/cyclic carbonate selectivity (>99%) and, if two oxirane monomers are used, random incorporation into the polymer feed. The resulting diblock mPEG-b-PGC polymer shows promise as a nanocarrier for surfactant-free, sustained chemotherapeutic delivery. mPEG-b-PGC, with paclitaxel conjugated to the pendant primary alcohol of the glycerol polymer backbone, readily forms 175 nm diameter particles in solution and contains 4.6 wt % paclitaxel (PTX), which is released over 42 days. The mPEG-b-PGC polymer itself is noncytotoxic, whereas the PTX-loaded nanoparticles are cytotoxic to lung, breast, and ovarian cancer cell lines.

Upgrading of Biobased Glycerol to Glycerol Carbonate as a Tool to Reduce the CO2 Emissions of the Biodiesel Fuel Life Cycle

With regards to oil-based diesel fuel, the adoption of bio-derived diesel fuel was estimated to reduce CO₂ emissions by approximately 75%, considering the whole life cycle. In this paper, we present a novel continuous-flow process able to transfer an equimolar amount of CO₂ (through urea) to glycerol, producing glycerol carbonate. This represents a convenient tool, able to both improve the efficiency of the biodiesel production through the conversion of waste streams into added-value chemicals and to beneficially contribute to the whole carbon cycle. By means of a Design of Experiments approach, the influence of key operating variables on the product yield was studied and statistically modeled.

PEGylated drug delivery systems in the pharmaceutical field: past, present and future perspective

Target-site drug delivery systems are gaining interest in the pharmaceutical field due to their great advantages, such as higher drug dosing capacity and better bioavailability. However, some existing problems need to be overcome. As an example, interaction between blood proteins and drug delivery systems. A potent candidate to approach the mentioned problem is based on polyethylene glycol (PEG) surface modifications. This polymer acts as a protector towards the external possible interactions with other compounds, making targeted delivery possible. Diseases such as cancer, diabetes, haemophilia and pain treatment can benefit from these new systems.This review aims to give an overview of drug delivery systems based on PEGylation as surface modification as pharmaceutical approach. Moreover, a deeper insight of the properties of PEG and its advantages is given, as well as brief overview of present therapies based on this technology.

Ultra-high drug loading improves nanoparticle efficacy against peritoneal mesothelioma

Peritoneal mesothelioma is an aggressive disease with a median survival of under three years, due to a lack of effective treatment options. Mesothelioma is traditionally considered a "chemoresistant" tumor; however, low intratumoral drug levels coupled with the inability to administer high systemic doses suggests that therapeutic resistance may be due to poor drug delivery rather than inherent biology. While patient survival may improve with repetitive local intraperitoneal infusions of chemotherapy throughout the perioperative period, these regimens carry associated toxicities and significant peri-operative morbidity. To circumvent these issues, we describe ultra-high drug loaded nanoparticles (NPs) composed of a unique poly(1,2-glycerol carbonate)-graft-succinate-paclitaxel (PGC-PTX + PTX) conjugate. PGC-PTX + PTX NPs are cytotoxic, localize to tumor in vivo, and improve survival in a murine model of human peritoneal mesothelioma after a single intraperitoneal (IP) injection compared to multiple weekly doses of the clinically utilized formulation PTX-C/E. Given their unique pharmacokinetics, a second intraperitoneal dose of PGC-PTX + PTX NPs one month later more than doubles the overall survival compared to the clinical control (122 versus 58 days). These results validate the clinical potential of prolonged local paclitaxel to treat intracavitary malignancies such as mesothelioma using a tailored polymer-mediated nanoparticle formulation.

Self-assembling poly(ethylene glycol)-block-polylactide-cabazitaxel conjugate nanoparticles for anticancer therapy with high efficacy and low in vivo toxicity

Traditional approaches used for transforming hydrophobic anticancer drugs into therapeutically available nanoparticles heavily rely on the noncovalent formulation of drugs within amphiphilic copolymers. However, these nanotherapies have not yet shown the expected favorable clinical outcomes in cancer patients, presumably due to their insufficient stability. To solve this dilemma, we conceive a new class of nanotherapies assembled with polymeric prodrugs that maintain pharmacological activity while substantially alleviate the drug toxicity in animals. By exploiting methoxypoly(ethylene glycol)-block-poly(D, L-lactic acid) (mPEG-PLA) as a promoiety, cabazitaxel is tethered to the terminus of the PLA fragment via a hydrolysable ester linkage. These conjugates recapitulate the self-assembly to produce colloidal stable nanotherapies. In a xenograft model of prostate cancer, this nanotherapy shows a durable inhibition of tumor progression upon the administration of a tolerable dose. Our results suggest that a hydrophobic and highly toxic drug can be rationally converted into a pharmacologically efficient and self-deliverable nanotherapy.

Polymer-drug conjugate therapeutics: advances, insights and prospects

Polymer-drug conjugates have long been a mainstay of the drug delivery field, with several conjugates successfully translated into clinical practice. The conjugation of therapeutic agents to polymeric carriers, such as polyethylene glycol, offers several advantages, including improved drug solubilization, prolonged circulation, reduced immunogenicity, controlled release and enhanced safety. In this Review, we discuss the rational design, physicochemical characteristics and recent advances in the development of different classes of polymer-drug conjugates, including polymer-protein and polymer-small-molecule drug conjugates, dendrimers, polymer nanoparticles and multifunctional systems. Current obstacles hampering the clinical translation of polymer-drug conjugate therapeutics and future prospects are also presented.

Poly(Alkyl Glycidate Carbonate)s as Degradable Pressure-Sensitive Adhesives

Insertion of CO₂ into the polyacrylate backbone, forming poly(carbonate) analogues, provides an environmentally friendly and biocompatible alternative. The synthesis of five poly(carbonate) analogues of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate) is described. The polymers are prepared using the salen cobalt(III) complex catalyzed copolymerization of CO₂ and a derivatized oxirane. All the carbonate analogues possess higher glass-transition temperatures (T_g =32 to -5 °C) than alkyl acrylates (T_g =10 to -50 °C), however, the carbonate analogues (T_d ≈230 °C) undergo thermal decomposition at lower temperatures than their acrylate counterparts (T_d ≈380 °C). The poly(alkyl carbonates) exhibit compositional-dependent adhesivity. The poly(carbonate) analogues degrade into glycerol, alcohol, and CO₂ in a time- and pH-dependent manner with the rate of degradation accelerated at higher pH conditions, in contrast to poly(acrylate)s.

Glutathione Triggered Cascade Degradation of an Amphiphilic Poly(disulfide)-Drug Conjugate and Targeted Release

A bioreducible poly(disulfide)-derived amphiphilic block copolymer-drug conjugate (loading content 31%) was synthesized by post-polymerization modification. It shows redox-responsive polymersome assembly in water with aggregation induced emission property arising from the appended Camptothecin (CPT) drug. Glutathione (GSH), a tripeptide overexpressed in cancer cells, triggers a cascade reaction resulting in simultaneous degradation of the polymer backbone (consisting of disulfide linkage) and the release of the pendant drug. The cascade reaction involves GSH trigger cleavage of the backbone disulfide bond producing free thiol followed by its intrachain nucleophilic attack to the adjacent carbonate group that links the appended drug molecule. The polymeric pro-drug exhibits killing efficiency to a cancer cell with remarkably low IC₅₀ value of 3.1 μg/mL (based on the CPT concentration) while it shows negligible toxicity to a normal cell up to polymer concentration 300 μg/mL.

Reinforcement of polymeric nanoassemblies for ultra-high drug loadings, modulation of stiffness and release kinetics, and sustained therapeutic efficacy

The optimization of current polymeric nanoparticle therapies is restricted by low drug loadings and limited tunability of core properties. To overcome these shortcomings, a novel self-association approach is utilized to fabricate a dual-loaded poly(1,2-glycerol carbonate)-graft-succinic acid-paclitaxel (PGC-PTX) conjugate nanoparticle (NP) in which the physical entrapment of free paclitaxel (PTX) affords unprecedented ultra-high drug loadings >100 wt%, modulation of mechanical stiffness, and tunable release kinetics. Despite high incorporation of free PTX (up to 50 wt%), the dual-loaded PGC-PTX nanocarriers (i.e., PGC-PTX + PTX NPs) exhibit controlled and sustained drug release over 15 days, without burst release effects. Importantly, optimization of drug/material efficiency concomitantly affords improved in vitro efficacy. In vivo, PGC-PTX + PTX NPs are safely administered at doses exceeding the median lethal dose of standard PTX, while a single high dose significantly extends survival relative to weekly PTX administrations in a murine model of peritoneal carcinomatosis.

Chemical Design of Both a Glutathione-Sensitive Dimeric Drug Guest and a Glucose-Derived Nanocarrier Host to Achieve Enhanced Osteosarcoma Lung Metastatic Anticancer Selectivity

Although nanomedicines have been pursued for nearly 20 years, fundamental chemical strategies that seek to optimize both the drug and drug carrier together in a concerted effort remain uncommon yet may be powerful. In this work, two block polymers and one dimeric prodrug molecule were designed to be coassembled into degradable, functional nanocarriers, where the chemistry of each component was defined to accomplish important tasks. The result is a poly(ethylene glycol) (PEG)-protected redox-responsive dimeric paclitaxel (diPTX)-loaded cationic poly(d-glucose carbonate) micelle (diPTX@CPGC). These nanostructures showed tunable sizes and surface charges and displayed controlled PTX drug release profiles in the presence of reducing agents, such as glutathione (GSH) and dithiothreitol (DTT), thereby resulting in significant selectivity for killing cancer cells over healthy cells. Compared to free PTX and diPTX, diPTX@CPGC exhibited improved tumor penetration and significant inhibition of tumor cell growth toward osteosarcoma (OS) lung metastases with minimal side effects both in vitro and in vivo, indicating the promise of diPTX@CPGC as optimized anticancer therapeutic agents for treatment of OS lung metastases.