Amphiphilic irinotecan–melampomagnolide B conjugate nanoparticles for cancer chemotherapy

A metal-coordination stabilized small-molecule nanomedicine with high drug-loading capacity and synergistic photochemotherapy for cancer treatment

Conventional nanomedicines typically employ a significant amount of excipients as carriers for therapeutic delivery, resulting in generally low drug-loading and compromised anti-cancer efficacy. Here, we propose a small-molecule nanomedicine (CMC NP) directly assembled using a chemotherapeutic drug (chlorambucil, CBL) and a phototherapeutic agent (chlorin e6, Ce6), and stabilized by metal coordination. The CMC NP exhibits exceptionally high drug loading (89.21%), robust stability, and smart disassembly in response to glutathione (GSH). Such a straightforward yet multifunctional delivery strategy could be a better alternative to overcome the above shortcomings of conventional nanomedicines while achieving enhanced efficacy. The CMC NP not only directly induces CBL-induced chemotherapy but also elicits synergistic antitumor responses through Ce6-mediated photodynamic and photothermal therapies. Owing to the multifaceted efforts from photodynamic, photothermal and chemo-therapies, the CMC NP exhibits excellent antitumor efficacy with negligible systemic toxicity which is untenable in traditional CBL-induced chemotherapy. Therefore, this study provides a feasible strategy for overcoming existing challenges and presents a potential opportunity to augment the clinical therapeutic effectiveness associated with conventional nanomedicine.

Current advances in nanoformulations of therapeutic agents targeting tumor microenvironment to overcome drug resistance

The tumor microenvironment (TME) plays a pivotal role in cancer development and progression. In this line, revealing the precise mechanisms of the TME and associated signaling pathways of tumor resistance could pave the road for cancer prevention and efficient treatment. The use of nanomedicine could be a step forward in overcoming the barriers in tumor-targeted therapy. Novel delivery systems benefit from enhanced permeability and retention effect, decreasing tumor resistance, reducing tumor hypoxia, and targeting tumor-associated factors, including immune cells, endothelial cells, and fibroblasts. Emerging evidence also indicates the engagement of multiple dysregulated mediators in the TME, such as matrix metalloproteinase, vascular endothelial growth factor, cytokines/chemokines, Wnt/β-catenin, Notch, Hedgehog, and related inflammatory and apoptotic pathways. Hence, investigating novel multitargeted agents using a novel delivery system could be a promising strategy for regulating TME and drug resistance. In recent years, small molecules from natural sources have shown favorable anticancer responses by targeting TME components. Nanoformulations of natural compounds are promising therapeutic agents in simultaneously targeting multiple dysregulated factors and mediators of TME, reducing tumor resistance mechanisms, overcoming interstitial fluid pressure and pericyte coverage, and involvement of basement membrane. The novel nanoformulations employ a vascular normalization strategy, stromal/matrix normalization, and stress alleviation mechanisms to exert higher efficacy and lower side effects. Accordingly, the nanoformulations of anticancer monoclonal antibodies and conventional chemotherapeutic agents also improved their efficacy and lessened the pharmacokinetic limitations. Additionally, the coadministration of nanoformulations of natural compounds along with conventional chemotherapeutic agents, monoclonal antibodies, and nanomedicine-based radiotherapy exhibits encouraging results. This critical review evaluates the current body of knowledge in targeting TME components by nanoformulation-based delivery systems of natural small molecules, monoclonal antibodies, conventional chemotherapeutic agents, and combination therapies in both preclinical and clinical settings. Current challenges, pitfalls, limitations, and future perspectives are also discussed.

Multicomponent carrier-free nanodrugs for cancer treatment

Nanocarriers can be used to deliver insoluble anticancer drugs to optimize therapeutic efficacy. However, the potential toxicity of nanocarriers cannot be ignored. Carrier-free nanodrugs are emerging safe drug delivery systems, which are composed of multiple components, such as drugs, bioactive molecules and functional ingredients, avoiding the usage of inert carrier materials and offering advantages that include high drug loading, low toxicity, synergistic therapy, versatile design, and easy surface functionalization. Therefore, how to design multicomponent carrier-free nanodrugs is becoming a priority. In this review, the common strategies for rapid construction of multicomponent carrier-free nanodrugs are briefly explored from the perspective of methodology. The properties of organic-organic, organic-inorganic and inorganic-inorganic multiple carrier-free nanosystems are analyzed according to wettability and in-depth understanding is provided. Further advances in the applications of multiple carrier-free nanodrugs are outlined in anticipation of grasping the intrinsic nature for the design and development of carrier-free nanodrugs.

Carrier-free prodrug nanoparticles based on lonidamine and cisplatin for synergistic treatment of breast cancer

Herein, we combined a derivative of cisplatin (CP) and the chemosensitizer lonidamine (LND) to design an amphiphilic prodrug, in which the ratio of LND to cisplatin was fixed at 2:1. Diaminedichlorodihydroxyplatinum (DH-CP) is a hydrophilic cisplatin derivative. Due to its appropriate amphiphilicity, this prodrug could self-assemble into stable nanoparticles (denoted as LNP-NPs). Under the action of excessive glutathione (GSH) in tumor cells, DH-CP could be reduced to cytotoxic cisplatin. In addition, the released LND could inhibit the metabolic process of tumor cells, and improving the sensitivity of tumor cells to cisplatin. In vitro studies demonstrated that LNP-NPs displayed significantly cytotoxicity on breast cancer cells, and the cell viability after co-incubation for 48 h (CP 16 μg/mL) were 18.77% (MCF-7) and 20.01% (EMT6), respectively. LNP-NPs could also significantly inhibit the growth of MCF-7 tumor-like spheroids, which were realized through the high coordination and cooperation between CP and LND. Therefore, the carrier-free drug delivery system based on LND and DH-CP is expected to achieve a good synergistic anti-tumor effect.

Transition Metal-Free Synthesis of Carbamates Using CO2 as the Carbon Source

Utilization of carbon dioxide as a C1 synthon is highly attractive for the synthesis of valuable chemicals. However, activation of CO₂ is highly challenging, owing to its thermodynamic stability and kinetic inertness. With this in mind, several strategies have been developed for the generation of carbon-heteroatom bonds. Among these, formation of C-N bonds is highly attractive, especially, when carbamates can be synthesized directly from CO₂ . This Minireview focuses on transition metal-free approaches for the fixation of CO₂ to generate carbamates for the production of fine chemicals and pharmaceuticals. Within the past decade, transition metal-free approaches have gained increasing attention, but traditional reviews have rarely focused on these approaches. Direct comparisons between such methods have been even more scarce. This Minireview seeks to address this discrepancy.

Carrier-free nanodrugs for safe and effective cancer treatment

Clinical applications of many anti-cancer drugs are restricted due to their hydrophobic nature, requiring use of harmful organic solvents for administration, and poor selectivity and pharmacokinetics resulting in off-target toxicity and inefficient therapies. A wide variety of carrier-based nanoparticles have been developed to tackle these issues, but such strategies often fail to encapsulate drug efficiently and require significant amounts of inorganic and/or organic nanocarriers which may cause toxicity problems in the long term. Preparation of nano-formulations for the delivery of water insoluble drugs without using carriers is thus desired, requiring elegantly designed strategies for products with high quality, stability and performance. These strategies include simple self-assembly or involving chemical modifications via coupling drugs together or conjugating them with various functional molecules such as lipids, carbohydrates and photosensitizers. During nanodrugs synthesis, insertion of redox-responsive linkers and tumor targeting ligands endows them with additional characteristics like on-target delivery, and conjugation with immunotherapeutic reagents enhances immune response alongside therapeutic efficacy. This review aims to summarize the methods of making carrier-free nanodrugs from hydrophobic drug molecules, evaluating their performance, and discussing the advantages, challenges, and future development of these strategies.

Floxuridine-chlorambucil conjugate nanodrugs for ovarian cancer combination chemotherapy

Due to no specific symptoms and lack of early diagnosis for ovarian cancer, most diagnosed patients are often in the terminal stage resulting that tumor tissue is unable to be resected completely by operation. So postoperative chemotherapy has become an important and indispensable treatment procedure for them. Up to date, it remains a challenge to treat ovarian cancer by an effective chemotherapy strategy. Recently, the strategy of ADDC has been regarded as a highly effective chemotherapy strategy to treat various cancers without any drug carriers. Here a novel ADDC is synthesized by linking a water-soluble antitumor drug floxuridine (Fud) and a water-insoluble antitumor drug chlorambucil (Cb) through the esterification. Then the Fud-Cb conjugate can form stable nanodrugs in water with an average size around 103.0 nm through molecular self-assembly. After internalization of cells, the ester bonds in nanodrugs can be degraded to release free Fud and Cb at a fixed ratio under the intracellular acid conditions, which exhibits the high synergistic effect on ovarian cancer cells. The cytotoxicity test results show that Fud-Cb nanodrugs can efficiently inhibit the growth of ovarian cancer cells. The apoptosis data exhibit that the cell necrotic and apoptotic rate treated with Fud-Cb nanodrugs is about 73.7 % and 18.76 % within 24 h. These results suggest that Fud-Cb nanodrugs based on ADDC strategy can effectively enhance synergistic anticancer efficacy to ovarian cancer.

Synthesis and biological evaluation of dehydroabietic acid-pyrimidine hybrids as antitumor agents

A series of novel dehydroabietic acid derivatives containing pyrimidine moieties were designed and synthesized. Some of them displayed more potent inhibitory activities compared with 5-FU.