Advances in the Mechanistic Understanding of Iron Oxide Nanoparticles' Radiosensitizing Properties

Inhibition of the thioredoxin system for radiosensitization therapy of cancer

Radiotherapy (RT) stands as a cornerstone in the clinical armamentarium against various cancers due to its proven efficacy. However, the intrinsic radiation resistance exhibited by cancer cells, coupled with the adverse effects of RT on normal tissues, often compromises its therapeutic potential and leads to unwanted side effects. This comprehensive review aims to consolidate our understanding of how radiosensitizers inhibit the thioredoxin (Trx) system in cellular contexts. Notable radiosensitizers, including gold nanoparticles (GNPs), gold triethylphosphine cyanide ([Au(SCN) (PEt3)]), auranofin, ceria nanoparticles (CONPs), curcumin and its derivatives, piperlongamide, indolequinone derivatives, micheliolide, motexafin gadolinium, and ethane selenide selenidazole derivatives (SeDs), are meticulously elucidated in terms of their applications in radiotherapy. In this review, the sensitization mechanisms and the current research progress of these radiosensitizers are discussed in detail, with the overall aim of providing valuable insights for the judicious application of Trx system inhibitors in the field of cancer radiosensitization therapy.

Advanced manufacturing of nanoparticle formulations of drugs and biologics using microfluidics

Numerous innovative nanoparticle formulations of drugs and biologics, named nano-formulations, have been developed in the last two decades. However, methods for their scaled-up production are still lagging, as the amount needed for large animal tests and clinical trials is typically orders of magnitude larger. This manufacturing challenge poses a critical barrier to successfully translating various nano-formulations. This review focuses on how microfluidics technology has become a powerful tool to overcome this challenge by synthesizing various nano-formulations with improved particle properties and product purity in large quantities. This microfluidic-based manufacturing is enabled by microfluidic mixing, which is capable of the precise and continuous control of the synthesis of nano-formulations. We further discuss the specific applications of hydrodynamic flow focusing, a staggered herringbone micromixer, a T-junction mixer, a micro-droplet generator, and a glass capillary on various types of nano-formulations of polymeric, lipid, inorganic, and nanocrystals. Various separation and purification microfluidic methods to enhance the product purity are reviewed, including acoustofluidics, hydrodynamics, and dielectrophoresis. We further discuss the challenges of microfluidics being used by broader research and industrial communities. We also provide future outlooks of its enormous potential as a decentralized approach for manufacturing nano-formulations.

In vitro hyperspectral biomarkers of human chondrosarcoma cells in nanoparticle-mediated radiosensitization using carbon ions

New therapeutic approaches are needed for the management of the highly chemo- and radioresistant chondrosarcoma (CHS). In this work, we used polyethylene glycol-encapsulated iron oxide nanoparticles for the intracellular delivery of the chemotherapeutic doxorubicin (IONPDOX) to augment the cytotoxic effects of carbon ions in comparison to photon radiation therapy. The in vitro biological effects were investigated in SW1353 chondrosarcoma cells focusing on the following parameters: cell survival using clonogenic test, detection of micronuclei (MN) by cytokinesis blocked micronucleus assay and morphology together with spectral fingerprints of nuclei using enhanced dark-field microscopy (EDFM) assembled with a hyperspectral imaging (HI) module. The combination of IONPDOX with ion carbon or photon irradiation increased the lethal effects of irradiation alone in correlation with the induction of MN. Alterations in the hyperspectral images and spectral profiles of nuclei reflected the CHS cell biological modifications following the treatments, highlighting possible new spectroscopic markers of cancer therapy effects. These outcomes showed that the proposed combined treatment is promising in improving CHS radiotherapy.

Radiation-activated nanoparticles: Which combination to optimize radiosensitization?

Radiotherapy plays a crucial role in the treatment of various cancers. With the ongoing technological advancements in radiotherapy equipment, allowing for increasingly precise targeting of tumours, there are numerous strategies being explored to enhance its effectiveness by combining it with other therapies. Among these, metal nanoparticles seem to have a promising future driven by their ability to locally amplify the dose deposited by ionizing radiation, and to radiosensitize cells by modifying their oxidative status. Recent advancements in understanding the mechanisms of action of these nanoparticles have provided valuable insights for the development of new therapeutic combinations. Among these, the combination with immunotherapies would make it possible to benefit both from the amplified local effect of radiotherapy by nanoparticles and to induce a better antitumour immune response. In this article, we review shortly the existing literature on ongoing combinations and suggest potential novel therapies associated with the combination of radiotherapy and nanoparticles.

A Moexitecan Magnetic Liposomal Strategy for Ferroptosis-Enhanced Chemotherapy

Moexitecan (Mex) is a novel camptothecin derivative that retains the potent antitumor properties of camptothecin drugs and has improved hydrophilicity to enhance biocompatibility in vitro. However, single-drug therapy still has limitations. In this study, magnetic liposomes loaded with both moexitecan and superparamagnetic iron oxide nanoparticles (SPIO) have been fabricated by a film hydration and filtration method, which is abbreviated as Mex@MLipo. By using liposomes as drug carriers, Mex can be delivered specifically to the target site, resulting in improved therapeutic efficacy and reduced toxicity. Morphology characterization results show that Mex@MLipo has a mean diameter of 180-200 nm with a round morphology. The loading efficiencies of Mex and SPIO are 65.86% and 76.86%, respectively. Cell toxicity, in vitro cell uptake, and in vivo fluorescence imaging experiments showed that Mex@MLipo was the most effective in killing HT-29 cells compared with HepG-2 and PC-3 cells, due to its ability to combine chemotherapy and induce ferroptosis, resulting in a strong anti-tumor effect. Thus, this study developed an innovative nanoscale drug delivery system that paves the way for clinical applications of moexitecan.

Radiation therapy-activated nanoparticle and immunotherapy: The next milestone in oncology?

Radiotherapy (RT) is a fundamental treatment at the locoregional or oligometastatic stages of cancer. In various tumors, RT effects may be optimized using synergistic combinations that enhance tumor response. Innovative strategies have been designed that explore the radiation mechanisms, at the physical, chemical and biological levels, to propose precision RT approaches. They consist in combining RT with immunotherapy to revert radiation immunosuppressive effects or to enhance radiation-induced immune defenses against the tumor to favor immunogenic cell death. Radiotherapy-activated nanoparticles are another innovation. By increasing radiation response in situ, nanoparticles improve tumor control locally, and can trigger systemic immune reactions that may be exploited to improve the systemic efficacy of RT. Strong clinical evidence of improved outcomes is now available for combinations of RT and immunotherapy on one hand and RT and nanoparticles on the other hand. The triple combination of RT, immunotherapy and nanoparticles is promising in terms of tolerance, local and systemic anti-tumor control. Yet, significant challenges remain to unravel the complexity of the multiscale mechanisms underlying response to this combination and their associated parameters. Such parameters include patient characteristics, tumor bulk and histology, radiation technique, energy, dose, fractionation, immunotherapy targets and predictive biomarkers, nanoparticle type, size, delivery (intratumoral/intravenous), distribution. The temporal combination is another critical parameter. The mechanisms of response of the combinatorial approaches are reviewed, with a focus on underlying mechanisms based on preclinical, translational and clinical studies. Opportunities for translation of current understanding into precision RT trials combined with immunotherapy and nanoparticles are also discussed.