Use of Amifostine for Cytoprotection during Radiation Therapy: A Review

A DNA tetrahedron-based nanosuit for efficient delivery of amifostine and multi-organ radioprotection

Unnecessary exposure to ionizing radiation (IR) often causes acute and chronic oxidative damages to normal cells and organs, leading to serious physiological and even life-threatening consequences. Amifostine (AMF) is a validated radioprotectant extensively applied in radiation and chemotherapy medicine, but the short half-life limits its bioavailability and clinical applications, remaining as a great challenge to be addressed. DNA-assembled nanostructures especially the tetrahedral framework nucleic acids (tFNAs) are promising nanocarriers with preeminent biosafety, low biotoxicity, and high transport efficiency. The tFNAs also have a relative long-term maintenance for structural stability and excellent endocytosis capacity. We therefore synthesized a tFNA-based delivery system of AMF for multi-organ radioprotection (tFNAs@AMF, also termed nanosuit). By establishing the mice models of accidental total body irradiation (TBI) and radiotherapy model of Lewis lung cancer, we demonstrated that the nanosuit could shield normal cells from IR-induced DNA damage by regulating the molecular biomarkers of anti-apoptosis and anti-oxidative stress. In the accidental total body irradiation (TBI) mice model, the nanosuit pretreated mice exhibited satisfactory alteration of superoxide dismutase (SOD) activities and malondialdehyde (MDA) contents, and functional recovery of hematopoietic system, reducing IR-induced pathological damages of multi-organ and safeguarding mice from lethal radiation. More importantly, the nanosuit showed a selective radioprotection of the normal organs without interferences of tumor control in the radiotherapy model of Lewis lung cancer. Based on a conveniently available DNA tetrahedron-based nanocarrier, this work presents a high-efficiency delivery system of AMF with the prolonged half-life and enhanced radioprotection for multi-organs. Such nanosuit pioneers a promising strategy with great clinical translation potential for radioactivity protection.

An unmet need for pharmacology: Treatments for radiation-induced gastrointestinal mucositis

Gastrointestinal mucositis (GIM) continues to be a significant issue in the management of abdominal cancer radiation treatments and chemotherapy, causing significant patient discomfort and therapy interruption or even cessation. This review will first focus on radiotherapy induced GIM, providing an understanding of its clinical landscape. Subsequently, the aetiology of GIM will be reviewed, highlighting diverse contributing factors. The cellular and tissue damage and associated molecular responses in GIM will be summarised in the context of the underlying complex biological processes. Finally, available drugs and pharmaceutical therapies will be evaluated, underscoring their insufficiency, and highlighting the need for further research and innovation. This review will emphasize the urgent need for improved pharmacologic therapeutics for GIM, which is a key research priority in oncology.

Swertiamarin relieves radiation-induced intestinal injury by limiting DNA damage

Radiotherapy is the conventional treatment for pelvic abdominal tumors. However, it can cause some damage to the small intestine and colorectal, which are very sensitive to radiation. Radiation-induced intestinal injury (RIII) affects the prognosis of radiotherapy, causing sequelae of loss of function and long-term damage to patients' quality of life. Swertiamarin is a glycoside that has been reported to prevent a variety of diseases including but not limited to diabetes, hypertension, atherosclerosis, arthritis, malaria, and abdominal ulcers. However, its therapeutic effect and mechanism of action on RIII have not been established. We investigated whether swertiamarin has a protective effect against RIII. In this article, we use irradiator to create cellular and mouse models of radiation damage. Preventive administration of swertiamarin could reduce ROS and superoxide anion levels to mitigate the cellular damage caused by radiation. Swertiamarin also attenuated RIII in mice, as evidenced by longer survival, less weight loss and more complete intestinal barrier. We also found an increase in the relative abundance of primary bile acids in irradiated mice, which was reduced by both FXR agonists and swertiamarin, and a reduction in downstream interferon and inflammatory factors via the cGAS-STING pathway to reduce radiation-induced damage.

Bioengineered Salivary Gland Microtissues─A Review of 3D Cellular Models and their Applications

Salivary glands (SGs) play a vital role in maintaining oral health through the production and release of saliva. Injury to SGs can lead to gland hypofunction and a decrease in saliva secretion manifesting as xerostomia. While symptomatic treatments for xerostomia exist, effective permanent solutions are still lacking, emphasizing the need for innovative approaches. Significant progress has been made in the field of three-dimensional (3D) SG bioengineering for applications in gland regeneration. This has been achieved through a major focus on cell culture techniques, including soluble cues and biomaterial components of the 3D niche. Cells derived from both adult and embryonic SGs have highlighted key in vitro characteristics of SG 3D models. While still in its first decade of exploration, SG spheroids and organoids have so far served as crucial tools to study SG pathophysiology. This review, based on a literature search over the past decade, covers the importance of SG cell types in the realm of their isolation, sourcing, and culture conditions that modulate the 3D microenvironment. We discuss different biomaterials employed for SG culture and the current advances made in bioengineering SG models using them. The success of these 3D cellular models are further evaluated in the context of their applications in organ transplantation and in vitro disease modeling.

The Impact of Radiation Therapy in Patients with Systemic Sclerosis and Head and Neck Cancer

OBJECTIVE

Systemic sclerosis (SSc) is considered a relative, or in some cases, absolute contraindication for radiation therapy for various cancers; however, radiation is the standard of care and the best option for tumor control for locally advanced head and neck (H&N) cancer. We present a case series to document postradiation outcomes in patients with SSc and H&N cancer.

METHODS

Patients with SSc and H&N cancer treated with radiation were identified from the Johns Hopkins Scleroderma Center and the University of Pittsburgh Scleroderma Center research registries. Through chart review, we identified whether patients developed predetermined acute and late side effects or changes in SSc activity from radiation. We further describe therapies used to prevent and treat radiation-induced fibrosis.

RESULTS

Thirteen patients with SSc who received radiation therapy for H&N cancer were included. Five-year survival was 54%. Nine patients (69%) developed local radiation-induced skin thickening, and 7 (54%) developed reduced neck range of motion. Two patients required long-term percutaneous endoscopic gastrostomy use due to radiation therapy complications. No patients required respiratory support related to radiation therapy. Regarding SSc disease activity among the patients with established SSc before radiation therapy, none experienced interstitial lung disease progression in the postradiation period. After radiation, one patient had worsening skin disease outside the radiation field; however, this patient was within the first year of SSc, when progressive skin disease is expected. Treatment strategies to prevent radiation fibrosis included pentoxifylline, amifostine, and vitamin E, while intravenous immunoglobulin (IVIG) was used to treat it.

CONCLUSION

Although some patients with SSc who received radiation for H&N cancer developed localized skin thickening and reduced neck range of motion, systemic flares of SSc were uncommon. This observational study provides evidence to support the use of radiation therapy for H&N cancer in patients with SSc when radiation is the best treatment option.

Biogenic crocetin-crosslinked chitosan nanoparticles with high stability and drug loading for efficient radioprotection

The risk of radiation exposure increases with the development of nuclear energy and technology, and radiation protection receives more and more attention from public health and safety. However, the numerous adverse effects and low drug utilization limit the practical applications of radioprotective agents. In this study, we developed a biogenic crocetin-crosslinked chitosan nanoparticle with high stability and drug loading for efficient radioprotection. In detail, the nanoparticles were prepared using the natural antioxidant crocetin as a cross-linking reagent in amidation reactions of chitosan and mPEG-COOH. The nanoparticles exhibit a quick scavenging ability for common reactive oxygen species and reactive nitrogen in vitro. Meanwhile, cellular experiments demonstrate the good biocompatibility of the nanoparticles and the alleviation of radiation damage by scavenging reactive oxygen species, reducing apoptosis, and inhibiting DNA damage, etc. Importantly, the nanoparticles are effective in mitigating oxidative damage in major organs and maintaining peripheral blood cell content. In addition, they perform better radioprotective properties than free drug due to the significant extension of the blood half-life of crocetin in vivo from 10 min to 5 h. This work proposes a drug-crosslinking strategy for the design of a highly efficient radioprotective agent, which exhibits a promising prospect in the fields of nuclear emergency and public health.

Prediction of Human Pharmacokinetics of E0703, a Novel Radioprotective Agent, Using Physiologically Based Pharmacokinetic Modeling and an Interspecies Extrapolation Approach

E0703, a new steroidal compound optimized from estradiol, significantly increased cell proliferation and the survival rate of KM mice and beagles after ionizing radiation. In this study, we characterize its preclinical pharmacokinetics (PK) and predict its human PK using a physiologically based pharmacokinetic (PBPK) model. The preclinical PK of E0703 was studied in mice and Rhesus monkeys. Asian human clearance (CL) values for E0703 were predicted from various allometric methods. The human PK profiles of E0703 (30 mg) were predicted by the PBPK model in Gastro Plus software 9.8 (SimulationsPlus, Lancaster, CA, USA). Furthermore, tissue distribution and the human PK profiles of different administration dosages and forms were predicted. The 0.002 L/h of CL and 0.005 L of Vss in mice were calculated and optimized from observed PK data. The plasma exposure of E0703 was availably predicted by the CL using the simple allometry (SA) method. The plasma concentration-time profiles of other dosages (20 and 40 mg) and two oral administrations (30 mg) were well-fitted to the observed values. In addition, the PK profile of target organs for E0703 exhibited a higher peak concentration (Cmax) and AUC than plasma. The developed E0703-PBPK model, which is precisely applicable to multiple species, benefits from further clinical development to predict PK in humans.

DTTZ suppresses ferroptosis and reverses mitochondrial dysfunction in normal tissues affected by chemotherapy

Conventional antineoplastic therapies cause severe normal tissue damage and existing cytoprotectants with acute toxicities or potential tumor protection limit their clinical application. We evaluated the selective cytoprotection of 2,2-dimethylthiazolidine hydrochloride in this study, which could protect normal tissue toxicity without interfering antineoplastic therapies. By using diverse cell lines and A549 xenograft model, we discovered a synthetic aminothiol 2,2-dimethylthiazolidine hydrochloride selectively diminished normal cellular ferroptosis via SystemXc-/Glutathione Peroxidase 4 pathway upon antineoplastic therapies without interfering the anticancer efficacy. We revealed the malignant and non-malignant tissues presenting different energy metabolism patterns. And cisplatin induces disparate replicative stress, contributing to the distinguishable cytoprotection of 2,2-dimethylthiazolidine in normal and tumor cells. The compound pre-application could mitigate cisplatin-induced normal cellular mitochondrial oxidative phosphorylation (OXPHOS) dysfunction. Pharmacologic ablation of mitochondria reversed 2,2-dimethylthiazolidine chemoprotection against cisplatin in the normal cell line. Combined, these results provide a potential therapeutic adjuvant to selectively diminish normal tissue damages retaining antineoplastic efficacy.

Amifostine ameliorates bleomycin-induced murine pulmonary fibrosis via NAD+/SIRT1/AMPK pathway-mediated effects on mitochondrial function and cellular metabolism

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating chronic lung disease characterized by irreversible scarring of the lung parenchyma. Despite various interventions aimed at mitigating several different molecular aspects of the disease, only two drugs with limited clinical efficacy have so far been approved for IPF therapy.

OBJECTIVE

We investigated the therapeutic efficacy of amifostine, a detoxifying drug clinically used for radiation-caused cytotoxicity, in bleomycin-induced murine pulmonary fibrosis.

METHODS

C57BL6/J mice were intratracheally instilled with 3 U/kg of bleomycin. Three doses of amifostine (WR-2721, 200 mg/kg) were administered intraperitoneally on days 1, 3, and 5 after the bleomycin challenge. Bronchoalveolar lavage fluid (BALF) was collected on day 7 and day 21 for the assessment of lung inflammation, metabolites, and fibrotic injury. Human fibroblasts were treated in vitro with transforming growth factor beta 1 (TGF-β1), followed by amifostine (WR-1065, 1-4 µg/mL) treatment. The effects of TGF-β1 and amifostine on the mitochondrial production of reactive oxygen species (ROS) were assessed by live cell imaging of MitoSOX. Cellular metabolism was assessed by the extracellular acidification rate (ECAR), the oxygen consumption rate (OCR), and the concentrations of various energy-related metabolites as measured by mass spectrum (MS). Western blot analysis was performed to investigate the effect of amifostine on sirtuin 1 (SIRT1) and adenosine monophosphate activated kinase (AMPK).

RESULTS

Three doses of amifostine significantly attenuated lung inflammation and pulmonary fibrosis. Pretreatment and post-treatment of human fibroblast cells with amifostine blocked TGF-β1-induced mitochondrial ROS production and mitochondrial dysfunction in human fibroblast cells. Further, treatment of fibroblasts with TGF-β1 shifted energy metabolism away from mitochondrial oxidative phosphorylation (OXPHOS) and towards glycolysis, as observed by an altered metabolite profile including a decreased ratio of NAD + /NADH and increased lactate concentration. Treatment with amifostine significantly restored energy metabolism and activated SIRT1, which in turn activated AMPK. The activation of AMPK was required to mediate the effects of amifostine on mitochondrial homeostasis and pulmonary fibrosis. This study provides evidence that repurposing of the clinically used drug amifostine may have therapeutic applications for IPF treatment.

CONCLUSION

Amifostine inhibits bleomycin-induced pulmonary fibrosis by restoring mitochondrial function and cellular metabolism.

Advances of Amifostine in Radiation Protection: Administration and Delivery

Amifostine (AMF, also known as WR-2721) is the only approved broad-spectrum small-molecule radiation protection agent that can combat hematopoietic damage caused by ionizing radiation and is used as an antitumor adjuvant and cell protector in cancer chemotherapy and radiotherapy. Amifostine is usually injected intravenously before chemotherapy or radiotherapy and has been used in the treatment of head and neck cancer. However, the inconvenient intravenous administration and its toxic side effects such as hypotension have severely limited its further application in clinic. In order to reduce the toxic and side effects, scientists are trying to develop a variety of drug administration methods and are devoted to developing a wide application of amifostine in radiation protection. This paper reviews the research progress of amifostine for radiation protection in recent years, discusses its mechanism of action, clinical application, and other aspects, with focus on summarizing the most widely studied amifostine injection administration and drug delivery systems, and explored the correlation between various administrations and drug efficacies.

Radiopaque and X-ray-Responsive Nanomedicine for Preventive Therapy of Radiation-Induced Heart Disease

Radiation-induced heart disease (RIHD) is a common radiotherapy complication. Reducing radiation exposure and post-irradiation antioxidant therapy are promising approaches. Here, a liquid metal-based core-shell nanomedicine (LMN) composed of a gallium core and a multifunctional polymeric shell with radiopaque, X-ray shielding, and X-ray-responsive antioxidation properties for preventive therapy of RIHD is developed. The liquid metal provides radiopaque properties to enhance X-ray and computed tomography imaging and attenuate radiation to prevent primary myocardial damage. Under X-ray radiation, cleavage of the diselenide bond on the polymeric shell results in the release of LMN and controlled antioxidation. In vitro and in vivo experiments have demonstrated that LMN significantly reduces myocardial injury and impaired cardiac function, stabilizes mitochondrial function, and inhibits myocardial fibrosis. This nanomedicine with radiographic contrast, radiation shielding, and responsive features provides a new strategy for the prevention of radiation-related diseases.

Modulatory effect of amifostine (WR-1065) against genotoxicity and oxidative stress induced by methotrexate in human umbilical vein endothelial cells (HUVECs)

Amifostine is used in chemotherapy and radiotherapy as a cytoprotective adjuvant alongside DNA-binding chemotherapeutic agents. It functions by reducing free radicals and detoxifying harmful metabolites. Methotrexate, as an antimetabolite drug has been considered for treating various cancers and autoimmune diseases. However, the cytotoxic effects of methotrexate extend beyond tumor cells to crucial organs, including the heart. This study applied the HUVEC cell line as a reference in vitro model for researching the characteristics of vascular endothelium and cardiotoxicity. The current study aimed to assess amifostine's potential cytoprotective properties against methotrexate-induced cellular damage. Cytotoxicity was measured using the MTT assay. Apoptotic rates were evaluated by Annexin V-FITC/PI staining via flow cytometry. The genoprotective effect of amifostine was determined using the comet assay. Cells were exposed to various amifostine doses (10-200 μg/mL) and methotrexate (2.5 μM) in pretreatment culture condition. Methotrexate at 2.5 μM revealed cytotoxicity, apoptosis, oxidative stress and genotoxicity while highlighting amifostine's cyto/geno protective properties on HUVECs. Amifostine significantly decreased the levels of ROS and LPO while preserving the status of GSH and SOD activity. Furthermore, it inhibited genotoxicity (tail length, %DNA in tail, and tail moment) in the comet assay. Amifostine markedly attenuated methotrexate-induced apoptotic cell death (early and late apoptotic rates). These findings convey that amifostine can operate as a cytoprotectant agent.

Peripheral neuropathy associated with monomethyl auristatin E-based antibody-drug conjugates

Since the successful approval of gemtuzumab ozogamicin, antibody-drug conjugates (ADCs) have emerged as a pivotal category of targeted therapies for cancer. Among these ADCs, the use of monomethyl auristatin E (MMAE) as a payload is prevalent in the development of ADC drugs, which has significantly improved overall therapeutic efficacy against various malignancies. However, increasing clinical observations have raised concerns regarding the potential nervous system toxicity associated with MMAE-based ADCs. Specifically, a higher incidence of peripheral neuropathy has been reported in ADCs incorporating MMAE as payloads. Considering the increasing global use of MMAE-based ADCs, it is imperative to provide an inclusive overview of diagnostic and management strategies for this adverse event. In this review, we examine current information and what future research directions are required to better understand and manage this type of clinical challenge.

N-acetyl-L-tryptophan (NAT) provides protection to intestinal epithelial cells (IEC-6) against radiation-induced apoptosis via modulation of oxidative stress and mitochondrial membrane integrity

BACKGROUND

Ionizing radiation generates oxidative stress in biological systems via inducing free radicals. Gastro-intestinal system has been known for its high radiosensitivity. Therefore, to develop an effective radiation countermeasure for gastrointestinal system, N-acetyl L-tryptophan was evaluated for its radioprotective efficacy using intestinal epithelial cells-6 (IEC-6) cells as the experimental model.

METHODS AND RESULTS

Cellular metabolic and lysosomal activity of L-NAT and L-NAT treated irradiated IEC-6 cells were assessed by MTT and NRU staining, respectively. ROS and mitochondrial superoxide levels along with mitochondrial disruption were detected using specific fluorescent probes.  Endogenous antioxidants (CAT, SOD, GST, GPx) activities were determined using calorimetric assay.  Apoptosis and DNA damage were assessed using flow cytometery and Comet assay, respectively. Results of the study were demonstrated that L-NAT pre-treatment (- 1 h) to irradiated IEC-6 cells significantly contribute to ensuring 84.36% to 87.68% (p < 0.0001) survival at 0.1 μg/mL concentration against LD50 radiation dose (LD50; 20 Gy). Similar level of radioprotection was observed with a clonogenic assay against γ radiation (LD50; 5 Gy). L-NAT was found to provide radioprotection by neutralizing radiation-induced oxidative stress, enhancing antioxidant enzymes (CAT, SOD, GST, and GPx), and protecting DNA from radiation-induced damage. Further, significant restoration of mitochondrial membrane integrity along with apoptosis inhibition was observed with irradiated IEC-6 cells upon L-NAT pretreatment.

WR1065 conjugated to thiol-PEG polymers as novel anticancer prodrugs: broad spectrum efficacy, synergism, and drug resistance reversal

The lack of anticancer agents that overcome innate/acquired drug resistance is the single biggest barrier to achieving a durable complete response to cancer therapy. To address this issue, a new drug family was developed for intracellular delivery of the bioactive aminothiol WR1065 by conjugating it to discrete thiol-PEG polymers: 4-star-PEG-S-S-WR1065 (4SP65) delivers four WR1065s/molecule and m-PEG6-S-S-WR1065 (1LP65) delivers one. Infrequently, WR1065 has exhibited anticancer effects when delivered via the FDA-approved cytoprotectant amifostine, which provides one WR1065/molecule extracellularly. The relative anticancer effectiveness of 4SP65, 1LP65, and amifostine was evaluated in a panel of 15 human cancer cell lines derived from seven tissues. Additional experiments assessed the capacity of 4SP65 co-treatments to potentiate the anticancer effectiveness and overcome drug resistance to cisplatin, a chemotherapeutic, or gefitinib, a tyrosine kinase inhibitor (TKI) targeting oncogenic EGFR mutations. The CyQUANT®-NF proliferation assay was used to assess cell viability after 48-h drug treatments, with the National Cancer Institute COMPARE methodology employed to characterize dose-response metrics. In normal human epithelial cells, 4SP65 or 1LP65 enhanced or inhibited cell growth but was not cytotoxic. In cancer cell lines, 4SP65 and 1LP65 induced dose-dependent cytostasis and cytolysis achieving 99% cell death at drug concentrations of 11.2 ± 1.2 µM and 126 ± 15.8 µM, respectively. Amifostine had limited cytostatic effects in 11/14 cancer cell lines and no cytolytic effects. Binary pairs of 4SP65 plus cisplatin or gefitinib increased the efficacy of each partner drug and surmounted resistance to cytolysis by cisplatin and gefitinib in relevant cancer cell lines. 4SP65 and 1LP65 were significantly more effective against TP53-mutant than TP53-wild-type cell lines, consistent with WR1065-mediated reactivation of mutant p53. Thus, 4SP65 and 1LP65 represent a unique prodrug family for innovative applications as broad-spectrum anticancer agents that target p53 and synergize with a chemotherapeutic and an EGFR-TKI to prevent or overcome drug resistance.

Localized Drug Delivery Systems: An Update on Treatment Options for Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world, with surgery, radiotherapy, chemotherapy, and immunotherapy being the primary treatment modalities. The treatment for HNSCC has evolved over time, due to which the prognosis has improved drastically. Despite the varied treatment options, major challenges persist. HNSCC chemotherapeutic and immunotherapeutic drugs are usually administered systemically, which could affect the patient's quality of life due to the associated side effects. Moreover, the systemic administration of salivary stimulating agents for the treatment of radiation-induced xerostomia is associated with toxicities. Localized drug delivery systems (LDDS) are gaining importance, as they have the potential to provide non-invasive, patient-friendly alternatives to cancer therapy with reduced dose-limiting toxicities. LDDSs involve directly delivering a drug to the tissue or organ affected by the disease. Some of the common localized routes of administration include the transdermal and transmucosal drug delivery system (DDSs). This review will attempt to explore the different treatment options using LDDSs for the treatment of HNSCC and radiotherapy-induced damage and their potential to provide a better experience for patients, as well as the obstacles that need to be addressed to render them successful.

PKCδ regulates chromatin remodeling and DNA repair through SIRT6

Protein kinase C delta (PKCδ) is a ubiquitous kinase whose function is defined in part by localization to specific cellular compartments. Nuclear PKCδ is both necessary and sufficient for IR-induced apoptosis, while inhibition of PKCδ activity provides radioprotection in vivo. How nuclear PKCδ regulates DNA-damage induced cell death is poorly understood. Here we show that PKCδ regulates histone modification, chromatin accessibility, and double stranded break (DSB) repair through a mechanism that requires SIRT6. Overexpression of PKCδ promotes genomic instability and increases DNA damage and apoptosis. Conversely, depletion of PKCδ increases DNA repair via non-homologous end joining (NHEJ) and homologous recombination (HR) as evidenced by more rapid formation of NHEJ (DNA-PK) and HR (Rad51) DNA damage foci, increased expression of repair proteins, and increased repair of NHEJ and HR fluorescent reporter constructs. Nuclease sensitivity indicates that PKCδ depletion is associated with more open chromatin, while overexpression of PKCδ reduces chromatin accessibility. Epiproteome analysis revealed that PKCδ depletion increases chromatin associated H3K36me2, and reduces ribosylation of KDM2A and chromatin bound KDM2A. We identify SIRT6 as a downstream mediator of PKCδ. PKCδ-depleted cells have increased expression of SIRT6, and depletion of SIRT6 reverses the changes in chromatin accessibility, histone modification and NHEJ and HR DNA repair seen with PKCδ-depletion. Furthermore, depletion of SIRT6 reverses radioprotection in PKCδ-depleted cells. Our studies describe a novel pathway whereby PKCδ orchestrates SIRT6-dependent changes in chromatin accessibility to increase DNA repair, and define a mechanism for regulation of radiation-induced apoptosis by PKCδ.

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Oral konjac glucomannan for prevention of ionizing radiation-induced injury by regulating gut microbiota and increasing short chain fatty acids

Ionizing radiation-induced injury commonly happens in radiotherapy, leading to damages of the hematopoietic and gastrointestinal systems. Radioprotective medications are mainly applied in hospitals, although only injections are available and their gut protection is limited. Here, oral konjac glucomannan (KGM), a natural macromolecule and soluble dietary fiber, was used against ionizing radiation-induced injury. The mice were fed with KGM (0.4 g/kg) for 3 days or injected with a clinical medication amifostine before 6.5 Gy γ-ray whole body irradiation (WBI) or 13 Gy whole abdominal irradiation (WAI). In the WBI experiments, KGM improved blood cell recovery and bone marrow cell proliferation in the femur and spleen, though its effect was weaker than or similar to that of amifostine. In the WBI experiments, the gut protection of KGM was similar to or a little better than that of amifostine, involving regenerated crypts numbers, villus length, and gut permeability. Moreover, KGM remarkably enhanced the survival rates of WBI and WAI mice, consistent with amifostine. KGM, as a prebiotic, enhanced gut microbiota abundance, probiotic numbers, and short chain fatty acid production, maintaining gut homeostasis. Moreover, KGM inhibited the apoptosis of irradiated human intestinal epithelial cells. KGM is a promising natural macromolecule against ionizing radiation-induced injury.

Alpha-thiol deoxynucleotide triphosphates (S-dNTPs) as radioprotective agents: A novel approach

In this study, the ability of a mixture of four different alpha-thiol deoxynucleotide triphosphates (S-dNTPs) each at a concentration of 10μM when incorporated into the genomic DNA of proliferating human HL-60 and Mono-Mac-6 (MM-6) cells in vitro to provide protection from 2, 5, and 10 Gy of gamma radiation was investigated. Incorporation of the four different S-dNTPs into nuclear DNA at 10 μM concentration for five days was validated by agarose gel electrophoretic band shift analysis. S-dNTP-treated genomic DNA reacted with BODIPY-iodoacetamide demonstrated a band shift to higher molecular weight to confirm the presence of sulfur moieties in the resultant phosphorothioate DNA backbones. No overt signs of toxicity or obvious morphologic cellular differentiation were noted in the presence of 10 μM S-dNTPs even after 8 days in culture. Significantly reduced radiation-induced persistent DNA damage measured at 24 and 48 h post-exposure by γ-H2AX histone phosphorylation using FACS analysis in S-dNTP incorporated HL-60 and MM6 cells indicated protection against radiation-induced direct and indirect DNA damage. Statistically significant protection by S-dNTPs was noted at the cellular level by CellEvent™ Caspase-3/7 assay, which assess the extent of apoptotic events, and by trypan blue dye exclusion to assed cell viability. The results appear to support an innocuous antioxidant thiol radioprotective effect built into genomic DNA backbones as the last line of defense against ionizing radiation and free radical-induced DNA damage.

Nanodrugs with intrinsic radioprotective exertion: Turning the double-edged sword into a single-edged knife

Ionizing radiation (IR) poses a growing threat to human health, and thus ideal radioprotectors with high efficacy and low toxicity still receive widespread attention in radiation medicine. Despite significant progress made in conventional radioprotectants, high toxicity, and low bioavailability still discourage their application. Fortunately, the rapidly evolving nanomaterial technology furnishes reliable tools to address these bottlenecks, opening up the cutting-edge nano-radioprotective medicine, among which the intrinsic nano-radioprotectants characterized by high efficacy, low toxicity, and prolonged blood retention duration, represent the most extensively studied class in this area. Herein, we made the systematic review on this topic, and discussed more specific types of radioprotective nanomaterials and more general clusters of the extensive nano-radioprotectants. In this review, we mainly focused on the development, design innovations, applications, challenges, and prospects of the intrinsic antiradiation nanomedicines, and presented a comprehensive overview, in-depth analysis as well as an updated understanding of the latest advances in this topic. We hope that this review will promote the interdisciplinarity across radiation medicine and nanotechnology and stimulate further valuable studies in this promising field.

Pathogenesis and therapy of radiation enteritis with gut microbiota

Radiotherapy is widely used in clinic due to its good effect for cancer treatment. But radiotherapy of malignant tumors in the abdomen and pelvis is easy to cause radiation enteritis complications. Gastrointestinal tract contains numerous microbes, most of which are mutualistic relationship with the host. Abdominal radiation results in gut microbiota dysbiosis. Microbial therapy can directly target gut microbiota to reverse microbiota dysbiosis, hence relieving intestinal inflammation. In this review, we mainly summarized pathogenesis and novel therapy of the radiation-induced intestinal injury with gut microbiota dysbiosis and envision the opportunities and challenges of radiation enteritis therapy.

The Progress in Reconstruction of Mandibular Defect Caused by Osteoradionecrosis

Osteoradionecrosis (ORN) is described as a disease with exposed, nonviable bone that fails to heal spontaneously or by means of conservative treatment after radiotherapy in at least 3 months. Though traditional theories in the early stage including hypoxic-hypocellular-hypovascular and fibro-atrophic in addition to new findings such as ferroptosis were put forward to explain the mechanisms of the osteoradionecrosis, the etiology of ORN is still unclear. With the high rate of occurrence in the head and neck area, especially in the mandible, this disease can disrupt the shape and function of the irradiated area, leading to a clinical presentation ranging from stable small areas of asymptomatic exposed bone to severe progressive necrosis. In severe cases, patients may experience pain, xerostomia, dysphagia, facial fistulas, and even a jaw defect. Consequently, sequence therapy and sometimes extensive surgery and reconstructions are needed to manage these sequelae. Treatment options may include pain medication, antibiotics, the removal of sequesters, hyperbaric oxygen therapy, segmental resection of the mandible, and free flap reconstruction. Microanastomosed free-flaps are considered to be promising choice for ORN reconstruction in recent researches, and new methods including three-dimensional (3-D) printing, pentoxifylline, and amifostine are used nowadays in trying increase the success rates and improve quality of the reconstruction. This review summarizes the main research progress in osteoradionecrosis and reconstruction treatment of osteoradionecrosis with mandibular defect.

Molecular Influence of the ATM Protein in the Treatment of Human Cells with Different Radioprotective Drugs: Comparisons between Antioxidative and Pro-Episkevic Strategies

The radiation protection strategy with chemical agents has long been based on an antioxidative approach consisting in reducing the number of radical oxygen and nitrogen species responsible for the formation of the radiation-induced (RI) DNA damage, notably the DNA double-strand breaks (DSB), whose subset participates in the RI lethal effect as unrepairable damage. Conversely, a DSB repair-stimulating strategy that may be called the “pro-episkevic” approach (from the ancient Greek episkeve, meaning repair) can be proposed. The pro-episkevic approach directly derives from a mechanistic model based on the RI nucleoshuttling of the ATM protein (RIANS) and contributes to increase the number of DSB managed by NHEJ, the most predominant DSB repair and signaling pathway in mammalians. Here, three radioresistant and three radiosensitive human fibroblast cell lines were pretreated with antioxidative agents (N-acetylcysteine or amifostine) or to two pro-episkevic agents (zoledronate or pravastatin or both (ZOPRA)) before X-ray irradiation. The fate of the RI DSB was analyzed by using γH2AX and pATM immunofluorescence. While amifostine pretreatment appeared to be the most efficient antioxidative process, ZOPRA shows the most powerful radiation protection, suggesting that the pro-episkevic strategy may be an alternative to the antioxidative one. Additional investigations are needed to develop some new drugs that may elicit both antioxidative and pro-episkevic properties and to quantify the radiation protection action of both types of drugs applied concomitantly.

Radioprotective countermeasures for radiation injury (Review)

A series of physiological and pathological changes occur after radiotherapy and accidental exposure to ionizing radiation (IR). These changes cause serious damage to human tissues and can lead to death. Radioprotective countermeasures are radioprotective agents that prevent and reduce IR injury or have therapeutic effects. Based on a good understanding of radiobiology, a number of protective agents have achieved positive results in early clinical trials. The present review grouped known radioprotective agents according to biochemical categories and potential clinical use, and reviewed radiation countermeasures, i.e., radioprotectors, radiation mitigators and radiotherapeutic agents, with an emphasis on their current status and research progress. The aim of the present review is to facilitate the selection and application of suitable radioprotectors for clinicians and researchers, to prevent or reduce IR injury.

Looking for the phoenix: the current research on radiation countermeasures

PURPOSE

Ionizing radiation (IR) is widely applied in radiotherapy for the treatment of over 50% of cancer patients. IR is also intensively used in medical diagnostics on a daily basis in imaging. Moreover, recent geopolitical events have re-ignited the real threat of the use of nuclear weapons. Medical radiation countermeasures represent one of the effective protection strategies against the effects of IR. The aim of this review was to summarize the most commonly used strategies and procedures in the development of radiation countermeasures and to evaluate the current state of their research, with a focus on those in the clinical trial phase.

METHODS

Clinical trials for this review were selected in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. The search was performed in the clinicaltrials.gov database as of May 2022.

RESULTS

Our search returned 263 studies, which were screened and of which 25 were included in the review. 10 of these studies had been completed, 3 with promising results: KMRC011 increased G-CSF, IL-6, and neutrophil counts suggesting potential for the treatment of hematopoietic acute radiation syndrome (H-ARS); GC4419 reduced the number of patients with severe oral mucositis and its duration; the combination of enoxaparin, pentoxifylline, and ursodeoxycholic acid reduced the incidence of focal radiation-induced liver injury.

CONCLUSION

The agents discovered so far show significant side effects or low efficacy, and hence most of the tested agents terminate in the early stages of development. In addition, the low profitability of this type of drug demotivates the private sector to invest in such research. To overcome this problem, there is a need to involve more public resources in funding. Among the technological opportunities, a deeper use of in silico approaches seems to be prospective.

Drug Therapeutics Delivery to the Salivary Glands: Intraglandular and Intraductal Injections

Salivary gland hypofunction and xerostomia following pathological conditions like Sjogren's syndrome or head and neck radiotherapy usually lead to tremendous impairment of oral health, speech, and swallowing. The use of systemic drugs to alleviate the symptoms of these conditions has been associated with various adverse effects. Techniques of local drug delivery to the salivary gland have grown enormously to address this problem properly. The techniques include intraglandular and intraductal injections. In this chapter, we will provide a review of the literature for both techniques while incorporating our lab experience in using them.

Higher radiation doses after partial laryngectomy may raise the incidence of pneumonia: A retrospective cohort study

Background

Currently, studies have shown that a high dose of radiotherapy to the throat have various harmful and adverse effects on the patients' laryngeal function, resulting in the development of pneumonia. This study aimed to explore how radiotherapy dose affected the probability of pneumonia following laryngeal cancer surgery.

Materials and methods

A retrospective analysis was done on patients diagnosed with laryngeal cancer between 2010 and 2020 and were treated surgically and with postoperative radiotherapy in the same institution. This study included 108 patients in total, 51 of who were in the low-dose group and 57 of whom were in the high-dose group. Age, gender, the location of laryngeal cancer, the presence or absence of lymph node metastasis, and other demographic and clinical characteristics were collected, and the prevalence of postoperative pneumonia was compared between the two groups.

Results

The total prevalence of postoperative pneumonia was 59.3%, but there was a significant difference between the two groups(high-dose group 71.9% VS low-dose group 45.1%; p=0.005). A total of 9.3% (10/108) of the patients had readmission due to severe pneumonia, and the rate of readmission due to pneumonia was significantly different between the two groups (high-dose group 15.8% VS low-dose group 2.0%, p=0.032). Additionally, the high-dose group's prevalence of Dysphagia was significantly higher than the low-dose group's. According to multivariate logistic modeling, high-dose radiation was a risk factor for pneumonia (OR=4.224, 95%CI =1.603-11.131, p=0.004).

Conclusion

Pneumonia risk could increase with radiotherapy doses > 50 Gy in the treatment of laryngeal cancer. Therefore, we recommend that when the radiation dose surpasses 50Gy, doctors should pay particular attention to the lung health of patients with laryngeal cancer.

RRx-001 and the "Right stuff": Protection and treatment in outer space

From antibiotics to aspirin to antimalarials and to anticancer agents, about half of the world's best-selling drugs are derived from nature. However, accelerating climatic disruption, habitat destruction, pollution, and biodiversity loss all negatively impact the potential of natural sources to continue to serve as repositories of novel pharmaceuticals. On that basis, the final frontier for drug development is perhaps not the rainforests, coral reefs, and other natural habitats but rather the aerospace industry with its virtually unlimited and inexhaustible man-made 'library' of potentially bioactive compounds. The first aerospace-sourced therapeutic to reach the clinic is RRx-001, an inhibitor of the NOD-like receptor - Nucleotide-binding oligomerization domain with Leucine rich Repeat and Pyrin domain (NLRP3) inflammasome in a Phase 3 trial for the treatment of small cell lung cancer (SCLC) and in a soon-to-start Phase 3 trial for protection against chemoradiotherapy-induced severe oral mucositis in first line head and neck cancer. As manned missions to the Moon, Mars, and asteroids as well as space tourism beckon, it is perhaps fitting that a compound like RRx-001, which is derived from 1,3,3-Trinitroazetidine (TNAZ), an explosive propellant for rockets, is a potential "all purpose" option to mitigate the major biomedical effects of space radiation exposures including cancer development and other tissue degenerations both within mission and after mission. This article highlights the promise of RRx-001 to attenuate the acute and late effects of radiation exposure on astronauts including the development of cancer.

The emerging role of exosomes in radiotherapy

Presently, more than half of cancer patients receive radiotherapy to cure localized cancer, palliate symptoms, or control the progression of cancer. However, radioresistance and radiation-induced bystander effects (RIBEs) are still challenging problems in cancer treatment. Exosomes, as a kind of extracellular vesicle, have a significant function in mediating and regulating intercellular signaling pathways. An increasing number of studies have shown that radiotherapy can increase exosome secretion and alter exosome cargo. Furthermore, radiation-induced exosomes are involved in the mechanism of radioresistance and RIBEs. Therefore, exosomes hold great promise for clinical application in radiotherapy. In this review, we not only focus on the influence of radiation on exosome biogenesis, secretion and cargoes but also on the mechanism of radiation-induced exosomes in radioresistance and RIBEs, which may expand our insight into the cooperative function of exosomes in radiotherapy.

ROS-Responsive and pH-Sensitive Aminothiols Dual-Prodrug for Radiation Enteritis

Radiation exposure can immediately trigger a burst of reactive oxygen species (ROS), which can induce severe cell death and long-term tissue damage. Therefore, instantaneous release of sufficient radioprotective drugs is vital to neutralize those accumulated ROS in IR-exposed areas. To achieve this goal, we designed, synthesized, and evaluated a novel oral ROS-responsive radioprotective compound (M1) with high biocompatibility and efficient ROS-scavenging ability to act as a promising oral drug for radiation protection. The compound is stably present in acidic environments and is hydrolyzed in the intestine to form active molecules rich in thiols. M1 can significantly remove cellular ROS and reduce DNA damage induced by γ-ray radiation. An in vivo experiment showed that oral administration of M1 effectively alleviates acute radiation-induced intestinal injury. Immunohistochemical staining showed that M1 improved cell proliferation, reduced cell apoptosis, and enhanced the epithelial integrity of intestinal crypts. This study provides a promising oral ROS-sensitive agent for acute intestinal radiation syndrome.

Synthesis of novel benzothiophene derivatives as protectors against cranial irradiation-induced neuroinflammation

Aim: Cranial irradiation results in many deleterious effects to normal tissues, including neuroinflammation. There is a need to explore radioprotective agents that could be safely used to ameliorate these effects. Method: Nine novel benzothiophene derivatives bearing pyrimidinone, pyrazolidinone, triazole and other active moieties were synthesized and evaluated as antioxidants in an in vitro screening experiment. The most potent compounds were then tested as protectors against radiation-induced neuroinflammation and oxidative stress in rat brains following cranial irradiation. Results: The most potent antioxidant compounds were compounds 3–5 and 10 . P-fluro,p- bromo and pyrido benzothiophene derivatives offered good antioxidant and anti-inflammatory effects. Conclusion: Compounds 3–5 may be introduced as nontoxic candidates for adjuvant therapeutic protocols used in head and neck tumor radiotherapeutic management.

DMA, a Small Molecule, Increases Median Survival and Reduces Radiation-Induced Xerostomia via the Activation of the ERK1/2 Pathway in Oral Squamous Cell Carcinoma

Survival, recurrence, and xerostomia are considerable problems in the treatment of oral squamous carcinoma patients. In this study, we investigated the role of DMA (5-(4-methylpiperazin-1-yl)-2-[2′-(3,4-dimethoxyphenyl)5″benzimidazoyl]benzimidazole) as a salivary gland cytoprotectant in a patient-derived xenograft mouse model. A significant increase in saliva secretion was observed in the DMA-treated xenograft compared to radiation alone. Repeated doses of DMA with a high dose of radiation showed a synergistic effect on mice survival and reduced tumor growth. The mean survival rate of tumor-bearing mice was significantly enhanced. The increased number of Ki-67-stained cells in the spleen, intestine, and lungs compared to the tumor suggests DMA ablates the tumor but protects other organs. The expression of aquaporin-5 was restored in tumor-bearing mice injected with DMA before irradiation. The reduced expression of αvβ3 integrin and CD44 in DMA alone and DMA with radiation-treated mice suggests a reduced migration of cells and stemness of cancer cells. DMA along with radiation treatment results in the activation of the Ras/Raf/MEK/ERK pathway in the tumor, leading to apoptosis through caspase upregulation. In conclusion, DMA has strong potential for use as an adjuvant in radiotherapy in OSCC patients.

Noninvasive Systemic Modalities for Prevention of Head and Neck Radiation-Associated Soft Tissue Injury: A Narrative Review

BACKGROUND

 Radiation-associated soft tissue injury is a potentially devastating complication for head and neck cancer patients. The damage can range from minor sequelae such as xerostomia, which requires frequent daily maintenance, to destructive degenerative processes such as osteoradionecrosis, which can contribute to flap failure and delay or reverse oral rehabilitation. Despite the need for effective radioprotectants, the literature remains sparse, primarily focused on interventions beyond the surgeon's control, such as maintenance of good oral hygiene or modulation of radiation dose.

METHODS

 This narrative review aggregates and explores noninvasive, systemic treatment modalities for prevention or amelioration of radiation-associated soft tissue injury.

RESULTS

 We highlighted nine modalities with the most clinical potential, which include amifostine, melatonin, palifermin, hyperbaric oxygen therapy, photobiomodulation, pentoxifylline-tocopherol-clodronate, pravastatin, transforming growth factor-β modulators, and deferoxamine, and reviewed the benefits and limitations of each modality. Unfortunately, none of these modalities are supported by strong evidence for prophylaxis against radiation-associated soft tissue injury.

CONCLUSION

 While we cannot endorse any of these nine modalities for immediate clinical use, they may prove fruitful areas for further investigation.

Prophylactic management of radiation-induced mucositis using herbal mouthwash in patients with head and neck cancer: an assessor-blinded randomized controlled trial

OBJECTIVES

Radiation-induced mucositis (RIOM) is one of the most common side effects from head and neck radiotherapy. Several reagents have been introduced to manage the symptom; however, there is still a limited number of effective reagents. Herbal mouthwashes with payayor (Clinacanthus nutans Lindau) and fingerroot (Boesenbergia rotunda) were tested their efficacies in preventing and reducing severity of RIOM in comparison with normal saline with sodium bicarbonate.

METHODS

One hundred twenty patients with head and neck cancer undergoing radiotherapy participated in the study and were randomly assigned into three treatment groups using block randomization method. The participants were assigned one of the three mouthwashes for use throughout their radiotherapy course and were assessed for their mucositis scores from week one to six into their radiotherapy course as well as at one-month follow-up. Body mass index was also measured for comparison of nutritional status.

RESULTS

The two mouthwashes were similarly effective in prophylaxis of RIOM in term of severity. The averaged mucositis scores were less than two for all groups. For the onset of RIOM, both herbal mouthwashes could slightly delay the symptom but not statistically significant. Patients' body mass index across the three treatment groups was also comparable. The patients were largely satisfied with all the mouthwashes with no clear preference on any of them.

CONCLUSIONS

Prophylactic treatment of RIOM using herbal mouthwashes could substitute the current standard of normal saline with bicarbonate. A different formulation of the two herbs could potentially improve the prophylactic outcome.

TRIAL REGISTRATION NO

NCT03359187.

Discovery of the radio-protecting effect of Ecliptae Herba, its constituents and targeting p53-mediated apoptosis in vitro and in vivo

Radiation protection drugs are often accompanied by toxicity, even amifostine, which has been the dominant radio-protecting drug for nearly 30 years. Furthermore, there is no therapeutic drug for radiation-induced intestinal injury (RIII). This paper intends to find a safe and effective radio-protecting ingredient from natural sources. The radio-protecting effect of Ecliptae Herba (EHE) was discovered preliminarily by antioxidant experiments and the mouse survival rate after ¹³⁷Cs irradiation. EHE components and blood substances in vivo were identified through UPLC‒Q-TOF. The correlation network of "natural components in EHE-constituents migrating to blood-targets-pathways" was established to predict the active components and pathways. The binding force between potential active components and targets was studied by molecular docking, and the mechanism was further analyzed by Western blotting, cellular thermal shift assay (CETSA), and ChIP. Additionally, the expression levels of Lgr5, Axin2, Ki67, lysozyme, caspase-3, caspase-8,8-OHdG, and p53 in the small intestine of mice were detected. It was found for the first time that EHE is active in radiation protection and that luteolin is the material basis of this protection. Luteolin is a promising candidate for RⅢ. Luteolin can inhibit the p53 signaling pathway and regulate the BAX/BCL2 ratio in the process of apoptosis. Luteolin could also regulate the expression of multitarget proteins related to the same cell cycle.

Screen identifies fasudil as a radioprotector on human fibroblasts

Background

Radioprotectors safeguard biological system exposed to ionizing radiation (IR) by protecting normal cells from radiation damage during radiotherapy. Due to the toxicity and limited clinical utility of the present radioprotectors, it prompts us to identify novel radioprotectors that could alleviate IR-induced cytotoxicity of normal tissues.

Aims and Methods

To identify new radioprotectors, we screened a chemical molecular library comprising 253 compounds in normal human fibroblasts (HFs) or 16HBE cells upon IR by CCK-8 assays and clonogenic survival assays. Fasudil was identified as a potential effective radioprotector.

Results

The results indicated that Fasudil exerts radioprotective effects on HFs against IR-induced DNA double-strand breaks (DSBs) through the regulation of DSB repair. Fasudil increased homologous recombination (HR) repair by 45.24% and decreased non-homologous end-joining (NHEJ) by 63.88% compared with untreated cells, without affecting changes to cell cycle profile. We further found that fasudil significantly facilitated the expression and foci formation of HR core proteins such as Rad51 and BRCA1 upon IR, and decreased the expression of NHEJ-associated proteins such as DNA-PKcs at 24 h post-IR.

Conclusion

Our study identified fasudil as a novel radioprotector that exert radioprotective effects on normal cells through regulation of DSB repair by promoting HR repair.

A chemical perspective on the clinical use of platinum-based anticancer drugs

Platinum drugs have been a mainstay of cancer chemotherapy since the introduction of cisplatin in the 1970s. Since then, carboplatin and oxaliplatin have been approved world-wide and nedaplatin, lobaplatin, heptaplatin, dicycloplatin, and miriplatin have been approved in individual countries. The three main platinum drugs are not used in isolation but are combined in chemotherapy protocols from a range of 28 drugs that include: anthracyclines, alkylating agents, vinca alkaloids, antimetabolites, topoisomerase inhibitors, taxanes, and monoclonal antibodies. Interestingly, they are not yet used in combination with tyrosine kinase inhibitors or proteasome inhibitors. How platinum drugs are formulated for administration to patients is important to minimise aquation during storage and administration. Cisplatin is typically formulated in saline-based solutions while carboplatin and oxaliplatin are formulated in dextrose. Pharmacokinetics are an important factor in both the efficacy and safety of platinum drugs. This includes the quantity of protein-bound drug in blood serum, how fast the drugs are cleared by the body, and how fast the drugs are degraded and deactivated. Attempts to control platinum pharmacokinetics and side effects using rescue agents, macrocycles, and nanoparticles, and through the design of platinum(IV)-based drugs have not yet resulted in clinically successful outcomes. As cancer is predominantly a disease of old age, many cancer patients who are administered a platinum drug may have other medical conditions which means they may also be taking many non-cancer medicines. The co-administration of non-cancer medicines to patients can potentially affect the efficacy of platinum drugs and/or change the severity of their side effects through drug-drug interactions.

Salidroside Ameliorates Radiation Damage by Reducing Mitochondrial Oxidative Stress in the Submandibular Gland

Radiotherapy for patients with head and neck cancer inevitably causes radiation damage to salivary glands (SGs). Overproduction of reactive oxygen species (ROS) leads to mitochondrial damage and is critical in the pathophysiology of SG radiation damage. However, mitochondrial-targeted treatment is unavailable. Herein, both in vitro and in vivo models of radiation-damaged rat submandibular glands (SMGs) were used to investigate the potential role of salidroside in protecting irradiated SGs. Cell morphology was observed with an inverted phase-contrast microscope. Malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), mitochondrial ROS, mitochondrial membrane potential (MMP), and ATP were measured using relevant kits. The mitochondrial ultrastructure was observed under transmission electron microscopy. Cell apoptosis was determined by Western blot and TUNEL assays. Saliva was measured from Wharton’s duct. We found that salidroside protected SMG cells and tissues against radiation and improved the secretion function. Moreover, salidroside enhanced the antioxidant defense by decreasing MDA, increasing SOD, CAT, and GSH, and scavenging mitochondrial ROS. Furthermore, salidroside rescued the mitochondrial ultrastructure, preserved MMP and ATP, suppressed cytosolic cytochrome c and cleaved caspase 3 expression, and inhibited cell apoptosis. Together, these findings first identify salidroside as a mitochondrial-targeted antioxidant for preventing SG radiation damage.

No time to die? Intrinsic apoptosis signaling in hematopoietic stem and progenitor cells and therapeutic implications

PURPOSE OF REVIEW

Dysregulated apoptosis contributes to the pathogenesis of many hematologic malignancies. BH3-mimetics, antagonists of antiapoptotic BCL-2 proteins, represent novel, and promising cancer drugs. While the acute myelosuppressive effects of Venetoclax, the first Food and Drug Administration approved BCL-2 inhibitor, are fairly well described, little is known about side effects of novel BH3-mimetics and effects of chronic Venetoclax treatment.

RECENT FINDINGS

Highly relevant publications focused on the effects of acute and chronic Venetoclax therapy, with focus on cell-type specific adaptive mechanisms, the emergence of clonal hematopoiesis, and the selection of BAX-mutated hematopoietic cells in patients treated with Venetoclax for a long period. Important advances were made in understanding primary and secondary Venetoclax resistance and prediction of Venetoclax response. Combination therapies of BH3-mimetics targeting different BCL-2 proteins are highly anticipated. However, human stem and progenitors require both MCL-1 and BCL-XL for survival, and serious myelosuppressive effects of combined MCL-1/BCL-XL inhibition can be expected.

SUMMARY

Long-term studies are indispensable to profile the chronic side effects of Venetoclax and novel BH3-mimetics and better balance their risk vs. benefit in cancer therapy. Combination therapies will be powerful, but potentially limited by severe myelosuppression. For precision medicine, a better knowledge of BCL-2 proteins in the healthy and diseased hematopoietic system is required.

Effects of Ultrafine Single-Nanometer Oxygen Bubbles on Radiation Sensitivity in a Tumor-Bearing Mouse Model

Radiation therapy against cancer cells often causes radiation resistance via accumulation of hypoxia-inducible factor 1 subunit alpha (HIF-1α) under hypoxic conditions and severe side effects. Radiation sensitizers without side effects are required to overcome hypoxia-induced radiation resistance and decrease radiation-related side effects in patients with refractory cancer. We previously developed oxygen nanobubble water (NBO₂ water) and demonstrated that it suppresses hypoxia-induced radiation resistance in cancer cell lines within the single-nanometer range. This study aimed to elucidate whether NBO₂ water could act as a radiosensitizer via regulation of HIF-1α in a tumor-bearing mouse model. Six-week-old female BALB/c mice subcutaneously injected with tumor cells received control water or NBO₂ water for 28 days, after which biochemical examinations and radiation treatment were performed. Hypoxic tumor regions were detected immunohistochemically. We found that NBO₂ water sensitized radiation reactivity in the xenografted tumors. Notably, NBO₂ water administration downregulated the accumulation of HIF-1α in xenografted tumors and did not affect the vital organs of healthy mice. The combination of radiation and single-nanometer NBO₂ water without severe side effects may be a promising therapeutic option to improve radiation sensitivity in cancer patients without tolerance to invasive treatments.

Salivary Gland Dysfunction Secondary to Cancer Treatment

The number of cancer survivors are increasing and so are the oral toxicities from cancer therapy. Most patients receiving treatment for cancer develop some form of oral adverse events including, but not limited to, mucositis, opportunistic infections, dry mouth, and/or osteonecrosis of the jaw. One of the most common complications from head and neck cancer radiation therapy is salivary gland dysfunction (SGD). SGD is an umbrella term that includes the subjective sensation of dry mouth (xerostomia) and hyposalivation (objective reduction of the salivary flow rate). Dry mouth in cancer patients may lead to functional defects (e.g., eating, speaking, and swallowing), increase the risk of dental caries and oral candidiasis, and can have a negative effect on the nutritional and psychological status of the patients. The aim of this mini review was to summarize the current criteria for diagnosis and management of SGD associated with cancer treatment.

Nuclear and Radiological Emergencies: Biological Effects, Countermeasures and Biodosimetry

Atomic and radiological crises can be caused by accidents, military activities, terrorist assaults involving atomic installations, the explosion of nuclear devices, or the utilization of concealed radiation exposure devices. Direct damage is caused when radiation interacts directly with cellular components. Indirect effects are mainly caused by the generation of reactive oxygen species due to radiolysis of water molecules. Acute and persistent oxidative stress associates to radiation-induced biological damages. Biological impacts of atomic radiation exposure can be deterministic (in a period range a posteriori of the event and because of destructive tissue/organ harm) or stochastic (irregular, for example cell mutation related pathologies and heritable infections). Potential countermeasures according to a specific scenario require considering basic issues, e.g., the type of radiation, people directly affected and first responders, range of doses received and whether the exposure or contamination has affected the total body or is partial. This review focuses on available medical countermeasures (radioprotectors, radiomitigators, radionuclide scavengers), biodosimetry (biological and biophysical techniques that can be quantitatively correlated with the magnitude of the radiation dose received), and strategies to implement the response to an accidental radiation exposure. In the case of large-scale atomic or radiological events, the most ideal choice for triage, dose assessment and victim classification, is the utilization of global biodosimetry networks, in combination with the automation of strategies based on modular platforms.

Salivary Gland Function, Development and Regeneration

Salivary glands produce and secrete saliva, which is essential for maintaining oral health and overall health. Understanding both the unique structure and physiological function of salivary glands, as well as how they are affected by disease and injury will direct the development of therapy to repair and regenerate them. Significant recent advances, particularly in the OMICS field, increase our understanding of how salivary glands develop at the cellular, molecular and genetic levels; the signaling pathways involved, the dynamics of progenitor cell lineages in development, homeostasis and regeneration and the role of the extracellular matrix microenvironment. These provide a template for cell and gene therapies as well as bioengineering approaches to repair or regenerate salivary function.

Microalgae-based oral microcarriers for gut microbiota homeostasis and intestinal protection in cancer radiotherapy

Protecting the whole small intestine from radiation-induced intestinal injury during the radiotherapy of abdominal or pelvic solid tumors remains an unmet clinical need. Amifostine is a promising selective radioprotector for normal tissues. However, its oral application in intestinal radioprotection remains challenging. Herein, we use microalga Spirulina platensis as a microcarrier of Amifostine to construct an oral delivery system. The system shows comprehensive drug accumulation and effective radioprotection in the whole small intestine that is significantly superior to free drug and its enteric capsule, preventing the radiation-induced intestine injury and prolonging the survival without influencing the tumor regression. It also shows benefits on the gut microbiota homeostasis and long-term safety. Based on a readily available natural microcarrier, this work presents a convenient oral delivery system to achieve effective radioprotection for the whole small intestine, providing a competitive strategy with great clinical translation potential.

1-Isobutanoil-2-isopropylisothiourea Phosphate, T1082: A Safe and Effective Prevention of Radiotherapy Complications in Oncology

The radioprotective effects of a new 1-isobutanoil-2-isopropylisothiourea derivative named T1082 are presented. Research methods included toxic characteristics, radioprotective activity (Till–McCulloch’s test and 30-day survival test) in γ-ray total-body-irradiated mice, and a clinical and histological study of the effect of T1082 on acute radiation skin reactions (RSR) in rats after a single or fractionated β-ray local irradiation. T1082 is more effective than its analogue, the NOS inhibitor T1023, at low concentrations and doses (1/12–1/8 LD₁₀), both parenterally and intragastrically. In this case, its therapeutic index (LD₅₀/ED₅₀) reaches 30, and the optimal radioprotective doses (ED_84–98—141–224 mg/kg) are an order less than the maximum tolerated doses—1/16–1/10 LD₁₀. These properties allowed T1082, at a low intragastrical dose (160 mg/kg; 1/14 LD10), to significantly limit the severity of acute RSR after single (40 Gy) and fractionated (78 Gy) β-ray irradiation. The results confirm T1082 as one of the safest emergency radioprotectors and indicate the prospects for its further development as a pharmacological agent for the prevention of RT complications.