Enhance Radiation Therapy Research Articles

Results from the phase I dose-escalation study of the radiation enhancer NBTXR3 for the treatment of HCC and liver metastases.

319 Background: NBTXR3, a first-in-class radioenhancer composed of functionalized hafnium oxide nanoparticles, is administered by one time intratumoral injection (ITI) and activated by radiotherapy (RT), such as stereotactic body RT (SBRT). NBTXR3 increases RT energy deposit inside tumor cells and subsequently increases tumor cell death compared to RT alone, while sparing healthy tissues. SBRT is well-tolerated in hepatocellular carcinoma (HCC) or liver metastases (mets) and a valuable alternative for patients not eligible for surgery or radiofrequency ablation. However, energy dose deposit to tumor cells is limited due to potential toxicity to surrounding healthy tissues. Patients with unresectable liver cancers including patients with liver or renal dysfunction might benefit from NBTXR3. A Phase 1 clinical trial was conducted to evaluate the safety and Recommended Phase 2 Dose (RP2D) of NBTXR3 activated by SBRT [NCT02721056] in these patients, here we report the results. Methods: A 3+3 dose escalation scheme tested 5 NBTXR3 levels: 10, 15, 22, 33, and 42% of baseline tumor volume. NBTXR3 ITI was followed by SBRT (45 Gy / 3 fractions / 5-7 days or 50 Gy / 5 fractions / up to 15 days) in patients with HCC or liver mets. Primary endpoints included RP2D determination and early DLT incidence. Secondary endpoints include safety profile, liver disease scores evolution, and early efficacy by response rate (mRECIST for HCC/RECIST 1.1 for liver mets). Results: 23 patients were treated: 6 patients at 10% (2 SBRT doses tested due to organ constraints), 4 patients each at 15% and 22% (due to fiducial displacement and ITI shift), 3 patients at 33% and 6 patients at 42%. No early DLT was observed at any dose level. 1 SAE (grade 3 late onset bile duct stenosis) related to NBTXR3 and RT occurred at 22%. There were 11 AEs related to NBTXR3 and/or ITI, of which grade 3 AEs were: 2 abdominal pain (ITI related; 15%) and 1 late onset bile duct stenosis (22%), lesion close to the bile duct. No NBTXR3 or ITI related grade 4-5 AEs were observed. RT related AEs were as expected with SBRT. No clinically meaningful changes in Child-Pugh score or APRI were observed post-treatment. CT-scan showed NBTXR3 present within the tumor without leakage to surrounding healthy tissues. Best observed responses (MRI) in injected target lesions from HCC patients (n = 15) were 5 CRs (33.3%), 5 PRs(33.3%), 1 SD (6.7%), 2 NE (13.3%), 2 patients did not have post baseline MRI and for liver mets (n = 8) were 5 PRs (62.5%), 2 SD (25.0%) and 1 NE (12.5%). Conclusions: No early DLTs were observed and NBTXR3 demonstrated a good safety and tolerability profile. The RP2D was determined to be 42% of tumor volume. Initial efficacy is promising and highlights the potential for NBTXR3 to address an unmet medical need in patients with unresectable primary or metastatic liver cancers. Clinical trial information: NCT02721056.

Enhancement of nanoparticle-mediated double suicide gene expression driven by ‘E9-hTERT promoter’ switch in dedifferentiated thyroid cancer cells

ABSTRACT Differentiated thyroid cancer (DTC), such as papillary thyroid cancer, has a good prognosis after routine treatment. However, in the course of treatment, 5% to 20% of cases may dedifferentiate and can be transformed into dedifferentiated DTC (deDTC) or anaplastic thyroid cancer, leading to treatment failure. To date, several drugs have been used effectively for dedifferentiated thyroid cancer, whereas gene therapy may be a potential method. Literature reported that double suicide genes driven by human telomerase reverse transcriptase promoter (hTERTp) can specifically express in cancer cells and kill them. However, the weak activity of hTERTp limits its further research. To overcome this weakness, we constructed a novel chitosan nanocarrier containing double suicide genes driven by a ‘gene switch’ (a cascade of radiation enhancer E9 and a hTERTp). The vector was labeled with iodine-131 (131I). On one hand, E9 can significantly enhance the activity of hTERTp under the weak radiation of 131I, thereby increasing the expression of double suicide genes in deDTC cells. On the other hand, 131I also plays a certain killing role when it enters host cells. The proposed nanocarrier has good specificity for deDTC cells and thus deserves further study.

Biocompatible Iron–Boron Nanoparticles Designed for Neutron Capture Therapy Guided by Magnetic Resonance Imaging

The combination of multiple functions in a single nanoparticle (NP) represents a key advantage of nanomedicine compared to traditional medical approaches. This is well represented by radiotherapy in which the dose of ionizing radiation should be calibrated on sensitizers biodistribution. Ideally, this is possible when the drug acts both as radiation enhancer and imaging contrast agent. Here, an easy, one-step, laser-assisted synthetic procedure is used to generate iron-boron (Fe-B) NPs featuring the set of functions required to assist neutron capture therapy (NCT) with magnetic resonance imaging. The Fe-B NPs exceed by three orders of magnitude the payload of boron isotopes contained in clinical sensitizers. The Fe-B NPs have magnetic properties of interest also for magnetophoretic accumulation in tissues and magnetic hyperthermia to assist drug permeation in tissues. Besides, Fe-B NPs are biocompatible and undergo slow degradation in the lysosomal environment that facilitates in vivo clearance through the liver-spleen-kidneys pathway. Overall, the Fe-B NPs represent a new promising tool for future exploitation in magnetic resonance imaging-guided boron NCT at higher levels of efficacy and tolerability.

Improving Radiation Response in Glioblastoma Using ECO/siRNA Nanoparticles Targeting DNA Damage Repair.

Simple SummaryGlioblastoma (GBM) is the most common form of brain cancer and among the most lethal of human cancers. Radiation therapy is a mainstay in the standard of care for GBM, killing tumor cells by creating DNA damage. Inhibiting DNA damage repair (DDR) proteins enhances radiation therapy by not allowing tumor cells to repair the DNA damage caused by radiation. The aim of our study was to investigate whether the novel nanoparticle material, ECO, could be used to deliver small interfering RNA (siRNA) to GBM tumor cells and temporarily reduce the production of DDR proteins to improve radiation therapy outcomes. SiRNAs can be designed to target an innumerable number of genes and with the right delivery vehicle can be used in a variety of disease settings. Our work provides support for the use of the novel ECO material for delivery of siRNA in GBM.Radiation therapy is a mainstay in the standard of care for glioblastoma (GBM), thus inhibiting the DNA damage response (DDR) is a major strategy to improve radiation response and therapeutic outcomes. Small interfering RNA (siRNA) therapy holds immeasurable potential for the treatment of GBM, however delivery of the siRNA payload remains the largest obstacle for clinical implementation. Here we demonstrate the effectiveness of the novel nanomaterial, ECO (1-aminoethylimino[bis(N-oleoylcysteinylaminoethyl) propionamide]), to deliver siRNA targeting DDR proteins ataxia telangiectasia mutated and DNA-dependent protein kinase (DNApk-cs) for the radiosensitzation of GBM in vitro and in vivo. ECO nanoparticles (NPs) were shown to efficiently deliver siRNA and silence target protein expression in glioma (U251) and glioma stem cell lines (NSC11, GBMJ1). Importantly, ECO NPs displayed no cytotoxicity and minimal silencing of genes in normal astrocytes. Treatment with ECO/siRNA NPs and radiation resulted in the prolonged presence of γH2AX foci, indicators of DNA damage, and increased radiosensitivity in all tumor cell lines. In vivo, intratumoral injection of ECO/siDNApk-cs NPs with radiation resulted in a significant increase in survival compared with injection of NPs alone. These data suggest the ECO nanomaterial can effectively deliver siRNA to more selectively target and radiosensitize tumor cells to improve therapeutic outcomes in GBM.

Mechanisms for Tuning Engineered Nanomaterials to Enhance Radiation Therapy of Cancer.

Engineered nanomaterials that produce reactive oxygen species on exposure to X‐ and gamma‐rays used in radiation therapy offer promise of novel cancer treatment strategies. Similar to photodynamic therapy but suitable for large and deep tumors, this new approach where nanomaterials acting as sensitizing agents are combined with clinical radiation can be effective at well‐tolerated low radiation doses. Suitably engineered nanomaterials can enhance cancer radiotherapy by increasing the tumor selectivity and decreasing side effects. Additionally, the nanomaterial platform offers therapeutically valuable functionalities, including molecular targeting, drug/gene delivery, and adaptive responses to trigger drug release. The potential of such nanomaterials to be combined with radiotherapy is widely recognized. In order for further breakthroughs to be made, and to facilitate clinical translation, the applicable principles and fundamentals should be articulated. This review focuses on mechanisms underpinning rational nanomaterial design to enhance radiation therapy, the understanding of which will enable novel ways to optimize its therapeutic efficacy. A roadmap for designing nanomaterials with optimized anticancer performance is also shown and the potential clinical significance and future translation are discussed.

Conjugation of Polymer-Coated Gold Nanoparticles with Anti-EGFR Antibodies for Enhanced Radiation Therapy

Conjugation of Polymer-Coated Gold Nanoparticles with Anti-EGFR Antibodies for Enhanced Radiation Therapy

Ultrathin gold nanowires to enhance radiation therapy

BackgroundRadiation therapy is a main treatment option for cancer. Due to normal tissue toxicity, radiosensitizers are commonly used to enhance RT. In particular, heavy metal or high-Z materials, such as gold nanoparticles, have been investigated as radiosensitizers. So far, however, the related studies have been focused on spherical gold nanoparticles. In this study, we assessed the potential of ultra-thin gold nanowires as a radiosensitizer, which is the first time.MethodsGold nanowires were synthesized by the reduction of HAuCl4 in hexane. The as-synthesized gold nanowires were then coated with a layer of PEGylated phospholipid to be rendered soluble in water. Spherical gold nanoparticles coated with the same phospholipid were also synthesized as a comparison. Gold nanowires and gold nanospheres were first tested in solutions for their ability to enhance radical production under irradiation. They were then incubated with 4T1 cells to assess whether they could elevate cell oxidative stress under irradiation. Lastly, gold nanowires and gold nanoparticles were intratumorally injected into a 4T1 xenograft model, followed by irradiation applied to tumors (3 Gy/per day for three days). Tumor growth was monitored and compared.ResultsOur studies showed that gold nanowires are superior to gold nanospheres in enhancing radical production under X-ray radiation. In vitro analysis found that the presence of gold nanowires caused elevated lipid peroxidation and intracellular oxidative stress under radiation. When tested in vivo, gold nanowires plus irradiation led to better tumor suppression than gold nanospheres plus radiation. Moreover, gold nanowires were found to be gradually reduced to shorter nanowires by glutathione, which may benefit fractionated radiation.ConclusionOur studies suggest that gold nanowires are a promising type of radiosensitizer that can be safely injected into tumors to enhance radiotherapy. While the current study was conducted in a breast cancer model, the approach can be extended to the treatment of other cancer types.

Encapsulating doxorubicin in PEGylation metal-organic frameworks for combined radiation therapy in liver cancer treatment

It is well known that nanoscale metal-organic frameworks (NMOFs) have exhibited brilliant advantages in cancer diagnosis and treatment due to their structural diversity, high intrinsic biodegradability, and drug-loading capacities. Herein, based on our previous results, hypoxia was suppressed by inhibiting the expression of the CA IX protein, produced from Zr-MOF nanoparticles, and enhancing radiation therapy (RT) effectiveness. We designed a nanocomposite by encapsulating doxorubicin into Zr-MOF nanoparticles. It is a highly effective drug for chemotherapy and MOF that can absorb X-rays well, applied to enhance RT as the radiosensitizer. PEG is used for surface modification in the nanoparticles and to improve circulation time by intravenous administration. These nanoparticles could be applied for RT combing with chemotherapy in vitro and vivo, obtaining excellent anticancer efficacy. Most importantly, Zr-MOF@Dox demonstrates high clearance from HepG2 tumor cells, reducing the circulation of toxicity in vivo. Our research exhibits a new approach to establishing Zr-MOF@Dox as a biodegradable drug-carrier system, containing chemotherapy drugs and functional elements that totally perform the diagnosis and treatment roles of RT.

Photoacoustic imaging biomarkers for monitoring biophysical changes during nanobubble-mediated radiation treatment

The development of novel anticancer therapies warrants the parallel development of biomarkers that can quantify their effectiveness. Photoacoustic imaging has the potential to measure changes in tumor vasculature during treatment. Establishing the accuracy of imaging biomarkers requires direct comparisons with gold histological standards. In this work, we explore whether a new class of submicron, vascular disrupting, ultrasonically stimulated nanobubbles enhance radiation therapy. In vivo experiments were conducted on mice bearing prostate cancer tumors. Combined nanobubble plus radiation treatments were compared against conventional microbubbles and radiation alone (single 8 Gy fraction). Acoustic resolution photoacoustic imaging was used to monitor the effects of the treatments 2- and 24-hs post-administration. Histological examination provided metrics of tumor vascularity and tumoral cell death, both of which were compared to photoacoustic-derived biomarkers. Photoacoustic metrics of oxygen saturation reveal a 20 % decrease in oxygenation within 24 h post-treatment. The spectral slope metric could separate the response of the nanobubble treatments from the microbubble counterparts. This study shows that histopathological assessment correlated well with photoacoustic biomarkers of treatment response.

4440 Enhanced radiation therapy using chlorin-e6 conjugated gold nanoparticles

OBJECTIVES/GOALS: Development of gold nanoparticles covalently linked to a photosensitizer for use to enhance radiation therapy. The particles will be thoroughly characterized structurally and mechanistically. The gold particles should enhance radiation activity by closer proximity to the photosensitizer and by increasing particle accumulation in the tumor.METHODS/STUDY POPULATION: Gold nanoparticles were synthesized and coated with amine-terminated poly(ethylene) glycol, then covalently conjugated to chlorin e6, a known FDA-approved photosensitizer. The system was characterized using UV-Vis spectroscopy, transmission electron microscopy, and nanoparticle tracking analysis. The generation of reactive oxygen species was measured after X-irradiation. Enhanced cell killing was evaluated clonogenically in addition to assessment of in vivo efficacy and tumor pathology.RESULTS/ANTICIPATED RESULTS: Conjugation of the particle to the photosensitizer was achieved, and the molecule was detected by UV-Vis spectroscopy. TEM and NTA showed no aggregation of the particles, and an increase in reactive oxygen species generation was observed. The conjugates increased cell killing during radiation treatment, whereas neither the particle alone nor the photosensitizer significantly affected clonogenic survival at the same concentrations. Breast tumors grown in immunocompetent mice showed increased necrotic tissue after a single 20 gy treatment in the presence of the conjugate.DISCUSSION/SIGNIFICANCE OF IMPACT: Radiation therapy is widely used clinically, but dosage is limited largely to prevent injury to adjacent normal tissue. By increasing the local effect of radiation therapy, our gold conjugate has the potential to augment the effective radiation dose in the tumor, thereby reducing damage to healthy tissue and providing a more effective therapy.

Barium tungstate nanoparticles to enhance radiation therapy against cancer

High-Z nanoparticles have emerged as a novel type of radiosensitizers due to their relatively large X-ray cross-section and ability to enhance radical production under irradiation. Recently, CaWO4 nanoparticles have been prepared and their potential as a radiosensitizer has been demonstrated. Herein, we investigated BaWO4 nanoparticles as a novel type of alkaline-earth metal tungstate radiosensitizer for radiotherapy (RT). We synthesized BaWO4 nanoparticles using hydrothermal reaction and coated them with polyvinylpyrrolidone (PVP). We found that BaWO4 nanoparticles could more efficiently enhance hydroxyl radical production under irradiation than CaWO4 nanoparticles. When tested in vitro, BaWO4 nanoparticles showed lower toxicity than CaWO4 nanoparticles in the absence of irradiation, but induced more significant oxidative stress under irradiation. When tested in vivo, BaWO4 nanoparticles led to more efficient tumor inhibition without causing systemic toxicity. Overall, our results suggest that BaWO4 nanoparticles can efficiently enhance RT and hold great potential as a novel type of radiosensitizing agent.

Biomimetic Engineering of a Scavenger-Free Nitric Oxide-Generating/Delivering System to Enhance Radiation Therapy.

Nitric oxide (NO) is a potent tumor-cell radiosensitizer but it can be readily scavenged by hemoglobin (Hb) in vivo. A biomimetic incubator that can generate and deliver NO in a scavenger (Hb)-free environment to enhance its radiosensitizing effect to maximize its efficacy in radiotherapy is proposed. This NO incubator comprises a poly(lactic-co-glycolic acid) (PLGA) hollow microsphere (HM) that contains an NO donor (NONOate) and a surfactant molecule (sodium caprate, SC) in its aqueous core. In acidic tumorous environments, the PLGA shell of the HM allows the penetration of protons from the outside, activating the hydrolytic cleavage of NONOate, spontaneously generating NO bubbles, which are immediately trapped/stabilized by SC. The SC-stabilized NO bubbles in the HM are then squeezed through the spaces of its PLGA matrices by the elevated internal pressure. Upon leaving the HM, the entrapped NO molecules may passively diffuse through their SC-stabilized/protected layer gradually to the tumor site, having a long-lasting radiosensitizing effect and inhibiting tumor growth. The entire process of NO generation and delivery is conducted in a scavenger (Hb)-free environment, mimicking the development of young ovoviviparous fish inside their mothers' bodies in the absence of predators before birth.

Toll-Like Receptor Agonists and Radiation Therapy Combinations: An Untapped Opportunity to Induce Anticancer Immunity and Improve Tumor control

The premise that therapies targeting immune checkpoints can enhance radiation therapy (RT)-induced antitumor immunity is being explored rigorously in the preclinical setting, and early clinical trials testing this hypothesis are beginning to report. Although such approaches might prove efficacious in certain settings, it is likely that many tumor types, particularly those that have a deeply immune-suppressed microenvironment with little or no T cell infiltration, will require alternative approaches. Thus, there is now considerable drive to develop novel immune modulatory therapies that target other areas of the cancer immunity cycle. Toll-like receptors (TLRs) are expressed on sentinel immune cells and play a key role in the host defense against invading pathogens. Innate sensing via TLR-mediated detection of pathogen-derived molecular patterns can lead to maturation of antigen-presenting cells and downstream activation of adaptive immunity. After demonstrating promising efficacy in preclinical studies, drugs that stimulate TLR have been approved for use clinically, albeit to a limited extent. There is a growing body of preclinical evidence that novel agonists targeting TLR3, TLR7/8, or TLR9 in combination with RT might lead to enhanced antitumor immunity. Mechanistic studies have revealed that TLR agonists enhance dendritic cell-mediated T cell priming after RT, in some cases leading to the generation of systemic antitumor immunity and immune memory. In this report, we describe results from preclinical studies that advocate the strategy of combining RT with TLR agonists, discuss reported mechanisms of action, and explore the exciting opportunities of how this approach may be successfully translated into clinical practice.

Application of Mitochondrially Targeted Nanoconstructs to Neoadjuvant X-ray-Induced Photodynamic Therapy for Rectal Cancer.

In this work, we brought together two existing clinical techniques used in cancer treatment—X-ray radiation and photodynamic therapy (PDT), whose combination termed X-PDT uniquely allows PDT to be therapeutically effective in deep tissue. To this end, we developed mitochondrially targeted biodegradable polymer poly(lactic-co-glycolic acid) nanocarriers incorporating a photosensitizer verteporfin, ultrasmall (2–5 nm) gold nanoparticles as radiation enhancers, and triphenylphosphonium acting as the mitochondrial targeting moiety. The average size of the nanocarriers was about 160 nm. Upon X-ray radiation our nanocarriers generated cytotoxic amounts of singlet oxygen within the mitochondria, triggering the loss of membrane potential and mitochondria-related apoptosis of cancer cells. Our X-PDT strategy effectively controlled tumor growth with only a fraction of radiotherapy dose (4 Gy) and improved the survival rate of a mouse model bearing colorectal cancer cells. In vivo data indicate that our X-PDT treatment is cytoreductive, antiproliferative, and profibrotic. The nanocarriers induce radiosensitization effectively, which makes it possible to amplify the effects of radiation. A radiation dose of 4 Gy combined with our nanocarriers allows equivalent control of tumor growth as 12 Gy of radiation, but with greatly reduced radiation side effects (significant weight loss and resultant death).

CRISPRi-based radiation modifier screen identifies long non-coding RNA therapeutic targets in glioma

BackgroundLong non-coding RNAs (lncRNAs) exhibit highly cell type-specific expression and function, making this class of transcript attractive for targeted cancer therapy. However, the vast majority of lncRNAs have not been tested as potential therapeutic targets, particularly in the context of currently used cancer treatments. Malignant glioma is rapidly fatal, and ionizing radiation is part of the current standard-of-care used to slow tumor growth in both adult and pediatric patients.ResultsWe use CRISPR interference (CRISPRi) to screen 5689 lncRNA loci in human glioblastoma (GBM) cells, identifying 467 hits that modify cell growth in the presence of clinically relevant doses of fractionated radiation. Thirty-three of these lncRNA hits sensitize cells to radiation, and based on their expression in adult and pediatric gliomas, nine of these hits are prioritized as lncRNA Glioma Radiation Sensitizers (lncGRS). Knockdown of lncGRS-1, a primate-conserved, nuclear-enriched lncRNA, inhibits the growth and proliferation of primary adult and pediatric glioma cells, but not the viability of normal brain cells. Using human brain organoids comprised of mature neural cell types as a three-dimensional tissue substrate to model the invasive growth of glioma, we find that antisense oligonucleotides targeting lncGRS-1 selectively decrease tumor growth and sensitize glioma cells to radiation therapy.ConclusionsThese studies identify lncGRS-1 as a glioma-specific therapeutic target and establish a generalizable approach to rapidly identify novel therapeutic targets in the vast non-coding genome to enhance radiation therapy.

Dendrimer‐Based Nanosensitizers: Targeted Tumor Hypoxia Dual‐Mode CT/MR Imaging and Enhanced Radiation Therapy Using Dendrimer‐Based Nanosensitizers (Adv. Funct. Mater. 13/2020)

In article number 1909285, Yong Liu, Xiangyang Shi, and co-workers report hypoxia-targeted dendrimer-based nanodevices, which can be employed as a contrast agent for dual mode CT/MR imaging of hypoxic tumors. Moreover, under X-ray irradiation, the developed nanohybrids enable enhanced reactive oxygen species production, promote DNA damage, and prevent DNA repair, facilitating sensitized radiotherapy of hypoxic tumors in vivo.

Monte Carlo simulation of free radical production under keV photon irradiation of gold nanoparticle aqueous solution. Part I: Global primary chemical boost

The use of gold nanoparticles to enhance radiation therapy efficiency has been thoroughly investigated over the past two decades. While theoretical studies have mostly focused on physical mechanisms and dose enhancement, studies of free radical production are scarce. In this work, we investigated the primary yield of free radicals (O•H and H2O2) induced by 20–90 keV monoenergetic photons, for small GNPs concentrations. Our study is based on a Monte Carlo approach which enables electron transport down to low energy, both in water and in gold. We obtained, for a gold concentration of 1 mg⋅mL−1, an average chemical enhancement varying from 6 to 14%, depending mostly on the photon energy and, to a lesser extent, on the chemical species and size of the GNP. This enhancement is strongly correlated to the dose deposition enhancement, although not strictly proportional. While supporting the hypothesis that therapeutic efficiency of GNPs may not simply be explained by an overproduction of free radicals in the early stage, our simulation provides inputs for further macroscopic simulations, including cumulative track effects and potentially GNP chemical reactivity.

Targeted Tumor Hypoxia Dual‐Mode CT/MR Imaging and Enhanced Radiation Therapy Using Dendrimer‐Based Nanosensitizers

AbstractThe efficacy of radiation therapy (RT) is often limited by the poor response of hypoxia inside most solid tumors. The development of a theranostic nanoplatform for precision‐imaging‐guided sensitized RT for tumor hypoxia is still challenging. Herein, the creation of hypoxia‐targeted dendrimer‐entrapped gold nanoparticles complexed with gadolinium(III) (Gd‐Au DENPs‐Nit) for dual‐mode CT/MR imaging and sensitized RT of hypoxic tumors is reported. In this work, generation 5 poly(amidoamine) dendrimers are partially conjugated with Gd(III) chelator, entrapped with Au nanoparticles, and conjugated with hypoxia‐targeting agent nitroimidazole via a polyethylene glycol linker, and ending with chelation of Gd(III) and conversion of their leftover amine termini to acetamides. The designed dendrimer‐based nanohybrids with 3.2 nm Au cores exhibit an excellent X‐ray attenuation effect, acceptable r1 relaxivity (1.32 mM−1 s−1), and enhanced cellular uptake in hypoxic cancer cells, affording efficient dual‐mode CT/MR imaging of tumor hypoxia. Under X‐ray irradiation, the Gd‐Au DENPs‐Nit nanohybrids can produce reactive oxygen species, promote DNA damage, and prevent DNA repair, facilitating sensitized RT of hypoxic cancer cells in vitro and tumor hypoxia in vivo. The developed hypoxia‐targeted dendrimer‐based nanohybrids may be employed as both contrast agents and nanosensitizers for precision tumor hypoxia imaging and sensitized tumor RT.

Correction: A mitochondria-targeted nanoradiosensitizer activating reactive oxygen species burst for enhanced radiation therapy

Correction for ‘A mitochondria-targeted nanoradiosensitizer activating reactive oxygen species burst for enhanced radiation therapy’ by Na Li et al., Chem. Sci., 2018, 9, 3159–3164, DOI: 10.1039/C7SC04458E.

Whole-body MRI: a powerful alternative to bone scan for bone marrow staging without radiation and gadolinium enhancer.

Whole-body magnetic resonance imaging (WB-MRI) is a radiation-free alternative to the 99mTc-HDP bone scan (BS) for the detection of bone metastasis. The major drawback is the long examination time and application of gadolinium enhancer. The aim of this study is to analyze (i) the performance of WB-MRI versus the BS and (ii) the diagnostic benefit of gadolinium (WB-MRI + Gd) compared to a non-enhanced protocol (NE WB-MRI). 1256 eligible WB-MRI scans were analyzed retrospectively with a single inclusion criterion, a clinical 12-month follow-up or a biopsy as ground truth. N = 285 patients received both a WB-MRI and a BS within 12months. All the patients were imaged with a coronal T1w and a STIR, and n = 528 (42%) received an additional T1w-mDixon with gadoteridol (0.1mmol Gd-DTPA/kg). From 1256 eligible patients, n = 884 (70%) had breast cancer as a primary disease, n = 101(8%) prostate cancer, and n = 77(6%) lung cancer. The sensitivity (Se) and negative predictive value (NPV) of the WB-MRI was 98/99%, significantly higher compared to BS with 82/89%, P < 0.001 Mc Nemar's test. The specificity (Spe) and positive predictive value (PPV) of the WB-MRI and BS was 85/82% and 91/86%, respectively. The interobserver agreement between WB-MRI and BS was 71%, Cohen's kappa 0.42. Analysis of the added diagnostic value of gadolinium revealed Se/Spe/PPV/NPV of 98/93/92/98% for the NE WB-MRI and 99/93/85/100% for the WM-MRI + Gd, P > 0.05 binary logistic regression with Fischer's exact test. WB-MRI exceeds the sensitivity of BS without compromising the specificity, even after omitting the gadolinium enhancer.