Theranostic nanoparticles enhance the response of glioblastomas to radiation

Multimodal In Vivo Tracking of Chimeric Antigen Receptor T Cells in Preclinical Glioblastoma Models

OBJECTIVES

Iron oxide nanoparticles have been used to track the accumulation of chimeric antigen receptor (CAR) T cells with magnetic resonance imaging (MRI). However, the only nanoparticle available for clinical applications to date, ferumoxytol, has caused rare but severe anaphylactic reactions. MegaPro nanoparticles (MegaPro-NPs) provide an improved safety profile. We evaluated whether MegaPro-NPs can be applied for in vivo tracking of CAR T cells in a mouse model of glioblastoma multiforme.

MATERIALS AND METHODS

We labeled tumor-targeted CD70CAR (8R-70CAR) T cells and non-tumor-targeted controls with MegaPro-NPs, followed by inductively coupled plasma optical emission spectroscopy, Prussian blue staining, and cell viability assays. Next, we treated 42 NRG mice bearing U87-MG/eGFP-fLuc glioblastoma multiforme xenografts with MegaPro-NP-labeled/unlabeled CAR T cells or labeled untargeted T cells and performed serial MRI, magnetic particle imaging, and histology studies. The Kruskal-Wallis test was conducted to evaluate overall group differences, and the Mann-Whitney U test was applied to compare the pairs of groups.

RESULTS

MegaPro-NP-labeled CAR T cells demonstrated significantly increased iron uptake compared with unlabeled controls ( P < 0.01). Cell viability, activation, and exhaustion markers were not significantly different between the 2 groups ( P > 0.05). In vivo, tumor T2* relaxation times were significantly lower after treatment with MegaPro-NP-labeled CAR T cells compared with untargeted T cells ( P < 0.01). There is no significant difference in tumor growth inhibition between mice injected with labeled and unlabeled CAR T cells.

CONCLUSIONS

MegaPro-NPs can be used for in vivo tracking of CAR T cells. Because MegaPro-NPs recently completed phase II clinical trial investigation as an MRI contrast agent, MegaPro-NP is expected to be applied to track CAR T cells in cancer immunotherapy trials in the near future.

Nanomaterial-Based Antivascular Therapy in the Multimodal Treatment of Cancer

Abnormal tumor vasculature and a hypoxic tumor microenvironment (TME) limit the effectiveness of conventional cancer treatment. Recent studies have shown that antivascular strategies that focus on antagonizing the hypoxic TME and promoting vessel normalization effectively synergize to increase the antitumor efficacy of conventional therapeutic regimens. By integrating multiple therapeutic agents, well-designed nanomaterials exhibit great advantages in achieving higher drug delivery efficiency and can be used as multimodal therapy with reduced systemic toxicity. In this review, strategies for the nanomaterial-based administration of antivascular therapy combined with other common tumor treatments, including immunotherapy, chemotherapy, phototherapy, radiotherapy, and interventional therapy, are summarized. In particular, the administration of intravascular therapy and other therapies with the use of versatile nanodrugs is also described. This review provides a reference for the development of multifunctional nanotheranostic platforms for effective antivascular therapy in combined anticancer treatments.

IONPs-Based Medical Imaging in Cancer Care: Moving Beyond Traditional Diagnosis and Therapeutic Assessment

Cancer-related burden of morbidity and mortality is rapidly rising worldwide. Medical imaging plays an important role in every phase of cancer management, including diagnosis, staging, treatment planning and evaluation. Iron oxide nanoparticles (IONPs) could serve as contrast agents or labeling agents to enhance the identification and visualization of pathological tissues as well as target cells. Multimodal or multifunctional imaging can be easily acquired by modifying IONPs with other imaging agents or functional groups, allowing the accessibility of combined imaging techniques and providing more comprehensive information for cancer care. To date, IONPs-enhanced medical imaging has gained intensive application in early diagnosis, monitoring treatment as well as guiding radio-frequency ablation, sentinel lymph node dissection, radiotherapy and hyperthermia therapy. Besides, IONPs mediated imaging is also capable of promoting the development of anti-cancer nanomedicines through identifying patients potentially sensitive to nanotherapeutics. Based on versatile imaging modes and application fields, this review highlights and summarizes recent research advances of IONPs-based medical imaging in cancer management. Besides, currently existing challenges are also discussed to provide perspectives and advices for the future development of IONPs-based imaging in cancer management.

Tumor protease-activated theranostic nanoparticles for MRI-guided glioblastoma therapy

Rationale: As a cancer, Glioblastoma (GBM) is a highly lethal and difficult-to-treat. With the aim of improving therapies to GBM, we developed novel and target-specific theranostic nanoparticles (TNPs) that can be selectively cleaved by cathepsin B (Cat B) to release the potent toxin monomethyl auristatin E (MMAE). Methods: We synthesized TNPs composed of a ferumoxytol-based nanoparticle carrier and a peptide prodrug with a Cat-B-responsive linker and the tubulin inhibitor MMAE. We hypothesized that intratumoral Cat B can cleave our TNPs and release MMAE to kill GBM cells. The ferumoxytol core enables in vivo drug tracking with magnetic resonance imaging (MRI). We incubated U87-MG GBM cells with TNPs or ferumoxytol and evaluated the TNP content in the cells with transmission electron microscopy and Prussian blue staining. In addition, we stereotaxically implanted 6- to 8-week-old nude mice with U87-MG with U87-MG GBM cells that express a fusion protein of Green Fluorescence Protein and firefly Luciferase (U87-MG/GFP-fLuc). We then treated the animals with an intravenous dose of TNPs (25 mg/kg of ferumoxytol, 0.3 mg/kg of MMAE) or control. We also evaluated the combination of TNP treatment with radiation therapy. We performed MRI before and after TNP injection. We compared the results for tumor and normal brain tissue between the TNP and control groups. We also monitored tumor growth for a period of 21 days. Results: We successfully synthesized TNPs with a hydrodynamic size of 41 ± 5 nm and a zeta potential of 6 ± 3 mV. TNP-treated cells demonstrated a significantly higher iron content than ferumoxytol-treated cells (98 ± 1% vs. 3 ± 1% of cells were iron-positive, respectively). We also found significantly fewer live attached cells in the TNP-treated group (3.8 ± 2.0 px2) than in the ferumoxytol-treated group (80.0 ± 14.5 px2, p < 0001). In vivo MRI studies demonstrated a decline in the tumor signal after TNP (T2= 28 ms) but not control (T2= 32 ms) injections. When TNP injection was combined with radiation therapy, the tumor signals dropped further (T2 = 24 ms). The combination therapy of radiation therapy and TNPs extended the median survival from 14.5 days for the control group to 45 days for the combination therapy group. Conclusion: The new cleavable TNPs reported in this work accumulate in GBM, cause tumor cell death, and have synergistic effects with radiation therapy.

Screening MT1-MMP Activity and Inhibition in Three-Dimensional Tumor Spheroids

Membrane type 1 matrix metalloproteinase (MT1-MMP) has been shown to be crucial for tumor angiogenesis, invasion, and metastasis, and thus MT1-MMP is a high priority target for potential cancer therapies. To properly evaluate MT1-MMP inhibitors, a screening protocol is desired by which enzyme activity can be quantified in a tumor microenvironment-like model system. In the present study, we applied a fluorogenic, collagen model triple-helical substrate to quantify MT1-MMP activity for tumor spheroids embedded in a collagen hydrogel. The substrate was designed to be MT1-MMP selective and to possess fluorescent properties compatible with cell-based assays. The proteolysis of the substrate correlated to glioma spheroid invasion. In turn, the application of either small molecule or protein-based MMP inhibitors reduced proteolytic activity and glioma spheroid invasion. The presence of MT1-MMP in glioma spheroids was confirmed by western blotting. Thus, spheroid invasion was dependent on MT1-MMP activity, and inhibitors of MT1-MMP and invasion could be conveniently screened in a high-throughput format. The combination of the fluorogenic, triple-helical substrate, the three-dimensional tumor spheroids embedded in collagen, and Hit-Pick software resulted in an easily adaptable in vivo-like tumor microenvironment for rapidly processing inhibitor potential for anti-cancer use.

Metal-Based Nanostructured Therapeutic Strategies for Glioblastoma Treatment-An Update

Glioblastoma (GBM) is the most commonly diagnosed and most lethal primary malignant brain tumor in adults. Standard treatments are ineffective, and despite promising results obtained in early phases of experimental clinical trials, the prognosis of GBM remains unfavorable. Therefore, there is need for exploration and development of innovative methods that aim to establish new therapies or increase the effectiveness of existing therapies. One of the most exciting new strategies enabling combinatory treatment is the usage of nanocarriers loaded with chemotherapeutics and/or other anticancer compounds. Nanocarriers exhibit unique properties in antitumor therapy, as they allow highly efficient drug transport into cells and sustained intracellular accumulation of the delivered cargo. They can be infused into and are retained by GBM tumors, and potentially can bypass the blood-brain barrier. One of the most promising and extensively studied groups of nanostructured therapeutics are metal-based nanoparticles. These theranostic nanocarriers demonstrate relatively low toxicity, thus they might be applied for both diagnosis and therapy. In this article, we provide an update on metal-based nanostructured constructs in the treatment of GBM. We focus on the interaction of metal nanoparticles with various forms of electromagnetic radiation for use in photothermal, photodynamic, magnetic hyperthermia and ionizing radiation sensitization applications.

Reprogramming of Neutrophils as Non-canonical Antigen Presenting Cells by Radiotherapy-Radiodynamic Therapy to Facilitate Immune-Mediated Tumor Regression

Ineffective antigen cross-presentation in the tumor microenvironment compromises the generation of antitumor immune responses. Radiotherapy-radiodynamic therapy (RT-RDT) with nanoscale metal-organic frameworks (nMOFs) induces robust adaptive immune responses despite modest activation of canonical antigen presenting dendritic cells. Here, using transplantable and autochthonous murine tumor models, we demonstrate that RT-RDT induces antitumor immune responses via early neutrophil infiltration and reprogramming. Intravenous or intratumoral injection of nMOFs recruited peripheral CD11b⁺Ly6G⁺CD11c^- neutrophils into tumors. The activation of nMOFs by low-dose X-rays significantly increased the population of CD11b⁺Ly6G⁺CD11c⁺ hybrid neutrophils with upregulated expression of the co-stimulatory molecules CD80 and CD86 as well as major histocompatibility complex class II molecules. Thus, nMOF-enabled RT-RDT reshapes a favorable tumor microenvironment for antitumor immune responses by reprogramming tumor-infiltrating neutrophils to function as non-canonical antigen presenting cells for effective cross-presentation of tumor antigens.

Ferumoxytol-enhanced vascular suppression in magnetic resonance neurography

OBJECTIVE

To evaluate ferumoxytol-enhanced vascular suppression for visualizing branch nerves of the brachial plexus in magnetic resonance (MR) neurography.

MATERIALS AND METHODS

Signal simulations were performed to determine ferumoxytol's effect on nerve-, fat-, and blood-to-muscle contrast and to optimize pulse sequence parameters. Prospective, in vivo assessment included 10 subjects with chronic anemia who underwent a total of 19 (9 bilateral) pre- and post-infusion brachial plexus exams using three-dimensional (3D), T₂-weighted short-tau inversion recovery (T₂-STIR) sequences at 3.0 T. Two musculoskeletal radiologists qualitatively rated sequences for the degree of vascular suppression and brachial plexus branch nerve conspicuity. Nerve-to-muscle, -fat, and -vessel contrast ratios were measured.

RESULTS

Quantitative nerve/muscle and nerve/small vessel contrast ratios (CRs) increased with ferumoxytol (p < 0.05). Qualitative vascular suppression and suprascapular nerve visualization improved following ferumoxytol administration for both raters (p < .05). Pre- and post-ferumoxytol exams demonstrated moderate to near-perfect inter-rater agreement for nerve visualization and diagnostic confidence for the suprascapular and axillary nerves but poor to no agreement for the long thoracic nerve.

CONCLUSION

Ferumoxytol in T₂-weighted brachial plexus MR neurography provides robust vascular suppression and aids visualization of the suprascapular nerve in volunteers without neuropathy.

Glioblastoma multiforme (GBM): An overview of current therapies and mechanisms of resistance

Glioblastoma multiforme (GBM) is a WHO grade IV glioma and the most common malignant, primary brain tumor with a 5-year survival of 7.2%. Its highly infiltrative nature, genetic heterogeneity, and protection by the blood brain barrier (BBB) have posed great treatment challenges. The standard treatment for GBMs is surgical resection followed by chemoradiotherapy. The robust DNA repair and self-renewing capabilities of glioblastoma cells and glioma initiating cells (GICs), respectively, promote resistance against all current treatment modalities. Thus, durable GBM management will require the invention of innovative treatment strategies. In this review, we will describe biological and molecular targets for GBM therapy, the current status of pharmacologic therapy, prominent mechanisms of resistance, and new treatment approaches. To date, medical imaging is primarily used to determine the location, size and macroscopic morphology of GBM before, during, and after therapy. In the future, molecular and cellular imaging approaches will more dynamically monitor the expression of molecular targets and/or immune responses in the tumor, thereby enabling more immediate adaptation of tumor-tailored, targeted therapies.

Iron Oxide Nanoparticles as Theranostic Agents in Cancer Immunotherapy

Starting from the mid-1990s, several iron oxide nanoparticles (NPs) were developed as MRI contrast agents. Since their sizes fall in the tenths of a nanometer range, after i.v. injection these NPs are preferentially captured by the reticuloendothelial system of the liver. They have therefore been proposed as liver-specific contrast agents. Even though their unfavorable cost/benefit ratio has led to their withdrawal from the market, innovative applications have recently prompted a renewal of interest in these NPs. One important and innovative application is as diagnostic agents in cancer immunotherapy, thanks to their ability to track tumor-associated macrophages (TAMs) in vivo. It is worth noting that iron oxide NPs may also have a therapeutic role, given their ability to alter macrophage polarization. This review is devoted to the most recent advances in applications of iron oxide NPs in tumor diagnosis and therapy. The intrinsic therapeutic effect of these NPs on tumor growth, their capability to alter macrophage polarization and their diagnostic potential are examined. Innovative strategies for NP-based drug delivery in tumors (e.g., magnetic resonance targeting) will also be described. Finally, the review looks at their role as tracers for innovative, and very promising, imaging techniques (magnetic particle imaging-MPI).

Noninvasive Imaging of Cancer Immunotherapy

Immunotherapy has revolutionized the treatment of several malignancies. Notwithstanding the encouraging results, many patients do not respond to treatments. Evaluation of the efficacy of treatments is challenging and robust methods to predict the response to treatment are not yet available. The outcome of immunotherapy results from changes that treatment evokes in the tumor immune landscape. Therefore, a better understanding of the dynamics of immune cells that infiltrate into the tumor microenvironment may fundamentally help in addressing this challenge and provide tools to assess or even predict the response. Noninvasive imaging approaches, such as PET and SPECT that provide whole-body images are currently seen as the most promising tools that can shed light on the events happening in tumors in response to treatment. Such tools can provide critical information that can be used to make informed clinical decisions. Here, we review recent developments in the field of noninvasive cancer imaging with a focus on immunotherapeutics and nuclear imaging technologies and will discuss how the field can move forward to address the challenges that remain unresolved.

Clinical failure of nanoparticles in cancer: mimicking nature's solutions

The use of nanotechnology has become a promising approach in the treatment of cancer. However, most intravenously injected nanoparticles (NPs) do not effectively reach the tumor mass due to the biological barriers in the body. In an attempt to unify clinical criteria and basic research, we have collected the latest studies and described novel alternatives such as the use of NPs covered with cell membranes to increase NP delivery efficiency. Furthermore, we focus on the prospect of using the cell's natural messengers, exosomes, as vehicles to transport anti-cancer agents and we discuss the technical complications involved. Finally, we propose novel approaches to produce engineered exosomes which may overcome such technical limitations in order to achieve a proper anti-cancer nanotherapy.

Exploiting proteases for cancer theranostic through molecular imaging and drug delivery

The measurement of biological processes at a molecular and cellular level serves as a basis for molecular imaging. As compared with traditional imaging approaches, molecular imaging functions to probe molecular anomalies that are the basis of a disease rather than the evaluation of end results of these molecular changes. Proteases play central role in tumor invasion, angiogenesis and metastasis thus can be exploited as a target for imaging probes in early diagnosis and treatment of tumors. Molecular imaging of protease has undergone tremendous breakthroughs in the field of diagnosis. It allows the clinicians not only to see the tumor location but also provides an insight into the expression and activity of different types of markers associated with the tumor microenvironment. These imaging techniques are expected to have a huge impact on early cancer detection and personalized cancer treatment. Effective development of protease imaging probes with the highest in vivo biocompatibility, stability and most appropriate pharmacokinetics for clinical translation will upsurge the success level of early cancer detection and treatment.

Colchicine Alkaloids and Synthetic Analogues: Current Progress and Perspectives

Colchicine, the main alkaloid of Colchicum autumnale, is one of the most famous natural molecules. Although colchicine belongs to the oldest drugs (in use since 1500 BC), its pharmacological potential as a lead structure is not yet fully exploited. This review is devoted to the synthesis and structure-activity relationships (SAR) of colchicine alkaloids and their analogues with modified A, B, and C rings, as well as hybrid compounds derived from colchicinoids including prodrugs, conjugates, and delivery systems. The systematization of a vast amount of information presented to date will create a paradigm for future studies of colchicinoids for neoplastic and various other diseases.